POSTERIOR TRIANGLE 



39 



verse cervical, and occipital arteries ; (4) lymph vessels, 

 passing from the superficial structures to the glands in the 

 triangle. It is frequently stated that the lesser occipital and 

 great auricular nerves and the nervus cutaneus colli also 

 pierce the roof. As a general rule, they turn round the 

 posterior border of the sterno-mastoid, under cover of the 

 fascia, and pierce the fascia which lies on the sterno-mastoid 

 muscle. 



The floor is formed by the splenius capitis, the levator 

 scapulae, the scalenus medius, and the scalenus posterior 

 muscles, with the addition, occasionally, of a small part of the 

 semispinalis capitis (O.T. complexus), above, and the upper 

 serration of the serratus anterior, below ; the latter appears 

 in the area of the triangle only when the clavicle is very 

 fully depressed. The muscles of the floor are covered with 

 a layer of fascia which is the backward continuation of the 

 prevertebral fascia of the anterior cervical region. 



The contents of the posterior triangle are : 



1. Fatty areolar tissue. 



2. The posterior belly of the omo-hyoid muscle. 



3. Lymph /Lateral superior deep cervical. 



Glands, \Inferior deep cervical (Supraclavicular). 

 f Third part of subclavian. 

 J Transverse cervical and its terminal branches. 

 [Occipital (sometimes). 

 f External jugular. 

 J Transverse cervical. 



5. Veins, 2 j Transverse scapular (O.T. suprascapular). 

 [Termination of anterior jugular. 

 Accessory. 

 Lesser occipital. 

 Great auricular. 

 Nervus cutaneus colli. 

 To levator scapulae, 

 trapezfus. 

 scalenus medius. 



, , posterior. 

 Supraclavicular. 



To posterior belly of omo-hyoid, from ansa hypoglossi. 

 Trunks of brachial plexus. 

 The nervus dorsalis scapulae. "| 



,, long thoracic. ^Branches of the brachial 



, suprascapular. | plexus. 



,, nerve to the subclavius. J 



1 The transverse scapular artery (O.T. suprascapular) lies posterior to 

 the clavicle and is not, strictly speaking, in the triangle. 



2 The subclavian vein is posterior to the clavicle and therefore is not 

 contained within the triangle. 



Hi 3 c 



4. Arteries, 1 



6. Nerves, 



Branches of cervical plexus. 



