FACIAL VEIN. 455 



these finally uniting into a single trunk, each vein terminates in the brachio- 

 cephalic of its own side. 



(c) The superior intercostal veins. The right superior intercostal vein 

 receives the blood from the first or the first two or three spaces, communicating 

 with the vessel in the space next below, and opens into the innominate trunk 

 of the same side, or into the vena cava. Frequently the veins at the right 

 side, corresponding with the superior intercostal artery, pass downwards 

 separately, to open into the azygos vein, as that vessel arches forwards to 

 join the upper vena cava : the separate vein thus formed is inferior in 

 size to that on the left side. The left superior intercostal vein varies in 

 length in different persons, being small when the azygos minor is large, and 

 vice versa. Usually it receives the veins from the three or four upper spaces, 

 and is then directed forwards over the left side of the spinal column and 

 the aorta to open into the left innominate vein. It receives in its course 

 the left bronchial vein. The left vein is sometimes directed downwards to 

 join an azygos vein on its own side. 



VEINS OF THE FACE, NECK, AND HEAD. 



The blood returning from the head and neck flows on each side into two 

 principal veins, the external and internal jugular. The veins of the head 

 and neck have generally no valves. The external jugular vein is provided 

 with a valve at its entrance into the subclavian vein, and in most cases with 

 another about the middle of its course : and the internal jugular is also 

 furnished with valves near its junction with the subclavian. These valves, 

 however, are not efficient in stopping the regurgitation of the blood, or the 

 passage of injections from below upwards. 



The veins on the exterior of the cranium and face converge and unite, so 

 as to form two trunks, the facial and the temporal veins. 



THE FACIAL VEIN. 



The facial vein lies obliquely along the side of the face, extending from 

 the inner margin of the orbit downwards and outwards to the anterior 

 border of the masseter muscle. Resting on the same plane as the facial 

 artery, but farther back, and less tortuous, it has very nearly the same 

 relations to contiguous parts. It commences at the side of the root of the 

 nose by a vein formed by the junction of branches from the forehead, eye- 

 brow, and nose, and increases by receiving others during its course. Below 

 the jaw it inclines outwards and backwards, covered by the cervical fascia 

 and the platysma muscle ; and soon unites with a large branch of commu- 

 nication derived from the temporal vein, to form the temporo-maxillary or 

 common facial vein, a short vessel of considerable size, which joins obliquely 

 the trunk of the internal jugular. 



TRIBUTARIES. (a) The frontal vein commences on the roof of the skull by 

 branches, which descend obliquely inwards upon the forehead, maintaining communi- 

 cations in their course with the anterior branches of the temporal vein. It descends 

 vertically, parallel with the corresponding vessel of the opposite side, with which it is 

 connected by transverse branches, and ends in the angular vein. In some instances 

 the veins of the two sides unite and form a short trunk, which again divides into 

 two branches at the root of the nose. As it descends from the forehead, the frontal 

 vein receives a branch from the eyebrow, and some, of smaller size, from the nose and 

 upper eyelid. 



