THE ANTERIOR PART OF THE NECK 225 



of the deep fascia about half-way between the sternum and 

 the thyreoid cartilage. The attachments of the second layer 

 of deep fascia of the lower part of the neck may be summarised 

 as follows. It is attached below to the posterior surface of 

 the manubrium sterni and to the posterior border of the 

 clavicle, to which it binds the posterior belly of the omo-hyoid 

 (p. 145). Above, it fuses with the more superficial layer, along 

 an oblique line which ascends from the level of the coracoid 

 process to the level of the upper end of the trachea. Above 

 that level it forms, with the superficial layer, a common lamella, 

 which ascends on the infra-hyoid muscles to gain attachment 

 to the body and great cornu of the hyoid bone. The space 

 between the two layers contains, in the region of the anterior 

 triangle, the lower parts of the anterior jugular veins, the 

 anastomosis between them, and the areolar tissue in which 

 they are embedded. In the posterior triangle its contents are 

 the lower end of the external jugular vein, the terminations of 

 the transverse cervical and transverse scapular veins, the 

 transverse scapular artery, and areolar tissue. Note that the 

 anterior jugular vein on each side lies superficial to the deep 

 fascia in the upper part of the neck ; then it pierces the first 

 layer of deep fascia and lies between the two layers, where it 

 anastomoses with its fellow of the opposite side ; finally it turns 

 laterally deep to the sterno-mastoid, and terminates in the 

 external jugular vein at the anterior boundary of the sub- 

 clavian part of the posterior triangle. 



Dissection. Make two incisions through the deep fascia of the upper 

 part of the anterior triangle, one along the lower border of the mandible 

 from the angle to half an inch from the chin, and a second at right angles 

 to the first, from its middle to the great cornu of the hyoid bone. Whilst 

 making the horizontal incision avoid injuring the external maxillary artery 

 (O.T. facial) and the anterior facial vein, which pierce the deep fascia at 

 the level of the anterior border of the masseter. Reflect the two triangular 

 flaps of fascia marked out by the incisions and expose the lower surface of 

 the submaxillary gland, the submaxillary lymph glands, the anterior and 

 posterior bellies of the digastric muscle, the lower part of the stylo-hyoid 

 muscle, and a further part of the anterior facial vein. 



The majority of the submaxillary lymph glands lie along 

 the lower border of the mandible on the superficial surface of 

 the submaxillary gland. The anterior facial vein crosses the 

 posterior part of the submaxillary gland superficially. The 

 external maxillary artery dips deeply between the lower border 

 of the mandible and the submaxillary gland. The posterior 



VOL. II 15 



