Localization of the Motoneurons Innervating the Forlimb Muscles in the Spinal Cord of the Domestic Fowl

The origins of the motor nerve fibers supplying the individual forelimb muscles were elucidated in the fowl by the retrograde degeneration method. Chromatolytic cells were seen in the ipsilateral lamina 9 of the cervical enlargement. Motoneurons innervating the individual forelimb muscles occupy the restricted area in the lamina 9. The muscles acting on the shoulder joint are supplied by motoneurons of the more cranial segments and the others acting on the elbow and the more distal joints by those of the more caudal ones. The origin of the dorsal cord is situated laterally in the lamina 9 and that of the ventral cord is located medially in it.