724 



THE NERVOUS SYSTEM OF THE DOG 



The sympathetic system of the ])i<>; has received veiy little attention from 

 anatomists. The superior cervical ganglion is long and fusiform. It gives off 

 filaments which join the vagus near the ganglion nodosum. The cervical trunk is 

 short and relatively larger than in the ox; it is inclosed in a common sheath with 

 the vagus in the neck and separates from that nerve to join the middle cervical 

 ganglion at the thoracic inlet. 



THE NERVOUS SYSTEM OF THE DOG 



The spinal cord is almost circular in cross-section except at the well-marked 

 cervical and lumbar enlargements, where it is compressed dorso-ventrally. The 

 conus medullaris lies over the junction of the sixth and seventh lumbar vertebrae. 



Fig. 539. — Bask of Brain of Dog. 

 a. Olfactory bull); a,' a", external and internal 

 olfactory tracts; li, optic nerve; c, oculomotor nerve; 

 d, trochlear nerve; c, trigeminus; /, abducens, u, facial; 

 h, auditory; t, glosso-j)harynKeal; k, vagus; /, spinal 

 accessory; m, hypoglossal; 2, trigonum olfactoriuin; 



5, anterior perforated substance; 4, tuber cinereum and 

 infundibulum; 4' , mammillary body; 5, pyriform lobe; 



6, temporal lobe; 7, i)arietal lobe; 8, frontal lobe; 9, 

 pons; 70, medulla oljlongala; //, cerebellum; 7;?, cere- 

 bral peduncle; IS, occijjital lobe. (EUenberger-Bauin, 

 Anat. d. Hundes.) 



Fig. 540. — Brain Stkm of Doo, Dorsal View. 

 a. Spinal cord; b, dorsal median groove; c, c\ 

 funiculus gracilis; c",clava; ri,d', funiculus cuneatus; d", 

 t\iberculum cuneatuin; e, funiculus lateralis; r' , tuber- 

 culum Rolandi; /, medulla oblongata; /,//,///, floor of 

 fourth ventricle (fossa rhomboidea) ; (/, limiting groove; 

 h, median fissure; i, eminentia medialis; k, ala cinerea; 

 /, /', pons; m, posterior peduncle, and 7i, middle peduncle 

 of cerebellum (cut); o, anterior peduncle of cerebellum; 

 ;), //.corpora quadrigemina, anterior and posterior; (],(/, 

 Ijpduncles (brachia) of corpora (luadrigemina; r, thala- 

 nitis; n, massa intermedia; /, stria medullaris; «, anterior 

 tubercle of thalamus; r, pulvinar; w, corpus geniculatum 

 laterale; r, cori)us geniculatum mediale. (After Ellen- 

 berger, in Leisering's .\tlas.) 



The length of the cord of a rather large dog was found to be aliout 38 cm.; of this, 

 the cervical part was 11 cm., the thoracic 17.4 cm., the lumbar about 7 cm., and 

 the sacro-coccygeal about 2.6 cm. (Flatau-Jacobson). 



The brain weighs about 60 to 70 g. in dogs of medium size, but there is, of 

 course, a wide range of weight in the different breeds. Thus in small terriers the 



