Side of Neck 



THE TRIANGLES OF THE NECK 



The side of the neck may be represented as an oblong divided by 

 the sterno-mastoid into a superior and inferior triangle. (The student 

 will find it useful to practise drawing these tri- 

 angles and their subdivisions in outline, and 

 roughly filling in their chief contents.) 



The posterior triangle has as its base that 

 part of the clavicle which is between the pos- 

 terior border of the sterno-mastoid and the 

 anterior border of the trapezius the muscles 

 which form its sides its apex being between 

 the occipital attachments of those muscles. 

 This triangle is divided by the posterior belly 

 of the omo-hyoid into an occipital and a sub- 



rlavi'an trio r> n-1 ^ x > submaxillary triangle; 2, 



Clavian triangle. superior carotid ; 3, inferior 



The sides of the occipital triangle are carotid; 4 , occipital; 5, sub- 

 formed by the borders of the trapezius and the 



sterno-mastoid, the posterior belly of the omo-hyoid being its base. In 

 its floor, from above downwards, are the splenius capitis, levator anguli 

 scapulas, and the scalenus medius and posticus. It is covered by skin 

 and fasciae, and by the platysma inferiorly. 



Superficial branches of the cervical plexus appear in the space, 

 namely, the lesser occipital, great auricular, and the superficial or trans- 

 verse cervical nerve (all of which wind round the posterior border of 

 the sterno-mastoid) and the supra-clavicular branches, which leave the 

 lower part of the triangle (v. p. 145). The spinal accessory nerve 

 traverses the middle of the triangle in its course from the sterno- 

 mastoid to the trapezius (p. 70), and the transverse cervical branch 

 of the thyroid axis (p. 233) crosses its lower part. The glandulas con- 

 catenates extend, deeply, along the posterior border of the sterno- 

 mastoid. 



The subclavian triangle is bounded below by the clavicle, in 

 front by the posterior border of the sterno-mastoid, and above by the 

 posterior belly of the omo-hyoid. It derives its name and its import- 

 ance from the fact that the subclavian artery is usually tied in its 

 depths. 



The more muscular the subject, the smaller is the triangle. It is 

 covered by the skin, fasciae, and platysma, and is crossed by the supra- 

 clavicular nerves. The external jugular vein (p. 35) pierces the deep 

 fascia just behind the origin of the sterno-mastoid, to end in the sub- 

 clavian vein, and it receives the suprascapular and transverse cervical 

 veins as it passes through the triangle. The suprascapular and posterior 

 scapular arteries also cross the space from beneath the sterno-mastoid. 

 The third part of the subclavian artery and the subclavian vein 



