Abstract
Spinal cord projections of the lower intercostal nerve in the rabbit were studied by axonal transport of wheat germ agglutinin conjugated horseradish peroxidase (WGAHRP) . To label the spinal motoneurous, WGA-HRP was injected into two intercostal nerve branches : the medial and lateral branches of the intercostal nerve (MIIC and LIIC) . The locations, numbers, and soma sizes of 316 labeled motoneurons were analyzed. Reaction products were identified in the spinal cord from one and a half segments rostral to half a segment caudal to the entry zone. No reaction products were found on the contralateral side. Labeled motoneurons containing dense granular reaction products and their dendritic processes were located in the lateral portion of the ventral horn gray matter. Labeled nerve fibers were recognized in laminaVII. Soma diameters ranged between 8, em and 50μm. The following conclusions were drawn: 1) Similar to the upper intercostal nerve, the LIIC nerve contains motor fibers that originate from ventral horn motoneurons. 2) Unlike the upper intercostal nerve, the lower one contains inhibitory nerve fibers. 3) Clinically, it is suggested that the lower intercostal nerve also be utilized for reconstruction of brachial plexus injury.
