Preparation Tool For Assessments/Exams: Click here where you can complete practice quizzes. The link is also here. Simply select the chapter out of the recommended text book, and proceed to the review questions etc. This will be a helpful preparation tool for your assessments.

Practical Exam: 90 seconds to answer 2 questions on a model skeleton. There will be a sticker on a particular part saying: ‘name this muscle’, ‘name it’s action’, ‘name an origin’. When it sais ‘name on action’ only put 1 down because if you write 2 and one is incorrect you get it all wrong.

https://www.getbodysmart.com/ap/muscularsystem

Topic 1. Introduction to Functional Human Anatomy

Week #1

Basic Functional Anatomy

Planes of Reference

Midsaggital (saggital) Plane:

Separating the body into left and right.

Think about how we move in yoga during sun salutations – very sagital plane dominent.

Coronal/Frontal Plane

Where abduction and adduction occur.

Think ‘grabbing a corona’ to the left and right

Transverse Plane

Separates top and bottom

Rotation

Directional Terms

E.G. The dorsal part of the hand is the back (darker side) because we must always consider that we’re referring to the body in the classic ‘anatomical’ position.

Ipsilateral: Same side of the body

E.G. The right arm is ipsilateral to the right leg, whereas the left arm is contralateral to the right leg.

Contralateral: Opposite side of the body

Practical implication: This becomes important when we discuss rotation of the trunk/neck, e.g. our external obliques does contralateral rotation  which mean’s the right external oblique is gonna rotate the body to the left.

Internal & External

Relative distance of a structure from the center of an organ.

Proximal & Distal Clarification

Proximal and distal mean’s ‘relative to something that’s attached’.

E.G. The knee is proximal to the foot because the knee is closer to the original attachment point (the hip) than what the foot is.

E.G.2 The foot is distal to the knee because it’s further away from the attachment point.

Terms Related to Movement

Body Cavities

Ventral (anterior) Body Cavities

Thoracic

Adominopelvic

Dorsal (posterior) Body Cavities

Cranial

Spinal

Organisation of Skeletal Muscle Fibers

Parallel Muscles: The fibers are running in the same direction (bicep)

Convergent Muscles: A wide base that converges on a tendon like a fan (pec major)

Pennate Muscles (contain more muscle fibers): Come in on an angle to a tendon.

Unipenate: coming in from ONE direction

Bipennate: Fibers coming in from TWO directions

Multipennate: Fibers coming in from multiple directions

Circular Muscles

Origins & Insertions

Origin: Is located at the fixed end of a muscle / It’s proximal and less moveable

Insertion: The movable end / It’s distal (further away from the attachment point) and most moveable

General Rule: The insertion moves towards the origin.

Muscle Contractions

Isometric: Muscle contracts/under tension while the limb’s don’t move/the join angle doesn’t change

Concentric: Muscle’s shorten under tension as the join angle usually get’s smaller

Eccentric: Muscle lengthens under tension (gravity or external load) as the joint angle usually get’s larger

Names of Skeletal Muscle

Fascicle Organisation:

Rectus = ‘straight’ e.g. rectus abdominis and rectus femoris muscle fibers run straight

Transverse = ‘running across the body’ e.g. transverse abdominis

Oblique = ‘running on an angle’ e.g. external oblique

Location:

Temporalis = ‘come’s off the temporal bone’ (side of the head)

Spinalis = ‘come’s off the spine’

Adominus = ‘belly region’

Relative position:

Superficialis & externus = superficial)

Profundus & internus = deep

Structure: Number of heads of origin, e.g. ‘bicep femoris’ has 2 heads which we can tell by the ‘bi’ portion, e.g. ‘tricep femoris’ has 3 heads which we can tell by the ‘tri’.

The name of the muscle can often reveal it’s join action. E.G. Flexor Digitorum will flex the fingers.

Size

Longus (long)

Magnus (big)

Major (bigger)

Maximus (biggest)

Minor (small)

Minimus (smallest)

Shape

Trapezius (trapezoid)

Deltoid (triangle)

Teres (long & round)

---

Topic 2. Bones Of The Axial Skeleton

Functions of the Skeletal System

Support (framework of the body)

Protection/Body Cavities

Movement

Storage (Minerals)

Blood Cell Formation (RBC)

Classifications of Bones

Long Bones: Humerus, femur, radius and ulna

Short Bones: Carpals/tarsal

Flat Bones: Cranium, sternum

Irregular Bones: Vertebrae

Sesamoid (formed within a tendon): Patella

Sutural: Cranium

Bony Landmarks

Articulating Surfaces:

Where a bone meet’s another bone.

Condyle: large round knob

Facet: flat articular surface

Head: prominent round head of a bone

Openings in a bone:

Foramen (a hole or opening in a bone)

Depressions:

Fossa: flat shallow surface (a depression in a bone where muscle often sits in)

Non-Articulating Surface:

Bony projections where muscles or ligaments attaches.

Epicondyle: projection adjacent to a condyle

Ramus: flat angular section of a bone

Trochanter: massive bony process found on the femur

Tubercle: small round bony process

Tuberosity: large, roughened process

The Axial Skeleton

Transmites the weight of our upper body into our pelvis and lower limbs.

Axial Components:

Forms the vertical axis of the body

Consists of 80 bones

Adjusts the positions of the head, neck & trunk

Performs respiratory motions

Stabilizers & positions the appendicular skeleton

Cranial Bones

Parietal x 2 (left and right) –Temporal x 2 –Frontal x1 (means there’s only one) –Occipital x 1 –Sphenoid x 1 –Ethmoid x 1

Parietal Bone

Lateral wall and roof of skull

Articulates (joins) with frontal, occipital, temporal & sphenoid bones

Should be able to identify important landmarks like the temporal line which is where the temporalis origin is which helps the jaw open and close.

Temporal Bone

Inferior lateral aspect of skull

Articulates with mandible, zygomatic, sphenoid, parietal & occipital bones

Important markings:

Zygomatic process (which is a projection towards the zygomatic bone)

Mandibular fossa (where the head of the mandible sits)

External auditory meatus (allows sound to travel through)

Styloid process (important muscles that support the larynx and the tongue insert off that)

Mastoid process (where the sternocleidomastoid connects)

Frontal Bone

Forehead and roof of orbits (eye sockets)

Articulates with parietal, sphenoid, ethmoid, nasal, lacrimal, zygomatic, and maxillary bones

Occipital Bone

Posterior aspect & base of skull

Articulates with parietal, temporal, sphenoid and atlas bones

Important markings:

External occipital protuberance

Foramen (hole/opening) magnum (large) where the spinal cord passes through

Occipital condyles (articulating surface) which meet’s with C1

Cranial Bones

Sphenoid Bone:

Keystone of skull

Forms part of base of skull

It unites the cranial bone to the facial bones and articulates with nearly every other bone in your skull

It’s also really important because it has an optic canal where the optic nerve runs through that transmits info from eye to the brain

Ethmoid Bone:

Most deeply situated bone of skull

Forms bony area between nasal cavity and orbits

Articulates with sphenoid and frontal bones

“The olfactory nerve has a close anatomical relationship with the ethmoid bone. Its numerous nerve fibres pass through the cribriform plate of the ethmoid bone to innervate the nasal cavity with the sense of smell.”

Facial Bones

Don’t need to know any landmarks just need to know if their paired or singular.

Nasal x 2 –Maxillae x 2 –Zygomatic (cheek bone) x 2 –Lacrimal x 2 –Palatine x 2 (back of the roof of the mouth) Vomer x 1 –Mandible x 1

Hyoid

U-shaped

Suspended from the temporal bones by ligaments & muscles and doesn’t articulate with any other bone.

Supports the tongue

Attachment site for infrahyoid & suprahyoid musculature

The Vertebral Column

C7 / T12 / L5 / S5 (5 fused vertebrae) / C4 (1-4 fused depending on the person)

Spinal Curves:

Primary & Secondary

Increase strength, help maintain balance in an upright position, absorb shock, protect vertebrae from fracture

Babies develop their spine shape and concave curves as they start crawling and gain the ability to support their head

Characteristics of a Typical Vertebrae

The spinous process is the projection ‘bumpy part’ you feel running your hand down a spine. Many ligaments and muscles attach from the spinous processes.

Where the superior articular facet connects with the inferior articular process is where movement of the spine orginates.

The spinal nerves pass through the interveterbral foramen. Nerve impingement from sciatica pain usually occur within the interveterbral foramen.

A disc actually doesn’t “slip”, instead you get a protrusion of a disc into where the spinal nerves are sitting which can “pinch” the nerve.

There are 2 vertebrae that are a-typical: C1 (atlas) & C2 (axis)

C1 doesn’t have a body or a spinous process.

C2 has a feature called a ‘dens’ which gives a pivot point for C1 to rotate around which is why it’s called axis – this is what helps the head rotate.

How would you distinguish the difference between a cervical, lumbar and thoracic vertebrae?

Cervical vertabrae have holes (foremens) in their transverse process which you don’t find in other areas.

Lumbar are easier to distinguish because they are the largest, typically their spinous process is projecting posterialy straight out the back of the vertabrae.

Whereas the thoracic vertebrae have spinous processes that project downwards.

The sacrum meets the pelvis at the sacroiliac joint where the majority of the weight is transferred from the upper body to lower body.

Bony Thorax

The ribs and sternum. Role is to protect vital organs.

Thorax:

Manibrium

Body

Xiphiod process

24 ribs in total: True ribs (first 7) which all have there own cartilage that connects to the sternum

False ribs (8-10) all join 7’s costal cartilage – that’ why their called false ribs, because they don’t have their own seperate costal cartlige.

Floating ribs (11-12) they are still classified as false ribs, but they don’t have any bony attachments anteriorly.

---

Topic 3. Muscles Moving the Axial Skeleton (Neck & Trunk)

Week #2

Prac exam: You will be asked to identify things like lateral flexsion of the neck and trunk. Make sure you don’t just state what movement it is but what direction – whether it’s moving to the left or right.

Muscle of the Neck

Anterior Neck

Sternocleidomastoid (SCM)

Originates from the manubrium/medial clavicle inserting to the mastoid process.

Flexion of cervical spine

Contralateral (opposite side of the body) rotation. If I’m rotating to the left the right SCM is on.

Ipsilateral (same side) lateral  flexion. So as you bring your neck down to your ear on the right side it’s the right SCM that activates.

Posterior Neck

Splenius Muscles (cervicis, capitis)

Cervicis – originates from spinous process of T3-T6 inserting at transverse process of C1-C3

Capitis – originates from spinous process C7, T1-T4 inserting at mastoid process and occipital bone

Don’t need to know specific origin and insertion but know where the muscles are.

Cervical extension

Ipsilateral rotation & lateral flexion

Anterolateral Abdominal Wall

Muscle of the Trunk

Structure: Bilaterally paired muscles in the anterolateral abdominal wall

3 flat muscles

External oblique

Internal oblique

Transverse abdominis (TVA)

1 vertical muscles

Rectus Abdominis

External Oblique

Most superficial of the three lateral muscles

Originates from the ribs and inserts at the pelvis & abdominal aponeurosisto the lineaalba (connective tissue that is often torn during child birth)

Compresses (flexsion) of the abdomen.

Exception to the rule where the origin actually moves towards the insertion instead of the usual other way around.

Laterally flexes the vertebral column

Contralateral rotator of the trunk because it inserts at pelvis and originates off the ribs

Internal Oblique

Middle layer of the three lateral abdominal muscles

Posterior fibres pass from the anterior trunk to the lumbar spine

Compresses the abdomen & stabilises the spine

Ipsilateral rotator of the trunk because it inserts at the ribs and originates off the pelvis

Transverse Abdominus

Deepest of the three lateral abdominal muscles

Passes from the anterior trunk to the lumbar spine

Compresses the abdomen & stabilises the spine

TVA becomes active prior to limb movement

Co-contract with Multifidis

Rectus Abdominis(RA)

Originates from the pelvis and inserts to the ribs & sternum

RA & lateral fibers of the EO prime movers of trunk flexion (predominantly sagittal plane movements)

Mobilisers

Better set up for rapid ballistic movements

Posterior Trunk Muscles

fQuadratus Lumborum

Posterior abdominal wall

Forms an important part of the corset

Originates from the iliac crest of the pelvis and inserts to the 12th rib & lumbar (L1-L4) vertebrae

Actions include ipsilateral lateral flexion and extension of the lumbar spine

Erector Spinae muscles

3 muscles together: iliocostalis, longissimus & spinalis muscles

Originate from iliac crest & sacrum to insertion points up to C2

Main action is trunk and neck extension because the fibers run vertical

Lumbar Multifidis

Covers a small number of spinal segments

Helps to stiffen and stabilise the spine prior to limb movement

Co-contraction with TVA

It’s an extensor because it’s located on the posterior chain

Nerve Supply

Because erector spinae and multifidus run all the way up the spine they get nervy supply from pretty much every area their next to.

Measuring Core Stability

Pressure Biofeedback Unit (blood pressure cuff) / Real-time US / Single leg stance (trendelenburgsign) / Single leg squat

Posterior Sling

This chain that allows us to transfer power from the lower to upper limb and vice versa.

---

Topic 4. Bones Of The Appendicular Skeleton (Upper Limbs)

Pectoral (Shoulder) Girdle

Connects the upper limb to the axial skeleton.

Includes: Clavicle & Scapula

Role: Position the shoulder join, Help move the upper limb  & Provide a base for muscle attachment

Where the sternum meets the clavicle is the only bony attachment site – which is why a fractured clavicle is common when people land on their outstretched arm, because that’s where the force transmutes to.

Claivicle

Articulation points: Where a bone meets another bone.

Acromial end (connects to the scapula is more thin and flat)

Sternal end (the knobby thicker end)

Identify which end is the acromial end and which is the sternal end.

Scapula

Articulation points

Acromion: where the acromial end of the clavicle meets the acromion

Glenoid fossa: the ball and socket joint of the humerus

Multiple muscle attachment sites

Humerus

Articulation points:

Head, Capitulum, Trochlea

Important muscle attachment sites:

Greater & lesser tubercles, Deltoid tuberosity

Lateral Epicondyle (Capitulum) articulates with the radius

Medial Epicondyle (Trochlea) articulates with the ulna

Why do we feel that sensation when we hit our “funny bone”: the ulna nerves wraps around the medial epicondyle, the ulna nerve is quite superficial which is why its so easy to knock the nerve.

Ulna

When looking from anatomical position the ulna is medial (pinky side). When in a pronated position the ulna is lateral.

Articulation points

Olecranon

Coronoid process

Trochlear notch: where the trochlera sits

Radial notch: where the radius sits

Radius

When looking from anatomical position the radius is lateral (thumb side). When in a pronated position the radius is medial.

Articulation points

Head

Ulna notch

Articulation for scaphoid & lunate

Important muscle attachment site:

Radial tuberosity: where the bicep brachii inserts

Carpals (Wrist)

Proximal row: Scaphoid – Lunate -Triquetrum – Pisiform (SLTP)

Distal row: Trapezium (is at the base of the thumb) – Trapezoid – Capitate – Hamate (TTCH)

Sally (Scaphoid) Left (Lunate) The (Triquetrum) Party (Pisiform) To (Trapezium) Take (Trapezoid) Charlie (Capitate) Home (Hamate)

Some lovers try positions that they can’t handle

Metacarpals (Hand) / Phalanges (Fingers)

Each finger has 3 phalanges except the thumb which has 2

Topic 5. Joint Structure & Function

Week #3

Joints

Articulations:

Where bones meet, hold bones together, various degrees of skeletal movement

Generally the more stable a joint the less stability it has and the less stable a joint is the more mobile it is.

Nice practical application

The shoulder joint relies on dynamic stability; the attaching muscles and ligaments to stabilise the joint and keep it in place. Whereas the hip joint  has a lot of static stability because the nature of the hip sockets depth and sturdiness.

Joint Classification

Structural Classification:

Fibrous (synarthrosis)

Cartilaginous (amphiarthrosis)

Synovial (all diarthrosis)

Functional Classification:

Relates to how much movement will occur at the joint.

Synarthrosis (joined together), Amphiarthrosis (slightly moveable), Diarthrosis (two, freely moveable)

Fibrous Joints

Fibrous joints are connected by dense connective tissue consisting mainly of collagen. These joints are also called fixed or immovable joints because they do not move. Fibrous joints have no joint cavity and are connected via fibrous connective tissue.

3 Types of Fibrous Joints:

1. Sutures (seam)

Thin layer of dense fibrous connective tissue

Only unites bones of the skull

Their interlocking edges add strength, thus reducing fractures

Functional classification: Immoveable (synarthroses)

2. Syndesmoses (fastening)

Location: between radius and ulna and tibia and fibula to prevent seperation of the two bones

Articulating bones are united either by a ligament or Interosseousmembrane

Anterior tibiofibularligament

Interosseousmembrane of the forearm

Functional classification: Slightly moveable (amphiarthroses)

3. Gomphoses (bolt)

Cone shaped peg fits into a socket

Articulations of the roots of the teeth are an example

Functional classification: Immoveable (synarthroses)

Cartilaginous Joints

2 Types of Cartilaginous Joints:

1. Synchondroses

Joined by hyaline cartilage between 2 bones

Epiphyseal growth plate is made from hyaline cartilage

Immoveable (synarthroses)

2. Symphyses (pelvis)

Articulating bones are united by either hyaline cartilage or fibrocartilage

Useful for shock absorbing

Slightly moveable (amphiarthroses)

Synovial Joints

All diarthrosis (freely moveable)

Structure of Synovial Joints

Articular Capsule comprises of:

Fibrous Capsule

Surrounds and encloses the joint

Continuation of the periosteum

Lined with synovial membrane which produces & secretes synovial fluid for joint lubrication

Synovial Membrane

Lines the inside of the capsule

Produces the synovial fluid which acts as a lubricant inside the joint capsule

Joint Cavity

Is a space between where the two bones meet which contains synovial fluid. Both cartilaginous and fibrous joints don’t have this joint cavity space.

Articular Cartilage (hyaline cartilage)

People with OA (osteoarthritis) damage the articular cartilage causing the joint space to narrow where you begin to get bone against bone instead of cartilage against it.

The problem with articular cartilage is that it’s avascular so it doesn’t get any blood supply and aneural so it doesn’t have nerve supply. So after damaging the cartilage it can’t repair itself unless you get something like stem cell treatment.

Covers the surface of articulating bones

Shock absorption

Reduces friction

Aneural & Avascular

Poor healing capacity

Ligaments

Thickenings in the fibrous capsule to make it stronger/reinforce the joint

Control & limit excessive joint movements

Occasionally intra-articular ligaments found in some joints

Accessory Structures

Articular discs / menisci

Fibrocartilage pads are shock absorbers that distribute force across a larger surface area

Bursae

Found around most synovial joints

Fluid filled sacs that reduce friction

Fat pad

Packing material & Protect the joint

Tendon Sheaths

Common in places where’s there’s lots of tendons (hands and feet)

Tendon sheaths are filled with synovial fluid

Reduce friction in joints

Wrap around tendons

Factors Influencing Joint Stability

Joint Congruency: how well two bones come together. A joint that doesn’t have high congruency is usually unstable (shoulder). A joint like this is highly reliant on strong and fluid motor control of the surrounding limbs/muscles.

Shape & fit of the articular surfaces

Ligaments prevent undesirable movements & help to direct joint movement

Tone of the muscles whose tendons cross a joint

Importance of regaining muscle tone & strength post injury

Synovial Joints

Classified according to structural category (movement)

Uniaxial: Moves in one direction (elbow)

Biaxial: Allow movement on two planes (wrist)

Multiaxial: Moves in multiple planes (knee)

Planar Joints:

Uniaxial –least mobile

Articulating bones are flat or slightly curved

Found in the intercarpal & intertarsal joints

Hinge Joints:

Uniaxial

Convex surface of one bone fits with a concave surface of another bone

Elbow, knee & Interphalangeal joints

Pivot Joints:

Rounded or pointed surface of one bone articulates with a ring formed by another bone & ligament

Uniaxial

Proximal Radioulnar Joint that is responsible for rotation of the ulna/radius

Condyloid (ellipsoidal) Joints:

Convex oval shaped projection of one bone fits into the oval shaped depression of another bone

Biaxial (the main difference between a ball and socket and condyloid is that ball & socket is multiaxial whereas condyloid is biaxial).

RadiocarpalJoint (wrist joint)

Saddle:

Modified CondyloidJoint

Biaxial

Carpometacarpal joint of thumb. This joint enables ‘opposition’ movement so we can grasp things.

Ball-and-Socket joint

Multiaxial

Hip & shoulder

---

Topic 6. Joints of the Upper Limb 1: Shoulder Girdle

Week #3

Know the ligament that support the area, be able to identify and know it’s joint actions.

Pectoral/Shoulder Girdle

Comprised of the Clavicle & Scapula

Part of the appendicular skeleton

Attaches the upper limb to the axial skeleton where the sternum attaches to the clavicle

Positions the humorous it can move correctly

Sternoclavicular Joint

Provides the only bony point of connection between the pectoral girdle, upper limb and the trunk/axial skeleton

Articulations of the Sternoclavicularjoint

Enlarged medialend of the clavicle articulates in the shallow socket formed by the manubrium & 1st costalcartilage

The claviculararticular surface tends to be larger than that on the sternum

Thus, the medial end of the clavicle projects above the upper margin of the manubrium sterni, creating poor congruency (how well the two bones come together)

Congruency is helped and provided by an intra-articular fibrocartilaginousdisc which helps increase the contact area between the two bones which results in more stability.

Articular Surfaces

The strong fibrocartilage disc separates the articular surfaces acts as a shock absorber

Is firmly attached to the joint capsule

Holds the medial end of the clavicle against the sternum

Prevents medial displacement –Helps to absorb shock waves transmitted along the clavicle

Ligaments of the SternoclavicularJoint

Strength of the SC joint is dependant on ligamentous support

Anterior & Posterior Sternoclavicular Ligaments

The anterior ligament prevents the clavicle from moving forward and the posterior one prevents the clavicle from moving backwards

Reinforces the joint capsule stability anteriorly & posteriorly

Passes from the clavicle to sternum anteriorly and posteriorly

Interclavicular Ligament

Runs between the two clavicles.

Strengthens the capsule superiorly to stop the clavicle moving upwards

Extends from the sternal end of one clavicle to the other

In between it attaches to the superior border of the manubrium

Costoclavicular Ligament

Runs from the costal cartilage (joins the ribs to the sternum)

Anchors the inferior surface of the sternal end of the clavicle to the 1st rib

Primary restraint for elevation of the pectoral girdle

Joint Stability

Stability is primarily dependant upon the strength & integrity of its ligaments, particularly the Costoclavicular ligament

Movements

Elevation / Depression

When we take our arm overhead the distal end of the clavicle is elevating relative to where the manubrium is.

Protraction / Retraction

The distal end of the clavicle moving relative to the SCJ (sternoclavicular joint) / whether your shoulder is moving forward or backward

Axial Rotation

Passive movement (i.e., no muscle involvement)

Produced by scapular rotation

When our scapula internally or externally rotates our clavicle rotates with it.

Acromioclavicular Joint (AC)

Gross Structure

Where the clavicle meets the acromium of the scapula

Plane type of synovial joint

Not to be confused with the glenohumeral joint

Located between the lateral end of the clavicle & the acromion of the scapula

Clavicle tends to override & project over acromion

Articular Surfaces

Acromial end of clavicle articulates with the acromion of the scapula

Articular surfaces are covered with fibrocartilage

An incomplete wedge-shaped articular disc separates the articular surfaces, thus adding some congruency to the joint

Joint Capsule

Is quite weak and loose, however it’s strengthened superiorly by the trapezius and acromioclavicular ligament therefore it’s going to rely my on ligament stability predomintly and some muscles that cross over the joint.

The fibrous capsule attaches to the margins of the articular surfaces

A synovial membrane lines the fibrous layer

3 Ligaments of the AC Joint

Joint is stabilized by 3 ligaments

1. Acromioclavicular Ligament

Fibrous band that extends from the acromion to the clavicle

Strengthens joint superiorly

Thickening of the joint capsule

2. Coracoclavicular Ligament

This joint gives stability

Strong pair of fibrous bands called the conoid (medial) ligament and the trapezoid (lateral) ligament that unite the Coracoid process of the scapula to the clavicle

You don’t need to be able to distinguish which one is which.

The 2 parts of this ligament are set so as to restrain opposite movements of the scapula with respect to the clavicle

The conoid ligament limits forward movement of the scapula

The trapezoid ligament limits backward movement

3. Coracoacromial Ligament

Runs from caracoid process to the acromium.

It actually does NOT help join the clavicle to the acromium at all and does NOT help stabalise the AC joint because its not joining the clavicle to the acromium.

Stability

Is essentially provided by the Coracoclavicular ligament

Upper fibres of the trapezius and deltoid will provide some dynamic stability in a healthy injury free AC joint

However, both muscles can create further damage to the AC joint during periods of injury if the muscles are contracting because they where their attachment points are.

Movements of the AC Joint

The acromion of the scapula rotates on the acromial end of the clavicle

These movements are associated with motions of the scapulothoracic joint

Anterior / posterior gliding of the acromion relative to the clavicle (e.g. protraction/retraction of shoulder blade)

Superior / inferior migration of the acromion when you elevate and depress your shoulders

Tilting (Anterior/Posterior)

Note: There are no direct muscles that move the AC joint. The axioappendicular muscles that attach and move the scapula cause the acromion to move on the clavicle

AC Joint Pathology

G1: Torn some fibers / G2: Ruptured ligament but the coracoclavicular ligament is still in tact so the clavicle wont ride up / G3: Complete rupture which is when the clavicle rides up

Scapulothoracic Biomechanics

Ability of the scapula to glide & upwardly and downwardly rotate relative to the posterior aspect of the rib cage

Practical Application:

Out of the 180 degrees of abduction our shoulder joint gets: 120 comes from the GH joint and 60 degrees comes from the scapula movement. (2:1 ratio). So if the scapula isn’t movement correctly your shoulder ROM will be limited.

Along with the Acromioclavicular & Sternoclavicular joints, scapulothoracic gliding enables the glenoid fossa to follow the head of the humerus

Helps to maintain maximum contact between the articular surfaces of the true shoulder joint

Muscles Controlling Scapular Upward/Downward Rotation

The below muscles origins are on the axial skeleton and their insertions are on the scapula. Therefore if insertions on the scapula this means those muscles are going to move the scapula because their always moving insertion relative to the origin.

Trapezius (all 3 portions)

Serratus anterior (upper & lower portions)

Rhomboids

Levator scapulae

Pectoralis minor to a lesser extent

Vital component of normal shoulder joint function

Practical Application:

If a back muscle is above the scapula it’s typically going to move the scapula upwards (elevation). If it’s origin is medial to the scapula it’s going to retract the scapula towards the midline. If it’s origin is inferior to the scapula it’s going to depress the scapula. 

---

Topic 7. Muscles Moving the Shoulder Girdle (Scapula)

Week #4

Upward rotators obviously rotate our scapula up, but when we come down it’s still our upward rotators working eccentrically to control that downward rotations as the muscle lengthens (so it’s not our downward rotators responsible for the joint action).

Axioscapular & Axioclavicular Muscles

Axioscapular/Clavicular Muscles

Axioscapular means the muscle attaches to the axial skeleton as well as the scapula

Position the scapula and clavicle by moving the Sternoclavicular and Scapulothoracic joints

Muscles involved work as a group to hold the scapula stable as it moves on the thorax

Muscles Include

Trapezius (force couple, force in opposing direction) – Serratus Anterior – Levator Scapulae – Rhomboids Major & Minor – Pectoralis Minor

Trapezius

Large muscle which can be separated according to fibres (sections)

Origin: Occipital bone, ligamentum nuchae, spinous process C7-T12

Insertion: clavicle, acromion, spine of scapula

Actions: Upper fibres (Upper trap): Elevation & upward rotation / Middle fibres (middle trap): Retraction (adduction), elevation / Lower fibres (lower trap): Depression

If a muscle is ABOVE the scapula it’s going to upwardly rotate/elevate.

If a muscle sits medial to the scapula it will retract it.

If a muscle is below the scapula it will depress/downardlly rotate.

If a muscle is more anterior to the scapula it will protract it.

Serratus Anterior

Is important role in scapulothoracic stability and keeping the medial border of the scapula flat on the thoracic cage (back). Which is a really important mechanical function to not allow scapula winging, which is when the medial border come up.

Origin: anterior margin ribs 1-9

Insertion: medial border of scapula

Action: Protraction (abduction) & upward rotation

 

Levator Scapulae

Common site for neck discomfort. People who sit a lot at a desk usually get tight levator scapulae’s – their scapula might be slightly elevated which shortens the LS and tightens it.

Origin: Transverse process C1-C4

Insertion: Superior medial border of scapula

Action: Elevation, downward rotation

Rhomboids

Deep to trapezius

Origin: Spinous process C7-T5

Insertion: Medial border of scapula

Action: Retraction (adduction), downward rotation, elevation

Pectoralis Minor

Can become tight with activities in front of the body (upper cross sydrome) / Sits deep compared to pec major

Origin: Anterior surface ribs 3-5

 Insertion: Coracoid process

Action: Protraction (abduction), downward rotation, assists in depression

Sumamary

Joint Actions Summary

Superior rotators = upward rotation / inferior rotators = downard rotation.

Scapulothoracic Posture

Scapulohumeral Rhythm

Synchronous scapula and humeral movement – 2:1 ratio = when we take our arm overhead we get 180 degrees of flexsion (abduction) = 120 degrees is coming from the glenohumeral joint and 60 is coming from the scapula. Practical Implication: People who can’t raise their arms full above their head.

If you don’t have healthy shoulder mechanics (rotator cuff and scapula rhythm) you can decrease the subacromial space and end up impinging the soft tissue against the bone causing inflammation and/or burisits.

 

 

---

Topic 8. Joints of the Upper Limb: Glenohumeral Joint

Week #4

Glenohumeral Joint

Where the glenoid cavity meets the humerus.

True Shoulder

Allows a wide range of movement

Mobility is gained at the expense of stability. The GH joint is most at risk in abduction and externally rotated positions (single arm throwing)

Agonists (prime-movers) of the shoulder are able to generate large forces

Counterbalanced by smaller less powerful stabilisers

 Articulations of the Glenohumeral Joint

Articular surfaces

Poorly matched (poor congruency)

Glenoid cavity accepts little more than 1/3rd of the large humeral head which is one reason why it’s not a very stable joint but quite mobile

Glenoid Labrum

A ring of fibrocartilage that wraps around the glenoid cavity to help deepen the socket – so it creates more contact between the humeral head and the glenoid

Slightly deepens & enlarges the Glenoid fossa

Helps decrease stress (force/area) on the glenoid fossa (the more contact area the less stress when force is being applied)

Also is the fibrous attachment of the glenohumeral ligaments and capsule to the glenoid rim

Articular Capsule of the GHJ

Joint Capsule

The loose capsule is attached proximally to the labrum and glenoid rim

Distally it attaches to the articular margins of the head of humerus

Posteriorly and inferiorly, the capsular insertion is directly onto the labrum

Inferioraly the capsule is quite loose/lax which decreases it’s stability but also helps increase its mobility enabling us to life our arm up.

Superiorly, the capsule is attached to the glenoid rim at the base of the labrum, and includes the origin of long head of biceps tendon

The capsule is reinforced by the tendons of the rotator cuff, and the tendon of long head of triceps below

Ligamentous Support of the GHJ

Ligaments of the Joint Capsule

Strengthened on its anterior surface by 3 capsular ligaments

Superior, Middle & Inferior Glenohumeral ligaments

Joint stability is largely maintained by the 4 rotator cuff muscles

Superior Glenohumeral Ligament (SGL)

Smallest of the glenohumeral capsular structures

It arises from the upper part of the glenoid margin and labrum

It inserts just superior to the lesser tuberosity in the region of the bicipital groove

Functions:

Contributes to superior stabilization

SGL Prevents posterior and inferior translation of the humeral head

SGL represents the primary capsuloligamentousrestraint to inferior translation of the unloaded, abducted shoulder joint

Middle Glenohumeral Ligament (MGL)

It arises inferior to the SGL

Attaches to the humerus on the front of the lesser tubercle inferior to the insertion of subscapularis

Functions:

Stabilizes the shoulder joint from 0º to 45º of abduction

In the lower and mid-ranges of abduction, it limits external rotation

Limits inferior translation when the shoulder is abducted and externally rotated (throwing)

Inferior Glenohumeral Ligament (IGL)

Arises from the margin of the glenoid fossa and the anterior border of the glenoid labrum

It descends obliquely to attach to the anatomical neck of the humerus

Functions:

Is lax in adduction

Tightens with increasing abduction

IGL is the primary restraint for anterior and posterior dislocations at 90º of abduction

Stability of the GHJ

Dynamic Stability

Shoulder joint stability is largely maintained by the rotator cuff muscles. They’re really important for keeping the humerus centered in the glenoid cavity.

 Teres minor, Infraspinatus, Supraspinatus, Subscapularis (TISS)

(Smallest to largest)

The Directional Pull Of The Rotator Cuff Muscles

Subscapularus, teres minor and infraspinatus (horizontal red arrows) directional pull is trying to suck that humeral head against the glenoid cavity to it doesn’t dislocate.

The deltoid (red vertical line) wants to pull the humeral head upwards/superioly translate. If the deltoid becomes too active/over in the presence of under active/tight rotator cuff muscles it can pull the humeral head to far vertically impinging on the bursa sac. That’s why having good control and strength in the rotator cuff mucsles is important to counter act to much superior translation.

Rotator Cuff

Join the scapula to the humerus

Prevent the head of the humerus from moving superiorly when the arm is raised

Work as a group to counteract the action of the deltoid muscle

Have their own actions & assist other muscles that move the shoulder joint & shoulder girdle

 

Coracoacromial Arch

Formed superiorly (the roof) by the…

Coracoid process

Coracoacromial ligament

Acromion

Formed inferiorly (the floor) by the…

Greater tubercle of humerus and the head of humerus

Prevents superior displacement of the humeral head from the glenoid cavity

Bursaeof the Glenohumeral Joint

Subscapular Bursa

Between the tendon of the Subscapularis & the neck of the scapula

Subacromial Bursa

Between the deltoid, tendon of Supraspinatus & shoulder joint capsule

Kinematics of the Glenohumeral Joint

Kinematics

Normal shoulder function requires the smooth integrated movement of the…

Scapulothoracicgliding mechanism

AC joint

SC joint

Scapulohumeral rhythm

Abnormal Scapulohumeral rhythm predisposes the shoulder joint to injury

---

Topic 9. Muscles Moving the Glenohumeral Joint

Week #5

Movements of the GH Joint

Muscles Moving the GH Joint

Scapulohumeral Muscles

Function: Provide motion and dynamic stabilization to the Glenohumeral joint

Muscles include: Deltoid, Teres Major, Rotator Cuff for stabilisation

Axiohumeral Muscles

Include the Pectoralis Major and Latissimus Dorsi

They attach to the thorax and the humerus

Function: Due to their CSA (cross sectional area) they are involved in providing additional strength to the movements of the shoulder

Remember: Latisimus dorsi and teres major often act synergistically. They both come in and have the same insertion point, the fibers run in a similar direction and they have similar actions.

Glenohumeral Joint Anatomy

Scapulohumeral Muscles

Deltoid

Functionally divided into three parts

Common insertion point: deltoid tuberosity of humerus

All heads to abduction.

Anterior Fibres

Origin: Lateral 1/3 of clavicle

Action: Abduction, flexion, internal rotation, horizontal adduction

Middle Fibres Origin:

Origin: Acromion

Action: Abduction

Posterior Fibres

Origin: Spine of scapula

Action: Abduction, extension, external rotation, horizontal abduction

Teres Major

Forms posterior wall of axilla

Close association with latissiumus dorsi

Provides dynamic inferior stabilisation to GH joint

Origin: lateral border of scapula

Insertion: Intertubercular groove of humerus

Action: Extension, adduction, internal rotation

Rotator Cuff Muscles (TISS)

Smallest to largest: Teres Minor, Infrapsinatus, Supraspinatus, Subscapularis

Note: All 3 posterior rotator cuff muscles (teres minor, supraspinatus and infraspinatus all insert on the greater tubercle of the humerus)

Function: Provide dynamic stabilisation to the glenohumeral joint

 Suprasinatus

Origin: Medial 2/3 of supraspinous fossa

Insertion: Superiorly on greater tubercle of humerus

Action: Initiates abduction, prevents superior translation of humeral head during abduction greater than 200, braces head of humerus against glenoid

Infraspinatus

Origin: Medial aspect of infraspinatus fossa

Insertion: Posteriorly on greater tubercle of humerus

Actions: External rotation

Teres Minor

Origin: Upper/middle lateral scapula border

Insertion: Posteriorly on greater tubercle of humerus

Actions: External rotation

Subscapularis

Is the only anterior muscle of the rotator cuff

Origin: Subscapular fossa

Insertion: Lesser tubercle of humerus

Action: Internal rotation, adduction.

Axiohumeral Muscles

Pectoralis Major

Large muscle of anterior thorax

Two distinct bellies

Smaller Clavicular portion (proximal)

Larger Sternocostal portion (proximal)

Common insertion point: Intertubercular groove of humerus

Clavicular Portion: 

Origin: Medial half of clavicle

Action: Internal rotation, horizontal adduction, flexion, abduction (above 90° of abduction)

Sternal Portion:

Origin: Costal cartilages of ribs 1-6 and adjoining portion of sternum

Action: Internal rotation, horizontal adduction, adduction & extension (from a flexed position to anatomical position

Latissimus Dorsi

Extensive attachment to spine and pelvis

Capable of producing large forces

Has link with contralateral gluteus maximus via thoracolumbar fascia (posterior sling)

We’re able to transfer power from our lower to upper body (and vice versa) via the posterior sling. Because the lats AND glutes connect to the same thoracolumbar fascia tension within these muscles can transfer diagonally across the body to produce force, e.g. a shot put.

Origin: Posterior iliac crest, sacrum, spinousprocess of T6-12 & L1-5

Insertion: Intertubercular groove of humerus

Action: Extension, adduction, internal rotation

 

Topic 10. Joints & Muscles of the Elbow & Radioulnar

Week #5

Elbow Joint Structure

Where the humerus meets the ulna (hinge joint): humeraulna joint.

Structure

Complex synovial hinge joint

Located 2-3 cm inferior to the epicondyles of the humerus

Articular Surfaces

Involves the distal end of the humerus and proximal ends of the radius & ulna

Distal region of the humerus has two important articular surfaces

Trochlea (articulates with the ulna) & capitulum (articulates with the radius)

Anatomical structures make it a stable joint

Articular surfaces are well matched anatomically

Articulations of the Humeroulnar Joint

Articular Surfaces

Largest and strongest articulation at the elbow

Trochlea of humerus articulates with Trochlea notch of ulna

Joint capsule completely encloses the joint

Articular Surfaces

Radial head articulates with the capitulum of the humerus

Not part of the true hinge joint

Articulations of the Superior Radioulnar Joint

Structure

Pivot joint

Articular Surfaces:

Head of radius articulates with radial notch of the ulna

Allows movement of the head of the radius on the ulna (pivot joint)

The radial head is held in place by the annular ligament of the radius – which is a really strong ligament that wraps around the head

Articular Capsule of the Elbow Joints

Joint Capsule

Anteriorly the joint capsule attaches to:

Upper margins of the coronoid and radial fossae;

To the front of the medial and lateral epicondyles AND; inferiorly to the margin of the coronoid process

Joint Capsule:

Posteriorly the joint capsule attaches to

The superior margins of the olecrannon fossae AND; inferiorly to the upper margins and sides of the olecranon process

Ligamentous Support of the Elbow

Ligamentous Support:

The collateral ligaments of the elbow joint are strong fibrous bands

They are thickenings of the joint capsule called Radial (lateral) collateral and Ulnar (medial) collateral ligaments

Annular ligament which wraps around the radial head

Radial Collateral

Strong triangular band that attaches to the lateral epicondyle, deep to the common extensor tendon

Below, it attaches to the annular ligament which surrounds the radial head

Function: Prevents the radius separating from the humerus

Ulnar Collateral Ligament

Fans out from the medial epicondyle & attaches to the coronoid process & olecranon

Consists of a thick anterior and posterior band

Intermediate (oblique) band unites anterior & posterior bands

Anterior band is intimately associated with the common flexor tendon

Thus, prone to injury. Especially with young baseballers when they reach back and throw which stretches the distance between your humerus and your ulna which gets irritated after so many reps under high velocity.

Function: Medial stability

Annular ligament

Function: Hold radial head against ulna and provides pivot point for it to rotate over the top of the ulna (pronation)

Very strong

Attaches to the radial notch anteriorly and ulna posteriorly

Anchors the radial head

This allows the radius to rotate

Inferior Radioulnar Joint Structure

Joint structure

Pivot joint

Head of the ulna articulates with the ulnar notch of the radius – remember the radius is bigger at the distal end

Elbow Joint Musculature

Movements at superior radioulnar joint

Pronationand supination (via pivot joint)

4 main muscles: Pronator teres, Pronator quadratus, Supinator, Biceps Brachii

Anterior Compartment of Arm: Flexor Compartment

Structure:

Contains Biceps Brachii

Brachialis

Coracobrachialis (actually moves the shoulder not the elbow)

All anterior muscles supplied by the: Musculocutaneous Nerve which is a terminal branch of the brachial plexus

Biceps Brachii

Bicep = 2 heads (2 origins)

Fusiform (spindle) muscle with bilateral head

Activity of this muscle affects Glenohumeral, humeroulnar and radioulnar articulations

Origin:

Long head from superior lip of glenoid fossa

Short head from coracoid process

Insertion: radial tuberosity

Action: elbow flexion, forearm supination, shoulder flexion (because it attached at the glenoid)

Brachialis

Deep to biceps on distal humerus

Is monoarticular (affecting only one joint of the body) – Actions only occur at the elbow

Sole action is elbow flexion

Works eccentrically to control the speed of extension

Origin: Distal anterior humerus

Insertion: Coronoid process of ulna

Action: elbow flexion (because it’s only attached onto the ulna)

 

Coracobrachialis

Makes up bulk of the arm

Crosses the shoulder joint

Acts only at shoulder

Origin: Coracoid process

Insertion: Medial humeral shaft

Action: Flexion & adduction of glenohumeral joint

Brachioradialis

(Thumb side)

Makes up bulk of forarm and seperates the extensors and flexors of the wrist

Superficial muscle of lateral forearm

Origin: Lateral supracondylar ridge of humerus

Insertion: Radial styloid process

Action: elbow flexion

Posterior Compartment of Arm: Extensor Compartment

Tricep Brachii

Principal Elbow Extensor

Constitutes the entire mass on the posterior aspect of the arm

Has three heads (origins)

Origin: Long head from infraglenoid tubercle of scapula; lateral head from posterior shaft of humerus; medial head from humeral shaft

Insertion: Olecranon process

Action: Chief elbow extensor

A small muscle that assists triceps in extending the forearm

Synergist muscle (not a prime mover)

Origin: Lateral epicondyle of humerus

Insertion: Olecranon process

Action: elbow extension

Pronators

Both insert onto the radius

Pronator Teres

Origin: medical epicondyle of humerus

Insertion: Lateral radius

Pronator Quadratus

Origin: Distal anterior ulna

Insertion: Distal anterior radius

Supinators

Supinator

Origin: Lateral epicondyle of humerus

Insertion: Proxmial radius

Biceps Brachii

---

Topic 11. Joints & Muscles of the Wrist & Forearm

Week #6

The name of the muscles/joint will help tell the joint action and where it is. Many also have common origin points.

Wrist Joint

Structure

Proximal segment of the hand

Is a complex of 8 carpal bones, articulating proximally with the forearm via the wrist joint and distally with the 5 metacarpals

Complex articulation consisting of the following joints: Radiocarpal Joint, Midcarpal Joint / Intercarpal Joints

Radiocarpal Joint

Articular Surfaces:

Ulna does not participate in the articulation at the wrist because we have an articular disc that separates it from the joint

Distal end of radius and the articular disc of the distal radioulnar joint articulate with the proximal row of carpal bones (except for the pisiform)

Bones are well matched anatomically

Condyloidsynovial joint means it gives us flexion/extension and abduction (radial deviation) /adduction (ulna deviation)

Carpals

Radiocarpal Joint

Joint capsule of the radiocarpal joint

Surrounds the wrist joint and encloses all of the articular surfaces. The joint capsule attaches from the distal end of the ulna and distal end of radius and inserts onto the proximal row of carpals

Collateral Ligaments of the radiocarpal joint

Ulnar Collateral Ligament

This is a strong ligament extending from the ulnar styloid process (the raised bump on the side of the wrist)

It has two components:

The palmar, which attaches to the pisiform

The dorsal,which attaches to the triquetral

Also blends with medial part of the flexor retinaculum

Radiocarpal Joint

Radial Collateral Ligament

The radial collateral (carpal) ligament originates on the tip of the styloid and inserts into the radial aspect of the scaphoid at its waist

Movements of the radiocarpal joint

Muscles Moving the radiocarpal joint

Flexion –FCR, FCU *have flexor in the first part of their name

Extension –ECRL, ECRB, ECU *have extensor in the first part of their name

Ulnar deviation –ECU, FCU *end in ulnaris (so it’s going to ulnar deviate)

Radial deviation –APL, FCR, ECRL, ECRB *all will have radials in their name except APL which is a thumb muscle

Abduction is less due to the radial styloid process

Muscles of the Forearm

Anterior Compartment (whiter side)

Flexors and pronators

Posterior Compartment (darker side)

Extensors

They’re all supplied by the radial nerve so if that nerve is damaged you loose a lot of function. It takes nerves about a 1mm per day to regenerate. E.G. If you fracture your humerus and damage the radial nerve in the upper arm it will take a long time to get back full function in the hand.

Functionally these muscles work as a group to:

Position the hand for reaching (extension)

Open the hand in preparation for grasping and pushing

Add strength to gripping/clenching through wrist extension

Assist hitting/striking and pushing movements

Anterior Compartment

Can be organised into 3 functional groups: 

1. Muscles that pronate the forearm & hand: pronator

2. Muscles that flex the wrist: carpi (if it has carpi in it’s name it means it must only work at the wrist)

3. Muscles that flex the digits: digitorum / pollicis (if it has digitorum in it’s name it means it’s not only going to flex the wrist, but the digits) (pollicis = thumb)

Pronators

Pronator Teres

Functions at the elbow and proximal radioulnar joint

Is a synergist in forearm Pronation

Important during pronation and elbow flexion when additional force is required

This has many functional implications: E.G closing jars, using a screw driver

Pronator Quadratus

Deepest muscle in the anterior aspect of the forearm

Cannot be palpated or observed except in dissection

Prime mover (agonist) in pronation of the forearm

All muscles in the superficial and middle layer all originate at the medial epicondyle of the humerus.

Wrist Flexors

Flexor Carpi Radialis

Problem Solving Rules:

Flexor = flexsion

Carpi = flexsion at the wrist

Radials = Radial deviation

Superficial = must originate at the medial epicondyle

Fusiform

Lies medial to pronator teres

Sole function is at the wrist

Works with a number of other muscles

Action: Wrist flexion & radial deviation (abduction)

Palmaris Longus

Palmaris = running to the palm palm

Small Fusiform muscle

Medial to flexor carpi radialis

Tendon centrally located in the forearm as it crosses the wrist

Missing in some people (10%)

Action: Weak wrist flexor

Flexor Carpi Ulnaris

Flexor = flexsion

Capri = Wrist flexsion

Ulnaris = Ulna deviation

Superficial = must originate at the medial epicondyle

Large pennate muscle

Very powerful

Responsible for stabilizing the wrist during such activities as slicing meat or using a hammer

Action: Wrist flexion & ulnar deviation (adduction)

Finger Flexors

Flexor Digitorum Superficialis (FDS)

Most superficial of the two flexor digitorum muscles

Action: Flexion of the MCP and proximal IP joints, wrist flexion

Flexor Digitorum Profundus (FDP)

Produndus = deep

Deep = so it has a different origin onto the anterior aspect of the ulna

Deep to FDS

Large CSA

Action: Flexion of the distal and proximal IP joints, MCP flexion, wrist flexion

Thumb Flexor

Flexor Pollicis Longus

Pollicis = flexes the thumb

Deepest layer

Only muscle that flexes the interphalangeal joint of the thumb

Action: Thumb IP and MCP flexion

Muscles can be divided into 3 layers (4:1:3)

Anterior Compartment

The superficial & intermediate layers of the flexor-pronator group are all attached to the medial epicondyle of the humerus via the common flexor tendon

Posterior Compartment

Muscles in the posterior forearm are extensors

They can be organised into 3 functional groups

1. Those that extend the wrist: carpi

2. Those that extend digits 2-5: digitorum

3. Those that extend the 1st digit (thumb): pollicis

All of the superior posterior muscles originate at the lateral epicondyle

Extensor Carpi Radialis Longus

Proximal attachment is covered by the brachioradialis

Has proximal attachments to the lateral epicondyle (lateral supracondylar ridge)

Distal attachments to the base of the 2nd metacarpal

Action: Wrist extension & radial deviation

Extensor Carpi Radialis Brevis

ECRB has a larger extensor moment arm and CSA than ECRL, thus ECRB contributes most to wrist extension

Has a smaller moment arm for radial deviation, thus is a secondary mover to ECRL

Action: Wrist extension & radial deviation (abduction)

Extensor Carpi Ulnaris

Extension

Carpri = Wrist extension

Ulnaris = Ulna deviaton

Is a pennate muscle

Similar in CSA to ECRB

Action: Wrist extension & ulnar deviation (adduction)

Digit extensors

Extensor Digitorum

Strong tendinous reinforcement

Tendons cross the dorsal surface of the wrist to the four fingers

Each tendon is attached to one another by the ‘Juncturae tendinae’

Action: Finger extension, wrist extension because it crosses the wrist

Digit extensors

Extensor Digiti Minimi

Minimi = little finger

Lies between Extensor Digitorum & Extensor Carpi Ulnaris

Action: Extension of little finger at MCP (metacarpophalangeal joints)  joint

Extensor Indices

Indicies = index finger

Small muscle that lies deep in the dorsum of the forearm

The primary functional role of the EI is to allow independent extension of the index finger

This is important as it is difficult (functionally) to obtain independent use of the other digits (due to the juncturae tendinae)

Action: Extension of MCP, PIP & DIP joints of index finger

Thumb Extensors

Extensor Pollicis Longus & Brevis

Lie deep to Extensor Carpi Ulnaris

Common origin

Longus inserts base of distal phalanx

Brevis inserts base of proximal phalanx

Action: Extends thumb at CMC, MCP & IP joints

Thumb abductors

Abductor Pollicis Longus

Forms the lateral border of the anatomical snuffbox

Snuffbox is composed of the Abductor pollicis longus, Extensor pollicis brevis and longus

The anatomical snuff box or snuffbox is a triangular deepening on the radial, dorsal aspect of the hand—at the level of the carpal bones, specifically, the scaphoid and trapezium bones forming the floor. The name originates from the use of this surface for placing and then sniffing powdered tobacco, or “snuff.”

APL is a strong muscle that affects the thumb and wrist

Action: Abducts & extends thumb at CMC, wrist radial deviation (abduction)

Abduction is going AWAY from your index finger whereas extension it moving laterally out.

Posterior Compartment

The superficial layers of the extensor group are all attached to the lateral epicondyle of the humerus via the common extensor tendon

---

Topic 12. Joints & Muscles Of The Hand

Week #6

Don’t need to know the origin and insertions just what compartment they sit in and what action they do (which again can be told in the name).

Joints of the Hand

Metacarpophalangeal Joint

Condyloid joint

Allow flexion / extension and abduction / adduction

Interphalangealjoints

Hinge joint

Allow flexion / extension

Muscles of the Hand

Intrinsic Muscles of the Hand

Muscles of the hand are divided into four compartments:

Thenar Eminence (muscles move the thumb)

Adductor Compartment (muscles that adduct the thumb)

Hypothenar Eminence (muscle that move the minimi)

Central Compartment (fine motor control)

Functions of the Intrinsic Muscles of the Hand

As they are shorter, more delicate muscles with shorter levers, there movements are weaker, thus making them ideal for positioning of the fingers for delicate movements (writing, typing, playing instruments)

Also allow for positioning of the fingers for more powerful movements (e.g. grasping)

Compartment 1. Thenar Eminence (3 Muscles)

Thenar muscles form the thenar eminence on the lateral surface of the palm

Action of the muscles in this region are  = Opposition of the thumb

Abductor Pollicis Brevis

Short muscle of the thumb

Forms the anterior-lateral part of the thenar eminence

Proximal attachment on flexor retinaculum / Distal attachment on base of proximal phalanx of thumb

It abducts the thumb and assists the opponens pollicis during early phases of opposition

Flexor Pollicis Brevis

Short flexor muscle of the thumb

Originates on the flexor retinaculum and insertson to base of proximal phalanx of thumb

Located medial to abductor pollicis brevis

It flexes the thumb and aids in opposition

Opponens Pollicis

Opponens = opposition

Lies deep to the abductor pollicis brevisand lateral to flexor pollicis brevis

Originates on the flexor retinaculum / Distal attachment onto the lateral border of 1st metacarpal

Action is to flex and rotate the 1st metacarpal medially during opposition

Compartment 2. Adductor Compartment of the Hand (1 Muscle)

Adductor Pollicis

Originates on the anterior surface of the 2nd & 3rd metacarpals / Inserts onto the medial surface of the proximal phalanx of the thumb

Action is to adduct the thumb when grasping objects (Adds strength and power to gripping movements)

Compartment 3. Hypothenar Eminence of the Hand (3 Muscles)

Abductor Digiti Minimi

Most superficial of the three muscles

Originates from the pisiform bone and tendon of FCU / Distal attachment onto medial surface of proximal phalanx of 5th finger

It abducts the little finger and assists in flexion of the proximal phalanx

Flexor Digiti Minimi

Lieslateral to abductor digiti minimi

Originates from the flexor retinaculum / Distal attachment onto medial surface of proximal phalanx of 5th finger

It’s actions include flexion of the proximal phalanx

Opponens Digiti Minimi

Lies deep to abductor and flexor digiti minimi

Originates from the flexor retinaculum / Distal attachment onto medial border of 5th metacarpal

It draws the 5th metacarpal anteriorly and toward the thumb to cup hand (helps opposition of thumb to minimi)

Compartment 4. Central muscles of the Hand (3 Muscles)

Lumbricals

Proximal attachment from tendons of FDP / Distal attachment onto the lateral side of corresponding tendons of extensor digitorium

Play a functional role in the dexterity of the hand and fine motor control

Assist in complex motions of the fingers, such as writing

Flex the MCP joint while extending the IP joint

Palmer Interossei (ADDUCTION)

Dorsal Interossei (ABDUCTION)

Dorsal & Palmar Interossei

Lie in the spaces between the metacarpals / Originate on the side of metacarpals and insert onto the bases of the proximal phalanxes

Actions:

Dorsal interossei: MCP (Metacarpophalangeal joint) abduction

Palmar interossei: MCP adduction

Both act with lumbricals to flex MCP and extend IP (Interphalangeal joint) joint

Carpal Tunnel

Structure

Osseofibrous canal

Formed by the flexor retinaculum stretched between the two rows of carpal bones

It is a passageway for:

Median Nerve – if this nerve is impinged/compressed is when you get pain/loss of function which is when carpal tunnel syndrome can occur

Tendon of flexor pollicis longus

Tendons of flexor digitorium superficialis and profundas

---

Topic 13. The Brachial Plexus

Week #7

The brachial plexus is comprised of the nerves that supply the pectoral girdle and entire upper limb

Consists of a branching network of nerves that carry impulses down from the motor cortex to the requisite muscles

Derived from the anterior rami C5-T1 spinal nerves

Most branches arise within the axilla

The brachial plexus is the network and the individual nerves are the things that supply the muscles that branch off around your axilla

Parts of the plexus from proximal to distal

Important to know the order of RTDC and overall structure – it’s not so important how they divide.

Roots

In the inferior part of the neck, the roots unite to form three trunks

Trunks

Superior, Middle & inferior

Divisions

Anterior & Posterior

Cords
Lateral, posterior & medial

 RTDC: Really Tired Drink CoffeeWhy C8? C8 is exiting below C7 and T1 is exiting below T1 etc etc.

5 roots give rise to 3 trunks

Superior, union of C5 & C6

Middle, continuation of C7 root

Inferior, union of C8 & T1 roots

Lie in the posterior triangle of the neck

Each trunk divides into anterior& posteriordivisions

Within the axilla the divisions combine to produce 3 cords

Lateral Cord

Superior & middle trunks of the anterior division unite to form the lateral cord

Medial Cord

Anterior division of the inferior trunk continues as the medial cord

Posterior Cord

All three trunks of the posterior division unite to form the posterior cord. Named according to their relationship with the axillary artery

Each cord ends at the lower border of the pectoralis minor

Each cord divides into terminal branches

Lateral cord

Gives way to the musculocutaneous nerve & lateral root of the median nerve

Medial cord

Ulnar nerve & medial root of the median nerve

Posterior cord

Axiliary & radial nerves

Which nerves supply which muscles

Lateral Cord

Musculocutaneous Nerve (C5-C7)

Innervates flexor muscles of the arm

Together with the medial cord contributes to the median nerve

Medial Cord

Ulnar nerve (C8-T1)

Innervates flexor muscles of forearm (flexor carpi ulnaris)

Median Nerve (C6-T1)

Innervates forearm flexors (flexor carpi radialus)

Posterior Cord

Axillary Nerve (C5-C6)

Innervates deltoid and teres minor

Radial Nerve (C5-T1)

Innervates posterior compartment of arm and forearm (wrist extensors/elbow extensors)

Cords

Lateral Cord -> Musculocutaneous nerve -> Coracobrahcialis, Brachialis, Biceps Brachii & also lateral root of median nerve

Posterior cord -> Axillary nerve (wraps around neck of humerus) -> Deltoid & Teres Minor

Posterior cord forarm muscles -> Radial nerve -> Posterior upper arm and forearm muscles

Medial cord  -> Median nerve (medial root) -> Anterior forearm muscles & thenar muscles

Medial cord -> Ulnar nerve -> Anterior forearm muscles & hypothenar muscles

Smaller branches of Brachial Plexus

Not important to remember in detail. The implications of this is knowing if you damage certain nerves what muscles will be inhibited.

Dorsal Scapular (C5) –Rhomboids, levator scapuale
Long Thoracic (C5-7) –Serratus anterior
Subscapular (C5-6) –Subscapularis, teres major
Medial Pectoral (C8-T1) –Pec major & minor
Thoracodorsal (C6-8) –Latissimus dorsi

Upper Brachial Plexus Injury

The following examples are not referring to damaging the spinal cord, it’s that we’ve damaged an important component of this neural network.

Injury to superior portion of Brachial plexus (C5-C6)

Musculocutaneousnerve (upper arm/flexors) & Axillary nerve (deltoid)

Usually result from an excessive increase in the angle between the neck and shoulder

Loss of sensation to lateral aspect of the upper limb

Loss of flexion, abduction & lateral rotation of the shoulder joint

Loss of flexion at the elbow

Muscles most affected are:

Deltoid
Biceps brachii
Brachialis
Brachioradialis
Supraspinatus
Infraspinatus
Teres minor

Lower Brachial Plexus Injuries

Injuries to inferior parts of the brachial plexus

Less common: May occur when the upper limb is suddenly pulled superiorly

Injury to the inferior trunk

Injury usually affects motor control of the hand, damaging parts of the ulnar nerve (lumbircles, interossei)

Radial Nerve Injury

If severed superior to the origin of the branches of the triceps = Impossible to extend elbow joint

Can happen during a really forceful single arm throw.

If severed mid humerus & distal to the origin of these nerves =

1. Elbow joint extension is unaffected

2. Wrist drop & inability to extend hand at wrist

Radial nerve Palsy

The palsy can be very acute or more chronic. Acutely can happen when you fall asleep on your arm and the pressure of pushing down on that arm results in a temporary loss of function/pins and needles.

Axillary Nerve

Winds around the neck of the humerus

Maybe injured during humeral neck fracture & dislocation of the shoulder joint

If severed-deltoid muscle is paralysed

Anesthesia may occur over the lateral side of the proximal arm (deltoid tuberosity)

Median Nerve Damage

Numbness, tingling & pain in the palm & fingers

Weak thumb movements like opposition

Inability to pronate the forearm

Difficulty in proper wrist flexion

Carpal Tunnel Syndrome

Compression of the median nerve inside the carpal tunnel at the wrist

Carpal tunnel is a narrow passage way

Formed anteriorly by the flexor retinaculum

Posteriorly by the carpal bones

Ulnar Nerve Damage

Indicated by

An inability to adduct or abduct the four fingers, but not the thumb

Weakness in flexing & adducting the wrist

Loss of sensation over the little finger

When you hit your “funny bone” thats what nerve triggers the sensation

Injury to Long Thoracic Nerve

Innervates Serratus Anterior

Serratus anterior on medial wall of axilla

Remember: Serratus anteriors job is to keep the scapula flat on the thoracic wall/rib cage to prevent winging/

Maybe injured by stab wound or thoracic surgery or the removal of cancerous axillary lymph nodes

Symptom: Winging of the scapula

---

Topic 14. Bones Of The Lower Limb

Week #7

Pelvic Girdle

Pelvis

It attaches the lower extremities to the axial skeleton and consists of the following fused bones fused at the acetablum

Ilium

Ischium

Pubis

Function of the Pelvic Girdle

Bears weight of the upper body when sitting

Transfers weight from the axial skeleton to the lower appendicular skeleton for standing & walking

Provide attachment for powerful muscles of locomotion & posture, as well as those of the abdominal wall, withstanding the forces generated by their actions

Organisation of the Pelvis

Remember: True vs False Pelvis

Pelvic inlet: E.G. Where a baby engages into before dropping and releasing through the pelvic outlet.

Pelvic outlet: E.G. Where a baby comes out of

Pelvic brim – The bony region that encloses the true pelvis.

Differences between Male Vs Female: Male pelvis sits higher/taller (more superiorly), thicker and heavier to support larger muscular system.

Females have a lower pelvis that is wider with an enlarged pelvic inlet and a more circular pelvic outlet for childbirth. The coccyx also is straighter and doesn’t angle anteriorly as much as a male pelvis to accommodate room for a baby.

Surface Landmarks

Pelvis:

Acetabulum is the socket of the hip bone where the head of the femur fits.

Auricular surface is joined onto the sacrum.

Greater sciatic notch: The sciatic nerve passes through this notice

Obturator foramen: remember foramen means a hole – OF is where nerves and blood vessels pass

Ischial tuberosity: What you sit on

Femur

Articulation (bone meets bone) points:

Femoral Head

Medial & lateral condyles (which meet the tibia)

Patella surface

Important muscle attachment sites:

Greater trochanter (lateral)

Lesser trochanter (medial)

Adductor tubercle (adductor muscles insert here)

Anterior

Posterior

Patella

Is a sesamoid bone (a bone within a tendon)

Articular surface covered in smooth hyaline cartilage

Lateral articulating surface generally larger than medial which means below is a left patella

Tibia

Articulation surfaces

Medial & lateral condyles connect to the condyles of the femur

Fibular articular facet (where the fibula head will sit on the tibia)

Medial malleolus (bony protuberance on medial side of the ankle) which meets the talus of the ankle

Important muscle attachment sites

Tibial tuberosity (all 4 quads attach here) where osgood schlatters growth pain occurs

Fibula

Articulation surface

Head

Lateral malleolus (the bony protuberance on the lateral side of your ankle) An easy way to distinguish is that the lateral malleolus is thinner than the head

Anterior

Posterior

Tarsals (7) & Metatarsals (5)

The talus meets the tibia to create the ankle joint

Calcaneus is the heel bone

Phalanges

Same as the phalanges in our hand. The big toe only has a proximal and distal. The rest have proximal, middle and distal.

Arches of the Feet

Medial arch includes:

Calcaneus, talus, navicular, cuneiforms & medial 3 metatarsals

Lateral arch:

Calcaneus, cuboid & lateral 2 metatarsals

Function of the Arches of the Feet:

The arches play an important role in shock absorption – by our arches collapsing and raising we’re able to absorb shock and conform our feet to different surfaces

Propel the foot during walking

Enable the foot to adapt to surface & weight changes

Medial longitudinal arch (inside of the foot) is higher than lateral

Pronation is a collapse of the arch – its actually a good thing because it enables us to conform to the ground and absorb shock. Its only when its excessive pronation or when your arch pronates and stays there as you try and push up is when its an issue (because when you push off you should be re-supinating) Hence why ‘athletes foot’ pronation insoles are usually over diagnosed. 

Movements of the lower limb

---

Topic 15. Joints of the Lower Limb 1: Hip Joint

Week #8

Hip Joint Structure

Forms the connection between the lower limb and the pelvic girdle

Strong & stable multiaxial ball & socket synovial joint

Femoral head is the ball

Acetabulum is the socket which accepts more of the femoral head than what happens at the GH joint, therefore it’s much more stable

Designed for stability over a wide range of movement

During standing, entire weight of upper body is transferred through the hip bones to the heads & necks of femurs

Articulations of the Hip Joint

Round head of femur articulates with the cup-like acetabulum of the pelvis

2/3rds of the head of femur is spherical in shape

Exception is the central pit, the fovea capitis, which is the attachment site for the ligamentum teres

Acetabulum

Deep socket

C-shaped articular area

Acetabular Fossa

Centrally located non- articular Fossa

Occupied with fat pad covered with Synovial membrane which functions to absorb shock/force

Margins give rise to ligamentum teres

Acetabular Labrum

Made of fibrocartilage which helps increases the depth of the acetabulum and helps distribute the stress around the entire area of the joint

Deepens the socket for the femoral head & helps to hold it into the acetabulum

Joint Capsule of the Hip Joint

Very strong

Consists of a fibrous external layer (fibrous capsule) & an internal synovial membrane

Forms a cylindrical sleeve that encloses the hip joint & most of the neck of the femur

Proximally, it attaches to the acetabulum & transverse acetabular ligament

Distally, attaches anteriorly to the femoral neck and posteriorly to the intertrochanteric crest

Ligamentous Support of the Hip Joint

Intrinsic ligaments that are thickened parts of the fibrous capsule strengthen the hip joint

Intrinsic ligaments = within the joint capsule (Iliofemoral, Pubofemoral, Ischiofemoral)

Extrinsic liagments = thickenings of the joint capsule (ligamentum teres)

Ligaments include:

Iliofemoral (runs from the illium and going to the femur)

Pubofemoral (runs from the pubis and going to the femur)

Ischiofemoral (runs from the ischium and going to the femur)

Ligamentum teres

Iliofemoral Ligament

Covers the anterior superior aspect of the hip joint

Screws the head of the femur into the acetabulum

Prevents over-extension of the hip during standing (leg going behind the trunk)

Attaches proximally to the AIIS (anterior inferior illiac spine – below the ASIS) and acetabular rim

Attaches distally to the intertrochanteric line

Pubofemoral Ligament

Covers the anterior inferior aspect of the fibrous capsule of the hip joint

 Prevents excessive abduction & extension of the thigh at the hip joint

Arises from the pubic bone and passes laterally and inferiorly to merge with the fibrous joint capsule

Ischiofemoral Ligament

Reinforces the fibrous capsule posteriorly

Arises from the ischial portion of the acetabular rim

Attaches superolaterally to the femoral neck

Weakest of the 3 ligaments

Prevents hyperextension of the thigh at the hip

Kinematics of the Hip Joint

Lateral rotation = external rotation / Medial rotation = internal rotation

Movements of the Hip Joint

Degree of hip flexion/extension is dependent upon the position of the knee

If the knee is flexed, relaxing the hamstrings, hip flexion is greatest

Hip abduction is greater than adduction

 Lateral rotation is greater than medial rotation and more powerful

Stability of the Hip

Via ligaments

Articular surfaces

Muscles that move the hip: Gluteus medius, Gluteus minimus, Lateral rotators

Like the rotator cuff pulls the humeral head back into the glenoid fossa, our lateral rotators of our hip pull the insertion point transversely ‘sucking’ the femoral head into the acetabulum.

Hip Drop

Ideally when we jump, land and balance on one foot the ASIS/PSIS will be level. The ipsilateral side (the balancing leg) glute med/min has to contract to keep your hip up. But many have a pelvic instability and end up with poorly aligned hips due to an instability in their glutes. This chronic instability can cause injuries up and down the chain (knees and ankles)

Hip Joint Pathology

Femoral Acetabular Impingement (FAI)

Improper ALIGNMENT between the head &/or neck of femur and acetabulum where the ball shaped femoral head rubs abnormally or does not permit a normal range of motion in the acetabular socket.

This causes a decreased range of hip joint motion, in addition to pain

FAI is a result of excess bone that has formed around the head and/or neck of the femur

Can result from repeated change of direction under load potentially leading to a bony growth and an improoer alingment between the femur and acetabulum.

CAM = Bony growth of the femoral neck

MIXED = A bit of both

PINCER = Bony growth of the acetabulum rim

Either of these are going to cause decreased ROM because as the femoral head tries to rotate in the acetabulum it’s being hindered by this excessive bony growth.

What Causes Femoroacetabular Impingement?

It is believed that many normal people have ‘bumps’ or slightly over-deep sockets and could potentially develop femoroacetabular impingement – this is just the way we are built and develop.

The result of these deformities is increased friction between the acetabular socket and femoral head, which may result in pain and decreased range of motion.

However, the hip has to also be provoked in some way to cause damage. This explains the tendency for athletes, sporting professionals and active people to be more susceptible to this form of injury.

---

Topic 16. Muscles Moving The Hip Joint

Week #8

Anterior Compartment

Psaos major & iliacus (iliopsoas), Rectus Femoris, Sartorius

Primary action at hip is hip flexion

Posterior Compartment

Gluteus Maximus, Biceps Femoris Longus, Semimembranosus, Semitendinosus,

Deep lateral rotators*

Primary action at the hip is extension

Medial Compartment

Primary action at the hip is adduction

Lateral Compartment

Gluteus medius, Gluteus minimus, Tensor Fasciae Latae, Deep lateral Rotators*

Primary action at the hip is abduction

1. Muscles Moving the Anterior Compartment of the Hip

Muscles Flexing the Hip

1. Psoas Major

Poorly understood muscle due to its deeplocation within the abdominal wall. SMR/myotherapy is usually done through the abdominal wall.

Action: Hip Flexion & stabilization of lumbar spine (co-contraction with rectus abdominus)

Origin: T12 –-L5

Insertion: Lesser trochanter of femur

2. Iliacus

Action: Hip Flexion

Insertion: (distal attachment): Lesser trochanter of femur.

Origin (proximal attachment): Iliac fossa

Together the psoas major and ilacus are known as iliopsoas

3. Sartorius

Longest muscle in the body

Is a biarticular strap muscle

Origin: (proximal attachment) ASIS

Insertion: (Distal attachment) medial surface of the shaft of tibia (medial to tibial tuberosity)

Action: Flexes the hip and flexes the knee because it crosses the knee and externally rotates the hip

Rectus Femoris

All quads insert on the tibial tuberosity

Only biarticular muscle (crosses two joints) of the quadriceps group – it’s also the only quad that crosses the hip

Origin: Anterior inferior iliac spine (AIIS) (just below ASIS)

Insertion: tibial tubersoity

Action: Hip flexion & knee extension

2. Muscles Moving the Posterior Compartment of the Hip

Muscles Extending the Hip

1. Gluteus Maximus

 

Largest & most superficial of gluteus muscles

Primary one-joint hip extensor

Works with the two-joint hip extensors the hamstrings

Not a postural muscle

Action: Used in forceful extension. Upper part: abduction/external rotation. Lower part: extension

Origin: Posterior illium and sacrum/coccyx

Insertion: Gluteal tubersoity of femur

2. Hamstring Musculature

Biarticular in nature, except biceps femoris short head

If the hamstrings are tight they’re going to posteriorly tilt the pelvis which will reduce lumbar lordosis (flatten the spine)

Comprise of the:

Biceps Femoris Longus (long head) + bicep femoris short head (doesn’t go up to the hip so it doesn’t act at the hip)

Semimembranosus, Semitendinosus (both run medial)

Origin: Common origin of the ischial tuberosity

Action: All extend the hip and flex the knee

Functional Role of Hamstrings:

Contribute to stability of the knee

Provide active resistance to anterior gliding of the tibia, thus reducing ACL strain (co-contraction with quads)

People with ACL insufficiencies increase the activity of their hamstring muscles

Act collectively to slow the swing leg during gait/running

Why Hamstring Injuries Often Occur When the Leg Is In The Air?

The hamstrings work eccentrically to control the rate of the swing phase during walking/running because they’re flexors of the knee. The hamstrings are producing high eccentric forces to try and slow the momentum of the swing phase – at the same time they’re getting stretched. So you’re getting maximum eccentric force production on stretch (as they lengthen), which is the when a strain/tear usually happens.

“Note: hamstrings produce optimal force at a longer length than some other muscles so the stretch is necessary for producing force. Think about bottom of RDL how much force is produced compared to half way up the thigh when stretch is less.

80% of strains are in the BF which is the lateral muscle so it doesn’t really account for other mechanisms of injury to say the ST which doesn’t get injured as frequently in sprinting (and why Nordics aren’t always the answer because they strengthen ST more than BF)” – Jay Ellis

Effect of Tightness in the Hamstrings:

Limitations in knee extension when the hip is flexed (leg press)

Posterior rotation of the pelvis

Decreased lumbar lordoticcurve

If you feel like you can’t sit up tall (with a lordotic) on the floor with your legs extended that’s usually because of the hamstrings pulling on the pelvis and not allowing you to anterioly tilt your pelvis.

Muscles Moving the Medial Compartment of the Hip

Muscles Adducting the Hip

Wedge-shaped compartment lying between the anterior & posterior compartments

All receive some innervation from obturator nerve

Primary one-joint adductors of the hip include:

Pectineus, Adductor Brevis, Adductor Longus, Adductor magnus

Common Insertion: All 3 adductors insert on the linea aspera (posterior shaft of the femur)

Two-joint hip adductor include:

Gracilis (superifical)

Muscles Adducting the Hip

Wedge-shaped compartment lying between theanterior & posteriorcompartments

All receive some innervation from obturator nerve

Primary One-Joint Adductors of the Hip Include: Pectineus, Adductor Brevis, Adductor Longus, Adductor magnus

Two-joint hip adductor include: Gracilis

1. Pectineus

Short flat muscle

Origin: Superior ramus (‘bridge between pubis and ischium’) of pubis

Insertion: Pectineal line on posterior femur (linea aspera)

Action: Hip adduction & flexion

2. Adductor Brevis

Shortest of adductor muscles, concealed by pectineus & adductor longus

Origin: Body & inferior ramusof pubis

Insertion: Linea aspera

Action: Hip adduction & flexion

Works during gait to flex the hip from toe-off

3. Adductor Longus

Almost exactly the same as adductor brevis – just longer.

Most anterior of the adductor muscles

Origin: Anterior pubis near symphysis

Insertion: Linea aspera

Action: Hip adduction & flexion

4. Adductor Magnus

Consist of an adductor and hamstring component because it also has an origin on the ischial tuberosity so it also helps in hip extension like a hamstring

Origin: Ischial tuberosity, ischium & inferior ramus of pubis

Insertion: entire length of line aspera & adductor tubercle

Action: Hip adduction & extension

Synergist with hamstrings during gait

Muscles Moving the Lateral Compartment of the Hip

Muscles Adducting the Hip

1. Gluteus Medius

Very important muscle during gait and single leg stance

Origin: Lateral ilium just inferior to iliac crest

Insertion: Lateral surface of greater trochanter

Action: Hip abduction & medial rotation (Anterior fibers internally rotate thigh at the hip and posterior fibers externally rotate thigh at the hip).

2. Gluteus Minimus

Deep to gluteus medius & smaller CSA

Origin: Lateral ilium inferior to gluteus medius

Insertion: Anterior surface of greater trochanter

Action: Hip abduction & extension

Functional Role of the Lateral Gluteal Muscles

When standing on the left leg the left glute med/min need to contract to hold the weight of the right side of the pelvis upwards to stop it from dropping down. 

If they don’t do that you end up with trendelenburg gait where one side of the pelvis drops (models cat walking).

3. Tensor Fascia Latae

Lies anterior to gluteus medius

Origin: anterior superior iliac spine (ASIS)

Insertion: Lateral tubercle of tibia (via the iliotibial tract (ITB) – connective tissue)

The ITB is connective tissue, so it’s not elastic in nature and doesn’t stretch very well. It’s also very highly invervated with pain sensory nerve endings, that’s why it’s sensitive to foam roll/release.

Action: Hip abduction, hip flexion & internal rotation

Muscles Moving the Posterolateral Compartment of the Hip

Muscles Laterally Rotating the Hip

6 Deep Lateral/External Rotators

Group of deeper & smaller muscles that sit under glute max

All act to stabilise the hip joint by steadying the head of the femur in the acetabulum. They do this because the fibers run diagonally which help pull the femoral head into the acetabulum.

Includes: Piriformis, Obturator internus, Obturator externus, Superior gemelli & Inferior gemelli, Quadratus femoris

Origin: Anterolateral sacrum, obturator foramen, ischial tuberosity, posterior portion of ischium

Common Insertion: Greater trochanter

Innervation: branches of sacral plexus & obturator nerve (only obturator externus)

If the deep lateral rotators are dysfunctional (specifically the piriformis) they can compress the sciatic nerve and cause pain. Scitatic pain doesn’t just have to originate from the back.

Summary of muscle actions

Pelvic Stabilization

Functional Importance of Pelvic Musculature

Ensures that head of femur is stabilized in the acetabulum of pelvis throughout hip motion

Poor pelvic stability often causes hip adduction and inappropriate loading of the knee

There is a link between pelvic instability and lower limb oversuse injuries (knee pain, groin etc)

A) Normal

B) Poor trunk control / weak glutes (compensation)

C) Pelvis dropping (weak glutes)

D) Weak hip abductors / weak vmo

Summary

Know common origin/insertion

All hamstrings originate on the ischial tuberosity

Adductors all insert on the linea spera (posterior shaft of femur)

Deep laterel rotators all insert on the greater trochantor

 

---

Topic 17. Joints of the Lower Limb: Knee Joint

Week #9

Gross Structure

Largest and most superficial joint

Primarily a hinge type synovial joint

Allows flexion & extension, however, the hinge movements are combined with gliding & rolling of the femoral condyles about a
vertical axis

Articulations & Articular Surfaces

Articular surfaces are large and incongruent

Knee joint consist of three articulations

Two tibiofemoral articulations (medial & lateral) between the lateral & medial femoral & tibial condyles

One intermediate patellofemoral articulation between the patella and the femur. Damage to this joint is typically as a result of overuse.

Synovial plane joint

Articular Capsule of the Knee

It has few thickened parts & is incomplete

Attaches superiorly to the femur, just proximal to the articular margins of the condyles

Posteriorly it encloses the condyles and intercondylar fossa

Patella & patellar ligament serve as a capsule anteriorly

Capsular Strengthening

Majority of the knee joint capsule is in fact ligamentous to provide stability.

Patellar ligament (patella tendon – can be considered both because it runs from patella to tib tub and also a continuetion of the quad running from a muscle to a bony point)

Lateral collateral ligament (LCL)

Medial collateral ligament (MCL)

Oblique Popliteal ligament

Arcuate popliteal ligament

Anterior View

Capsular Ligaments of the Knee Joint

Patellar ligament (ligamentum patella)

Distal continuation of the quadriceps tendon

Originates from the apex of the patella (the inferior pole of the
patella) to insert at the upper half of the anterior surface of the tibial tuberosity

It is a strong, flat band that attaches to the medial and lateral patellar retinacula (connective tissue on either side of the patella) to help hold the patella in place

The patella also increases the moment arm of the quads which make it easier for the quads to produce knee extension.

Medial collateral ligament (MCL)

Strong, flat band on the medial aspect of the knee joint

Attaches superiorly to the medial femoral epicondyle & attaches inferiorly to the medial border of the tibia

Prevents to abduction (valgus) and medial tibial rotation

Lateral collateral ligament (LCL)

Attaches superiorly to the lateral femoral epicondyle

Attaches inferiorly to the fibular head

Prevents varus rotation (adduction) of the knee

Combined with the other lateral structures, the LCL is a significant restraint to external rotation of the tibia (relative to the femur)

Oblique popliteal ligament

Arises posteromedial to the medial tibial condyle

Runs upwards and laterally behind the knee joint

Blends with the posterior surface of the capsule of the knee before
attaching to the intercondylar line and the lateral femoral condyle.

Prevents hyperextension

Intracapsular Ligaments of the Knee Joint

Include the cruciate ligaments and the menisci (cartilage pads)

Cruciate ligaments named with regard to the positions of their
attachments on the tibial plateau

ACL attaches to the anterior intercondylar area of the tibial plateau

PCL being attached to the posterior intercondylar area of the tibial plateau

They are named cruciate ligaments as they cross each other (like
the limbs of the letter X)

Intra-Articular Ligaments of the Knee Joint

Anterior Cruciate Ligament:

The ACL lies entirely within the capsule of the knee joint

 ACL runs from the posterior femur to the anterior side of the tibia

Intracapsular Ligaments of the Knee Joint

Function of the ACL:

Slack when the knee is flexed

Taut when the knee is fully extended

Prevents anterior translation of the tibia on the femur

Posterior displacement of the femur on the tibia & hyperextension of knee joint

You can function without an ACL but it increases your risk of OA / degeneration.

ACL injury mechanism

Posterior cruciate ligament (PCL):

Runs from the anterior inferior femur to the posterior side of the tibia

Strongest ligament in the knee joint because its thicker and stronger. So it takes more force to damage.

The force necessary to disrupt the PCL is twice that needed to disrupt the anterior cruciate

Function of the PCL:

Tightens during knee flexion

Prevents posterior translation of the tibia on the femur (or the femur coming forward). Can be injured in car accidents and the dashboard hits the front of the tibia and send it backwards which can damage the PCL)

Prevents hyperflexion & is the main stabilizing factor in a weight bearing flexed knee

Menisci of knee

Medial and lateral meniscus

Two semilunar fibrocartilage discs

Medial meniscus larger (bigger and more open)

 Lateral meniscus more mobile

Outside edge thicker than inside border

Function of the menisci

To increase congruency of the articular surfaces of the tibia
and femur and help

To participate in weightbearing across the joint

To act as shock absorbers.

Remember: Stress = Force / Area

Left photo without a menisci the femur has a small contact area with the tibia. So there’s a lot more stress going through the contact point at the knee compared to the right with the menisci which increases the contact area.

Even if the exact same force is going through the knee, the knee with the smaller contact area will have more stress going through it.

Bursae

Several bursae found in and around knee:

Suprapatella bursa

Prepatellar (before the patella) bursa

Infrapetellar bursae

Act to reduce friction between moving structures

Stability of the Knee Joint

Mechanically weak due to incongruency of its articular surfaces

Stability is dependant upon:

Surrounding muscles & ligaments

Inferior fibres of VMO most important

Knee is most stable in erect upright position (optimum congruency)

Co-contraction of hamstrings & quadriceps upon landing/deceleration

Strength equality between hamstring & quadriceps

To keep the patella tracking well we need to have a good balance of strength between the lateral and medial quads.

There’s a really strong pull laterally on the patella and a way to counteract that is by VMO balancing it out to pull it back medially.

Lecture review / learning goals

3 articular surfaces: 2 tibiofemoral and patellafemoral

The capusl isn’t strong therefore it relies on ligaments

---

Topic 18. Muscles moving the knee joint

Week #9

Organisation

Muscles anterior to knee:  Are primary knee extensors and stabilizers of the patellofemoral joint

Muscles posterior to knee:  Are primary knee flexors and important gait cycle muscles

Anterior compartment of thigh

Muscles extending the knee

Rectus Femoris

(only quad that crosses the knee joint)

Vastiigroup: Vastuslateralis, Vastusmedialis, Vastusintermedius (deep to rec fem and in between lateralis and medialis)

Together these muscles are known as quadriceps femoris

Common insertion tendon (quadriceps tendon): inserts onto tibialtuberosity via the patella ligament

All innervated by the femoral nerve (L2-4)

Rectus Femoris

Only biarticular (crosses the hip) muscle of the quadriceps group

Spans both the hip & knee joints

 Fibres are orientated 5 degrees to the long axis of the femur

Origin: AIIS

Actions: Knee extension and hip flexion

Effect of Rectus femoris tightness

Reduces ROM in the combined movements of knee flexion and hip extension

May change orientation in pelvis and lumbar alignment and create an APT (anterior pelvic tilt) because it crosses the hip which would increase the lumbar lordosis

Muscles extending the knee

Vastii Group:

All cross the knee joint only

All attach distally onto the tibial tuberosity via the patellar ligament

However, the angle of insertion onto the patella in respect to the long axis of the femur are different

The VMO is really important in keeping the patella centered within the patella surface of the femur. If we are weak in our VMO the patella can track abnormally causing pain and wearing away cartilage. 

Vastus lateralis:

Large pennate muscle of the lateral thigh

Active during knee extension

Insertion angle is 20 to 400 to the long femoral axis

Vastus medialis:

Most studied of the 4 heads of the quadriceps

It consists of 2 parts

Vastus medialis longus (VML) and Vastus medialis oblique (VMO)

VML insertion angle is ~ 500

VMO insertion angle is ~ 65 (the angle of the muscle helps keep the knee cap in that patella surface)

Actions include: knee extension and patella stabilization

It is active throughout full knee extension

Functional role of vastus medialis

Stabilizes the patella during active knee extension by counteracting the line of pull from the Rectus Femoris and Vastus Lateralis

This medial restraint to lateral glide is due to the VMO angle of insertion

VMO is the primary dynamic stabilizer of the patella, keeping it centred in the patella surface of the femur

Centred position of patella, improves the mechanical efficiency of the quads during knee extension

Both Vastus Lateralis and Rectus Femoris pull laterally (glide test)

Deficits in vastus medialis activity have been associated with PFPS (patella femoral pain syndrome)

Electrical activity of the muscle from the NS.

Control group = healthy people. VMO and VL switch on at the same time.

PFPS group = imbalance in electrical activity timing. VMO and VL are recruited one after the other instead of at once.

Practical implication: If they are recruited at different times the patella is likely to be pulled laterally (even if it’s only milliseconds) – doing thousands of jumps and steps overtime it can wear away the joint.

Muscles extending the knee

Vastus intermedius

Deep to rec fem

Central position on anterior thigh

Located behind rectus femoris between VL and VM

Functional role of the quadriceps

Function as extensors of the leg in the OKC (open chain – distal limb is freely movable, throwing, kicking)

Work to decelerate the leg in CKC (closed chain – distal limb is fixed – pushup, squat, deadlift). CKC deaccelerate the rate of knee flexion.

Posterior compartment of thigh

Muscles flexing the knee

Muscles Posterior to the Knee

Are primary knee flexors and stabilizers of the medial aspect of the knee (pes anserinus)

 Muscles are: Biceps Femoris, Semimembranosus Semitendinosus, Sartorius, Gracilis

Note:

Sartorius (inserts posterior to knee but is located on anterior thigh)

 Gracilis (inserts posterior to knee but is located on medial thigh)

Muscles flexing the knee

Hamstring Musculature:

Biarticularin nature, except biceps femoris short head

Comprise of the: Biceps Femoris, Longus, Semimembranosus, Semitendinosus

Common origin of the ischial tuberosity (except for bicep fem short head)

All flex the knee

Muscles flexing the knee

Biceps Femoris, Semimembranosus, Semitendinosus

Anterior compartment of thigh

Functional role of the hamstring musculature

Contribute to stability of the knee (because of insertion point at the back of the tibia)

Provide active resistance to anterior glide of the tibia, thus reducing ACL strain

People with ACL insufficiencies increase the activity of their hamstring muscles

Provide 30 – 50% of hip extension strength

 Key consideration in hamstring rehab

Act collectively to slow the swing leg during gait

Functional role of the hamstring musculature

The hamstrings control the rate of knee extension working hard to slow it down during the late swing phase where the hamstrings are working hard eccentrically.

Sartorius

Is a biarticular strap muscle (longest muscle in body)

Proximal attachment from the ASIS

Distal attachment to the medial surface of the shaft of tibia

Acts as both a hip and knee flexor

Supports the medial aspect of the knee via the pes anserinus

Is active during swing phase of gait cycle

Gracilis

 Is mainly a hip adductor but also assists as a knee flexor

Supports the medial aspect of the knee via the pes anserinus (3 tendons crossing the medial side of the knee joint)

Origin: Medial side of inferior ramus of pubis

Insertion: Upper part of medial tibial shaft

Summary of muscle actions

---

Topic 19. Joints of the lower limb: Ankle & Foot

Week #10

Ankle Joint

Talocrural Joint

Hinge type synovial joint

Located between the distal ends of the tibia & fibula & the superior margins of the talus

The weight bearing component is where the talus meets the tibia

Action: Plantar flexion and dorsi flexion

Articulations of the Talocrural Joint

Articular Surfaces (1)

Lower end of the tibia, two malleoli and the body of the talus

Forms a deep box like socket or mortise

Well matched anatomically

Note: Inversion and eversion DOESNT happen the talocrural joint because there’s bones either side blocking it

Articular Surfaces (2)

The medial surface of the lateral malleolus articulates with the lateral surface of the talus

The tibia articulates with the talus in 2 places:

Inferior surface of tibia forms the roof of the malleolar mortise, transferring the body’s weight to the talus

Medial malleolus articulates with the medial surface of the talus

Articular Surfaces (3)

The malleoli grip the talus tightly as it rocks in the mortise during movement

The grip of the malleoli is strongest during dorsiflexion

Why Dorsi Flexion Is A More Stable Position Than Plantar Flexion

Talus is wider anteriorly than posteriorly, thus during dorsiflexion the anterior talar dome migrates posteriorly increasing joint congruency. Compared to plantar flexion where the congruency is not as a strong as there’s less bone to bone contact – i.e. only the posterior part of the talus is in contact with the tibia. (Talar dome narrows posteriorly, thus it migrates anteriorly reducing joint congruency) Therefore a more stable position for our ankle joint is in dorsi flexion. 

Joint Capsule

The articular capsule encloses the joint and only attaches superiorly to the tibia & malleoli & inferiorly to the talus (no attachments to the fibula)

Thin anteriorly & posteriorly

 Reinforced on each side by strong collateral ligaments

Ligaments of the Talocrural Joint

Medial (Deltoid) ligament (attach to the tibia)

Tibionavicular, Tibiocalcaneal, Anterior & posterior tibiotalar (not expected to remember 3 portions of the deltoid ligament)

Lateral Ligament

Need to know these one’s but they’re easy to understand look at the name’s which give away position.

Anterior Talofibular Ligament

Calcaneofibular Ligament

Posterior Talofibular

Deltoid Ligament

All deltoid ligaments attach to the tibia.

Provide a strong stabilizing factor on the medial aspect of the ankle joint.

Main role to prevent excessive eversion to hold the calcaneus and navicular against the talus

 Superiorly it attaches to the tip of the medial malleolus

Inferiorly attaches to the body of the talus, calcaneus and navicular via four adjacent and continuous parts

Lateral Ligament (attach to the fibula)

All lateral ligaments attach to the fibula.

Main role to prevent excessive inversion (‘rolling ankle’)

Not as strong as the deltoid ligament because they’re 3 small individual ligaments. Lateral side is more commonly injured during an inversion sprain.

 Anterior Talofibular ligament runs from the lateral malleoli to the lateral surface of the talus

Calcaneofibular ligament runs from the lateral malleoli to the lateral surface of the calcaneus

Posterior Talofibular ligament runs from the lateral malleoli to the posterior surface of the talus

Lateral ligaments injury

Normally will damage the anterior talofibular ligament as a typical grade 1 type inversion strain.

Remember: The main role of the lateral ligaments is to prevent this from happening – to prevent excessive inversion (‘rolling ankle’)

Articulations of the Subtalar joint

Articular Surfaces

The inversion and eversion action come’s from the subtalar joint which is the articulation between the talus and calcaneus

Synovial plane joint which means these two bones glide relative to each other

Anteriorly a convex area of talus fits on a concave area of the calcanues

Posteriorly a concave area of the talus sits on a convex area of the calcaneus

Retinaculums of ankle and foot

Extensor retinaculum

Strong band of connective tissue that sits on top of the tendons/ligaments

Has superior and inferior bands

Binds down the tendons of the extensor compartment of the leg and prevents bow stringing of these tendons

Flexor retinaculum

Forms the roof of the tarsal tunnel (floor formed by medial calcaneus)

The posterior tibial vessels, tibial nerve and the tendons of tibialis posterior, flexor hallucis longus and flexor digitorum longus pass through the tarsal tunnel

Entrapment of the tibial nerve in tunnel = tarsal tunnel syndrome

Talocrural & Subtalar Joint Kinematics

Movements of the Talocrural Joint: Dorsiflexion, Plantarflexion

Subtalar Joint: Inversion, Eversion

---

Topic 20. Muscles moving the Ankle & Foot

Week #10

Anatomical Organisation of the Leg

The leg is divided into 3 compartments by the: Tibia, Fibula, Interosseous membrane

Compartments are: Anterior Compartment (dorsi flexors), Lateral Compartment (evertors), Posterior Compartment (plantar flexors)

Interossi membrane separates the compartments.

Anterior Compartment (Dorsi-Flexors)

Don’t get confused by the ‘extensor’ names – the extensors DONT extend the ankle. They extend the toes – that’s why their called that. But they also help in dorsi-flexsion of course.

Is a relatively small & confined compartment, therefore susceptible to compartment syndrome which is where repetitive contractions of the muscle can elevate the pressure of that compartment on the connective tissue causing pain during exercise.

Inferiorly the retinacula (superior & inferior) holds the tendons of the muscles of the anterior compartment before and after they cross the ankle joint

The dorsiflexors control the ankle and toes during the gait cycle to prevent the foot from dropping

1. Tibialis Anterior

Most medial and superficial of the dorsiflexors

Due to the length of the tendon, it is the most powerful muscle of dorsiflexion

Helps strengthen the medial longitudinal arch

Origin: Lateral tibial condyle and lateral surface of tibia

Insertion: Base of the 1st metatarsal and medial cuneiform

Action: Dorsiflexion of ankle and inversion of the foot

2. Extensor Digitorum Longus

Most lateral of the anterior leg muscles

The muscle becomes tendinous superior to the ankle, forming 4 tendons that attach to the lateral 4 phalanges

Origin: Mostly from the medial surface of the fibula & superior aspect of the interosseous membrane

Insertion: Middle & distal phalanges of the 4 toes

Actions: Extension of lateral 4 toes & dorsiflexion of the ankle

3. Extensor Hallucis Longus

Thin muscle that lies deeply between the TA & EDL

Origin: Middle part of the anterior surface of the fibula & interosseous membrane

Insertion: Distal phalanx of great toe

Actions: Extension of great toe & dorsiflexion of the ankle

Functional Role of the Muscles in the Anterior Compartment

All are active during the gait cycle

They concentrically contract to raise the forefoot to clear the ground during the swing phase

The dorsi-flexors eccentrically contract to lower the forefoot to the ground after heel strike

Control the descent of the toes onto the ground during heel strike

Note: The muscles of the hand have so many inricite muscles the control each digit. Whereas the foot only has 3 main muscles to control the anterior compartment. The reason being is that we’ve evolved to need much more finer motor control of our hands compared to our feet. 

Lateral Compartment of the Leg (Plantar-Flexors & Everters)

1. Peroneus Longus (Fiburalis Longus)

Is longer & more superficial of the two lateral muscles

Specifically, its tendon forms a sling under the sole of the foot, reinforcing the transverse arch

Origin: Head & upper 2/3 of lateral fibula

Insertion: Underside of medial cuneiform (sole of the foot) and 1st metatarsal

Action: Plantarflexion of the ankle and eversion of the foot

Peroneus Brevis (Fiburalis Brevis)

Smaller muscle, lies deep to Peroneus longus

Origin: Middle to lower 2/3 of lateral fibula

Insertion: Base of 5th metatarsal

Action: Plantarflexion of the ankle and eversion of the foot

Posterior Compartment of the Leg (Plantar-Flexors)

Superficial

Is the largest of the 3 leg compartments

It is divided into superficial & deep compartments

Muscles in this compartment produce plantarflexion at the ankle, inversion at the subtalar joints, & flexion of the toes

Superficial Musculature: Gastrocnemius, Soleus, Plantaris

Deep Musculature: Flexor hallucis, longus, Flexor digitorum longus, Tibialis posterior

Tom (Tib post) – Dick (flexor dig long) & Harry (flexor hall long)

 

1. Gastrocnemius

Most superficial muscle in the posterior compartment

two-headed, biarticular muscle

Orientation of the muscle fibers are vertical, thus contractions of this muscle produces rapid movement in activities such as running & jumping

It functions best in knee extension as it crosses the knee joint.

E.G. Standing vs. seated calf raise – gastroc works best in knee extension. When you go into knee flexion you minimize gastroc ability to produce plantar flexion and I assume recruit muscle fibers. A seated calf raise activates soleus more efficiently than gastroc.

Gastroc inserts onto the calcaneus via the achilis tendon

Origin: Posterior surface of medial and lateral condyles of femur

Insertion: Posterior calcaneus via the calcaneal tendon

Action: Plantarflexion of ankle and knee flexion

2. Soleus

Located deep to gastrocnemius

Maintains posture-steadies the leg on the foot

Slower contractions stability-type postural muscle than the Gastrocnemius which is more balisitic in nature.

Origin: Posterior surface of upper 2/3 of interosseus membrane and adjacent tibia & fibula

Insertion: Posterior calcaneus via the achilis (calcaneal) tendon

Action: Plantarflexion of ankle

For Kellie:

I know you wanna keep growing your calves a little more Kel. Here’s some useful info about the calves that I just learnt in my functional human anatomy unit that applies to what we do.

The gastroc nemius is the superficial long bump you see (as im sure you know). The gastroc’s muscle fibers run vertically, therefore it’s more balisitic and fast twitch in nature. So if you wanna keep growing them, playing netball will be one of the biggest help’s because there’s a lot of ballistic type explosive movements.

Standing vs. seated calf raise – the gastroc works best in knee extension (standing movements). When you go and do a seated calf raise you put yourself into knee flexion which minimizes gastroc’s ability to produce force and recruit muscle fibers. So during a seated calf raise you typically wont be targeting gastroc. BUT this isnt necessarily bad, instead, you will be targeting the deeper muscle that sits behind gastroc: the soleus. So seated calf raise will activate soleus more efficiently than gastroc. Soleus is more slow twtich, so may benefit from higher rep and higher time under tension during seated calf work. So there’s some info on calves so you can understand which movements will produce which adaptation.

Function of the Calacaneal (Achilles)Tendon

The achilles is the biggest and strongest tendon that is very elastic which helps store energy and produce force. This helps during running, sprinting, jumping. The longer tendon the more elastic energy it can store and produce which explains why some people with thin legs and calves can jump really high due to their long tendon length. Think about an animal like a horse which has really long tendons with more of the muscle mass sitting more proximally. 

Improves the action of the triceps surae

Tricep Surae: means gastroc + soleus because they have the same insertion point and action. So they function as a group called Triceps Surae.

Adds important & useful length to these muscles

Improves the efficiency of the gait cycle due to elastic storage and potentiation during stance phase

Slow to heal due to low metabolic rate & poor blood supply

Importance of eccentric exercise in treating calf muscle strains & musclotendinous injuries

3. Tibialis Posterior (Tom)

Important role in controlling forefoot (arch) during gait by preventing collapse of the medial longitudinal arch because it attaches to nearly all tarsals and metatarsals

Is the deepest (anterior) muscle in the posterior compartment

Lies between the FDL & FHL

Origin: Upper interosseous membrane, posterior surface of the tibia & fibula

Insertion: Tuberosity of the navicular, cuneiforms & cuboid, bases of the 2nd, 3rd, & 4th metatarsals

Actions: Plantarflexion of ankle and inversion of foot

4. Flexor Digitorum Longus (Dick)

Has a smaller CSA to FHL, even though it moves a greater number of joints

Origin: Middle 1/3 of posterior tibia

Insertion: Base of distal phalanges of the lateral 4 toes

Actions: Flexion of lateral 4 toes, plantar flexion of ankle & support s longitudinal arches of foot

5. Flexor Hallucis Longus (Harry)

Is a powerful “push off’ muscle during activities such as running, walking & jumping

Works with the triceps surae to deliver a final thrust at toe off during gait

Largest of the deep muscles

Origin: Middle 2/3 of posterior fibula

Insertion: Base of distal phalanx of the great toe

Actions: Flexion of great toe, plantarflexion of ankle & support s medial longitudinal arch

Anatomical Organisation of the Foot

Intrinsic Muscles of the Foot

Don’t need to remember the names of all of them.

All have their origins and insertion on bones within the foot – that’s why they’re intrinsic 

1 is located on the dorsal aspect (EDB)

The remainder are found on the plantar (sole) surface of the foot

The plantar muscles (sole of the foot) are arranged in 4 layers

The plantar muscles function primarily as a group during the support phase of the gait cycle, thus maintaining the arches of the feet

They resist forces that tend to reduce the longitudinal arches

Are similar to the muscles in the palm of the hand

Organisation of the Plantar Muscles

Superficial Layer (Layer 1)

Composed of (medial to lateral), Abductor Hallucis, Flexor Digitorium Brevis, Abductor Digiti Minimi

Layer 2: Quadratus Plantae, Lumbricals (4)

Layer 3: Flexor Hallucis Brevis, Adductor Hallucis, Flexor Digiti Minimi Brevis

Deep Layer 4: Consists of 7 Interossei muscles: Three Plantar Interossei, Four Dorsal Interossei

Intrinsic Muscles of the Foot

Functional Roles

Most people are not capable of individually isolating the foot musculature. That’s how there are less muscles. Thus the muscles of the feet function as a group during weight bearing activities.

Work as a group to increase the pressure applied to the ground during postural balance tasks, thus controlling COM/COP

Collectively play a critical role during the stance phase of gait

Work eccentrically to resist collapsing of the MLA

---

Topic 21:The Lumbosacral Plexus

Week #11

Nerves of the Posterior Abdominal

Lumbar Plexus (L1-4)

Major neural network supplying the lower limbs

It’s less complex than brachial plexus

Formed within the Psoas major muscle from the anterior rami of the upper 4 lumbar nerves

Divide into posterior & anterior divisions

Anterior  division goes to the obturator nerve

Posterior division goes to the femoral nerve

Obturator Nerve (L2-4)

Descends through the Psoas Major muscle

Crosses the sacroiliac joint & enters pelvis minor

Exits pelvis & enters thigh through the obturator foramen

Supplies adductors & gracilis muscles in medial thigh and Obturator externus in the deep gluteal region

Femoral Nerve (L2-4)

Pierces the Psoas Majormuscle

Supplies the Psoas & Iliacusmuscles in the abdomen

Passes distallyin the femoral triangle

Several terminal branches supply the anterior thigh muscles (hip flexors)

Sartorius, Rectus Femoris, Vastus Group, Iliopsoas

Damaging the femoral nerve would effect knee extension and hip flexion and gait.

Smaller branches of lumbar plexus

Ilioinguinal & Iliohypogastric nerves

Both derived from the L1 segment by a common stem

Supply skin of the suprapubic & inguinal regions (the feeling of touch around the groin area)

Supply branches to the abdominal musculature: External oblique, Internal oblique, Transverse abdominis, Inferior fibres of rectus abdominis

Sacral Plexus

Formed by the lumbosacral trunk (L4-L5) & ventral rami of S1-S4 spinal nerves

Located in pelvis minor

Most branches exit pelvis through the greater sciatic notch

Divides into anterior (tibial nerve) and the posterior divisions (fibular/perineal nerve) – they are bound together to form the sciatic nerve (largest nerve in the body)

Divisions of Sacral Plexus

Even though it sais anterior division it’s going to the posterior muscles

Anterior division tend to supply the muscles that flex the knee and plantarflex the ankle (posterior muscles)

Posterior division tend to supply the muscles that dorsiflex the ankle (anterior muscles)

Sciatic Nerve

Largest nerve in body formed by the tibial & peroneal nerve in one sheath.

It comes out through the greater sciatic notch and either goes underneath OR through piriformis – most people it’s sitting underneath but some people it’s going through the muscle.

Ventral rami of L4,L5,S1,S2 & S3

Usually supplies no structures in the gluteal region

Tibial portion (L4-S3) innervates:

Semitendinosus, biceps femoris longus, semimembranosus & hamstring portion of adductor magnus in posterior thigh

At the knee level the nerve splits off into the tibial nerve and the peroneal nerve:

Tibial nerve past the knee supplies:

Gastrocnemius, soleus, popliteus, tibialis posterior, flexor digitorum logus & flexor hallucis longus in posterior leg

Plantar foot muscles

Common Peroneal nerve (L4-S2)

Most commonly injured nerve in the lower limb because it’s so superficial

Winds superficially around the neck of the fibula

Innervates Biceps femoris brevis in thigh & anterior and lateral compartment of the leg via deep and superficial portions

Common Peroneal Nerve

Deep branch (L4-S1)

Supplies muscles in the anterior compartment of the leg (dorsi flexors and toe extensors)

Tibialis anterior, extensor hallucis longus, extensor digitorum longus

Injury of the common peroneal nerve results in ‘Footdrop’ & loss of skin sensation

Superficial branch (L5-S2)

Supplies muscles in the lateral compartment of the leg: Peroneus longus & brevis

---