Lateral cervical nucleus of the dog: anatomical and microelectrode studies

¹ Department of Anatomy, Wayne State University School of Medicine, Detroit, Michigan

The lateral cervical nucleus (LCN) of the dog (Canis familiaris) was investigated by histological and microelectrode technique. The LCN extends from the obex to the upper C₃ and is located ventrolateral to the dorsal horn. Cell counts showed over 6,000 cells in the nuclei on both sides and the cell size varied from 20 to 45 µ. Single-unit analysis of the 220 neurons showed that the majority of cells responded to touch, some to pressure, some to pressure and touch, and an extremely limited number to joint movement. All responses were recorded from the ipsilateral half of the body. More than half of these neurons had small peripheral receptive fields located mostly in the distal parts of the limbs. The rest, with large receptive fields, were located mainly in the proximal parts of the limbs and the trunk. The peripheral receptive fields were almost equally distributed among the forelimb, trunk, and hindlimb for touch. The prominence of the hindlimb representation over the forelimb was found for pressure and for touch and pressure. The results indicate that the organization of the afferent input to the LCN has some similarity to that of the medial lemniscus system.

Key Words: spinal afferents

Submitted on January 15, 1965