538 DE. J. MUEIB ON THE ANATOMY OF THE SEA-LION. 



constrictor, then on the hyoglossus muscle, giving branches to both. As it traverses 

 the latter it is covered by the styloglossus muscle, then, dipiDing underneath both, it 

 enters the substance of the tongue, distributing its branches to the genio-hyoglossus, 

 lingualis, &c., while the main trunk of the artery corresponding to the ranine proceeds 

 onwards to the fraenum, and inosculates with its fellow of the opposite side. 



The trunk of the external carotid beyond its lingual branch continues towards the 

 cranium, and between the tympanic and condyloid eminence divides into several 

 branches near each other. The facial artery traverses the groove of the mandibular 

 angle under cover of the digastric muscle, and loops round the ramus, being freely 

 distributed to the oral muscles. The occipital branch, diverging beneath the stemo- 

 mastoid muscle near its paramastoid attachment, supplies the occipital parts, overlain, 

 however, by the great sheet of the cephalo-humeral muscle. As to the temporal branch, 

 which is comparatively small, it reaches the surface of the temporalis muscular layers 

 in front of the outer flexible tube of the auditory apparatus. The internal maxillary 

 artery is by far the most important of the ectocarotid divisions. In the emargination 

 beneath the neck of the condyle at the rear of the pterygoid muscles it sends down a 

 large inferior dental branch. The main vessel, thence continuing obliquely forwards 

 and inwards, penetrates the alisphenoid canal at the root of the pterygoid. Anteriorly 

 it pursues a course on the surface of the palatine arch ; and then it becomes the supe- 

 rior maxillary accompanying the infraorbital plexus of nerves, its peripheral divisions 

 being distributed to the parts around the mouth, muzzle, and nose. Within the large 

 spheno-palatine and orbital space various muscular, superior dental, and nasal derivatives 

 are sent off. The marginal vessels appear to enter the foramen lacerum medium ; but 

 they may nevertheless find entrance to the cranial cavity by the interior minute cleft 

 spoken of as representative of foramen spinosum. 



Internal carotid artery. — This strikes deeply backwards, and, rounding the internal 

 groove of the tympanic in close relation to the jugular vein, traverses the canal of the 

 periotic, crosses the foramen lacerum medium, lies in the carotid groove, and joins in the 

 circle of Willis. 



Arteries of the base of the brain. — Within the spinal canal and previous to forming 

 the basilar artery, two large anterior spinal arteries converge backwards into a single 

 vessel of considerable magnitude, which becomes the anterior median artery of the cord. 



Much smaller-sized inferior cerebellar arteries are also derived from the front of the 

 vertebral. The basilar artery is about 2 inches long, relatively large, and sends off, 

 almost at right angles, the usual transverse, superior cerebellar and posterior cerebral 

 branches. The two latter are situated rather widely apart. The " circle of Willis " is 

 complete. The posterior communicating branches of the internal carotid are short and 

 wide, with the internal carotid of but moderate size placed in their middle, and not so 

 close to the anterior and middle cerebral as in the human brain. 



Subclavian trunks and branches derived therefrom. — The right subcla\ian artery, on 



