The teres major muscle: An anatomic study of its use as a tendon transfer Angela A. Wang, MD, Robert J. Strauch, MD, Evan L. Flatow, MD, Louis U. Bigliani, MD, and M&in P. Rosenwasser, MD, New York, NY E/even fresh-frozen cadaver shoulders were dissected to define the anatomy of the teres major muscle and tendon and to determine the muscle’s potential for use as a tendon transfer to the humeral head. Of the I I specimens, 7 had Mathes type II circulation. The primary and secondary pedicles, from the circumflex scapular artery, entered the muscle 4.1 cm and 0.5 cm from the scapula, respectively. The lower subscapular nerve entered 4. I cm from the scapula. Mean tendon and muscle lengths were 2.0 and I 7.8 cm, respective/y. As a unipolar transfer, the tendon reached the greater tuberosity in all but 7 specimen. The bipolar transfer offered numerous theoretical possibilities. We believe that the teres major has an appropriate vascu- lar supply and adequate length to make it suitable for ten- don transfer to the humeral head. (9 Shoulder Elbow Surg 1999;8:334-8.) T d en on transfers about the shoulder have long been described in the treatment of obstetric brachial plexus palsy. In 1934, L’Episcopo 15 described the transfer of first the teres major, then the latissimus dorsi tendon to an external rotator insertion point on the humerus in 6 children. Since then, several authors have studied the use of combined latissimus dorsi and teres major ten- don transfers in cases of pediatric high brachial plexus palsy. The results have been generally good with regard to improvement of abduction and external rota- tion of the shoulder.8113J3 Children with a high (Erb’s or C&,) brachial plexus palsy have the basic defor- mity of fixed internal rotation and adduction of the shoulder caused by an imbalance between the internal and external rotators; the upper extremity is in a poor functional position. In such cases of high obstetric brachial plexus palsy, the nerves are damaged and the deltoid, supraspinatus, and infraspinatus muscles are paralyzed; this results in the functional equivalent of a rotator cuff tear. From the Hand and Shoulder Services, Department of Ortho- paedic Surgery, New York Orthopaedic Hospital, Columbia- Presbyterian Medical Center. Reprint requests: Melvin P. Rosenwasser, MD, Department of Orthopaedic Surgery, 622 West 168th Street, PH 1 1 19, New York, NY 10032. Copyright 0 1999 by Journal of Shoulder and E/bow Surgery Board of Trustees. 1058-2746/99/$8.00 + 0 32/l/94925 334 In 1947, Zachary and Leeds27 documented a com- bin-ed latissimus dorsi and teres major tendon transfer in 1 adult patient with an acquired traumatic brachial plexus palsy. In 1988, Gerber et all 1 noted that the deficits of children with high brachial plexus palsy and adults with massive rotator cuff tears were similar; both groups had losses in shoulder abduction and external rotation. They proposed that the functional deficits in adults might be treated with methods analogous to the methods used for children. They were able to transfer the latissimus dorsi tendon to an external rotator loca- tion in the shoulders of 14 adults with good functional results.1 1#12 In adult patients with massive rotator cuff tears, transfer of the latissimus dorsi to an insertion at the greater tuberosity could correct a rotator cuff defect and improve humeral head containment. Furthermore, the transfer could function as a humeral head depres- sor and external rotator either actively or by acting as a tenodesis. Gerber et all 1 also raised the possibility of using the teres major tendon for transfers. They believed the teres major would be desirable as a trans- fer but questioned whether the tendon was too bulky or too short to be effective or safe. The teres major and latissimus dorsi have similar functions during humeral extension, internal rotation, and adduction. In addition, these 2 muscles contract as a unit, as demonstrated by electromyogram stud- ies.14,22 The anatomy of the latissimus dorsi has been well described with respect to its use as a muscle and tendon transfer.zf9 The teres major originates from the inferior angle of the scapula and inserts on the medial lip of the bicipital groove of the humerus, posterior to the insertion point of the latissimus dorsi. It is innervat- ed by the lower subscapular nerve (C&J, originating from the posterior cord of the brachial plexus. The vas- cular supply is thought to derive from the circumflex scapular artery. The teres major borders a quadrangu- lar space that is also bordered by the teres minor, tri- ceps and humerus; the space transmits the axillary nerve and posterior circumflex humeral artery. Cornbe& and Combes and Mansat performed ana- tomic studies of the teres major muscle and believed that the teres major might be useful in aiding external rotation in massive rotator cuff tears. We also believed that the teres major warranted further investigation, and in this article we attempt to delineate its anatomy and assess its potential for use as a tendon transfer to the humeral head.