Purpose: The serratus anterior muscle allows independent orientation to produce different force vectors because several individual muscle slips can be transferred on one vascular pedicle. Our study of intramuscular anatomy demonstrates this possibility.

Method: Muscle slips 5-9 (and 10, if present) in 50 specimens in 27 cadavers were studied following intra-arterial latex injection. Eight specimens were injected with radiopaque material for x-ray delineation of intramuscular vascular pattern.

Results: Slips 5-9 are supplied by a single dominant branch of the thoracodorsal artery and innervated by the long thoracic nerve, which with its branches invariably followed the artery and divided proximal to the corresponding arterial division. The vascular pattern is consistent: the serratus artery gives rise to common slip arteries, each of which supplies adjacent muscle slips. The mean length of a muscle slip from its origin on the rib periosteum to the division of the common slip artery is 9.6cm.

Conclusions: Slips may be separated to the level of these common slip arteries, transferring up to five slips on a single neurovascular pedicle, with each slip oriented independently to provide multiple muscle force vectors. This may make possible restoration of more natural facial animation and better upper extremity intrinsic muscle function.