144 APPLIED ANATOMY. 



border of the thyroid cartilage. It will be necessary to push the sternomastoid 

 muscle posteriorly, as its anterior margin overlies the vessel. The internal jugular 

 vein is to its outer side and between the two and posterior is the pneumogastric 

 nerve. The sympathetic nerve lies behind it but is separated by a layer of fascia and 

 is not liable to be caught up in passing the aneurism needle. The lingual, facial, 

 and laryngeal veins may be encountered and are apt to cause trouble. They will 

 have to be held aside or ligated and divided. The ascending pharyngeal artery may 

 lie close to the internal carotid and care should be taken not to include it in the 

 ligature. The needle is to be passed from without inward. 



The External Carotid Artery. Of recent years the external carotid artery 

 has been ligated far more often than formerly, as it was customary to ligate the 

 common carotid instead. The external carotid runs from the upper border of the 

 thyroid cartilage to the neck of the mandible. It supplies the outside of the head, 

 face, and neck. These parts are the seat of various operations for tumors, especially 

 carcinoma of the mouth and tongue, diseased lymph-nodes, and other affections, and 



Facial artery 

 Lingual artery 



Greater cornu of ^ __ Stylohyoid muscle 



hyoid bone ~BTi,J^S 5!c - ~~^-- ^_ 



Superior laryn- __ , ^KSJ^-J^i ~^T" - ^_ ~~" Digastric muscle 



Ext. carof^ery 6 . I^^jH -Occipital artery 



Superior thyroid JS , JHP5P^4 -^De y S cendens nypoglossi 



nerve 



artery 



Internal carotid artery 

 vein 



Sternomastoid artery 

 Common carotid artery 



FIG. 1 73. Ligation of external carotid artery and its branches. 



the external carotid and its branches are not infrequently ligated in order to cut off 

 their blood supply. 



In extirpation of the Gasserian ganglion, hemorrhage has been such an annoying 

 and dangerous factor that a preliminary ligation or compression (Crile) of the 

 external carotid is frequently resorted to. This artery may also be ligated for 

 wounds, resection of the upper jaw, hemorrhage from the tonsils, and angiomatous 

 growths affecting the region which it supplies. 



Unlike some other arteries the external carotid sometimes seems to have no 

 trunk, consisting almost entirely of branches. Therefore in ligating it one should 

 not expect to find a big artery the size of the internal carotid, but often one only half 

 as large. The branches of the external carotid artery are the superior thyroid, lin- 

 gual, and facial, which proceed anteriorly toward the median line ; the occipital 

 and posterior auricular, which supply the posterior parts ; the ascending pharyngeal, 

 which comes off from its deep surface and ascends to the base of the skull ; and 

 the temporal and internal maxillary arteries, which are terminal. It is ligated either 

 near its commencement just above the superior thyroid artery or behind the angle 

 of the jaw above the digastric muscle. 



Ligation of the External Carotid Artery above the Superior Thyroid. At its 

 commencement at the upper border of the thyroid cartilage the artery is quite 



