Radicular innervation of hindlimb muscles of the rat

In 20 adult rats under Nembutal anaesthesia ventral spinal roots L1-S1 were stimulated in turn and electromyographic responses were recorded from various hindlimb muscles; in addition, the motor and sensory radicular supply of the main hindlimb nerves was examined by their stimulation and recording from ventral and dorsal roots. After averaging the results of individual experiments, the following radicular innervation of different functional muscle groups was found: L2-L5 for hip flexors (iliopsoas), thigh adductors (pectineus, anterior gracilis, adductor magnus) and knee extensors (quadriceps femoris), L3-L6 for hip extensors (gluteal muscles), L3-L5 for knee flexors (biceps femoris, semitendinosus) and ankle flexors (anterior tibial) and L4-L5 for ankle extensors (triceps surae). The femoral nerve is supplied by L2-L5, the obturator nerve by L2-L4, the peroneal nerve by L4-L5 and the tibial nerve by L4-L6 spinal roots. Comparison of the ventral and dorsal roots which supplied a given nerve revealed that the radicular distribution of the afferent fibres in the nerve matched that of the efferent fibres. These results are, in general, in accordance with anatomical data in the literature. However, the radicular supply of some hindlimb muscles in the rat was found to be somewhat more extensive, when evaluated electrophysiologically, than that reported on the basis of anatomical dissection.