SINUSES OF THE DURA MATER. 



149 



Ficr. 130. 



The principal trunks, viz., the temporal^ internal maxillary^ and 

 occipital, join to form 

 a superficial vein of the 

 neck, called external 

 jugular. 



External jugularj^ 

 — Receives the blood 

 from the temporal,* oc- 

 cipital,^ and internal 

 maxillary. It com- 

 mences at the lower 

 edge of the parotid 

 gland, and descends 

 the neck superficially, 

 being merely covered 

 by the skin, platysma 

 myoides muscle, and 

 superficial fascia. Its 

 course is towards the 

 middle of the clavicle. 

 It crosses obliquely the 

 sterno - cleido - mastoid 

 muscle, and empties 

 into the subclavian out- 

 side of the origin of this 

 muscle. It is frequently 

 selected for bleeding in 

 children. 



Internal jugular}^ 

 — This vein is the largest of the neck. It receives the blood from 

 the sinuses of the cranium, and also from some superficial veins. 



The facial vein^^ empties into the internal jugular, and also forms 

 a communication* between it and the external jugular. It descends 

 the neck in a sheath with the carotid artery, being on the outer side. 

 The par vagum nerve is in the same sheath. The vein empties 

 into the subclavian on the inner side of the origin of the sterno- 

 cleido-mastoid muscle. This junction forms the innominata. 



SINUSES OF THE DURA MATER. 

 These are channels between the laminae of the dura mater, which 

 remove the blood from the brain. (Fig. 131.) 



Superior longitudinal si?ius^ — This is a triangular channel, 

 commencing at the foramen csecum by a small vein from the nose, 

 and gradually increasing in size by the junction of the veins of the 

 pia mater^ in an oblique manner, forms an arch in the median line 

 of the arch of the cranium, which terminates at the internal occipital 



13* 



