VERTEBRAL SINUSES. 25? 



dent in this institution, in 1813, and now in the Anatomical Ca- 

 binet, where the ascending cava, instead of emptying, as usual, 

 into the lower part of the right auricle, ascended on the right 

 side of the dorsal vertebrae, and supplanting in situation and of- 

 fice the vena azygos, discharged itself into the descending>cava, 

 in a manner corresponding with the vena azygos, by making a 

 curvature forwards over the root of the right lung. 



The Sinuses of the Vertebral Column* (Sinus Columnce 

 Vertebralis) are situated in the vertebral cavity, on the poste- 

 rior face of the bodies of the vertebra?, and in front of the dura 

 mater of the spinal marrow. They are two long veins, one 

 at each margin of the posterior vertebral ligament, and extend 

 from the foramen magnum occipitis to the inferior end of the 

 sacrum. They are maintained in their places by a loose cel- 

 lular tissue between the bones and the dura mater, and, there- 

 fore, unlike the sinuses of the brain, are entirely independent 

 of the dura mater. 



These sinuses are small where they begin in the sacrum, and 

 are there merely two cylindrical veins surrounded by the loose 

 cellular matter, and which have an anastomosis between them. 

 In ascending the spine they enlarge, but not continually, as 

 they are somewhat smaller in the cervical than in the dorsal 

 vertebra. On the body of each vertebra they are rather larger 

 than on the iritervertebral substance: this gives them a knotted 

 appearance, which is especially distinct in the loins. 



At the middle of each vertebra they are joined to one ano- 

 ther by transverse branches, which pass beneath the posterior 

 vertebral ligament, and receive the veins belonging to the cel- 

 lular structure of the bone. Externally, they communicate 

 with the vertebral veins in the transverse processes of the neck, 

 with the intercostal, and with the lumbar veins, as an opening 

 occurs between the adjacent vertebra. They also receive many 

 delicate veins from the dura mater of the spine. These two 

 trunks terminate at their upper end by an anastomosis, through 

 the anterior condyloid foramen, with the internal jugular: they 

 also terminate by anastomosis with the anterior occipital sinus 

 and with the vertebral veins. 



* G. Breachet, Essai ur les Veines du radii?. Paris, 1819. 

 23* 



