THE JUGULAR VEIN 139 



upper lip, where its terminal branches anastomose with those 

 of the superior labial branch of the submaxillary artery. 



The Internal Carotid Artery. — This vessel takes a course upwards 

 from the cricoid cartilage across the guttural pouch, in a fold of 

 which it is enveloped. It reaches the upper border of the wing of 

 the post-sphenoid bone, and passing through the innermost of the 

 three notches in this wing it gains the cranial cavity. It next 

 pierces the cavernous sinus and concurs in the formation of the 

 Circle of Willis. 



THE JUGULAR VEIN 



This vein commences below the temporo-maxillary joint by the union 

 of the superficial temporal and internal maxillary veins, the two veins 

 which correspond to the terminal branches of the external carotid artery. 



Passing downwards and backwards, the vein is lodged at first in the 

 substance of the parotid gland, and then takes its course down the neck 

 in the jugular furrow. Near the entrance to the chest the two jugulars 

 unite with one another. The confluence occurs between the two first 

 ribs, and on the inferior aspect of the trachea. It is surrounded by the 

 prepectoral lymphatic glands. Fibrous bands fix the confluent to the first 

 ribs and surrounding parts, so that its walls do not collapse when it is 

 emptied of its contents. This point is of considerable surgical import- 

 ance in connection with the operations on the vessel to be hereafter 

 described. 



The upper extremity of the vein is surrounded by the glandular 

 tissue of the parotid, and forming its external covering throughout rhe 

 remainder of its course is a thin sheet of muscle which is the cervical 

 portion of the panniculus. Inwardly it is related in the upper part of 

 the neck to the subscapulo-hyoideus muscle, which separates the vein 

 from the carotid artery, and the vagus and recurrent laryngeal nerves. 

 In the inferior cervical region it is in direct relationship to the carotid, 



