Motor-end-plate and nerve distribution in a histochemically compartmentalized pennate muscle in the cat.

Previous investigations in this laboratory have shown the flexor carpi radialis muscle (FCR) of the cat to be compartmentalized with regard to the distribution of muscle fiber types. This study was undertaken to determine whether each compartment of the FCR had a distinct motor innervation band, or whether there was only one innervation band, as has been reported previously for other muscles. In order to assess variation in motor innervation banding patterns, the innervation bands were correlated with the muscle-tendon architecture. Each compartment of the FCR possessed a distinct innervation band. In addition, it was observed that the nerve to the FCR divided into a number of separate intramuscular branches which were distributed to the different histological compartments. It is possible that muscle fibers innervated by a single intramuscular nerve branch, and possessing a discrete innervation band, are locally organized within subdivisions of the FCR. It is hypothesized that the compartmental organization of the FCR would allow discrete regions of the muscle to function independently when performing different motor tasks.