Atlas of Human Anatomy by Netter

FACTS & HINTS

HIGH-YIELD FACTS

Clinical Points
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page 219

Fracture of the Clavicle

Common, especially in children

Usually results from a fall on outstretched hand or direct trauma to the shoulder

Fractures of middle third are most frequently seen

Sternocleidomastoid muscle pulls the proximal fragment superiorly and the shoulder pulls the distal fragment inferiorly

Small lump may remain after the clavicle has healed

Calcific Supraspinatus Tendonitis

Inflammation and calcification of the subacromial bursa resulting in pain, tenderness and limitation of movement of the shoulder joint

Calcium deposits frequently also seen in the supraspinatus tendon

Pain is especially severe with the arm abducted between 50 to 130 degrees (the painful arc) as the supraspinatus tendon is in contact with

the inferior surface of the acromion here

Shoulder Dislocation

High mobility and instability of the glenohumeral joint leads to frequent dislocation

95% of dislocations are in anteroinferior direction, caused by excessive extension and lateral rotation of humerus (e.g., in the throwing

motion)

Humeral head places stress on joint capsule, which may be torn anteriorly, with elements of the rotator cuff

Axillary and musculocutaneous nerves may also be injured

Posterior dislocation is uncommon, but may occur during epileptic seizure or electrocution

Rotator Cuff Injury

Musculotendinous rotator cuff may be damaged by trauma or degenerative disease

One or more of tendons may be torn when the arm is forcefully abducted, leading to pain in the anterosuperior aspect of the shoulder

Supraspinatus tendon is most commonly involved in degenerative tendonitis

Leads patient's arm to drop suddenly at approximately 90-degree abduction, when instructed to lower it slowly from a fully abducted position

MNEMONICS

Memory Aids

Rotator cuff muscles: SITS = Supraspinatus, Infraspinatus, Teres minor, Subscapularis