THE MEDULLA OBLONGATA. 



885 



meatus of the ear. In addition, the region contains the end-nuclei which 

 receive the fibres of the above afferent root cells (the descending stems of the 



A. B. 



FIG. 360. Diagrams to show the situation of the chief nerve nuclei in the medulla 

 oblongata and pons near the floor of the fourth ventricle. A, from behind ; 

 B, profile view of the right half, the medulla and pons being supposed to be 

 transparent. The efferent or motor nuclei are shaded with oblique lines, the 

 afferent or sensory nuclei with dots. In A the efferent or motor nuclei are 

 represented on the right side only, the afferent or sensory on the left. Ill, 

 IV, oculomotor and trochlear nucleus ; Vd, descending root of the fifth nerve ; 

 Vs, so-called sensory nucleus of the fifth ; Va, ascending root of the fifth ; 

 Vm, motor nucleus of fifth nerve ; VI, nucleus of abducens ; VII, nucleus of 

 facial ; n. VII, root of facial curving round abducens nucleus ; VIII., inner or 

 dorsal nucleus of auditory ; VIII', outer or ventral nucleus of auditory ; 

 IX, X, vago-glosso-pharyngeal nucleus; n.a, nucleus ambiguus, accessory 

 or efferent vago-glosso-pharyngeal nucleus ; XI. nucleus of spinal accessory ; 

 XII, nucleus of hypoglossal ; XII', issuing roots of hypoglossal. Schafer 

 (twice the natural size). 



afferent fibres of the vagus, tract, solitarius, partly pass to crossed nuclei, 

 nuc. commissurales, and the end-nuclei also for three other afferent roots. 

 First, for the afferent root cells (in trigeminus), leading from the frontal, ocular, 

 nasal, facial, buccal, and lingual skin; second (GolPs nucleus), for afferent 



