THE VEINS. 325 
thence proceeds caudoventrad obliquely over the surface of the 
cerebellum, unites with veins from the ventral side of the 
brain, leaves the skull by the jugular foramen, forming thus 
the inferior cerebral vein, and joins the internal jugular vein. 
On the ventral side of the brain are the following sinuses of 
the dura mater: 
3. Sinus cavernosus.—A short broad venous sinus, one 
on each side of the hypophysis, on the body of the sphenoid. 
It receives veins from the side and ventral surface of the brain. 
The two sinuses are connected by communicating branches 
craniad and caudad of the hypophysis. From them branches 
pass out through the orbital fissure to join the plexus formed 
by the branches of the posterior facial vein. 
4. Sinus petrosus inferior.—This arises from the sinus 
cavernosus and passes caudolaterad in the groove between the 
edge of the petrous bone and the basilar portion of the occipi- 
tal. Reaching the jugular foramen it divides; part joins the 
termination of the sinus transversus to form the inferior cere- 
bral vein, which passes through the jugular foramen to join the 
internal jugular vein. The other portion of the sinus petrosus 
inferior passes through the condyloid canal of the occipital 
bone, communicates by a strong transverse branch across the 
surface of the basioccipital with the vein of the opposite side, 
and enters the spinal canal through the foramen magnum. 
Here it joins the sinus of the vertebral column. 
5. Sinus columne vertebralis.—On the ventral surface of 
the vertebral canal, beneath the periosteum, are two wide 
venous sinuses, one on each side of the middle line. These 
sinuses extend the entire length of the spinal cord. At the 
atlantal foramen each sends a strong branch to the internal 
jugular vein. Farther caudad they send branches to the verte- 
bral, intercostal, and lumbar veins, and communicate with each 
other by numerous transverse branches. They receive many 
small veins from the spinal cord. 
3. Vena cava inferior (Fig. 129, ¢c; Fig. 126, a). 
The inferior vena cava (Fig. 126, a) is formed at about the 
level of the last lumbar vertebra by the union of the two common 
