ANATOMICAL PARTITIONING AND NERVE BRANCHING PATTERNS IN THE ADULT-RABBIT MASSETER

The masseter muscle is functionally heterogeneous with a complex archi tecture consisting of multiple tendons and a multipennate arrangement of muscle fibers. In this study, the anatomical partitioning of the ra bbit masseter is described on the basis of the tendons of origin and i nsertion, general partition orientation relative to the zygomatic arch , motor endplate descriptions, and primary nerve branches that innerva te these partitions. This work refines previous descriptions of the ra bbit masseter and describes 13 anatomical partitions, each with a uniq ue tendinous attachment. In addition, 14 naturally occurring primary n erve branches were identified and found to innervate different regions of the muscle, After correlating the anatomical partitions and the as sociated neural innervation pattern, it was determined that simple bra nch order will not adequately define all the neuromuscular compartment s in the rabbit masseter.