THE SHOULDER JOINT T H E G L E N O H U M E R A L ( G H ) J O I N T

THE SHOULDER JOINT T H E G L E N O H U M E R A L ( G H ) J O I N T

CLARIFICATION OF TERMS Shoulder girdle = scapula and clavicle Shoulder joint (glenohumeral joint) = scapula and humerus Lippert, p115

OSTEOLOGY OF THE GH JOINT(BONES) Scapula Glenoid fossa Glenoid labrum Subscapular fossa Infraspinous fossa Supraspinous fossa Axillary border Acromion process

(Vertebral) (Axillary)

Scapula (Dorsal aspect) (Axillary) (Vertebral)

OSTEOLOGY OF THE GH JOINT(BONES) CONT Humerus Head Surgical neck Anatomical neck Shaft Greater tubercle Lesser tubercle Deltoid tuberosity Bicipital groove Bicipital ridges

(Posterior aspect) Intertubercular groove (Bicepital groove)

Intertubercular Groove (bicepital groove) Anatomical Neck Deltoid Tuberosity

JOINT STRUCTURE OF THE GH JOINT Ball and socket joint Movement in all three planes (3 degrees of freedom) Articulation between the humeral head of the humerus and the glenoid fossa of the scapula One of the most movable joints in the body and, consequently, one the stable. Lippert, p131

JOINT MOVEMENT OF THE GH JOINT Osteokinematics Flexion Extension Hyperextension Abduction Adduction Medial rotation (internal rotation) Lateral rotation (external rotation) Horizontal abduction Horizontal adduction Circumduction Scaption

JOINT MOVEMENT OF THE GH JOINT CONT Arthrokinematics Concave-convex rule The convex humeral head moves within the concave glenoid fossa The convex joint surface (humeral head) moves in a direction opposite to the movement of the body segment (humeral shaft) Flexion humeral head glides Abduction humeral head glides Extension humeral head glides Adduction humeral head glides Internal rotation humeral head glides External rotation humeral head glides Lippert, p132

JOINT MOVEMENT OF THE GH JOINT CONT Arthrokinematics The articular surface of the humeral head is greater than that of the glenoid fossa If the humeral head simply rotated in the glenoid fossa, it would run out of articular surface before full abduction occurred So, as abduction occurs, the humeral head rolls across the glenoid fossa and glides inferiorly (thanks to the rotator cuff) Complete abduction can occur only with full external rotation

SUPPORTING STRUCTURES OF THE GH JOINT Rotator cuff SITS muscles surround humeral head and actively hold it against the glenoid fossa Capsular ligaments Relatively loose capsule attaches the rim of the glenoid fossa and anatomic neck of the humerus Coracohumeral ligaments Connects coracoid process and anterior side of greater tubercle Glenoid labrum A fibrocartilaginous ring that encircles the rim of the glenoid fossa, deepening the socket and sealing the joint Long head of the Biceps The proximal portion of the tendon wraps around the superior aspect of the humeral head, providing anterior stability Mansfield, p58

MYOLOGY OF THE GH JOINT (MUSCLES) Deltoid Pectoralis major Latissimus dorsi Teres major Supraspinatus Infraspinatus Teres minor Subscapularis Coracobrachialis Biceps brachii Triceps brachii, long head

Deltoid: Anterior Origin Insertion Action Innervation Axillary n. Anterior surface of the lateral aspect of the clavicle Deltoid tuberosity of the humerus Sh flexion, HADD, Sh IR, Sh ABD Anterior Lippert, p136

Deltoid: Middle Origin Insertion Action Superior lateral surface of the acromion Deltoid tuberosity of the humerus Sh ABD, Sh flexion Innervation Axillary n. Middle Deltoid Lippert, p136

Deltoid: Posterior Origin Insertion Action Spine of the scapula Innervation Axillary n. Deltoid tuberosity of the humerus Sh extension, HABD, Sh ER Lippert, p136

Pectoralis Major Origin Clavicular portion: anterior margin of the medial portion of the clavicle Sternal portion: lateral margin of the manubrium and body of the sternum and cartilage of the first 6-7 ribs Insertion Action Crest of the greater tubercle of the humerus Clavicular: Sh IR, Sh flexion, HADD Sternal: Sh IR, Sh ADD, Sh extension, Sh depression Innervation Clavicular: lateral pectoral n. Sternal: lat & medial pectoral n. Mansfield, p82

Latissimus Dorsi Origin Insertion Action Thoracolumbar fascia, spinous processes of lower thoracic and lumbar vertebrae, posterior iliac crest, lower 4 ribs and inferior angle of scapula Floor of intertubercular groove of humerus Sh ADD, Sh extension, Sh IR, scapular depression Innervation Thoracodorsal n. tidbit Necessary for crutchwalking and transfers! Lippert, p137

Teres Major Origin Insertion Inferior angle of the scapula Crest of the lesser tubercle of the humerus Action Sh ADD, Sh extension, Sh IR Innervation Lower scapular n. Lippert, p138

SITS Supraspinatus Infraspinatus Teres Minor Subscapularis

Supraspinatus Origin Insertion Action Supraspinatus fossa of the scapula Greater tubercle of the humerus Sh ABD, stabilization of the GH, slight ER Innervation Suprascapular n. Tidbit One of the rotator cuff muscles Lippert, p138

Infraspinatus Origin Insertion Action Infraspinatus fossa of the scapula Greater tubercle of the humerus Sh ER, stabilization of the GH joint Innervation Suprascapular n. tidbit One of the rotator cuff muscles Lippert, p138

Teres Minor Origin Insertion Action Posterior lateral border of the scapula near the inferior angle Greater tubercle of the humerus (inferior to the infraspinaus) Innervation Axillary n. Sh ER, stabilization of the GH joint Lippert, p139

Subscapularis Origin Insertion Action Innervation tidbit Subscapular fossa of the scapula Lesser tubercle of the humerus Sh IR, stabilization of the GH joint Upper and lower subscapular n. One of the rotator cuff muscles Lippert, p140

Coracobrachialis Origin Insertion Action Coracoid process of the scapula Medial aspect of the proximal shaft of the humerus Sh flexion Innervation Musculocutaneous n. Lippert, p140

Biceps Brachii Origin Insertion Action Long head: supraglenoid tubercle of glenoid fossa Short head: coracoid process of the scapula Radial tuberosity of the radius Sh flexion, elbow flexion, forearm supination Innervation Musculocutaneous n. tidbit The actions of the biceps brachii are perfect in combination for opening a bottle of wine. The Corkscrew effect Biceps Brachii Mansfield, p78

Long Head of the Triceps Brachii Origin Insertion Action Innervation Radial n. Infraglenoid tubercle of the scapula Olecranon process of the ulna Sh extension, elbow extension Mansfield, p80

MYOLOGY OF THE GH JOINT (MUSCLES) CONT Anatomical Relationsips Muscles that stabilize are deep to muscles that move. Therefore, glenohumeral joint muscles are superficial to shoulder girdle muscles Deltoid: forms a superficial cap over the anterior, lateral and posterior sides of the shoulder Anteriorly, pectoralis major covers most of the superficial chest wall Biceps brachii and triceps brachii encompass most of the anterior and posterior arm, respectively If the trapezius were removed, you would see the supraspinatus above the scapular spine and in descending order, the infraspinatus, teres minor and teres major below the scapular spine The latissimus dorsi covers the lumbar and lower thoracic region of the back Lippert, p140

MYOLOGY OF THE GH JOINT (MUSCLES) CONT Anatomical Relationsips Lippert, p140

MYOLOGY OF THE GH JOINT (MUSCLES) CONT Summary of Muscle Action: Action Flexion Muscles (Lippert, p142) Anterior deltoid, pectoralis major (clavicular) Extension Hyperextension Abduction Adduction Horizontal abduction Horizontal adduction Lateral rotation Medial rotation Posterior deltoid, lattisimus dorsi, teres major, pectoralis major (sternal) Latissimus dorsi, posterior deltoid Deltoid, supraspinatus Pectoralis major, teres major, latissimus dorsi Posterior deltoid, infraspinatus, teres minor Pectoralis major, anterior deltoid Infraspinatus, teres minor, posterior deltoid Latissimus dorsi, teres major, subscapularis, pectoralis major, anterior deltoid

MYOLOGY OF THE GH JOINT (MUSCLES) CONT Summary of Muscle Innervation: Lippert, p143 Muscle Nerve Segment Subscapularis Upper and lower subscapular C5, C6 Teres major Lower subscapular C5, C6 Pectoralis major Lateral and medial pectoral C5, C6, C7 & C8, T1 Latissimus dorsi Thoracodorsal C6, C7, C8 Supraspinatus Suprascapular C5, C6 Infraspinatus Suprascapular C5, C6 Deltoid Axillary C5, C6 Teres minor Axillary C5, C6 Coracobrachialis Musculocutaneous C6, C7 Biceps Musculocutaneous C5, C6 triceps radial C7, C8

What upper extremity muscles can you identify on him?

REFERENCES Lippert, L.S. (2011). Clinical Kinesiology and Anatomy, 5 th ed. Philadelphia, PA: F.A. Davis. Mansfield, P.J., & Neumann, D.A. (2009). Essentials of Kinesiology for the Physical Therapist Assistant. St. Louis, MO: Mosby Elsevier.