THE NECK. 441 



its ramifications ; it is thick over the trachea and great 

 vessels, for which it forms sheaths ; it is attached poste- 

 riorly to the superior curved line of the occipital bone, 

 to the ligamentum nuchse. and the spine of the scapula; 

 also, to the spines and transverse processes of the cervical 

 vertebrae ; it passes forward to the posterior border of 

 the sterno-mastoid muscle, where it splits into two leaf- 

 lets, to invest the muscle. The superficial layer becomes 

 continuous with the superficial layer of the opposite 

 side ; the deep layer joins the superficial layer anterior 

 to the sterno-mastoid ; it then dips down and surrounds 

 the internal jugular vein, common carotid artery, and 

 pneumogastric nerve, forming their sheath ; it is then 

 reflected over the pharynx, making its fibrous coat. 

 It forms, by its reflexions and reduplications, sheaths for 

 the vessels, nerves, and muscles, and is attached to all 

 the prominent osseous structures ; its attachment to the 

 first rib forms the pulley for the play of the tendon of 

 the omo-hyoid muscle. Between the superficial and 

 deep fasciae are numerous superficial veins and nerves. 

 Of these, the most important is the external jugular 

 vein, which arises near the angle of the jaw and empties 

 into the subclavian vein, just above the middle of the 

 clavicle. The anterior jugular vein is inconstant ; it is 

 usually found near the anterior median line of the neck, 

 and opens generally into the subclavian. A number of 

 the superficial branches of the cervical plexus are seen 

 running upward, transversely, and downward. Of these 

 the great auricular, derived from the second cervical, 

 emerges behind the sterno-mastoid, and is distributed to 

 the facial and auricular regions. The small occipital, 

 from the second or third cervical, runs along the poste- 

 rior border of the sterno-mastoid, and is distributed to 

 the occipital region. The descending nerves are dis- 



