Bones & Joints of the Shoulder Girdle

Clavicle Scapula Manubrium of the sternum Proximal humerus

• Sternoclavicular joint (SC joint) • Acromioclavicular joint (AC joint) • Glenohumeral joint (GH joint)

• It is a long bone • Connects the upper limb to the axial skeleton (only bone to do so) • Acts as a strut to hold the upper limb away from the trunk for maximum range of motion • Articulates at acromioclavicular (AC) and sternoclavicular (SC) joints • Superior surface is smooth • Inferior surface is rough for the attachment of ligaments and muscles

• Flat bone • Triangle shaped bone • Overlies posterolateral aspect of 2nd to 7th ribs • Important for connection of the upper limb to the thoracic cage as well as a significant portion of upper limb range of motion

-Largest bone of the upper limb -Long bone -Articulates with: .Scapula at the glenohumeral (GH) joint .Radius and ulnar at the elbow joint -Serves as location for many muscle attachments

• Articulation between the sternal/proximal end of clavicle and the manubrium of the sternum (only articulation b/w upper limb and axial skeleton) • Saddle synovial joint - however it functions like a ball & socket joint • Articular disc (fibrocartilage, shock absorber)

• Articulation between the acromial/distal end of clavicle and acromion of the scapula • Plane type of synovial joint • Articular disc - Fibrocartilage • No muscles directly cross and move the AC joint. Rather, the axioappendicular muscles move the scapula, which then moves the acromion on the clavicle

• Articulation between the humeral head and the glenoid fossa/cavity of the scapula • Ball and socket type of synovial joint • Wide range of movement, however as a result it is relatively unstable • Glenoid labrum – fibrocartilaginous ring increases congruency • Relies heavily upon the rotator cuff muscles for stability

• Sternoclavicular ligaments (anterior and posterior) (relatively weak) – b/w the sternum & clavicle - Interclavicular ligament (relatively weak) – b/w the two clavicles - Costoclavicular ligament (very strong!) – b/w rib 1 and inferior clavicle

• Medial supraclavicular nerve • Nerve to subclavius • Protraction & retraction of the clavicle • Elevation & depression of clavicle • Rotation about the longitudinal axis – assists the above movements

Acromioclavicular ligament (weak) - b/w the clavicle and acromion Coracoclavicular ligament (very, very strong) - Conoid and Trapezoid parts - b/w the coracoid process of scapula and clavicle, holds the scapula up onto the clavicle Coracoacrominal ligament - b/w the coracoid process and acromion of the scapula, provides indirect protection from superior displacement of the humerus

lateral supraclavicular nerve lateral pectoral nerve axillary nerve Acromion of the scapula glides on the acromial end of the clavicle as the scapula moves on the thoracic cage Axioappendicular muscles move the scapula which in turn moves the acromion on the clavicle

• Glenohumeral ligaments (Superior/Middle/Inferior) that reinforce the joint anteriorly - Transverse humeral ligament – b/w greater and lesser tubercle of humerus, holds long biceps tendon in place (see image next slide) - Coracohumeral ligament – strong band b/w the coracoid and greater tubercle of humerus - Coracoacromial ligament - indirect protection, prevents superior displacement of the humerus – b/w the coracoid process and acromion of the scapula

• Axillary nerve • Suprascapular nerve • Lateral pectoral nerve Flexion/extension Abduction/adduction Internal (medial) and external (lateral) rotation Circumduction

• A fibrocartilaginous ring-like structure that lines the outer rim of the glenoid fossa • Increases depth of fossa to increase congruency of glenohumeral joint • Maintains negative pressure within the joint (like the suction of a vacuum) • Provides insertion for stabilising structures – eg articular capsule and glenohumeral ligaments

Formed by • Coracoid process • Acromial process (acromion) • Coracoacromial ligament Function • Protective arch over the glenohumeral joint • Prevents superior displacement (dislocation) of humeral head • Supraspinatus muscle passes beneath the arch • The suprapinatus tendon is separated from the arch by the subacromial bursa • This region is clinically relevant in ‘impingement’ of subacromial structures, where the tendon and/or bursa are pinched between the humeral head & coracoacromial arch

-Deep fascia is a dense, organised connective tissue which covers most of the body deep to the skin and subcutaneous tissue (fat) Functions of fascia: • Packages & protects body structures • Limits spread of infection • Aids the musculovenous pump by limiting outward expansion of muscles • Holds tendons in place (retinaculae)

fascia can surround a section of the body Pectoral fascia – chest region Brachial fascia – arm Antebrachial fascia – forearm Palmar aponeurosis – palm of hand Fascia forms dense bands which hold down tendons to prevent bow stringing • Flexor retinaculum (palmar surface of hand/wrist) • Extensor retinaculum (dorsum of hand/wrist)