Discussion Detailed Neurovascular Anatomy of the Serratus Anterior Muscle: Implications for a Functional Muscle Flap with Multiple Independent Force Vectors Discussion by Rudolf F. Buntic, M.D., and Harry J. Buncke, M.D. San Francisco, Calif. Dr. Godat and his coauthors have reported new details of the serratus muscle vascular and neural anatomy. Using 50 cadaver muscles, the authors set out to clarify the anatomy of the arterial and neural patterns of the lower slips of the serratus, a muscle flap frequently used in microsurgical reconstruction since 1982. 1 Al- though much of the gross anatomy to the lower slips of the serratus has been described, 2–4 the authors correctly point out that the intramus- cular neurovascular anatomy has not been fully defined. The authors examined fresh cadavers with in situ and ex vivo latex injections and dissection of the neurovascular pedicle and lower muscle. They looked at the clinically important slips 6 through 9 (or 10 when present) to reveal in- tramuscular arterial anatomy. Dissections of the specimens were thorough, performed un- der both loupe and microscopic magnification. Numerous data points were collected and su- perb photographs are presented. To explain the results and avoid confusion, the authors defined their terminology exactly in a table. Arterial inflow was demonstrated to be present to paired muscle slips, arising from a “common slip artery,” with each individual slip receiving flow from a “proper slip artery.” Their analogy to hand anatomy is an exquisite one. Nerve anatomy was also consistent, with a pattern mimicking the arterial “common slip” and “proper slip” supply. They noted that two to five slips could be separated to the level of the common slip artery. Fundamentally, the authors demonstrated a consistent pattern of arterial and nerve anat- omy at the slip level of the serratus. This find- ing is consistent with a smaller study using human cadavers and sheep. 5 The serratus mus- cle has potential for the development of a more complex multivector functional muscle, or a simpler single-slip functional serratus. We have similarly separated the gracilis muscle lon- gitudinally into two vector units with indepen- dent motor fascicles for facial reanimation. 6 Certainly, using the added details of the serra- tus intramuscular nerve and arterial anatomy, the muscle can be thinned more aggressively on initial transplantation. We were impressed with the thoroughness of the study, the precise definitions of terminology, and the capture of hand anatomy concepts to explain new find- ings in a chest muscle. This was a logical ap- proach. The simple and precise terminology will be beneficial to other investigators exam- ining the detail of serratus muscle and function. The gracilis muscle has become the pre- ferred choice for facial reanimation. Dissection is straightforward, there is segmental innerva- tion with fascicular dissection, the muscle is amenable to intraoperative thinning and there is minimal donor-site morbidity. However, no donor has been ideal for facial reanimation, as evidenced by the numerous muscles that have been used, including the latissimus, 7–9 rectus, 10 rectus femoris, 11 abductor hallicis, 12 pectoralis minor, 13,14 and extensor brevis. 15 The facial expression muscles work together in a complex arrangement to produce expres- sion that is not adequately reconstructed with a single muscle vector. For this reason, surgeons From the Buncke Clinic and the Division of Microsurgery, California Pacific Medical Center, Davies Campus. Received for publication August 27, 2003. DOI: 10.1097/01.PRS.0000129073.11466.8A 30