The subscapularis muscle and its glenohumeral ligament-like bands. A histomorphologic study.

The subscapularis muscle and the distribution of its tendinous bands is of significance in the surgical management of the shoulder joint. This distribution pattern has not been previously described in detail. We feel that, in any anterior approach to the glenohumeral joint for fracture fixation, joint replacement, and soft tissue reconstruction, a thorough understanding of the distribution pattern of the subscapularis bands is essential. We examined the subscapularis muscles from five cadavers. Four sections from the lateral one-half of each muscle were custom-mounted and stained with Masson's trichrome. We found a consistent pattern in which the tendinous bands were evenly interspersed in the midportion of the muscle and condensed laterally into a single large, flat tendon in the superior two-thirds of the muscle. The inferior one-third remained muscular. Understanding this pattern should help the surgeon have confidence that he/she has obtained a more secure repair in procedures involving the subscapularis muscle.