VEINS OF THE SCALP. 967 



roof of the upper part of the posterior triangle, to its termination in the external 

 jugular vein. 



As the external jugular vein pierces the deep cervical fascia in the subclavian 

 triangle, its wall is closely attached to the margin of the opening through which 

 it passes ; and as it is crossing in front of the third part of the subclavian artery it 

 is joined by the transverse scapular, transverse cervical, and anterior jugular veins. 



There are usually two valves in the lower part of the vein one, at its termina- 

 tion, which is generally incompetent, and a second at a higher level. 



Tributaries. In addition to the posterior auricular vein and the branch from 

 the posterior facial vein by which it is formed, the external jugular vein receives the 

 posterior external jugular vein, which has already been described, the transverse 

 cervical and transverse scapular veins from the region of the shoulder, and the 

 anterior jugular vein. Occasionally the cephalic vein also opens into it. 



The posterior auricular vein (Fig. 785) receives tributaries from the posterior parts 

 of the parietal and temporal regions and from the medial surface of the auricle. It is 

 considerably larger than the posterior auricular artery, which it accompanies only in the 

 scalp. At the base of the scalp it leaves the artery and descends in the superficial fascia, 

 over the upper part of the sterno-mastoid, to join the external jugular vein. 



The transverse cervical and transverse scapular veins accompany the corresponding 

 arteries ; not infrequently they open directly into the subclavian vein. 



The anterior jugular vein commences in the submental region, and is formed by the 

 union of small veins from the lower lip and chin. It descends, in the superficial fascia, at 

 a variable distance from the median plane, perforates the superficial layer of the deep 

 fascia, a short distance above the sternum, and enters the suprasternal space (Burns) 

 between the first and second layers of the deep fascia. In the space it anastomoses with 

 its fellow of the opposite side and receives a communication from the common facial vein. 

 Then it turns laterally, between the sterno-mastoid superficially and the sterno-hyoid, 

 sterno-thyreoid, and scalenus anterior muscles deeply, and terminates in the external 

 jugular vein at the posterior border of the sterno-mastoid. 



The external jugular vein sometimes receives the occipital vein or a communication 

 from it. 



THE VEINS OF THE SCALP. 



The veins which drain the blood from the superficial parts of the scalp are the 

 frontal, the supra- orbital, the superficial temporal, the posterior auricular, and the 

 occipital. The blood from the deeper part of the scalp, in the region of the 

 temporal fossa, on each side, passes into the deep temporal veins, which are 

 tributaries of the pterygoid plexus. 



The frontal and supra-orbital veins receive blood from the medial and anterior 

 part of the scalp. They unite together, near the medial commissure of the eyelids, 

 to form the angular vein ; before the union is effected the supra-orbital vein sends a' 

 branch backwards, through the supra-orbital notch, into the orbital cavity, where 

 it terminates in the ophthalmic vein, and as this branch passes through the notch 

 it receives the frontal diploic vein (p. 969). 



The superficial temporal vein (Figs. 759, 785) is formed by frontal and parietal 

 tributaries which accompany the corresponding branches of the superficial temporal 

 artery. They drain the lateral frontal, the superficial part of the temporal, and the 

 anterior part of the parietal region of the scalp, and unite to form a single trunk 

 which descends to the upper border of the zygoma, immediately anterior to the 

 auricle, where it terminates in the posterior facial vein (see p. 968). 



The posterior auricular vein drains the posterior portions of the temporal and 

 parietal areas of the scalp (see above). 



The occipital vein (Figs. 759, 785) receives tributaries from the parietal and 

 occipital regions. As a rule it pierces the occipital origin of the trapezius, and, 

 passing into the sub-occipital triangle, terminates in a plexus of veins which is 

 drained by the vertebral and deep cervical veins. It sometimes communicates with 

 the external jugular vein, and occasionally an offset from it accompanies the corre- 

 sponding artery and ends in the internal jugular vein. 



62 & 



