| Subscapularis muscle | |
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| Deep muscles of the chest and front of the arm, with the boundaries of the axilla. (Subscapularis visible near center top.) | |
| Latin | musculus subscapularis |
| Gray's | subject #123 440 |
| Origin | subscapular fossa |
| Insertion | lesser tubercle of humerus |
| Artery | transverse cervical artery, [1] subscapular artery |
| Nerve | upper subscapular nerve, lower subscapular nerve (C5, C6) |
| Actions | rotates medially humerus; stabilizes shoulder |
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.
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Origin and insertion
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 laminæ 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 lateralward, and, gradually converging, end in a tendon which is inserted into the lesser tubercle of the humerus and the front of the capsule of the shoulder-joint.
Relations
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.
Innervation
Innervation to subscapularis is supplied by the upper and lower subscapular nerves, branches of the posterior cord of the brachial plexus.
Actions
The Subscapularis rotates the head of the humerus medially (internal rotation); when the arm is raised, it draws the humerus forward and downward. It is a powerful defense to the front of the shoulder-joint, preventing displacement of the head of the humerus.
Injury diagnosis
The Bear Hug test (internal rotation while palm is held on opposite shoulder and elbow is held in a position of maximal anterior translation) for Subscapularis muscle tears has high sensitivity. Positive Bear-Hug and Belly Press tests indicate significant tearing of subscapularis.[1]
Additional images
 Diagram of the human shoulder joint |
 Left scapula. Costal surface. |
 Left humerus. Anterior view. |
 The axillary artery and its branches. |
References
- ^ "Tufts". http://iris3.med.tufts.edu/headneck/Triangles/Posterior%20Triangle%20of%20the%20Neck.htm. Retrieved 2007-12-11.
External links
- LUC subs
- Subscapularis+muscle at eMedicine Dictionary
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
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