518 THE VEINS OF THE HEAD AND NECK, 



Varieties of the superficial veins of the head and neck. These veins are subject to 

 many deviations from the arrangement above described. Thus, the relative size of the two 

 divisions of the temporo-maxillary rein varies greatly, and it not unfrequently happens that 

 one is very small or even absent, so that the trunk is continued mainly or wholly in one set 

 of cases into the external jugular vein, in another set into the internal jugular through the 

 common facial vein. The facial vein occasionally passes backwards over the sterno-mastoid 

 muscle and joins the external jugular vein ; or it may be continued downwards, by means of 

 an enlargement of the normal communicating branch, into the anterior jugular vein. In 

 those instances in which the temporo-maxillary vein passes entirely into the internal jugular, 

 the external jugular vein is very small, being formed solely by the posterior auricular vein ; 

 and in such cases the posterior auricular vein may also join the temporo-maxillary trunk, so 

 that the external jugular vein is then altogether wanting in the greater part of the neck. 

 The lower part of the external jugular vein is occasionally connected with the cephalic vein 

 of the arm by means of a branch passing downwards over the clavicle, and in rare cases the 

 whole vein has been seen taking this course and dipping into the infraclavicular fossa to join 

 the cephalic, or to open into the subclavian vein above the subclavius muscle. The transverse 

 cervical and mprascapular veins not unfrequently open independently into the subclavian 

 vein. The anterior jugular vein varies greatly in size, and the right and left veins are some- 

 times united into a single median vessel for a part of their length. As a rare occurrence the 

 anterior jugular vein passes outwards in front of the sterno-mastoid muscle. 



Internal jugular vein. This vein, receiving the blood from the cranial 

 cavity, is continuous at its upper extremity with the lateral sinus within the skull, 

 and terminates inferiorly in the innominate vein. It commences in the large pos- 

 terior compartment of the jugular foramen by a more or less marked dilatation 

 which is termed the sinus or bulb of the internal jugular vein, 1 and then makes its 

 appearance below the base of the skull, where it rests against the rectus capitis 

 lateralis muscle, being placed close behind the internal carotid artery. Inclining 

 gradually to the outer side of that vessel, it descends with a nearly straight course 

 in the neck, and becoming considerably increased in size about the level of the hyoid 

 bone by the junction of the common facial, as well as of several deep veins, it 

 thence accompanies the common carotid artery to the back of the clavicle, under 

 cover of which it unites at a right angle with the subclavian vein. The internal 

 jugular vein lies on the outer side of, and frequently overlaps somewhat, the com- 

 mon carotid artery, and the two vessels, together with the pneumo-gastric nerve, are 

 contained in the same sheath of the deep cervical fascia. Close to, or within an inch 

 of, the lower end of the vein is placed a single or double valve, which is however 

 generally insufficient to completely prevent regurgitation, especially on the left side, 

 where it is not unfrequently absent. 



Lateral tributaries. (a) The inferior petrosal sinus leaves the skull by the ante- 

 rior compartment of the jugular foramen, and opens immediately into the internal 

 jugular vein. 



(b) Pharyngeal veins. These veins form a plexus which covers the outer surface 

 of the pharynx, communicating above on the inner side of the internal pterygoid 

 muscle with the pterygoid plexus, and collecting branches also from the soft palate, 

 the Eustachian tube, and the prevertebral muscles. From this plexus two or three 

 vessels descend, and open into the internal jugular or the common facial vein, either 

 separately or in union with the lingual or superior thyroid veins. 



(c) Lingual veins. The blood conveyed to the tongue by the lingual artery is 

 returned by means of 1, the ranine vein, the largest of the lingual veins, which 

 commences below the tip of the tongue, and passes backwards at first beneath the 

 mucous membrane, and afterwards across the outer surface of the hyo-glossus muscle, 

 in company with the hypoglossal nerve, receiving branches from the substance of 



1 According to Langer the so-called bulb does not belong to the internal jugular vein, but is simply 

 the convexity of a sharp bend formed by the lateral sinus just before it terminates in that vein ('' Ueber 

 den Ursprung der inneren Jugularvene," Wiener Sitzungsberichte, 1884). 



