594 



THE ARTESIES. 



Fig. 288. 



in an extremely complicated manner. Its inferior extremity, passing into the supra- 

 sphenoidal canal, receives the generating arteries. The posterior extremity, covered by the 

 clinoid process, is in communication with the spheno-spinous artery, which there expends 

 itself. Towards its middle part, and above, the twigs forming it reconstitute them- 

 selves into a single trunk analogous to the intercranial portion of the internal carotid of 

 Solipeds (Fig. 287, 17), and which traverses the dura mater, dividing into three branches. 

 These are the anterior, middle, and posterior cerebral arteries ; the latter anastomoses, by 

 convergence, with the homologous artery of tlie opposite side, behind the pituitary 

 gland, to form the basilar trunk and the median spinal artery, which continues it. 



This singular disposition of the arteries of the encephalon well deserves the name of 

 rgseau admirable (admirable network), by which it is known. If we were desirous of 

 giving a summary idea of this network, we might compare it to a lymphatic gland, whose 

 efferent vessels would be represented by the originating arteries with the spheno-spinous, 

 and the elferents by the originating trunk of the encephalic arteries. 



8. Next comes the superior dental, whose orbital branch presents a considerable 

 volume, and terminates on the anterior surface of the head by long superficial divisions. 

 Some of these, the ascending, anastomose with tlie inferior branches of the arterial 

 circle situated around the base of the horn; while others, the descending, communicate 

 with the infra-orbital branch of the same vessel, and witli the superior coronary 

 artery. 



9. The last to be given off are the nasal and palatine arteries, which tenninate the 



internal maxillary : the nasal artery is disposed 

 as in the Horse ; the palatine goes entirely to the 

 palate. 



B. In the Ox, we find all the peculiarities 

 just euumenited, save with the following differ- 

 ences : 



1. A little above the origin of the lingjial 

 artery, the external carotid gives rise to an 

 external maxillary artery, wliioh turns round 

 the infeiior border of the maxillary bone, in 

 company with its satellite vein, and terminates 

 on the forehead, as in the Horse, after supply- 

 ing the coronary arteries. 



2. I'he maxillo-muscular artery is distributed 

 to the two masseters — to the external as well as 

 the internal. 



3. The transverse artery of the face does not 

 foi-m the coronary arteries, as these come from 

 the external maxillary; it is altogether ex- 

 pended in the masseter muscle. 



i. The anterior auricular artery sends an 

 enormous branch into the temporo-parietal canal, 

 by the orifice situated behind the supercondyloid 

 process. 



5.^ The ophthalmic artery and the generating 

 arteries of the re'seau admirable proceed from a 

 common trunk. 



6. The rd'seau itself shows some differences. 

 We do not find, as in the Sheep, two lateral 

 elongated lobes, almost independent of each 

 other, but a circular mass surrounding the sella 

 turcica. Besides, the occipital arteries concur 

 1, Jieseau admirable ; 2, Trunk of the m its formation, and pass iuto its posterior part 

 ongiuating arteries of the reseau ad- (Fig. 288). 



mirable; 3, Spheno-spinous artery; 4, (This reseau admirable is the "rete mira- 



Irunk of the encephahc, or internal UU" of Galen, and would appear to be formed 



carotid arteries; 5, Branches of the on the carotid and vertebral arteries of animals, 



occipital passing to the reseau admir- which, in a state of nature, feed from the 



a6te; 6 Interspinal arterial canal, ground ; the object being to furnish an equable 



termed by the intei-vertebral spinal and prolonged supply of blood without the risk 



br?nches. of check or hindrance, and thus to obviate the 



J , , .^. ,„,,„,. t'^iideocy to congestion of the brain during the 



dependent position of the head. This mmute subdivision and subsequent reconstitution 



ot an artery, with a like intention, is also observed in other creatures besides grazing 



THE EESEAU ADMIRABLE OF THE OX ; 

 POSTEBIOK FACE. 



