PLATE XXXVIII. 

 THE POSTERIOR TRIANGLE. 



This plate shows a dissection of the posterior triangle of the neck after removal of 

 the cervical fascia which roofs it in, anil the dense fibro-fatty tissue it contains. The 

 upper portion of the triangle is that which needs most care, as the connective tissue is 

 extremely tough and fibrous. 



The Posterior triangle is bounded 



In front. By the posterior edge of the sterno-mastoid. 



Behind. ~By the anterior edge of the trapezius. 



Below. By the middle third of the clavicle. 



The Floor is formed from above downward by the splenius, levator anguli scapulae, 

 scalenus medius and post in is. 

 and the first serration of the 

 serratus magnus appears in the 

 lower and outer portion of the 

 triangle when the arm is 

 strongly depressed. 



It is divided into two tri- 

 angles by the omo-hyoid muscle, 

 which crosses its lower part 

 obliquely, an upper and larger, 

 the occipital, and a lower and 

 smaller the subclavian, the 

 size of which varies as the 

 omo-hyoid crosses higher or 

 lower above the clavicle. 



The Occipital triangle 

 contains 



The cervical plexus, and 

 its small occipital, great auri- 

 cular, superficial cervical, de- 

 scending or supra-clavicular 

 branches, muscular branches 

 to the levator anguli scapulw, 

 communicating branches to 

 the spinal accessory (those from the third and fourth also supplying the trapezius), the 

 spinal accessory, upper cords of the brachial plexus, nerve to the rhomboids, and nerve 

 to the subclavius, the supra-scapular and origin of the posterior thoracic. 



The transverse cervical, superficial ascending cervical and posterior scapular artery 

 and veins, posterior jugular vein. 



The glandulse concatenate along the posterior edge of sterno-mastoid. 



The Subclavian triangle contains 



The subclavian artery (third part), the transverse cervical and supra-scapular 

 vessels, the end of the external and posterior jugular veins. The cords of the brachial 

 plexus, supra-scapular and posterior thoracic nerves and nerve to the subclavius 

 muscle. 



Diapknxpn 



DIAGRAM or THK CERVICAL PLEXUS 



