The ideal donor muscle for facial and hand reanimation has yet to be found. Donors commonly used today, such as gracilis and pectoralis minor, are limited by bulkiness. In addition, they can provide a maximum of three force vectors. In our study of 50 fresh cadaver serratus anterior muscles, we further describe neurovascular anatomy of the muscle slip (portion of the muscle which inserts on a rib) and subslip (superficial or deep subdivision of the slip after division along a loose areolar plane). All 260 slips could be separated into a deep and superficial subslip yielding a total of 520 subslips. A branch of the serratus artery (a terminal branch of the thoracodorsal artery serving the lower 5-7 slips of the muscle) and a branch of the long thoracic nerve were identified for each of these. Deep subslips were thinner than superficial subslips both at the origin of the slip on the rib periosteum (2.4mm versus 3.0mm, p<0.0001, paired t-test) and centrally at the serratus artery (3.3mm versus 4.0mm, p<0.0001, paired t-test). In addition, the subslips of the most inferior slip were thinner than those of more superior slips both at the origin of the slip (2.3 versus 2.8, p<0.0001 by student’s t-test) and at the serratus artery (3.0 versus 3.8, p<0.0001, student’s t-test). Fine anastomosing vessels were present between the slips and subslips. Over 75% of these occurred in the central third of the muscle (determined by mean total length of the slip). An average of 1.7 anastomosing vessels were present between adjacent slips and 2.1 between the subslips of a given slip. Given the thinness of these vessels (all < 0.2mm) compared to those of the vascular pedicle of the subslip (mean 0.7mm, all > 0.4mm), we believe these can be safely divided without compromising subslip vascularity. After division of these vessels a mean length of 9.6 +/- 1.5 cm is available to allow independent orientation of each subslip. By separating the serratus muscle flap into its component subslips, a maximum of 10 possible force vectors may be transferred on a single vascular pedicle. Subslips are significantly thinner than donor muscles commonly used today. These two advantages offer the potential for significant functional and aesthetic improvement when the serratus anterior muscle flap is used for face and hand reanimation. Mimetic muscles such as the orbicularis oculi and orbicularis oris could possibly be reconstructed in their proper anatomic position.