374 MUSCLES. 



ty of breathing, from the air not passing through the larynx 

 sufficiently rapidly to keep pace with the dilatation of the thorax. 

 He illustrates the opinion by a case very much in point, of a gen- 

 tleman who had lost this fascia and the muscles by suppuration, 

 and who was afterwards incommoded by atmospheric pressure 

 upon the trachea at this place.* Mr. Velpeau, on the contrary, 

 asserts that cutting through it in opening abscesses and in ope- 

 rations has no such consequence.t 



The external borders of the fascia profunda are continued 

 into the sheaths of the great vessels of the neck. It and the 

 fascia superficialis are also continuous with one another along 

 the anterior edge of the sterno-cleido mastoideus. 



Within the inferior maxilla, at its angle, a ligamentous ex- 

 pansion arises at the pterygoideus externus muscle, and is 

 spread out between the styloid process, and the ramus of the low- 

 er jaw. This membrane, described as the stylo-maxillary liga- 

 ment, is joined at its inferior edge by the fascia superficialis, 

 just before the upper part of the sterno-mastoideus, and which in- 

 creases its breadth downwards in the neck, giving it somewhat 

 the condition of a vertical septum of that region; at its lower edge 

 it runs into the theca of the great vessels of the neck. Through 

 its lower part penetrate the stylo-hyoideus and digastricus 

 muscles, and the upper part separates the parotid from the 

 sub-maxillary gland. It is felt like a cord extending downwards 

 and backwards below the angle of the maxillainferior. It 

 is connected at its internal edge with the compages of the 

 nerves and vessels of the part, in such a manner as to forbid 

 description, but the practical anatomist will find no difficulty 

 in discovering and understanding it. 



Below this septum, the round ligament, like a nerve, passes 

 from the extremity of the styloid process to the appendix of 

 the os hvoides. 



The fascia profunda colli is also well marked in the foetus, 

 and not much blended with adipose matter. It, like the fascia 

 superficialis, is only the sheath the for muscles which it sur- 



* The late Dr. La\vrcnce informco! inc that the fascia profumla is well developed 

 in the neck of a cat, end that having occasion to remcvc it in an experiment, the 

 respiration of the animal w;;s conducted with great difficulty, amounting almost 

 tt suffocation. This is a jrood confirmation of Mr. Burns's hypothesis. 



f Anat. Chir. Vol. i. p. 438, 2nd edit. 



