THE OCCIPITAL ARTERY 



545 



major/ The internal carotid artery, the inferior cerebral vein, and the accessory, 

 vagus, and sympathetic nerves cross its deep face. It gives twigs to the sub- 

 maxillary gland, the anterior 

 straight nmscles, the guttural 

 pouch and the adjacent lymph 

 glands, and two named collateral 

 branches. The condyloid or pre- 

 vertebral artery (A. condyloidea) 

 is a small vessel which passes up- 

 ward and forward on the guttural 

 pouch, and divides into muscular 

 and meningeal bi"anches. The 

 latter enter the cranium through 

 the foramen lacerum and hypo- 

 glossal foramen and are dis- 

 tributed to the dura mater. This 

 artery is very variable in its 

 origin. The posterior meningeal 

 or mastoid artery (A. meningea 

 caudahs) is a mucli larger vessel 

 which runs upward and forward 

 between the small o])liciue muscle 

 and the paramastoid process, 

 passes through the mastoid fora- 

 men into the parieto-temporal 

 canal, enters the cranial cavity, 

 and is distributed to the dura 

 mater. 



The posterior or retrograde 

 branch (Ramus descendens) of 

 the occipital passes up through 

 the foramen transversarium of 

 the atlas and joins the vertebral 

 artery. It gives jjranches to the 

 great o])li(iue nuiscle of the head, 

 which covers it. 



The anterior or occipital 

 branch (Ramus occipitalis) passes 

 through the alar (antero-ex- 

 ternal) foramen of the atlas and 

 supplies the muscles and skin 

 of the poll, anastomosing with 

 the deep cervical artery and its 

 fellow of the opposite side. In 

 the alar furrow it gives off the 

 cerebrospinal artery, which en- 

 ters the spinal canal through 

 the intervertebral (antero-in- 

 ternal) foramen of the atlas, 



perforates the dura mater, and divides into cerebral and spinal branches. The 

 cerebral branch unites with that of the opposite side to form the basilar 



Fig. 434. — Vessels and Nerves of B.\se of Br.\in' of Horse. 

 IS, Cerebro-spinal artery; 14, niiddle spinal artery; 16, 

 basilar artery; 16, posterior cerebellar artery; 17, anterior 

 cerebellar artery; 18, internal auditory artery; 19, posterior 

 cerebral artery; 20, deep cerebral artery; 21, stump of internal 

 carotid artery; 22, anterior choroid artery; 23, anterior menin- 

 geal artery; 24, middle cerebral artery; 25, artery of corpus 

 callosum; 26, anterior communicating artery; 1, 1' , 1" , ol- 

 factory tracts; V" , olfactory peduncle; 2-12, cranial nerves; 

 a, olfactory bulb; 6, trigonura olfactorium; c, lamina perforata 

 anterior; d, fossa transversa; e, pyriform lobe; /, cerebral 

 peduncle; g, tractus transversus; h, corpus mammillare; i, tuber 

 cinereum; k, lateral fissure (of Sylvius); I, presylvian fissure; 

 n>, pons; o, pyramid; p, facial eminence; </, corpus restiforme; 

 r, cerebellum; s, middle peduncle of cerebellum. (After Ellen- 

 berger Baum, Top. Anat. d. Pferdes.) 



1 The relation to the guttural pouch is not constant. In some cases — especially when the 

 head and neck are extended — the artery lies behind the pouch. The backward extension of the 

 latter is variable. 

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