608 '////: r/ 7\x 



; 



shins, channeled near the free border of the face of the brain. j 

 behind into tho torcular Hcrophili. 



THE SPINAL SINUSES IN PARTICULAR. We tlius designate in Veterinary 

 Anatomy, and with good reason, two series of venous reservoirs which are 

 found throughout tho whole extent of tho vertebral column, on the sides of 

 the roof of tho spinal canal. Lodged in tho lateral depressions of the 

 superior face of the vertebral bodies, at the side of the common SIIJH rior 

 vertebral ligament, and covered by the dura mater, these reservoirs. 

 continued from one vertebra to the other, are like two large, irregular, 

 parallel veins, which commence at the atlo-axoid articulation, terminate 

 on the first coccygeal vertebrae, where their presence is yet well defined, 

 and communicate with one another during their course by transversal 

 anastomoses. 



AFFLUENT VEINS THAT OPEN INTO THE SINUSES OF THE DURA. MATER. 

 These are the vessels which carry blood either from the dura mater itself, 

 or from the substance of the nervous centres : those of the first category are 

 rare, but the second are numerous. Although wo are unwilling to make a 

 detailed study of the latter, we must nevertheless notice what is most 

 remarkable in their disposition. 



a. On the encephalon, the veins form a much richer and closer network 

 than that of the arterial ramifications; from this network proceed a 

 certain number of principal branches, which throw themselves into the 

 sinuses of the cranial dura mater. Tho veins of the cerebrum, for tho most 

 part, gain the median and transverse sinuses ; a few only pass into tho 

 cavernous sinuses. Those of the isthmus and cerebellum go to tho petrosal 

 and occipito-atloid sinuses. 



\Yith regard to the internal veins of the brain those which, by their 

 interlacing, constitute the choroid plexus we see them unite into a large 

 trunk the great vein of the brain, or vena Galeni, which bends round 1 in- 

 superior extremity of the corpus callosum, reaches the interlobular fissure, 

 and throws itself into the falciform or middle sinus, near its posterior 

 extremity, after receiving the superficial veins from the inner face of tho 

 hemispheres. 



b. The venules arising from the spinal cord are also very remarkable for 

 the fine network they form on the surface of the organ. They collect into a 

 common trunk the median spinal vein, which runs from before to behind, 

 throughout the whole extent of the superior groove in the spinal cord ; thus 

 occupying an analogous, though opposite, position to that of the artery of 

 the same name. From this vein escape, at intervals, emergent branches which 

 open into the spinal reservoirs. 



EFFLUENT CANALS OF THE DURA MATER SINUSES. We have to notice. 

 under this designation, the veins which transport tho blood from the sii.i 

 and we will consider in succession those which commence at tho encephalic 

 reservoirs, as well as those that emerge from the interspinal canals. 



a. To be carried from the encephalic sinuses, tho blood flows into two 

 kinds of double gulfs, known as the parieto-temporal and aubujtlu'iHu'ilitJ 

 confluents. 



The parieto-temporal confluents are lodged in the canals of the same na: 

 alonf with tho mastoid artery. Each commences at tho base of tho internal 

 parietal protuberance, and terminates behind the supercondyloid cininenre. 

 The median and transverse sinuses ore confounded with the superior 

 extremity of these reservoirs, and empty into them tho blood coming from 

 the encephalic mass. This fluid is subsequently taken away by the super- 





