Subscapularis

Subscapularis muscle
Subscapularis muscle (in red). Ribs are shown as semi-transparent.
Details
Origin	Subscapular fossa
Insertion	Lesser tubercle of humerus
Artery	subscapular artery
Nerve	Upper subscapular nerve, lower subscapular nerve (C5, C6)
Actions	Internally (medially) rotates humerus; stabilizes shoulder
Identifiers
Latin	Musculus subscapularis
TA	A04.6.02.012
FMA	13413
Anatomical terms of muscle []

The subscapularis is a large triangular muscle which fills the subscapular fossa and inserts into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint.

It arises from its medial two-thirds and from the lower two-thirds of the groove on the axillary border (subscapular fossa) of the scapula.

Some fibers arise from tendinous laminae which intersect the muscle and are attached to ridges on the bone; others from an aponeurosis, which separates the muscle from the teres major and the long head of the triceps brachii.

The fibers pass laterally and coalesce into a tendon which inserts into the [lesser tubercle]] of the humerus and the anterior part of the shoulder-joint capsule. Tendinous fibers extend to the greater tubercle with insertions into the bicipital groove.

The tendon of the muscle is separated from the neck of the scapula by a large bursa, which communicates with the cavity of the shoulder-joint through an aperture in the capsule. The subscapularis is separated from the serratus anterior by the subscapularis (supraserratus) bursa.

Innervation to subscapularis is supplied by the upper and lower subscapular nerves, branches of the posterior cord of the brachial plexus. (C5-C7)