VEINS OF THE HEAD AND NECK. 831 
VEINS OF THE HEAD AND NECK. 
Internal jugular veins (Figs. 552 and 582).—Kach internal jugular vein (v. 
jugularis interna) commences in the posterior compartment of the jugular foramen, 
as the direct continuation of the lateral sinus, and terminates behind the 
cartilage of the first rib by uniting with the subclavian vein of the same side to 
form the innominate vein. 
At its commencement it is dilated, forming the bulb of the jugular vein, and 
in this situation it hes behind and somewhat to the outer side of the internal 
carotid artery and the last four cranial nerves. As it descends it accompanies 
first the internal and then the common carotid artery; inclining forwards during 
its descent, it gradually passes from its original position, behind and to the outer 
side of the internal carotid artery, and les more completely to the outer side of the 
internal and common carotid arteries, and indeed somewhat overlaps the latter in 
front. This is more especially the case on the left side, for both internal jugular 
veins trend slightly towards the right as they descend; consequently at ae root 
of the neck the right vein is separated from the right common carotid artery by a 
small interval filled by areolar tissue, whilst the left vein is more diree tly in front 
of the corresponding common carotid artery. 
Within an inch of its lower extremity each internal jugular vein is pro- 
vided with a valve consisting of one or two cusps, which, however, is frequently 
incompetent. 
Relations.—The vein lies in front of the transverse processes of the cervical verte- 
bree, the rectus capitis lateralis, rectus capitis anticus major, and scalenus anticus muscles, 
the ascending cervical artery, which runs upwards in the interval between the attach- 
ments of the two latter muscles, and the phrenic nerve; the suprascapular and the 
transverse cervical arteries intervene between it and the scalenus anticus. At the root of 
the neck the vein les in front of the first part of the subclavian artery and the origins 
of the vertebral artery and the thyroid axis, and on the left side it is in front of the 
terminal part of the thoracic duct. 
On the inner side of the internal jugular vein, immediately below the skull, are the 
internal carotid artery and the last four cranial nerves; in the rest of its extent it is in 
relation internally either with the internal or the common carotid artery, whilst to its 
inner side and somewhat posteriorly, between it and the large arteries, lies the vagus 
nerve. 
Each internal jugular vein is covered in the whole of its length by the sterno-mastoid 
muscle ; near its upper end it is crossed by the posterior belly of the digastric, whilst in 
its lower half, in addition to the sterno-mastoid, the omo-hyoid, the sterno-hyoid, and the 
sterno-thyroid muscles are superficial to it. Just below the transverse process of the atlas, 
and under cover of the sterno-mastoid, the vein is crossed on its outer side by the spinal 
accessory nerve and by the occipital artery ; about the middle of its course it is also 
crossed by the communicans cervicis nerve, and near its lower end by the anterior jugular 
vein ; the latter vessel, however, is separated from it by the sterno-hyoid and sterno- 
thyroid muscles. Superficial to the vein are numerous deep cervical lymphatic glands. 
Tributaries.—(a) The inferior petrosal sinus, which joins it near its commencement. 
(2) Pharyngeal branches from the venous plexus on the wall of the pharynx. (c) The 
common facial vein, which receives the facial vein and its tributaries. (dd) The lingual 
veins (vy. linguales), small vene comites, which commence chiefly in the sublingual 
and dorsalis linguze veins, and accompany the first and second parts of the lingual artery. 
(ec) The ranine vein, which commences beneath the tip of the tongue, and accompanies 
at first the two terminal parts of the lingual artery, and afterwards the hypoglossal 
nerve. (f) The superior thyroid vein (v. thyreoidea superioris), Which accompanies the 
corresponding artery. (g) The middle thyroid vein, which passes backwards from the 
lateral lobe of the thy roid body and crosses the middle of the outer aspect of the common 
carotid artery. (h) The occipital vein (vy. occipitalis) occasionally terminates in the 
internal jugular vein. In many cases, however, it ends in the suboccipital plexus, which 
is drained by the vertebral and deep cervical veins (see p. 830). 
The common facial vein (v. facialis communis) is formed by the union of the facial 
vein (v. facialis anterior) with the anterior division, or terminal branch, of a venous 
trunk which lies in substance of the parotid gland, and which is called the temporo- 
maxillary vein (v. facialis posterior). It accompanies the first part of the facial artery 
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