THE NECK 1359 



border of the hyoid bone. Anastomosing branches of the superior thyreoid form an arch along 

 the upper border of the isthmus. The lingual artery arises from the parent trunk, opposite the 

 tip of the great cornu of the hyoid, and passes forward just above the great cornu, crossed by 

 the hypoglossal, and thence to the side of the tongue. In the first part of its course, before it 

 reaches the hyo-glossus, it is curved, at first ascending, and then, having descended slightly, 

 before it reaches the hyo-glossus, and while it lies under it, its curve is gentle, with the concavity 

 upward; beyond the hyo-glossus, as it lies on the muscles of the tongue beneath the mucous 

 membrane, it is tortuous. The lingual vein, it will be remembered, does not run with its artery, 

 but lies superficial to the hyo-glossus. It receives the two small venae comitantes which run 

 with the lingual itself just before it crosses the common carotid. The line of the external 

 maxillary (facial) artery (fig. 1093), which often arises with the lingual, has been given on p. 1343. 

 The occipital artery, starting on the same level as the facial (i. e., at a point a little above and 

 outside the tip of the great cornu of the hyoid bone), follows a line drawn upward and laterally, 

 first to the interval between the transverse process of the atlas and the mastoid process, the 

 former bone being felt just below and in front of the tip of the latter; thence, lying in the occipital 

 groove of the mastoid, the artery ascends gradually, enters the scalp, together with the great 

 occipital nerve, a little medial to a point midway between the external occipital protuberance 

 and the mastoid process, to follow, tortuously and superficial to the aponeurosis, the line of the 

 lambdoid suture. 



The surface marking of the digastric and omo-hyoid, which subdivide the anterior triangle 

 into the three smaller subtriangles above described, should be noted. The line of the posterior 

 belly of the digastric corresponds to one drawn from the apex of the mastoid process to a point 

 just above the junction of the great cornu and body of the hyoid bone; and from this spot, 

 which gives the point of meeting of the two tendons, one slightly curving upward to a point 

 just behind the symphysis menti, would give that of the anterior belly. 



To trace the omo-hyoid, a line should be drawn from the lower margin of the side of the 

 hyoid bone obliquely downward, so as to cross the common carotid opposite the cricoid carti- 

 lage and thence curving laterally under the sterno-mastoid at the junction of its middle and 

 lower thirds, and then onward and still laterally parallel with and a little above the clavicle, 

 as far as its centre. 



Posterior triangle. — This shows in its lower part a wide depression, the supra- 

 clavicular fossa. Here the brachial plexus may be felt, and, by pressure down- 

 ward and backward immediately behind the clavicle, just lateral to and behind the 

 lateral margin of the sterno-mastoid, the pulsation of the subclavian artery can be 

 stopped against the first rib. 



The supra-clavicular fossa should be opened out by depressing the arm, and parts relaxed 

 by carrying the shoulder forward and turning the head to the same side. This vessel curves 

 upward and laterally from behind the sterno-clavicular joint to disappear behind the centre of 

 the clavicle, the highest point of the curve being 1.2 to 2.5 cm. (^ to 1 in.) above the bone. 

 The artery on the left side lies more deeply than the right, and does not rise so high into the neck. 

 The subclavian vein lies at a lower level, separated by the scalenus anterior, and under cover of 

 the clavicle. Into the above curve rise the pleura and lung. The pleura must be expected to 

 rise 2.5 cm. (1 in.) above the clavicle, behind the clavicular head of the sterno-mastoid. 



The transverse scapular and transverse cervical vessels run laterally, parallel with the 

 clavicle. The former lies behind the bone and subclavius ; the latter also runs laterally in a trans- 

 verse direction, across the root of the neck, but on a slightly higher plane, and thus a little above 

 the clavicle. 



Ligature of the third part of the subclavian is best performed by an angular incision, the 

 horizontal portion along the centre of the clavicle, and the vertical one along the posterior 

 border of the sterno-mastoid, with partial division of this and the trapezius when closely ad- 

 jacent. The chief points to bear in mind are the venous plexus into which the external jugular, 

 transverse cervical, transverse scapular, and cephalic veins enter; the omo-hyoid and division 

 of the fascia which ties this to the clavicle; identification of the lateral margin of the scalenus 

 anterior and the scalene tubercle; care of the transver.se scapular artery and the descending 

 branch of the transverse cervical. The needle is passed from above downward so as not to in- 

 clude the lowest cord of the brachial plexus, the vein, if distended, being depressed with a blunt 

 hook. If the nerve to the subclavius be seen, it must be uninjured, as it occasionally forms an 

 important part of the phrenic. The collateral circulation is given at p. 1360. 



Crossing the sterno-mastoid, a little obliquely, in a line drawn from a point 

 just below and behind the angle of the jaw w^hich marks its origin in the union of 

 the posterior part of the internal maxillary and the posterior auricular veins to the 

 centre of the clavicle, runs the external jugular vein. Above, it lies between the 

 platysma and deep fascia, and is accompanied by the group of superficial cervical 

 nodes (p. 709). About 3.7 cm. (Ih in.) above the clavicle it perforates the deep 

 cervical fascia, its coats being blended with the opening. Gentle pressure with a 

 finger at this point renders the vein above clearly visible. The dilated part 

 between this point and the subclavian vein is called the sinus, and is marked by 

 two valves, neither of which is usually perfect. 



Opening into the external jugular, in the middle or lower third of its course, is the posterior 

 external jugular, a vessel which begins in the occipital region superficially and runs down in front 

 of the anterior border of the trapezius, across the posterior triangle. 



