266 ABDOMINAL FASCLE. 



ascending layer is attached to the trachea, and becomes continuous with 

 the sheath of the carotid vessels, and with the deep cervical fascia ; the 

 descending layer descends upon the trachea to its bifurcation, surrounds 

 the large vessels arising from the arch of the aorta, and the upper part of 

 the arch itself, and is continuous with the fibrous layer of the pericardium. 

 It is connected also with the venae innominatae and superior cava, and is 

 attached to the cellular capsule of the thymus gland. 



" The thoracic fascia," writes Sir Astley Cooper, "performs three im- 

 portant offices : 



" 1st. It forms the upper boundary of the chest, as the diaphragm does 

 the lower. 



" 2d. It steadily preserves the relative situation of the parts which enter 

 and quit the thoracic opening. 



" 3d. It attaches and supports the heart in its situation, through the 

 medium of its connexion with the aorta and large vessels which are placed 

 at its curvature." 



ABDOMINAL FASCIA. 



The lower part of the parietes of the abdomen, and the cavity of the 

 pelvis, are strengthened by a layer of fascia which lines their internal sur- 

 face, and at the bottom of the latter cavity is reflected inwards to the sides 

 of the bladder. This fascia is continuous throughout the whole of the 

 above-mentioned surface ; but for convenience of description is considered 

 under the several names of transversalis fascia, iliac fascia, and pelvic 

 fascia ; the two former meet at the crest of the ilium and Poupart's liga- 

 ment, and the latter is confined to the cavity of the true pelvis. 



The fascia transversalis (Fascia Cooperi)* is a cellulo-nbrous lamella, 

 which lines the inner surface of the transversalis muscle. It is thick and 

 dense below, near the lower part of the abdomen ; but becomes thinner 

 as it ascends, and is gradually lost in the subserous cellular tissue. It is 

 attached inferiorly to the reflected margin of Poupart's ligament and to the 

 crest of the ilium; internally, to the border of the rectus muscle ; and, at 

 the inner third of the femoral arch, is continued beneath Poupart's liga- 

 ment, and forms the anterior segment of the crural canal, or sheath of 

 the femoral vessels. 



The internal abdominal ring is situated in this fascia, at about midway 

 between the spine of the os pubis and the anterior superior spine of the 

 ilium, and half an inch above Poupart's ligament ; it is bounded upon its 

 inner side by a well-marked falciform border, but is ill defined around its 

 outer margin. From the circumference of this ring is given off an infundi- 

 buliform process, which surrounds the testicle and spermatic cord, consti- 

 tuting the fascia propria of the latter, and forms the first investment to the 

 sac of oblique inguinal hernia. It is the strength of this fascia, in the in- 

 terval between the tendon of the rectus and the internal abdominal ring, 

 that defends this portion of the parietes from the frequent occurrence of 

 direct inguinal hernia. 



INGUINAL HERNIA. 



Inguinal hernia is of two kinds, oblique and direct. 



In OBLIQUE INGUINAL HERNIA the intestine escapes from the cavity of 



* Sir Ai.iey Cooper first described this fascia in its important relation to inguinal 

 hernia 



