Friday, October 31, 2008
14429

Topographic and Microangiographic Anatomy of the Teres Major Muscle – a New Free Functional Muscle Flap?

Goetz Andreas Giessler, MD, Sara Doll, BS, and Guenter Germann, MD, PhD.

The teres major can be seen as an additional head of the latissimus dorsi muscle for extension, adduction and inward rotation of the arm. It gained importance in pedicled muscle transfers for the treatment of plexus palsies and shoulder instability. Its supplying vessels belong to the subscapular system and, according to the literature, the muscle was transferred only once as a free microvascular but nonfunctional graft. The detailed topographic and microangiographic anatomy was investigated to determine the potential use as a free functional muscle flap.

Eleven flaps from fresh cadavers were dissected and perfused with radiopaque media. Three different routes of access to the flap are possible. The mean length of the flap was 158 mm, the distal and proximal tendinous width 24 mm and 52 mm, respectively. A Taylor-type 1 nerve and Mathes-type-1 vessel distribution was found in all specimens. The pedicle is situated in the middle third of the superomedial border of the flap and derives almost exclusively from the circumflex scapular artery. No second pedicle was found in this study. Radioangiograms indicate possible splitting of the muscle both in transverse and longitudinal direction. The nerve could always be isolated to a considerable length (66 mm) before reaching the posterior cord.

This anatomical study indicates, that the teres major can be seen as a separate entity in the subscapular system and can be transferred as a free flap either alone or in combination. As from what is known from pedicled transfers, the donor site morbidity should be expectedly low, if the latissimus dorsi is left intact. According to its anatomical features, the flap may be interesting for upper extremity and plexus reconstructions as well as for tongue reconstruction.