98 ANTHROPOLOGY. 



Tho basal sinuses are, the circular^ the cavernous^ the superior petrosal, the 

 vnfer'iAv petrosal, and the occipital. 



Tue Inteenal Jugular Veins. The blood from the brain and cranial 

 cavity is received by the internal jugular veins, which are continuous at 

 their upper extremities with the lateral sinuses and terminate inferiorly in 

 the venae innominatas. The junction of the internal jugular vein with the 

 lateral sinus takes place in the broad- part of the foramen lacerum. Passing 

 down to a level with the os hyoides, it receives the common trunk of the 

 facial and temporal veins, and then enlarges considerably. Previously to 

 the junction with the facial vein, it receives the lingual vein from the 

 tongue, the pharyngeal from the back and sides of the pharynx, the superior 

 thyroid and the occipital from the back of the head. 



The Vertebral Veins commence among the deep muscles beneath the 

 occiput, inosculate with the occipital vein, and enter the canal in the trans- 

 verse processes between the foramen magnum and the atlas. Descending 

 they receive various muscular branches, and empty into the subclavian vein 

 nearly opposite to and behind the internal jugular. 



Inferior Thyroid or Tracheal Veins form a plexus in front of the 

 trachea. They commence about the thyroid body, and open into the vena 

 innominata or into the cava. 



The Ven^ Innominate. These, as already remarked, unite to form 

 the superior vena cava. The left vena innominata is about three inches 

 long, and receiving the thoracic duct at its commencement, is joined in its 

 course by the left vertebral, the inferior thyroid, internal mammary, supe- 

 rior phrenic, and mediastinal veins. The right vena is an inch in length, 

 ,and descends almost perpendicularly. It receives at its commencement 

 the right absorbent trunk, and in its course the right vertebral vein, and 

 sometimes the right inferior thyroid and right mammary and mediastinal 

 veins. 



The Superior Vena Cava descends from the confluence of the venae 

 innominatas almost vertically, enters the pericardium, and opens into the 

 right auricle behind its appendix. The vena azygos joins it just before it 

 .enters the pericardium. It returns the blood from the supra-diaphragmatic 

 part of the body, and communicates with the inferior vena cava through 

 . the vena azygos and the vertebral veins. 



The Azygos Veins constitute important appendages to the venae cavae, 

 »maintaining numerous communications between their branches, securing 

 the course of the circulation, notwithstanding any local impediment in any 

 particular vessel. ^\i& right or greater azygos commences in the abdomen, 

 and ascending through the aortic passage of the diaphragm, empties into 

 the back part of the superior cava. It receives several branches, and 

 drains the thorax. 



PI. 133, fig. 1, superficial veins of the head and neck : ', pericardium 

 displayed; ', right auricle; ', superior vena cava invested by the pericar- 

 dium ; ', do. above the pericardium ; ', right subclavian ; ", root of the 

 internal mammary vein; ', left subsclavian vein; ', internal jugular ; ', thy- 

 roid; '", transverse cervical and scapular veins; ", anterior facial vein; 

 304 



