23 6 



HEAD AND NECK 



nuchae. The lamella which covers the deep surface of the 

 sterno-mastoid is blended with the lateral surface of the carotid 

 sheath. The pretracheal layer, which has been dissected 

 already in the median plane, ensheaths the thyreoid gland 

 and blends postero-laterally with the medial surface of the 

 carotid sheath. The prevertebral layer covers the anterior 

 surfaces of the prevertebral muscles and, passing laterally, 

 blends with the posterior aspect of the carotid sheath ; then, 



turning round the tips 

 of the transverse pro- 

 cesses of the vertebrae, 

 it passes posteriorly, 

 covering the muscles 

 which form the floor of 

 the posterior triangle ; 

 and it becomes continu- 

 ous with the sheaths of 

 the deep muscles of the 

 posterior part of theneck. 

 Laterally and pos- 

 teriorly, the superficial 

 layer of the deep fascia 

 passes upwards over the 

 sterno-mastoid and the 

 trapezius to be attached 

 to the superior nuchal 

 lines and the mastoid 



F,o. 95,-Diag^deep cervica, fascia portions of the temporal 



bones. In the anterior 



cervical region it is attached to the body and the great cornua 

 of the hyoid bone, and then, as it is prolonged further upwards, 

 it splits anteriorly to enclose the submaxillary gland, and 

 posteriorly to enclose the parotid. It has been noted already 

 that the lamella which passes superficial to the submaxillary 

 gland is attached to the lower border of the mandible, and 

 that which passes deep to the gland is connected above to 

 the mylo-hyoid line on the inner surface of the mandible. The 

 layer which passes superficial to the parotid gains attachment 

 to the zygoma and is prolonged forwards to blend with the 

 fascia covering the masseter. The lamella which passes deep 

 to the parotid covers its postero-medial and antero-medial 

 surfaces ; the posterior part is attached above to the lower 



First layer of deep fascia 

 Pretracheal layer 



Isthmus of thyreoid gland 

 Prevertebral fascia 



First layer 

 Second layer 

 Pretracheal layer 

 Left innominate v 



Mediastinal tissue 



