Location of proprioceptive neurons innervating the muscle spindles of the snout muscles in the talpoides

Distribution of sensory ganglion cells innervating facial muscles in the cat. An anatomical study with the horseradish peroxidase technique

The question of a possible sensory component in branches of the facial nerve innervating facial mimetic muscles in the cat was examined by the technique of retrograde axonal transport of horseradish peroxidase (HRP). HRP was applied to the proximal cut end of facial nerve branches innervating different facial muscle groups. Following survival periods of 71-75 h the animals were fixed by perfusion. Certain craniospinal sensory ganglia and the brain stem were processed histochemically for demonstration of HRP. HRP-labelled cell bodies, structurally resembling sensory neurons, were consistently observed ipsilaterally in the geniculate and proximal vagal ganglia and under certain conditions in the trigeminal ganglion. Measurements of HRP-labelled neurons in the geniculate and proximal vagal ganglia showed a wide size range but a unimodal size distribution with peaks in the small size range. These findings support the view that facial nerve branches innervating the mimetic muscles contain different types of sensory fibers.

The seventh cranial nerve of the rat. Visualization of efferent and afferent pathways by cobalt precipitation

The cobalt sulphide precipitation technique, in conjunction with Timm's intensification procedure, was used to delineate the afferent and efferent intramedullary pathways of the seventh cranial nerve complex in the rat. The branchial motor nucleus with the accompanying first part, genu, and second part of the root are described. The motor branches to the superficial facial musculature do not contain fibres of geniculate ganglion origin or fibres which terminate in the spinal trigeminal nucleus. The motor branches to the deep facial muscles arise from the dorsal part of the branchial motor nucleus and traverse to the midline medial to the genu, then project under the genu into the lateral reticular formation before exiting with the facial nerve. The salivatory and lacrimal nuclei and their intramedullary pathways are described. Sensory fibres from the cutaneous auricular branch enter the spinal trigeminal tract and most of the chorda tympani gustatory fibres enter the fasciculus solitarius. A smaller number of gustatory fibres extend medially to the region of the salivatory nucleus. Fibres of greater superficial petrosal origin also enter the fasciculus solitarius as well as the medial reticular formation. These findings are discussed in relation to previous anatomical, physiological and clinical reports.