92 A MANUAL OF ANA TO MY. 



under the occipital artery, stylohyoid and posterior belly 

 of the digastric muscles. 



The Internal Jugular Vein. Fig. 15. 



This vein is formed just at the base of the skull by the 

 junction of the inferior petrosal (anterior) and lateral (pos- 

 terior) sinuses. Diags. I, 5. 



Its course is along the posterior surface of the internal 

 and common carotid arteries to behind the sternoclavicular 

 articulation, where it is joined by the subclavian, to form 

 the innominate vein. See page 99. 



In its course it receives veins corresponding to the 

 branches of the external carotid artery. 



It is also connected by communicating veins with the 

 external and internal jugular veins. 



DISSECTION. 



The internal jugular vein should be tied off and divided about two inches 

 from the clavicle, and as high toward the head as possible, and the intervening 

 portion with all its tributaries removed. 



Keep in mind that the thoracic duct opens into the angle at the junction of 

 the internal jugular and the subclavian veins. The description of the duct is 

 given with the dissection of the thorax. 



The External Carotid. Figs. 16, 17, 18. 



This is the outer branch of the common carotid. It ex- 

 tends from the bifurcation of the common carotid at the 

 level of the upper border of the thyroid cartilage to behind 

 the neck of the inferior maxilla, where it divides into the 

 temporal and internal maxillary arteries. 



At its beginning it lies anterior to the internal carotid, 

 and at its termination superficial to the same. 



The natural guide to the artery is the anterior border of 

 the sternomastoid muscle. 



Relations, External, or superficial. Skin, platysma, deep 



