212 LABORATORY MANUAL OF HUMAN ANATOMY 



Distinguish in it 



(1) A deep or intermuscular layer. 



(2) A superficial or premuscular layer. 



The suprasternal space (sometimes called Burns' space) is 

 situated between the superficial layer of the fascia colli and the 

 premuscular layer of the middle layer of the fascia colli. 

 (Charpy.) Examine its contents. The interaponeurotic veins 

 near the base of the neck are aspirated during inspiration. 

 Hence this is the most dangerous area for the entrance of air 

 into the veins during surgical operations. 



The Deep Part (Fascia praevertebralis). 

 Note its two parts : 



(1) That extending from the anterior longitudinal ligament of the 

 spine to the anterior tubercles of the transverse processes; it covers 

 the pre vertebral muscles proper (Mm. longi colli et capitis). Observe 

 the relation of the N. sympathicus to this part. 



(2) That extending from the anterior to the posterior tubercles 

 around the Mm. scaleni. Observe the relation of the N. phrenicus 

 and of the Nn. cervicales to this part. 



The fascia praevertebralis is part of the great common sheath 

 of the body-cavity, being for the neck what the endothoracic 

 fascia, the transversalis fascia, and the pelvic fascia are for the 

 other visceral cavities. (Fawcett.) 



The Visceral Sheath. 



Contents. Thyreoid gland, trachea, oesophagus, and pharynx. 



Shape. In cross-section, semicylindrical. 



Attachments. 



Behind, by lateral angles to the vertebral column; between these two 

 attachments is left a retrovisceral or prevertebral space. This is 

 of especial interest in the retropharyngeal region (postpharyngeal 

 abscess, etc.). 

 Above, to base of skull. 

 Below, extends into mediastinum. 



The Vascular Sheath. 



(a) Common sheath. (Note relation of ramus descendens N. hypo- 



glossi.) Observe attachment lateralward to deep layer of fascia 

 colli and medialward to visceral sheath. The common sheath 

 encloses b, c } and d. 



(b) Sheath for A. carotis (loose, to permit of pulsation). 



(c) Sheath for V. jugularis interna (dense, especially between artery 



and vein, septum vasorum). 



(d) Sheath for N. vagus (always satellite of artery, even in embryonic 



life, when vein is distant). 



