306 THE RHOMBENCEPHALON. 



The nucleus alee cinerece of the vagus and glossopharyngeal 

 nerves (Fig. 93) contains in its lateral part a group of small fusi- 

 form cell-bodies like those in the posterior columna. These 

 fusiform cells constitute the terminal nucleus of the sensory fibers 

 of the vagus, and it is probable that a few glossopharyngeal fibers 

 also arborize and end in the nucleus. Cortical Connection. 

 Axones of this nucleus probably enter into the medial fillet, the 

 spino-thalamic tract and the medial longitudinal bundle. The 

 two former conduct tactile, muscular, pain and temperature impul- 

 ses to the thalamus, whence the cortical fillet carries them to the 

 cortex; the latter establishes its reflex connection with motor 

 nerves. 



Nucleus Tractus Solitarii (Figs. 92 and 94). The nucleus of 

 the solitary tract surrounds the tractus solitarius with which it 

 coincides in extent. It is gelatinous in appearance and is situated 

 just lateral to the nucleus of the ala cinerea. In its descent it 

 trends dorsally and toward the median line. It is joined to the 

 opposite nucleus, at its spinal end, by the nucleus commissuralis 

 (Cajal). The nucleus of the solitary tract is the terminal nucleus 

 of the afferent fibers of the intermediate and glossopharyngeal 

 nerves and, probably, receives a few fibers from the vagus. It is 

 thus the nucleus of the nerves of taste and forms the first relay 

 station in the gustatory path. The axones of the cell-bodies in 

 the nucleus tractus solitarii establish reflex connections with effer- 

 ent nuclei and continue the taste path toward the thalamus, but 

 their exact course has not been worked out. 



Nucleus Tractus Spinalis Nervi Trigemini (Figs. 92 and 95). 

 The nucleus of the spinal tract of the trigeminal nerve is gelatinous 

 in character. It is continuous with the sensory pontine nucleus 

 of the trigeminal nerve, above; and, below, is continued in the 

 gelatinous substance of the posterior columna of the spinal cord. 

 As low down as the second cervical segment it receives fibers 

 from the trigeminal nerve, so the terminal nucleus of this nerve 

 extends from the middle of the pons to the second cervical nerve. 

 The nucleus of the trigeminal is embraced between the emergent 

 part of the facial nerve, medially, and the vestibular nerve, later- 

 ally, in the lower portion of the pons; in the upper medulla, the 



