THE CRANIAL NERVES 



647 



reflex reaction. This lower center is intimately connected with the 

 path for tactile and auditory sensations by way of the neighboring 

 cerebral peduncle and is closely associated with the nuclei of the third 

 and fourth cranial nerves. Connection is also made here with the 

 other cranial and spinal nerves by way of the fasciculus longitudinalis 

 medialis, 



3. The oculomotor nerve arises from the oculomotor nucleus 

 situated in the central gray matter near the floor of the aqueduct of 



FIG. 320. DIAGRAM OF THE PRINCIPAL COMPONENTS OF THE OPTIC APPARATUS. 



(Cunningham.) 



Sylvius. The latter is composed of three groups of cells, namely, 

 (a) a lateral colony of large ganglion cells situated next to the median 

 line below the aqueduct, (6) a smaller median colony consisting of large 

 cells, and (c) a median colony composed of much smaller cells. This 

 nerve is motor in its function and embraces fibers for: 



(a) The internal rectus, superior rectus, inferior rectus and inferior oblique 

 muscles of the eye. According to Bernsheimer, l these fibers arise in the group of 

 cells constituting the lateral subnucleus. The coordination of these muscles with 

 those of the opposite eyeball, is not under the guidance of the will. This nerve 

 also innervates the muse, levator palpebrse superioris. 



1 Handbuch der Augenheilkunde, Leipzig, 1900. 



