PRIMORDIAL CRANIUM OF THE CAT 315 



It stretches across the lateral wall of the cochlear capsule, beween 

 the geniculate ganghon and a plexus of nerves about the internal 

 carotid artery. In the plexus it joins the N. pterygoideus Vidi- 

 ani (fig. 3). Leaving the region of the geniculate ganglion the 

 facial nerve enters upon the second part of its cranial course. It 

 undergoes first its characteristic bend and then passes nearly 

 straight caudad, lying for a short distance upon the prominen- 

 tia utriculoampullaris superior, then enters the sulcus facialis. 

 Above the nerve is the lateral semicircular canal, separated by a 

 floor of thick cartilage from the sulcus faciahs. Continuing its 

 course, backward through the groove, the nerve crosses dorsad 

 of the incudo-stapedial articulation, separated from the vestib- 

 ular window and basis stapedis which he ventrad. Passing be- 

 neath and laterad of the origin of the stapedius muscle (origi- 

 nates from the roof and lateral wall of the sulcus facialis) to 

 which it suppUes a twig, the facial reaches the base of Reichert's 

 cartilage, where, bending sharply ventrad it leaves the groove. 

 The term foramen stylo-mastoideum primitivum has been given 

 by Broman ('99) to the exit from the sulcus facialis bounded by 

 the upper, proximal division of Reichert's cartilage and the ear 

 capsule. After passing the confines of this ill defined foramen 

 (fig. 19) the facial nerve descends upon the caudal vside of Reich- 

 ert's cartilage and leaves the otic region. 



At the side of Reichert's cartilage the facial nerve gives off 

 its chorda tympani branch (figs. 2, 22). This stout nerve winds 

 about the lateral side of Reichert's cartilage, ascends somewhat 

 and, tm-ning mesad and cephalad, enters the region of the first 

 pharyngeal pouch. Here it lies at first upon the medial surface 

 of the manubrium of the cartilaginous malleus, ventrad of the 

 insertion of the M. tensor tympani and of the incudo-stapedial 

 articulation. Proceeding forward it passes out of the t>anpanic 

 region, following closely the medial and ventral surface of 

 Meckel's cartilage. 



Acustic nerve. Two chief branches were present, an anterior 

 and posterior. The anterior ramus gives a twig to the recessus 

 utricuU, one to the ampulla anterior, another to the ampulla 

 externa. The posterior ramus gives rise to a ramulus sacculi, a 



