THE NERVOUS SYSTEM OF THE DOG 



727 



6. The ectolateral fissure lies between the posterior part of the ectomarginal 

 fissure and the suprasylvian fissure. 



7. Th(^ entomarginal fissure Hes between the anterior ]iart of the ectomarginal 

 fissure and the dorso-niedial border. It is often indistinct and not rarely absent. 



8. The presylvian fissure begins at the sulcus rhinalis, a little in front of its 

 middle, and curves over the anterior third of the lateral surface of the hemisphere 

 in front of the coronal fissure. 



9. The cruciate fissure is the deepest and most characteristic. It cuts deeply 

 into the anterior third of the dorso-medial border and runs almost straight outward. 

 It is continuous on the inner surface of the hemisphere with the calloso-marginal 

 or splenial fissure. 



10. The sulcus rhinalis is continued on the tentorial surface of the hemisphere 



Fig. 545. — Dkep Dissection of Head of Dog, showing Especially Trigeminal and Hypoglossal Nerves 

 a. Hypoglossal nerve; h, cervical branch of a; c, mandibular division of trigeminus; d, lingual nerve; e 

 nerve to submaxillary gland; f, deep temporal nerve; g, pterygoid nerve; /), buccinator nerve (cut); i, inferior 

 alveolar or dental nerve; k, staphyline branch of lingual nerve; /, chorda tympani; m, mylo-hyoid nerve; n, 

 sphenopalatine nerve; o, lesser palatine nerve; p, great palatine nerve; q, infraorbital nerve.s; ?", siibcutaneus 

 malae; s, branch of oculomotor nerve to inferior oblique muscle; t, lacrimal ner\-e; (/, frontal nerve; v. trochlear 

 nerve; w, abducens; 7, carotid artery; ^, lingual artery; 3, internal maxillary arterv; 4. thyro-pharjngeus muscle; 

 o, hyo-pharyngeus muscle; 6. thyro-hyoideus; 7, sterno-hyoideus; 8, baseo-glossus. 9. genio-hyoideus; 10. 

 genio-glossus; //, stylo-glossus; i^, pterygoideus internus; i.i?, outline of submaxillary gland (dotted); /4, atlas; 

 /5, bulba ossea; 7(?, zygomatic arch (dotted) ; i7, rectus oculi inferior; /g, obliquus oculi inferior. (Ellenberger- 

 Baum, .\nat. d Hundes.) 



by the occipito-temporal fissure. Anteriorly it is prolonged as the olfactory fi.s- 

 sure, which is concealed by the olfactory bulb and tract. 



11. The calloso-marginal or splenial fissure is parallel with the spleiiium and 

 middle part of the corpus callosum on the inner surface of the hemisphere. It is 

 continuous in front with the cruciate fissure and runs downward and outward 

 across the tentorial surface to join the occipito-temporal fissure and sulcus 

 rhinalis. It gives off from its highest part the short lesser or accessory cruciate 

 fissure. 



12. The suprasplenial fissure runs almost parallel with the posterior part of 

 the calloso-marginal fissure on the inner and tentorial surfaces of the hemisphere. 



The olfactory bulb is large and is strongly compressed laterally; its anterior 

 end projects beyond the frontal pole of the hemisphere. The tract is short and is 



