240 ANATOMY OF THE DOMESTIC FOWL 



nerve. It collects the blood from the choroidea of the brain and 

 from the skin of the frontal region. It receives laterally the veins 

 of the nose, the vena ophthalmica, and the sinus transversus. 



The sinus occipitalis (Fig. 62, No. A, 4) forms the continuation 

 of the transverse sinus. It is located in the posterior cerebral 

 cavity, and is wing-shaped, extending both to the right and to the 

 left. 



The sinus foraminis occipitalis a continuation of the sinus occip- 

 italis, lies transversely on the ventral side of the cranial cavity 

 and rece ves the veins from the medulla oblongata. One branch 

 passes through the os occipitalis basilare, and then extends side- 

 wise to the foramen magnum and anastomoses with the vena 

 occipitalis. 



The sinus transversus (Fig. 62, No. A, 6) extends in a pair from 

 the internal occipital protuberance between the cerebrum, cere- 

 bellum, and the corpus quadrigeminum. It receives vessels from 

 the upper surface of the cerebellum. The sinus has three branches, 

 all of which empty into the sinus semicircularis. 



The sinus semicircularis extends along the dorsal petrosal rim, 

 anterior to the inner ear, and from this point backward. Near the 

 foramen magnum it passes through the os occipitale and empties 

 into the external occipital vein. 



The vena occipitalis externus extends near the foramen magnum, 

 surrounds the basis occipitalis, and receives the semicircular sinus 

 and thorugh the semicircular sinus the blood from the sinus trans- 

 versus. 



The sinus petrosus sphenoideus, passing in company with the 

 occipital sinus, extends from the transverse sinus to the cavity near 

 which the trigeminus lies. The sinus dividing into two branches, 

 one of these extends to the hypophysis and unites with the basal 

 veins of the brain; the other passes with the rete out of the cranial 

 cavity along with a branch of the trigeminus, and communicates 

 with jthe rete mirabile temporale. 



The sinus temporo-sphenoideus (Fig. 62, No. A, 5) extends for- 

 ward and outward from the transverse sinus, and, between the 

 corpus quadrigeminum and the cerebrum, unites with the sinus 

 venosus annularis basilaris. 



The sinus venosus annularis basilaris lies in the region of the 

 optic nerve and surrounds the hypophysis, forming a complete circle. 

 It receives small vessels from the cerebrum, the corpora quadri- 



