The central projections of the great auricular nerve primary afferent fibers — an HRP transganglionic tracing method

Abstract

A study of the central distribution of the primary afferent fibers of the great auricular nerve (GAN) was made in 18 rabbits by means of transganglionic transport of horseradish peroxidase (HRP), HRP applied in the cut central end of the GAN was detected ipsilaterally in the dorsal root ganglion cells (segments C 2-C 3) and the superior cervical ganglion cells. The transganglionically labeled fibers were seen in the dorsal column of the upper 4 cervical segments and in the cranial nerve nuclei of the medulla oblongata. The afferent projections were rather strong in the regions of laminae I–V of C 2, the caudal subnucleus of the spinal tract of the trigeminal nerve (NVSpc), the solitary nucleus (SN), the medial and lateral cuneate nuclei etc. The results showed that the primary afferent impulses of the GAN and the peripheral nerves which supply the head, face, trunk and viscera might converge on the upper cervical cord, the NVSpc and the SN, and play a certain role of modulation on the transmission of somaticovisceral sensations, especially pain.