THE PERIPHERAL NERVOUS SYSTEM. 373 



nerve which leaves the caudal angle of the sphenopalatine 

 ganglion and passes caudad. It enters the orbital fissure, lying 

 in a groove on its ventral wall (the cranial end of this groove 

 is sometimes converted into a canal). The groove ends 

 caudally in a foramen which pierces the sphenoid bone between 

 the wing and the body and lies just mediad of the foramen 

 rotundum. The groove and foramen constitute the pterygoid 

 canal (from which the nerve is named). After emerging from 

 the pterygoid canal onto the ventral surface of the basisphenoid 

 the nerve enters the tympanic bulla along with the Eustachian 

 tube, lying on the medial side of the latter. Just after enter- 

 ing, on reaching the internal carotid artery, it divides into two. 

 One of these, N. petrosus superficialis major (p. 375), passes 

 into the hiatus facialis of the petrous bone and joins the facial 

 nerve. The other, N. petrosus profundus, accompanies the 

 internal carotid artery caudad, turning therefore out of the 

 bulla and passing caudad along its medial side ; it finally joins 

 the superior cervical ganglion of the sympathetic system. 



3. N. mandibularis. The third division of the fifth, the 

 mandibular nerve, takes origin by a strong root from the 

 semilunar (or Gasserian) ganglion, and receives also after 

 separating from the ganglion the smaller ventral root (pdrtio 

 minor) of the fifth nerve. The root from the ganglion is sen- 

 sory; the smaller root is motor, so that the mandibular nerve 

 is both sensory and motor. The nerve passes through the 

 foramen ovale, and sends off at once the following branches : 



a. N. auriculotemporalis (Figs. 154 and 155, ). This 

 passes dorsad between the cartilaginous auditory meatus and 

 the zygomatic process of the temporal bone (Fig. 154, ?z), 

 emerges at the caudal border of the masseter muscle (Fig. 

 155, ), and divides into two chief branches. One, the auric- 

 ular branch, passes along the cranial side of the external ear 

 and is distributed to its integument. The other, the temporal 

 branch, passes along the zygomatic arch, gives branches to the 

 temporal muscle and to the skin, follows the zygomatic arch 

 almost to the angle of the mouth, and anastomoses with the 

 superior buccal branch of the facial (Fig. 155, K). 



