90 SURGICAL ANATOMY OF THE 



interspersed between the fascia and the sheath. This 

 fascia should be cautiously divided on a director, so as 

 to expose the sheath, upon or beneath which is the de- 

 scendens noni nerve. 



Next a small portion of the sheath is to be pinched 

 up and "nicked/ 7 by holding the blade of the knife 

 horizontally, immediately over the inner aspect of the 

 vessel, as far from the vein as possible ; and an aneurism 

 needle is to be passed from without inwards, and kept 

 closely round the artery, so as to avoid wounding the 

 internal jugular vein or including the pneumogastric 

 nerve. There is a tough layer of areolar tissue between 

 the sheath and the artery, which must be gently "teased' 7 

 through, by the needle, on being pushed against the 

 finger nail. The jugular vein may be compressed above 

 and below during the operation, as it is liable to become 

 suddenly so distended as to conceal the parts. Should 

 any difficulty in reaching the vessel be met with, owing 

 to engorgement of the veins, an important landmark 

 will be found in the anterior tubercle of the transverse 

 process of the sixth cervical vertebra, which is behind 

 and a little internal to the carotid process, and against 

 this the carotid may be compressed. 



Below the crossing of the Omo-hyoid. Tying the vessel 

 below the omo-hyoid is much more difficult, owing to its 

 greater depth, and to the size of the veins: an incision 

 should be made about three inches in length from the 

 cricoid cartilage, along the anterior border of the sterno- 

 cleido-mastoid (which is to be drawn outwards), taking 

 care to avoid wounding the lower sterno-mastoid artery 

 and the middle thyroid vein: the fascia covering the 

 sterno-hyoid and sterno-thyroid muscles is next seen, 

 and must be cautiously divided, and these muscles 



