I.] THE FROG. 109 



and under the jugal, to reach the outer side of 

 the mandible. 



/>. The facial nerve. Its hyoid branch ; seen on dis- 

 secting away the membrana tympani and outer 

 end of the columella auris. It leaves the skull 

 immediately behind the squamosal and passes 

 downwards and backwards, giving off 

 a. A small branch to the integument of the cheek 



(in close apposition with the jugal bone). 

 /?. A mandibulo-hyoid branch ; continued along the 

 inner face of the mandible, and giving off nerves 

 to the muscles and skin adjacent. (Be careful 

 not to confuse these with the branches of the 

 mandibular nerve.) 



c. The Qth and i2th (cf. 4); the former will be 

 seen to pass internally, the latter externally, to 

 the anterior cornu of the hyoid. Remove the 

 hypoglossal with care, thus laying bare 



d. The loth (vagus). Seen to pass downwards and 

 backwards, externally to the posterior cornu of 

 the hyoid. At the side of the gullet it breaks up 

 into the under-mentioned 



a. The gastric rami ; two or more in number, dis- 

 tributed to the stomach. They pass through 

 the so-called diaphragm. 



(3. The pulmonary ramus, to the lung; accom- 

 panying the pulmonary artery. 



y. The cardiac ramus, to the heart; arising in 

 front of /? and coursing along the dorsal wall 

 of the atrium. (Sympathetic fibres are bound 

 up with this, if not with a and /? also.) 



