140 A MANUAL OF ANATOMY. 



Below, it passes along with the great vessels (trachea 

 and oesophagus) into the thorax, forming their sheaths, and 

 becomes continuous with the fibrous layer of the pericar- 

 dium. 



Laterally, this fascia passes outward under the clavicle 

 with the subclavian artery and vein and brachial plexus, 

 forming their sheath. In the axilla it receives the name of 

 that region (axillary sheath). 



(4) The fourth or prevertebral layer of fascia. The 

 name indicates its position to be in front of the vertebrae 

 (and their muscles). It lies immediately behind the third 

 layer, and covers over the rectus capitis anticus major 

 and minor, and longus colli muscles. 



Above, it is attached to the basilar process of the occipi- 

 tal bone. Laterally, to the inner surface of the first layer 

 along the side of the neck ; below, it passes into the thorax 

 behind the oesophagus, and extends into the posterior me- 

 diastinum. 



While these various layers are described, it should be 

 remembered that they are so described more for convenience 

 and to indicate a general lamination, than to mean that 

 these layers will be found as distinct and separated from 

 each other as the description would indicate. On the con- 

 trary, all these layers blend wherever they come in contact, 

 for the deep cervical fascia is only a part of the connective- 

 tissue system of the body, whose function is to connect and 

 support the various organs between which it is developed. 

 Consequently, the student will obtain a more correct view 

 of the cervical fascia (as well of any other) if he will imagine 

 all the muscles, veins, arteries, and nerves of the neck 

 removed, and the sheaths, capsules, and envelopes of 

 these and the connective tissue which bind them all in 

 position only remaining. This will then show that the 



