olfactory nerve 



olfactory bulb 



cerebrum 



pineal body 

 hobenulo 

 optic lobe 



pituitary 



X-XI 



medulla oblongata 



olfactory nerve 



chorioid plexus in 

 cerebral ventricle 

 paraphysis 

 supracommissure 



pineal body 

 posterior commissure 

 midbrain 

 cerebellum 



endolymphatic sac 



"1st spinal nerve 



B 



Figure 13-6. The brain and cranial nerve roots of Necfurus. A, dorsal view; B, ventral view; 

 C, medial view of rigtit half. (In part after McKibbin, 1913) 



rans. This branch, along with buccal and mental branches, 

 serve the sensory lines. The superficial ophthalmic branch 

 of the trigeminal is small or lacking. These branches are 

 comparable to those observed in the fishes and are lacking 

 in the amniotes. Sensory-line branches of the ninth and 

 tenth nerves are also present. 



In the mammals, birds, reptiles, and anurans, the trunk 



of the seventh nerve passes back above the stapes and then 

 down behind that bone. The internal mandibular branch, 

 the chorda tympani. passes forward above the stapes (or 

 columella) and then down to the mandible in all of these 

 except the anurans in which it passes forward below this 

 bone. In the urodeles the seventh nerve root passes below 

 the stapes in most salamanders and Cryptubranchus (Figure 



pineal body 

 epidermis- ' " ' Jl ' ' '-, " l" 



bone 



pineal nerve 



paraphysis 



soccus dorsalis 



habenular commissure 



foramen of Monroe 



pallial commissure 



anterior commissure 



cavities of epiphysis (pineal) 

 optic lobe 

 posterior commissure (dashed outline) 

 subcommissural organ 



trochlear chiosmo 

 cerebellum 



chorioid plexus 



aquaeduct of Sylvius 

 pars nervosa of pituitary 



preoptic recess 



optic chiosmo 



infundibulum^ °"'^^'°^ '°b^ °' P''"''°'>' 

 Figure 13-7. Medial view of right half of frog's brain. (In port after Oksche, 1960) 



390 



THE NERVOUS SYSTEM 



