862 



HUMAN ANATOMY. 



Relations. — In the upper part of its course the internal jugular rests upon the 

 rectus capitis lateralis and the trans\'erse processes of the upper cervical vertebrae. 

 To its inner side and somewhat in front of it is the internal carotid artery, the glosso- 

 pharyngeal, pneuinogastric, spinal accessory, and hypoglossal nerves separating the 

 two vessels above. The external branch of the spinal accessory crosses it obliquely 

 either in front or behind, and somewhat lower it is crossed anteriorly by the stylo- 

 hyoid muscle and the posterior belly of the digastric and also by the occipital and 

 posterior auricular arteries. To its inner side is the wall of the pharynx, with which it 

 is not, however, directly in contact. 



Tliroughout the neck it lies beneath the sterno-cleido-mastoid muscle, imme- 

 diatel}- to the outer side of the common carotid artery, being enclosed in a common 



Superficial temporal vein ^ 

 Posterior auricular vein 



Fig. 753. 



External auditory meatus 



Mastoid vein 



Occipital vein 



Internal maxillary vein 



Temporo-maxillary vein 



Posterior trunk of temporo- 



maxillarj' vein 



(Interior trunk of temporo- 

 maxillary vein 



External jugular vein 



Lingual vein 



Internal carotid artery- — 



Internal jugular vei.i 



Posterior external jugular vein 



Superior thyroid veia 



Common carotid artery 



Transverse 

 '•ervical vein 



Temporal muscle, cut 



Internal maxillary vein 



Facial vein 



posterior 

 SG'pular vein 



Subclavian vein 



Pterygoid 

 venous plexus 



Internal 

 pterygoid 

 muscle 



Common facial vein 



Ext. carotid artery 

 Communication bet. lin- 

 gual and anterior jugulaj 

 Middle thyroid \ein 



■Anterior 



jugular \ ein 

 Left internal 



jugular \ein 



Left subclavian vein 



Clavicle 



Left innominate veia 



Left superior 

 intercostal vein 



Innominate artery 



Right innominate vein 



I. rib Internal mammary vein Superior vena cava Inferior thyroid veins 



Dissection showing deep veins of neck and head. 



sheath with it, as is also the pneumogastric nerve, which lies behind and between the 

 two vessels. Below the omohyoid muscle the vein tends to separate from the artery, 

 passing somewhat more anteriorly. In this part of its course it, or, to be more pre- 

 cise, the inferior bulb, is situated immediately behind the space which separates the 

 two heads of the sterno-cleido-mastoid. Behind, it rests upon the inner border of the 

 scalenus anticus, crosses the subclavian artery, and has the pneumogastric and phrenic 

 nerves passing downward on either side. 



Variations. — Variations of the internal jugular vein are not numerous. It may be noted, 

 however, that in its course down the neck it occasionally overlaps the carotid artery to a con- 

 siderable extent, — a condition which is especially marked in the region of the inferior bulb when 

 this is well developed. 



