THE NECK in 



Deep Cervical Fascia. The deep fascia of the neck con- 

 sists of an investing layer and of several subsidiary processes. 



(a) The Investing Layer forms the roof of the anterior 

 triangle, and is firmly bound down to the hyoid bone. Traced 

 laterally, it encloses the sterno-mastoid, forms the roof of the 

 posterior triangle, and then invests the trapezius (Fig. 36). It 

 is attached above to the lower border of the mandible, but, in 

 the neighbourhood of the angle, it is carried upwards, enclosing 

 the parotid gland, to the zygomatic arch and the antero-inferior 

 border of the external acoustic (auditory) meatus. It is attached 

 to the mastoid process, the superior nuchal line of the occipital 

 bone, and the external occipital protuberance, i.e. it corresponds 

 to the attachments of the sterno-mastoid and the trapezius. 



Between the angle of the mandible and the greater cornu 

 of the hyoid bone, the investing layer blends with the fascial 

 sheath of the posterior belly of the digastric ; between the chin 

 and the greater cornu a similar connection is formed with the 

 fascial sheath of the anterior belly of the digastric. In this 

 way the submaxillary and submental regions are shut off from 

 one another and from the rest of the neck (p. 145). 



Just above the jugular (suprasternal) notch the investing 

 layer splits into two lamellae, which are attached to the front 

 and back of the manubrium sterni. The space between them 

 the suprasternal space (of Burns} contains one or two lymph 

 glands and a communication between the two anterior jugular 

 veins (Fig. 51). Traced laterally, these two layers enclose the 

 sterno-mastoid, and pass down to the clavicle. In the lower 

 part of the posterior triangle the same two layers can again be 

 recognised, and, for about an inch above the clavicle, they are 

 separated by some loose fat. The deeper layer encloses the 

 posterior belly of the omo-hyoid, and holds it down in place ; the 

 superficial layer, which is very thin and ill-defined, is continuous 

 with the fascia covering the trapezius. 



The investing layer is much stronger over the triangles than 

 it is over the trapezius and the sterno-mastoid. So firmly does 

 it bind the structures together that, in operations on the neck, 

 good exposure can be obtained only after it has been divided 

 freely. In flap operations the flap should consist of all the tissues 

 down to and including the deep cervical fascia. 



(b) The Prevertebral Fascia covers the muscles which are 

 closely applied to the anterior aspects of the cervical vertebrae. 

 It is attached above to the basi-occiput, and it passes down as 



