HSE102 – Functional Human Anatomy

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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

Quadratus 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

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

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

Triceps 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

Anconeus

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