THE AETEBIES 747 



course on the nuchal surface of the occipital bone parallel with the nuchal crest, 

 anastomoses with the opposite artery, and ramifies in the nuchal muscles. It 

 gives collateral branches to the ventral straight muscles and to the pharynx. It 

 also gives off the condyloid and posterior meningeal arteries. The latter passes 

 through the mastoid foramen and ramifies in the dura mater. The cerebrospinal 

 artery passes through the intervertebral foramen, and unites in the vertebral canal 

 with its fellow and a branch from the vertebral artery to form the basilar artery. 

 The recurrent branch anastomoses with the vertebral as in the horse. 



The internal carotid artery, also small, arises just behind the occipito-mandib- 

 ularis muscle; it passes to the foramen lacerum posterius, enters the carotid canal, 

 and forms a bend before entering the cranial cavity through the carotid foramen. 

 It forms a plexus which is connected by branches with the middle meningeal and 

 external ophthalmic arteries. It then perforates the dura mater and enters into 

 the formation of the circulus arteriosus, which is formed in a manner similar to that 

 of the horse. The anterior cerebral artery gives off the internal ophthalmic artery 

 which accompanies the optic nerve to the eyeball. The middle cerebral artery is 

 large, and gives off the choroid artery. 



The external carotid artery is the direct continuation of the common carotid. 

 It passes along the lateral wall of the pharynx, emerges from beneath the occipito- 

 mandibularis, and divides behind the postglenoid process into superficial temporal 

 and internal maxillary arteries. It gives off the following collateral branches: 

 The large flexuous lingual artery passes to the side of the root of the tongue, runs 

 forward under cover of the hyo-glossus, and continues to the tip of the tongue in 

 company with a satellite vein and the hypoglossal nerve. It ramifies in the 

 tongue and gives collateral branches to the pharynx and soft palate. , The external 

 maxillary artery, smaller than the lingual, passes along the upper border of the occipi- 

 to-mandibularis, gives off the sublingual, gains the anterior border of the masseter, 

 and divides into superior and inferior labial and the angularis oris. The last-named 

 vessel passes forward on the cheek between the labials to the angle of the mouth. 

 The sublingual artery passes along the upper border of the occipito-mandibularis, 

 then between the mylo-hyoideus and the ramus of the mandible. The great auric- 

 ular artery arises at the anterior border of the occipito-mandibularis, gives branches 

 to the parotid and mandibular salivary glands and the adjacent muscles, and ter- 

 minates in three auricular branches which ramify on the convex face of the concha. 

 These branches anastomose with each other and the anterior auricular artery. 



The superficial temporal artery, after giving off the anterior auricular artery 

 and a small transverse facial artery, turns forward under the temporal fascia toward 

 the eye, and divides into upper and lower branches which supply the frontal region 

 and the eyelids. It also supplies branches to the parotid gland and the masseter 

 and temporalis muscles. 



The internal maxillary artery pursues a course similar to that of the horse, 

 and ends in the pterygo-palatine fossa by dividing into the infraorbital artery and a 

 common trunk for the greater palatine and sphenopalatine arteries. The mental 

 branches of the inferior alveolar artery are of considerable size and are distributed 

 in the lower lip and gums. Two or three deep temporal arteries are present; the 

 anterior one may arise from the buccinator artery. The middle meningeal artery 

 enters the cranium through the foramen ovale, ramifies in the dura mater, and sends 

 a branch to the carotid plexus. The external ophthalmic artery is connected with 

 the internal carotid by a large ramus anastomoticus which passes through the 

 orbital foramen. The superficial branches of the infraorbital artery replace the 

 dorsal and lateral nasal arteries, and compensate for the small size of the superior 



labial. 



The brachial artery in its course in the arm presents no special features. At 

 the elbow it passes between the biceps and the pronator teres, descends as the 



