40 Venous Sinuses of Head 



nearness of the sinus to the middle ear explains how in abscess of that 

 cavity septic thrombosis may occur. 



The position of the lateral sinus is indicated by a line running 

 horizontally outwards from the occipital protuberance to within about 

 an inch of the external auditory meatus, and thence downwards to the 

 mastoid process. 



The cavernous sinus, at the side of the body of the sphenoid, 

 receives the blood of the ophthalmic vein, which flows into it through 

 the sphenoidal fissure. It also receives cerebral veins. It is emptied 

 by the two pctrosal sinuses. On the inner wall of the sinus winds the 

 internal carotid artery, with the sixth nerve on its outer side, and in 

 the outer wall of the sinus are the third and fourth nerves and the first 

 division of the fifth. Tillaux alludes to some cases of aneurysmal 

 communication between the internal carotid and the sinus ; the signs 

 of such lesion are dilatation of the ophthalmic vein and a pulsatory 

 swelling behind the internal angular process of the frontal. 



The inferior longitudinal sinus runs along the concave border of 

 the falx, and ends in the straight sinus, which latter passes along the 

 union of falx and tentorium to the torcular Herophili or into one of 

 the lateral sinuses. The straight sinus also carries blood backwards, 

 which the veins of Galen, emerging from beneath the corpus callosum, 

 have brought from the interior of the brain. The straight sinus also 

 receives veins from the upper surface of the cerebellum. 



The veins of 

 the dip Joe do not 

 take their respec- 

 tive names pre- 

 cisely from the 

 bone in which 

 they ramify ; they 

 are not confined 

 to any individual 

 bone, but com- 

 municate across 

 the sutures. The 

 frontal diploic 

 vein joins the 

 supra-orbital as it 

 passes through 

 the supra-orbital 

 foramen. The 

 anterior temporal 

 comes chiefly 

 from the frontal bone, to end in a deep temporal vein, and the posterior 

 temporal emerges from the parietal bone to empty in the lateral sinus. 

 The occipital flows into an occipital vein or into the lateral sinus. 



VEINS OF DIPLOE I 



i, frontal ; 2 and 3, ant. temporal ; 4, post, temporal ; 5, occipital. 



