SURGICAL ANATOMY. 



THE TRIANGLES OF THE NECK. 



THE general outline of the neck is somewhat quadrilateral. 

 Bounded in front by the median line, behind by the trapezius 

 muscle, above by the lower border of the body of the maxilla, and 

 below by the clavicle. It is divided by the sterno-mastoid muscle 

 running obliquely through it into two large triangles, an ante- 

 rior and a posterior triangle. These are again subdivided by 

 the crossing of the omo-hyoid muscle into two smaller triangles 

 each. The anterior into the superior and inferior carotid tri- 

 angles, and the posterior into the occipital and subclavian tri- 

 angles. The digastric muscle, at the upper part of the anterior 

 triangle, separates a triangular space called the submaxillary 

 triangle. 



The anterior triangle of the neck is bounded as follows : 



Front, median line of the neck ; 



Behind, anterior border of the sterno-mastoid muscle ; 



Above, lower border of the body of the lower jaw, and a line 

 from its angle to the mastoid process, forming the base of the 

 triangle ; 



Below, the top of the sternum, forming the apex. 



The floor is formed by the sterno-hyoideus, sterno-thy- 

 roideus, thyro-hyoideus, inferior and middle constrictors of the 

 pharynx, the anterior belly of the digastricus, the mylo-hyoideus, 

 stylo-hyoideus, and hyoglossus muscles. The roof is formed by 

 the skin, superficial fascia, platysma myoides, and deep fascia. 



The inferior carotid triangle is the most inferior subdivision 

 of the anterior triangle, and is bounded as follows : 



Front, median line of the neck ; 



Behind, anterior border of the sterno-mastoideus ; 



Above, anterior belly of the omo-hyoideus ; 



Below, the apex of the anterior triangle. 



It contains the following structures : 



Thyroid gland and lower part of the trachea and larynx ; 



Inferior thyroid and common carotid arteries; 



Inferior thyroid and internal jugular veins; 



Pneumogastric, recurrent laryngeal, descendens noni, com- 

 municans noni, and sympathetic nerves. 

 (374) 



