Subscapularis

Anatomy

Origin:
Medial two thirds of the costal surface of the scapula.

Insertion:
Lesser tubercle of humerus and anterior of capsule of shoulder joint.

Key Relations:
-Forms much of the posterior axillary wall.
-One of the four muscles of the rotator cuff muscle group.

Functions

-Medially rotates the arm at the glenohumeral joint.
-Adducts the humerus e.g when tucking your shirt into the back of your trousers.
-Contributes to the stability of the shoulder joint with the other rotator cuff muscles.

Supply

Nerve Supply:
Superior and inferior subscapular nerves (C5, C6, C7).

Blood Supply:
Suprascapular, Axillary and Subscapular arteries.

Clinical

Examination of the function of subscapularis is done by a test known as the bear hug test. Ask the patient to flex the forearm and bring the hand of the flexed forearm to rest on the opposite shoulder to the arm in question. If the clinician is able to pull the hand away, the test is positive and subscapularis function is understood to be decreased.

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