THE SINUSES OF THE DURA MATER 591 



9. Muscular, tracheal, and oesophageal veins. 



10. The cephalic vein (X'cna ('(>i:)luilica) enters the jugular near its termination. 

 It will be (lescrihed with tlie veins of the thoracic limb. 



11. The inferior cervical vein (V. cervicalis ascenclens) accompanies the artery. 

 It may open into the l)rachial vein. 



The Sinuses of the Dura Mater 



These (Sinus durse matris) are blood-spaces l)etween the meningeal and 

 periosteal layers of the dura mater and are lined with endothelium. In many 

 places the lumen is crossed by fibrous strands. They receive the veins of the brain, 

 communicate with the meningeal and diploic veins, and with veins outside of the 

 cranium; their connections with the latter are by means of small emissary veins 

 (Emissaria). They convey. the blood directly or indirectly to the jugular veins. 

 Some are paired, others unpaired. They may be divided into dorsal and basilar 

 systems. The dorsal system comprises the following: 



The superior longitudinal or sagittal sinus (S. sagittalis superior) is situated 

 in the u])i)er boi'der of the falx cerebri along the internal sagittal crest. It begins 

 at the crista galli and ends at the tentorium osseum by dividing into two transverse 

 sinuses. It receives the superior cerebral veins. Along each side are small pouches 



Fig. 464. — Median Section of Head of Horse, Upper Part with Septum Nasi Removed. 

 a, Lateral mass of ethmoifl bone; 6, superior turbinal; c, inferior turbinal; rf, rf', turbinal folds; c, frontal 

 sinus; /, falx cerebri; g, tentorium cerebelli; h, medial surface of hemisphere; i, cerebellum; k, occipital bone; 

 k' , occipital condyle; k" , paramastoid process; /, external auditory meatus; m, temporal condyle; n, parieto- 

 temporal canal; / , branches of ethmoidal artery; 2, 2' , branches of sphenopalatine artery; 3, 3' , branches of spheno- 

 palatine vein; 4, branches of ethmoidal nerve; 6, 5' , branches of sphenoj)alatine nerve; 6, artery of corpus callo- 

 sum; 7, superior sagittal sinus; 8, straight sinus; 9, vena magna cerebri; 10, inferior sagittal sinus; IJ, 11', 

 transverse sinuses; 12, superior petrosal sinus; 13, superior occipital sinus; 14, superior cerebral vein; 15, corpus 

 callosum; 16, fornix. (After Ellenberger, in Leisering's .\tlas.) 



(Lacunae laterales) into which the veins open. The lumen of the sinus is traversed 

 by fibrous bands and is partially divided by a longitudinal septum. 



The transverse sinuses (S. transversi), right and left, pass outward in the 

 transverse grooves of the parietal bones, enter the parieto-temporal canals, and 

 are continued by the superior cerebral veins to the superficial temporal veins. 

 The two sinuses are connected by the sinus communicans. 



The inferior longitudinal or sagittal sinus (S. sagittalis inferior) runs backward 

 on the upper surface of the corpus callosum along the concave edge of the falx 

 cerebri and joins the great cerebral vein (of Galen) to form the straight sinus. 



The straight sinus (S. rectus) passes upward and backward between the cere- 

 bral hemispheres and in the tentorium cerebelli and joins the superior sagittal sinus. 

 The point of meeting is the confluence of the sinuses (C'onfluens sinuum). 



The occipital sinuses (S. occipitales) lie on either side of the vermis cerebelli. 

 They empty anteriorly into the sinus communicans and communicate behind with 

 the spinal veins. 



The superior petrosal sinuses (S. petrosi superiores) pass in the tentorium 

 cerebelli to end in tiie transverse sinuses. 



