THE XECK 



1101 



at a varying level tlie outer l)or(ler of the cLivicular (iri.LMii. n\\\>\ lie reinciiilxTcil in 

 such operations as tenotomy liere. These veins are joined Ity numerous transverse 

 branches, and become larger Ijelow. 



The anterior jugular vein, commencing in the submaxillary regi(»n, descends a little 

 to one side of the middle line. Just above the clavicle each vein turns outwards 

 and, })iercing the deep cervical fascia, passes under the sterno-mastoid, and opens 

 into the external jugular or subclavian vein. It has no valves. 



Behind the sterno-clavicular joint liis the commencement of the innominate 

 veins, the bifurcation of the innominate artery on the right, and the eomnifm 

 carotid artery on tlie left; dee])er still lie the pleura and hmg. The occasional 

 high position of the innominate on the trachea may be a point of importance in 

 tracheotomy, both at the time of the o))eration and later on, from the fatal facility 

 with which a metal tube, if long retained after a low tracheotomy, may ulcerate 

 into the vessel. 



Fig. 675. — Axtekior and Latkkal Ckuvual Mu.scles. 



Stylo-glossus 



Hyo-gl08SU8 



Mylo-hyoid 



Anterior belly of 

 digastric 



Eaphe of mylo- 

 hyoid 



Thyro-hyoid 



Inferior eoustrietor 



Anterior belly of omo- 

 hyoid 



Sterno-hyoid 

 Steruo-thyroid 



Stylo-hyoid 



Posterior belly of digastric 



Splenius capitis 



Sterno-mastoid 



Levator anguli scapulae 



Scalenus medius 

 Trapezius 



Scalenus posticus 



Posterior belly of 

 omo-hyoid 



In front of the sterno-mastoid is the anterior triangle, which is subdivided 

 into three smaller triangles by the digastric mu.^cle above, and the anterior 

 bellv of the omo-hyoid below. Thi'se smaller triangles are called, from aV)ove. the 

 subiiiaxillarv. the superior and inferior carotid triangles. The submaxillary or 

 supra-hyoid triangle is bounded above l)y the jaw, and a line drawn l«ack t«i the 

 mastoid process; below, by the digastric and stylo-hyoid muscles; and in front by 

 the middle line of the neck. This space contains the submaxillary gland, and 

 embedded in the gland is the facial artery; deeper than the gland are tiie sub- 

 mental vessels and the mylo-hyoid vessels and nerve. Posteriorly, and separated 

 from the above structures by the stylo-mamlibular ligament, is the upjier ))art of 

 the external carotid artery which is embedded in the parotid glan<l. where it gives 

 off its two terminal and the posterior aurii-ular liranches. More deeply lie the 

 internal jugular vein, internal carotid artery, and the vagus. 



