Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: S: Subscapularis

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Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: S

Subscapularis

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed

The most important variation is an additional muscle, subscapularis minor or s. secundus, which arises from the upper part of the axillary border of the scapula and is inserted into the capsule of the joint, onto the crest of the lesser tubercle of the humerus, or somewhat below the lesser tubercle. It was found by Gruber in 10 of 200 limbs.

A rarer variation is a slip arising from the subscapular tendon and passing to the axillary fascia and skin at the base of the axilla. A slip connecting subscapularis to pectoralis major has been observed and sometimes the tendon is connected to the short head of the biceps muscle.

Other variants include tensor capsulae (Schwegel) , which arises from an accessory process below the lesser tubercle, crosses the tendon of subscapularis, and inserts into the joint capsule; and glenobrachialis (Gruber), which arises with the long head of the biceps from the supraglenoid tubercle of the scapula and inserts onto the surgical neck of the humerus. Gruber saw this variation once in 380 cases studied.

Confusion often occurs when a variant has too many names. For example, Theile, Otto, and Gruber named the tensor capsulae (Schwegel), the Deltoideus profundus, later Gruber called the same variant, the depressor which is synonomus (s.) with retinaculum musculare tendinis subscapularis majoris and capsularis humero-scapularis superior and finally, Macalister named the same muscle coraco-capsularis. No criticism is meant here only the difficulty in communication leading to the profusion of names that appeared because of the intense interest and work that was "a la mode" at that time (middle 1800's).

Syn.: m. infrascapularis, immersus, Unterschulterblattmuskel, Vorderschulterblattmuskel (Arnold), Sous-scapulaire.

References

Gruber, W. (1857) Die Muscull subscapulares (Major et Minor) und die neuen supernumerären Schulter-muskeln des menschen. Máemoires de I'Acadáemie Impáeriale des Sciences de Saint Páetersbourg par Divers Savans et Lus dans ses Assembláees 8(Mai 1):220-258.

Henle, J. (1871) Handbuch der Muskellehre des Menschen, in Handbuch der systematischen Anatomie des Menschen. Verlag von Friedrich Vieweg und Sohn, Braunschweig.

Macalister, A. (1875) Observations on the muscular anomalies in the human anatomy. Third series with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci. 25:1-130.

Miyasawa, Y. (1956) One case of the M. subscapularis minor. Tokyo Jikeikai Ikadaigaku Kaibogaku Kyoshitsu Gyosekishu 14:1-4. In Japanese.

Paterson, A.M. (1916) The subscapularis muscle. J. Anat. Physiol. 46:11.

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