2 Musc/es of Head and Neck 



then passes over the two posterior triangles, being attached to the 

 occiput and the mastoid process, and, having reached the hinder 

 border of the sterno-mastoid, splits to enclose it. At the front of that 

 muscle the two layers again join, and, covering in the anterior triangle, 

 the sheet blends in the middle line with that of the opposite side. 



Over the posterior triangle the fascia is attached to the clavicle, 

 being there perforated by the external jugular vein, which had hitherto 

 lain between the deep fascia and the platysma. 



In the anterior triangle it is attached to the lower jaw, and sends 

 an offshoot to the zygoma to cover the masseter. Another sheet 

 passes over the parotid gland, and an important slip from the angle 

 of the jaw to the styloid process the stylo-maxillary ligament 

 separates the parotid from the submaxillary gland. 



In the front of the neck, where the deep fascia is attached to the 

 hyoid bone, it is thin, but as it descends it becomes thicker, and splits 

 into two layers, the more superficial of which is attached to the front 

 of the manubrium, whilst the deeper incloses the sterno-hyoid and 

 thyroid, and is connected with the back of the sternum. It also straps 

 the tendon of the omo-hyoid to the first rib. One offset from the 

 fascia beneath the sterno-mastoid joins with and strengthens the 

 carotid sheath, another intervenes between the sterno-thyroid and the 

 trachea (see 'Tracheotomy,' p. 131), which, descending in front of the 

 trachea and of the carotid vessels, unites with the pericardium. 



Deeper than all these, a layer, the prcevertebral fascia, passes 

 behind the pharynx and cesophagus, which, binding down the rectus 

 anticus major, the longus colli, and the scaleni, descends with the 

 brachial plexus and the subclavian vessels to blend with the sheath of 

 the axillary vessels. 



Suppuration beneath the deep fascia demands prompt drainage 

 or it may become diffuse, causing great damage to such tissues as 

 temporarily impede its course. At the front of the neck the pus ma)' 

 in time find its way to the surface, but it may be guided by the deep 

 fascia into the anterior mediastinum, and then possibly set up an 

 empyema. I once dissected a specimen in which the pus had found 

 its way into the subclavian vein, causing fatal pyaemia. When beneath 

 the deep fascia of the posterior triangle it may find its way into the 

 cesophagus or chest, or may wander in the track of the subclavian 

 vessels and set up an axillary abscess. The subject of post- 

 pharyngeal abscess is alluded to on page 210. 



The trapezius arises from the inner third of the superior curved 

 line of the occiput, the ligamentum nuchas, and all the dorsal spines 

 and their supraspinous ligaments. The highest fibres descend, the 

 median pass horizontally, and the lowest ascend to their insertion intr> 

 the angle between the clavicle and the spine of the scapula. Thus 

 the muscle is attached to the back of the flattened part of the clavicle 

 and to the upper part of the spine of the scapula. 



