NERVUS FACIALIS OF ALBINO MOUSE 85 



lateralis of the vestibular nerve. Anterior to it close to the pons, 

 is the trigeminal nerve. More laterally a thin shell of bone and 

 the geniculate ganglion separate it from the cranial cavity (figs. 

 2, 3, and 9). Posteriorly the facial nerve is overlapped by the 

 vestibular ganglion and is related, farther laterally, to the ampul- 

 lae of the semicircular canals. 



The genu externum lies between the ampullae of the semicir- 

 cular canals and the stapedial artery. The bend is a little more 

 than a right angle. In the dorsal wall of the tympanic cavity the 

 facial nerve lies dorsal to the stapedial artery and the stapes, 

 and lateral to the stapedius muscle. Behind the tympanic cav- 

 ity it bends ventrally and anteriorly with an inclination later- 

 ally, so that as the nerve passes anteriorly it lies ventral to the 

 external auditory meatus. 



From this position the facial nerve passes forward just lateral 

 to the attachment of the cartilage of the auricle to the bone and 

 beneath the parotid gland. Anterior to the meatus it gives off 

 its cervical branches and divides into four parts. 



The branches and distribution of the motor part of the facial 

 nerve can be briefly summarized as follows (fig. 14 A) : 



1. Cervical branches. Four or five small branches arising 

 from the trunk of the nerve and passing ventrally and poste- 

 riorly, some between the lobules of the parotid gland, some be- 

 neath it, to supply the superficial muscle (panniculus carnosus, 

 musculus cutaneus) of the neck and the region superficial to the 

 parotid gland. 



2. Temporopalpebral branches. Branches arising immediately 

 anterior to the preceding and passing anteriorly and dorsally be- 

 neath the parotid gland. These are accompanied by the auric- 

 ulotemporal nerve and are distributed to the muscles anterior 

 to the auricle. One small palpebral branch continues farther 

 anteriorly and ends in the muscles of the upper eyelid. 



3. Buccal branches. Two large branches which compose the 

 greater part of the nerve, the upper being accompanied by a few 

 fibers from the auriculotemporal nerve. These pass in a hori- 

 zontal direction across the cheek, beneath the parotid gland at 

 first, then beneath the cutaneous muscle. Their fibers supply 



