ABDOMINAL FASCIAE. 249 



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 innominatse and superior cava, and is attached to the 

 cellular capsule of the thymus gland. 



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

 important offices : 



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

 does the lower. 



" 2nd. 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 inter- 

 nal surface, and at the bottom of the latter cavity is reflected in- 

 wards to the sides of the bladder. This fascia is continuous through- 

 out the whole of the surface ; but for convenience of description it 

 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 ligament, and the latter is confined to the cavity 

 of the true pelvis. 



The fascia transversalis (Fascia Cooperi)* is a cellulo-fibrous 

 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 sub- 

 serous 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 ligament, and forms the ante- 

 rior 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 infundibiliform process which surrounds the 

 testicle and spermatic cord, constituting 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 interval between the 

 head of the rectus and the internal abdominal ring, that defends this 



* Sir Astley Cooper first described this fascia in its important relation to inguinal 

 hernia. 



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