PHTY 101 – WEEK 1

1.7 Classify the shoulder (glenohumeral) joint and identify and/or describe its:

• The glenohumeral joint is a multiaxial, synovial, ball and socket joint • Movements: o Flexion and extension- transverse axis o Abduction and adduction- anteroposterior axis o Internal and external rotation- longitudinal axis • Greatest amount of motion and most unstable joint in body • Function: positions and directs humerus, elbow and hand in relation to trunk (radioulnar joint deal with palm and fingers) • Combines with scapulothoracic, acromioclavicular and sternoclavicular joints • Articular surfaces: o Humeral head- ½ sphere, faces medially o Glenoid fossa- very shallow, faces laterally o Only 25-30% contact between articular surfaces o Shallower and smaller surface compared to hip • Glenoid labrum o Glenoid labrum- fibrous structure around glenoid fossa (adheres to edges), central part avascular and edges not greatly vascularised à doesn’t heal well, labrum functions to; - Facilitate mobility - Increase glenoid concavity- increasing mobility - Provide attachment for joint capsule, ligaments and muscles • Joint capsule o Very thin and lax- doesn’t compromise ROM o Attaches to glenoid labrum o Reflected (folded) inferiorly onto medial shaft of humerus o Reinforced by; - Rotator cuff tendons- supraspinatus, infraspinatus, teres minor, subscapularis - Rotator cuff tendons- action: internal or external rotation, function: pull humerus head in against fossa - Glenohumeral and coracohumeral ligaments (capsular) • Synovial membrane o Lines joint capsule o Lines bony surfaces inside joint capsule which are not covered by articular cartilage • Ligaments o Coracoacromial: (coracoid to acromion) - Prevents superior dislocation of humerus - Doesn’t attach to humerus o Coracohumeral: (coracoid to greater tubercle of humerus) - Prevents lateral and therefore inferior dislocation of humerus o Glenohumeral: (anterior glenoid rim to humerus) § Three bands § Superior- prevents lateral and therefore inferior dislocation of humerus, limits external rotation § Middle- limits external rotation § Inferior- prevents anterior dislocation when fully flexed/ abducted o Transverse humeral: § Holds long head of biceps brachii in the bicipital groove § Acts as retinacula- prevents bowstringing by locking in tendon in groove

1.8 Describe the precise direction in which the glenoid fossa faces when the upper limb is in the anatomical position (hanging) and describe the functional significance of this alignment.

• Glenoid fossa is directed laterally, anteriorly and slightly superiorly • Humeral head is directed superiorly, medially and posteriorly • This is to prevent the anterior and posterior dislocation of the humerus

1.10 Identify and classify the sternoclavicular joint:

- Classification: synovial, multiaxial, plane - Articular surfaces: o Sternal end of clavicle (male) o Clavicular notch of sternum (female) o Costal cartilage of rib 1 - Articular capsule: • Strong • Reinforced by capsular ligaments - Synovial membrane: • 2 separate synovial membranes • Intra-articular disc: vertical disc dividing joint cavity into medial and lateral compartments • Disc functions: § Shock absorption § Prevents superior dislocation of clavicle by thrusting forces or weight in hand - Ligaments: • Costoclavicular: (rib 1 to clavicle) § Bilaminar (two layers) running at 90 degrees to one another § Limits elevation of clavicle § Limits protraction and retraction § Acts as a fulcrum or pivot about which movements occur- ligament acts as an anchor on one end of clavicle, little movement on lateral side but great movement on medial side

• Anterior sternoclavicular: (sternum to clavicle) • Limits retraction • Posterior sternoclavicular: (sternum to clavicle) o Limits protraction • Interclavicular: (between clavicles)

1.12 Identify and describe the acromioclavicular joint:

- Classification: synovial, multiaxial, plane - Articular surfaces: o Acromial end of clavicle o Anterior, medial acromion - Articular capsule: o Loose o Reinforced by capsular ligaments o Intra-articular disc: partial disc which functions as a shock absorber - Ligaments: o Coracoclavicular: (coracoid to clavicle) o Conoid part- attaches to Conoid tubercle, anchors clavicle to acromion process, limits protraction of scapula, produces axial rotation of clavicle o Trapezoid: (attaches to trapezoid line) o Limits retraction of scapula o Prevents medial dislocation of scapula

1.14 Define and demonstrate movements at the shoulder joint and movements of the scapula

• Scapula movements: 2. Elevation and depression 3. Protraction and retraction 4. Lateral (upward) rotation and medial (downward) rotation