ANATOMY IN A NUTSHELL. IS', 



the arachnoid and pia mater. In the upper part of the neck these veins empty 

 into the inferior cerebellar veins or the inferior petrosal sinus. Below this 

 they empty into the veins of the spinal canal. None of the spinal veins have 

 valves. 



LESSON CLVIII. 



Veins of Diplce. 



These veins lie between the two plates of the bones of the cranium and can 

 be seen by removing the outer plate of the skull. They are, (1) the frontal, 

 which empties into the supraorbital vein, (2) the anterior temporal which joins 

 the deep temporal vein, (3) posterior temporal which joins the lateral sinus, 



(4) the occipital which joins the occipital vein or lateral sinus. 



Emissary veins are small veins which pass through foramina in the bones of 

 the cranium to connect the sinuses with the external veins of the head. The 

 principal ones are as follows: (1) One which passes thorugh the parietal for- 

 amen to connect the veins of the scalp with the superior longitudinal sinus. 

 (2) One which passes through the mastoid foramen to connect the posterior 

 auricular vein or occipital vein with the lateral sinus. (3) One which passes 

 through the anterior condyloid foramen to connect the vertebral vein and deep 

 veins of neck with occipital sinus. (4) One which passes through the posterior 

 condyloid foramen to connect the lateral sinus with the deep veins of the neck. 



(5) One which passes through the foramen ovale. (6) Two or three which 

 pass through the middle lacerated foramen. (7) One which passes through the 

 foramen of Vesalius. The fifth, sixth, and seventh all connect the cavernous 

 sinus with pterygoid and pharyngeal plexuses. (8) One which passes through 

 the carotid canal to connect the cavernous sinus with the internal jugular vein. 



Cerebral Veins. 



The cerebral veins havethin coatsandno muscular coat or valves. They are 

 divided into a superficial set and a deep set. Under the superficial set we have 

 (1) superior cerebral veins, which are lodged in the fissures on the cerebral sur- 

 face and pass forward and inward to the superior Longitudinal sinus, (2) The 

 median cerebral veins which collect the blood from the convolutions of the 

 mesial surface of the hemispheres. These veins empty into the superior veins 

 or into the inferior longitudinal sinus. 



(3) Inferior cerebral veins collect the blood on the lower pari of 

 the outer and on the under surface of the cerebral hemisphere. Under these 

 veins we have, (a) middle cerebral which runs along the fissure of Sylvius on 

 the under surface of the temporal lobe and empties into the cavernous sinus. 

 (b) the great anastomotic vein of the Trolard runs along the horizontal Limb 

 of the fissure of Sylvius and empties into the anterior part of the cavernous 

 sinus, (c) the other veins on the under surface of the brain empty into the super- 

 ior petrosal sinus and lateral sinus. 



