EXTERNAL AXV IXTERXAL JUGULAR VEINS. 459 



THE EXTERNAL JUGULAR VEIN. 



The external jugular vein commences on a level with the angle of the 

 lower maxilla, at the end of the temporal vein, and descends perpendicu- 

 larly between the platysma and fascia, crossing the sterno-mastoid muscle. 

 In consequence of the oblique direction of that muscle, the vein gets to its 

 outer border, and continues behind it down to the lower part of the neck, 

 where it pierces the fascia to terminate either as a single trunk, or by two 

 or three branches in the subclavian vein. It is provided with a valve at its 

 lower end, and in most cases with another about the middle of its course. 



TRIBUTARIES. The external jugular vein receives some large branches from behind, 

 and superficial branches from the fore part of the neck. The largest branches are 

 the following. 



(a) The posterior branch, lying at first between the splenius and trapezius muscles, 

 passes down at the outside of the jugular vein, and below the middle of the neck 

 opens into that vessel. 



(&) The suprascapular and posterior scapular veins, corresponding to the arteries 

 of the same name, pass transversely inwards to join the external jugular vein close to 

 its termination. 



The anterior jugular vein arises from the convergence of some superficial 

 branches in the submaxillary region. This vessel lies along the fore part of 

 the neck, sometimes near the sterno-mastoid muscle, and either terminates 

 by inclining outwards to join the external jugular vein, or, after giving to it 

 a branch of communication, sinks beneath the sterno-mastoid muscle, and 

 ends in the subclavian vein. The lower ends of the two anterior jugular 

 veins are frequently united by a transverse branch placed behind the sterno- 

 mastoid muscles and top of the sternum. 



The external jugular vein is very variable in size. It is frequently very small, and 

 may be absent altogether. The anterior jugular vein is likewise very variable. 



INTERNAL JUGULAR VEIN. 



The internal jugular veins, receiving the blood from the brain and cranial 

 cavity, are contiguous at their upper extremities with the lateral sinuses 

 within the cranium, and terminate inferiorly in the innominate or brachio- 

 cephalic veins. The commencement of each internal jugular vein at the 

 wide part (jugular fossa) of the foramen jugulare, is somewhat enlarged, 

 and has been named the sinus or gulf of the internal jugular vein. Beneath 

 the skull, the vein is supported by the rectus lateralis muscle, and lies close 

 to the outer side of the internal carotid artery, as far as the cornu of the 

 os hyoides. It is joined at this point by the common facial vein, and 

 becomes considerably enlarged ; it then descends parallel with the common 

 carotid artery, lying at its outer side and enclosed in the same sheath, 

 together with the vagus nerve. At the root of the neck it joins nearly at a 

 right angle with the subclavian vein, and so forms the innominate or 

 brachio-cephalic vein. Close to the lower termination of the jugular, or 

 from half an inch to an inch above it, is placed a double valve as in other 

 veins. (Struthers, " Anat. and Phys. Observ.," p. 173.) 



TRIBUTARIES. Previously to its junction with the facial vein, the internal jugular 

 receives the lingual, pharyngeal, and occipital veins ; one or more of which, however, 

 very frequently end in the common facial trunk. 



(a) The lingual vein begins at the side and upper surface of the tongue, and passes 

 backwards, receiving branches from the sublingual gland; occasionally the ranine 

 vein joins it, and sometimes also the pharyngeal. 



H H 2 



