1262 



HUMAN ANATOMY. 



within the dorsal nucleus and the nucleus ambiguus. The fibres proceeding from the dorsal nu- 

 cleus are distributed to involuntary muscle ; hence the nucleus is sometimes called the sympathetic 

 motor. Those taking origin from the nucleus ambiguus supply voluntary muscle and pass at first 

 toward the floor of the fourth ventricle ; they then abruptly change their direction by bending out- 

 ward and, joining the fibres arising from the dorsal motor nucleus, proceed ventro-Iaterally through 

 the gray reticular formation, just ventral to or across the spinal root of the trigeminus, to emerge 

 at their superficial origin along the bottom of the postolivary sulcus, incorporated with the 

 afferent fibres in the five or six root-fasciculi forming the entire ninth nerve. The cortical con- 

 nections of the motor fibres are established by cortico-bulbar fibres that arise from cells situated 

 within the gray matter of probably the lower part of the precentral gyrus. After traversing 

 the motor path through the corona radiata, internal capsule, cerebral peduncle and pons, the 

 cortical fibres end, on reaching the upper level of the medulla, in arborizations around the motor 

 root-cells chiefly of the opposite side. 



Fig. 1074. H 



Branch of supraorbital nerve 

 Supraorbital nerve 



Olfactory bulbs 



Optic nerve 

 lotemal carotid artery 



Optic chiasm 



V. nerve, sensory 

 root 



Cerebral peduncle 



Middle peduncle of 

 cerebellum 



IX..X.andXI. 



nerves 



Lachrymal gland 



Supratrochlear nerve 

 Superior rectus muscle 

 Levator palpebrae superioris 

 Lachrymal nerve 



IV. nerve 



Ophthalmic ner\'e at 

 poini of division 



Maxillary nerve 

 IV. nerve 



XII. nerve 



Mandibular nerve 



VII. nerve, motor part 

 Pars intermedia 



VIII. nerve 



Superior peduncle of 

 cerebellum, cut 



IX., X. and XI. nerves 



Floor of IV. ventricle 



■Spinal portions of XI. nerves 



Interior aspect of base of skull, viewed from above and behind, showing particularly posterior group of cranial 

 nerves passing from brain-stem to points of emergence through dura ; posterior part of skull has been removed. 



Central Connections of the Sensory Part of the Glosso-Pharyngeal Nerve. — The afferent 

 or sensory fibres of the glosso-pharyngeal nerve are the axones of cells within the jugular and 

 petrous ganglia situated along the upper part of the nerve-trunk. Entering the skull through 

 the jugular foramen, the sensory fibres approach the brain-stem in the five or six delicate root- 

 bundles that reach the medulla along the groove between the olivary eminence and the inferior 

 cerebellar peduncle. Passing to the ventral side of the spinal root of the trigeminus, or 

 traversing this field, in company with the motor fibres, the afferent fibres continue dorso- 

 mesially through the formatio reticularis grisea towards the dorsal nucleus. Just before reach- 

 ing the latter, however, the sensory fibres separate into two groups, a medial and a lateral. The 

 first and smaller of these continues its course to the dorsal sensory nucleus, around the cells 

 of which its fibres end. It is probable that the cells constituting the upper groups of the dorsal 

 sensory nucleus are particularly concerned in receiving the impulses of common sensation from 

 the middle ear, pharynx, tonsils, and posterior part of the tongue and mouth. The second and 

 much larger group turns outward and abruptly downward to form the chief constituent of 

 the spinal tract, the fasciculus solitarius. In transverse sections (Fig. 927) the latter appears 

 as a conspicuous, compact, rounded bundle that lies lateral to the dorsal nucleus and 

 behind the strands of root-fibres. The solitary fasciculus is accompanied throughout its course 

 by a slender column of gray matter, which lies partly on the surface of. the bundle and partly 



