138 HEAD AND NECK 



with the fascia on the anterior aspect of the vertebral column 

 in the posterior mediastinal region. 



The Carotid Sheath. The term carotid sheath is applied 

 to the fascia which surrounds and embeds the carotid arteries, 

 the internal jugular vein, and the vagus nerve. Part of it has 

 been removed already, and the dissector will have noted that 

 it is in no sense a membrane, but merely the fibro-areolar 

 tissue which fills the interval between the transverse processes 

 of the vertebrae posteriorly, the trachea, larynx, pharynx, 

 oesophagus, and the lobe of the thyreoid gland medially, 

 and the sterno-mastoid laterally ; that it is continuous with 

 the fascial planes in its immediate neighbourhood, and that 



Capsule of thyreoid gland First layer of deep fascia 



(black line) | Sheath of thyreoid gland 



Infra-hyoid muscles !9&L\ (pretracheal fascia) 



. Sterno-mastoid 

 Scalene muscle ^ 



Second layer of deep fascia 



Omo-hyoid 

 Trapezius 



FIG. 48. Diagram of the deep Cervical Fascia in a transverse section 

 of the lower part of the neck. 



through it run the carotid arteries, the internal jugular vein, 

 and the vagus nerve, each in its own special compartment. 



Dissection. Remove the areolar tissue and the glands which 

 lie under cover of the sterno-mastoid ; stitch together the two 

 parts of the divided anterior belly of the omo-hyoid muscle and 

 fix the muscle to the common carotid artery and the internal 

 jugular vein with one or two stitches ; then proceed to display 

 the structures which lie under cover of the sterno-mastoid. A 

 glance at the following list will convince the dissector that they 

 are very numerous. 



Structures under cover of the Sterno-Mastoid. 



Muscles. The upper part of the splenius capitis ; the 

 upper and posterior part of the posterior belly of the digastric; 

 the origins of the levator scapulae, the scalenus medius, the 

 longus capitis (O.T. rectus capitis anticus major), the rectus 



