MUSCLES OF THE NECK. 373 



Of the Fascia Profunda Cotti. 



When the origin of the sterno-cleido mastoideus is turned to 

 one side, the Fascia Profunda of the neck is seen beneath the 

 fascia superficialis, and somewhat separated from it by a lami- 

 na of cellular adipose matter. This membrane arises from the 

 larynx, forms a thin capsule to the thyroid gland, and, being 

 closely attached to its inferior margin, descends by investing 

 the sterno-hyoid and thyroid muscles, being well seen on 

 their anterior surfaces. It is firmly fastened to the upper edge 

 of the sternum, to the sternal end of the clavicles, and to the 

 cartilages of the first ribs, forming an elastic and resisting 

 membrane from the larynx to the thorax. By turning off the 

 sterno-hyoid and thyroid muscles from their attachment to the 

 sternum, the fascia profunda will be seen still more distinctly, 

 passing behind them from the inferior margin of the thyroid 

 gland, to the upper bone of the sternum: this lamina of it is in- 

 serted into the sternum, twelve or fifteen lines below the upper 

 edge. It encloses or surrounds the transverse vein and the ar- 

 teria innominata. Beneath the fascia profunda, are the tra- 

 chea, the roots of the arteries of the head and upper extremi- 

 ties and the trunks of their veins. There is much loose 

 cellular and adipose matter placed at the lower part of the 

 neck, beneath this fascia ; and between it and the trachea; 

 through which the thyroid veins with their ramifications pass. 

 This last circumstance must always render suppurations and 

 operations in the part highly dangerous, as the pus will form 

 fistulas under the sternum; moreover, the continual motion of the 

 part in respiration, prevents adhesions from forming, and, there- 

 fore, disposes to ulceration. An ingenious idea on the uses of this 

 fascia and of the sterno-hyoid and thyroid muscles as connect- 

 ed with it, was suggested by the late Allen Burns: he con- 

 ceived that they were a defence to the upper part of the thorax, 

 and sustained, in inspiration, the atmospheric pressure, which, 

 without them, would fall upon the trachea and produce difficul- 



to reach as far as the rcctus abcbminis muscle, and even to the point of the third 

 bone of the sternum. The fissure between the sternal and clavicular portions in 

 mammiferous animals, i.-?, naturally, so much extended, as to produce two dis- 

 tinct muscles. 



VOL. I. 32 



