THE EXTERXAL CAROTID ARTERY. Vl 



the side of the tied artery, and that the anastomosis between the branches of the external carotid 

 on the affected side and those of the same artery on the sound side was free, so that the external 

 carotid was pervious throughout. 



The External Carotid Artery. 



The external carotid artery (Fig. 347) commences opposite the upper border of 

 the thyroid cartilage, and taking a slightly curved course, passes upward and for- 

 ward, and then inclines backward to the space between the neck of the condyle 

 of the lower jaw and the external meatus. where it divides into the superficial 

 temporal and internal maxillary arteries. It rapidly diminishes in size in its 

 course up the neck, owing to the number and large size of the branches given 

 off from it. In the cbild it is somewhat smaller than the internal carotid, but in 

 the adult the two vessels are of nearly equal size. At its commencement this 

 artery is more superficial, and placed nearer the middle line than the internal 

 carotid, and is contained in the triangular space bounded by the Sterno-mastoid 

 behind, the Omo-hyoid below, and the posterior belly of the Digastric and Stylo- 

 hyoid above. 



Relations. It is covered by the skin, superficial fascia. Platysma, deep fascia, 

 and anterior margin of the Sterno-mastoid, crossed by the hypoglossal nerve, and 

 by the lingual and facial veins ; it is afterward crossed by the Digastric and 

 Stylo-hyoid muscles, and higher up passes deeply into the substance of the parotid 

 gland, where it lies beneath the facial nerve and the junction of the temporal and 

 internal maxillary veins. 



InttrnMy is the hyoid bone, wall of the pharynx, the superior laryngeal 

 nerve, and higher up it is separated from the internal carotid by the Stylo-glossus 

 and Stylo-pharyngeus muscles, the glosso-pharyngeal nerve, and part of the paro- 

 tid gland. Anteriorly is the ramus of the jaw, from which it is separated by a 

 portion of the parotid gland. Externally, in the lower part of its course, is the 

 internal carotid artery. 



Surface Marking. The position of the external carotid artery may be marked out with 

 sufficient accuracy by a line drawn from the front of the meatus of the external ear to the side 

 of the cricoid cartilage, slightly arching the line forward. 



Surgical Anatomy. The application of a ligature to the external carotid may be required 

 in^ case of wounds of this vessel, or of its branches when these cannot be tied, and in some cases 

 of pulsating tumor of the scalp or face. The operation has not received the attention which it 

 deserves, owing to the fear which surgeons have entertained of secondary haemorrhage, on 

 account of the number of branches given off from the vessel. This fear, however, has been 

 shown by Mr. Cripps not to be well founded. 1 To tie this vessel near its origin, below the point 

 where it is crossed by the Digastric, an incision about three inches in length should be made 

 along the margin of the Sterno-mastoid. from the angle of the jaw to the upper border of the 

 thyroid cartilage. The ligature should be applied between the lingual and superior thyroid 

 branches. To tie the vessel above the Digastric, between it and the parotid gland, an incision 

 should be made, from the lobe of the ear to the great cornu of the os hyoides. dividing succes- 

 sively the skin. Platysma. and fascia. By drawing the Sterno-mastoid outward, and the posterior 

 belly of the Digastric and Stylo-hyoid muscles downward, and separating them from the parotid 

 gland, the vessel will be exposed, and a ligature may be applied to it. The circulation is at once 

 re-established by the free communication between most of the large branches of the artery 

 (facial, lingual, superior thyroid, occipital) and the corresponding arteries of the opposite side, 

 and by the anastomosis of its branches with those of the internal carotid, and of the occipital 

 with the branches of the subclavian. etc. 



PLAX OF THE RELATIONS OF THE EXTERNAL CAROTID. 



Externally. 



Skin, superficial fascia. 

 Platysma and deep fascia. 

 Anterior border of Sterno-mastoid. 

 Hypoglossal nerve. 

 Lingual and facial veins. 

 Digastric and Stylo-hyoid muscles. 



Parotid gland with facial nerve and temporo-maxillary vein in its substance. 

 Internal carotid artery. 



1 Med.-Chir. Trnn.*., Ixi. 229. 



