MUSCLES OF THE SHOULDER GIRDLE The deltoid forms

MUSCLES OF THE SHOULDER GIRDLE The deltoid forms the contour of the shoulder. Deep to it are : n Supraspinatus. n Infraspinatus. n Subscapularis. n Teres minor. n Teres major. n n

DELTOID It is triangular in shape. It is functionally n divided into: anterior, middle and posterior parts. Origin : n Anterior fibers: lateral 1/3 of the anterior border of the clavicle. n n

DELTOID Middle fibers : n lateral border of the acromion. Posterior fibers: n lower border of the spine of the scapula.

DELTOID Insertion : n deltoid tuberosity n (middle of the lateral surface of the humerus).

DELTOID Nerve supply : Axillar nerve. n n

DELTOID Action: n 1. Middle fibers: n abduction of the arm (helped by supraspinatus). 2. Anterior fibers: n flexion and medial rotation. 3. Posterior fibers : n extension and lateral rotation.

AXILLARY NERVE Origin : n Posterior cord of the n brachial plexus (in the axilla).

AXILLARY NERVE Course : n Passes through n the quadrangular space. It is closely n related to the inferior part of the shoulder joint and the surgical neck of the humerus.

AXILLARY NERVE Branches : n 1. Articular : to the shoulder n joint. 2. Anterior branch : n deltoid muscle and the skin n covering its lower half. 3. Posterior branch : n Deltoid. n Teres minor. n Upper lateral cutaneous n nerve of the arm.

QUADRANGULAR SPACE It is an n intermuscular space. Boundaries : n Superior n (posterior) : Teres minor. Superior n (anterior): Subscapularis n Inferior : Teres n major.

QUADRANGULAR SPACE Medially : Long n head of triceps. Laterally : n Surgical neck of the humerus. Contents : n Axillary nerve. n Posterior n circumflex humeral vessels.

ROTATOR CUFF It is formed of (4) n muscles Supraspinatus. n Infraspinatus. n Teres minor. n Subscapularis. n It lies on the superior, posterior and anterior aspects of the shoulder joint. It is deficient n inferiorly. n

ROTATOR CUFF Function : n The tone of the n muscles holds the head of the humerus in the glenoid cavity. So they assist in n stabilization of the shoulder joint.

SUPRASPINATUS Origin : n Supraspinous fossa of the scapula. n

SUPRASPINATUS Insertion : n Upper facet of n the greater tuberosity of the humerus and The capsule of • the shoulder joint.

SUPRASPINATUS Action : n 1. It initiates n abduction of the shoulder joint. 2. Rotator cuff. n

INFRASPINATUS Origin : n Infraspinous fossa. n

INFRASPINATUS Insertion : n Middle facet of n the greater tuberosity of the humerus.

INFRASPINATUS Action : n 1. Lateral n rotation. 2. R. C. n

NERVE SUPPLY Suprascapular nerve. n

SUPRASCAPULAR NERVE Origin : n Upper trunk of the n brachial plexus in the posterior triangle.

SUPRASCAPULAR NERVE Course : n It descends behind the suprascapular ligament in company with the suprascapular vessels. Branches : n Supraspinatus, Infraspinatus and Shoulder joint. n

TERES MINOR Origin : n Upper 2/3 of the lateral border of the scapula. n

TERES MINOR Insertion : n Lower facet of n the greater tuberosity of the humerus.

TERES MINOR Nerve supply : n Axillary nerve. n Action : n 1. Lateral n rotation. 2. R. C. n

SUBSCAPULARIS Origin : n Subscapular fossa. n

SUBSCAPULARIS Insertion : n Lesser tubercle of the humerus. n

SUBSCAPULARIS Nerve supply : n Upper & lower n subscapular Action : n 1. Medial rotation. 2. R. C. n n

ROTATOR CUFF TENDINITIS Manifestations : n Spasm n associated with pain in the middle range of abduction. It is a common n cause of pain in the shoulder region.

ROTATOR CUFF TENDINITIS Cause : n Excessive overhead n activity of the upper limb which can cause degenerative changes in the subacromial bursa. This is followed by n degenerative changes in the supraspinatus tendon and extend to the other tendons of the rotator cuff.

TERES MAJOR Origin : n Inferior angle n and lower third of lateral border of the scapula.

TERES MAJOR Insertion : n Medial lip of the bicipital groove of the humerus. n

TERES MAJOR Nerve supply : Lower n subscapular Action : n 1. Adduction. n 2. Medial n rotation. n