Central projections of the radial nerve and of one of its cutaneous branches in the pigeon.

After horseradish peroxidase (HRP) treatment of the radial nerve and of a cutaneous branch of this nerve, dense labeling of afferent terminal fields was found in laminae I-III of the dorsal horn of the spinal segments C11 and C12. However, treatment of the cutaneous branch labeled only lateral parts of the dorsal horn. This points to a distinct somatotopy. Labeling was also observed in the dorsal column nuclei and a rostral terminal field near or within the pars interpolaris of the descending trigeminal system. No labeling was observed after dorsal rhizotomy.