OF THE ABDOMEN 



437 



UMBILICAL 

 VEIN 



LINEA ALBA 



INTERVASCULAR 

 FOSSA 



HYPOGASTRIC 

 ARTERY 



FIG. 329. The umbilicus of the fetus 

 seen from within the abdomen. (Poirier 

 and Charpy.) 



The remains of the umbilical vein constitute the round ligament of the liver, and this cord 

 passes .upward (Fig. 329). The remains of the hypogastric arteries pass downward (Fig. 329). 

 The remains of the allantois become the urachus, which passes to the summit of the bladder 

 (Fig. 329). The depression of the umbilicus is created by the urachus. 



The lineae semilunares (Figs 319 and 325) are two curved tendinous lines placed one on 

 each side of the linea alba. Each corresponds with the outer border of the Rectus muscle, and 

 each extends from the cartilage of the ninth rib to the 

 pubic spine, and is formed by the aponeurosis of the 

 Internal oblique at its point of division to enclose the 

 Rectus, where it is reinforced in front by the External 

 obliijue and behind by the Transversalis. 



Actions. The abdominal muscles perform a three- 

 fold action: 



When the pelvis and thorax are fixed, they compress 

 the abdominal viscera, by constricting the cavity of the / 

 abdomen, in which action they are materially assisted by I 

 the descent of the Diaphragm. By these means assist- / ' 

 ance is given in expelling the fetus from the uterus, ihe/j 

 feces from the rectum, the urine from the bladder, and 

 the contents of the stomach in vomiting. 



If the pelvis and vertebral column be fixed, these 

 muscles compress the lower part of the thorax, mate- 

 rially assisting expiration. If the pelvis alone is fixed, 

 the thorax is bent directly forward when the muscles of 

 both sides act, or to either side when those of the two 

 sides act alternately, rotation of the trunk at the same 

 time taking place to the opposite side. 



If the thorax be fixed, these muscles, acting together, 

 draw the pelvis upward, as in climbing, or, acting singly, 

 they draw the pelvis upward, and bend the vertebral 

 column to one side or the other. The Recti muscles, 



acting from below, depress the thorax, and consequently flex the vertebral column; when acting 

 from above, they flex the pelvis upon the vertebral column. The Pyramidales are tensors 

 of the linea alba. 



The fascia transversalis (fascia transversalis} is a thin aponeurotic membrane 

 which lies between the deep surface of the Transversalis muscle and the extra- 

 peritoneal fat. It forms part of the general layer of fascia which lines the interior 

 of the abdominal and pelvic cavities, and is directly continuous with the iliac and 

 pelvic fascia?. In the inguinal region the transversalis fascia is thick and dense 

 in structure, and joined by fibres from the aponeurosis of the Transversalis 

 muscle, but it becomes thin and cellular as it ascends to the Diaphragm, and blends 

 with the fascia covering this muscle. In front, it unites across the middle line 

 with the fascia on the opposite side of the body, and behind it becomes lost in the 

 fat which covers the posterior surfaces of the kidneys. Below, it has the following 

 attachments: Posteriorly, it is connected to the whole length of the crest of the 

 ilium, between the attachments of the Transversalis and Iliacus muscles; between 

 the anterior superior spine of the ilium and the femoral vessels it is connected 

 to the posterior margin of Poupart's ligament, and is there continuous with the 

 iliac fascia. Internal to the femoral vessels it is thin and attached to the pubis 

 and to the iliopectineal line, behind the conjoined tendon, with which it is united; 

 and, corresponding to the point where the femoral vessels pass into the thigh, 

 this fascia descends in front of them, and forms the anterior wall of the femoral 

 sheath. Beneath Poupart's ligament the transversalis fascia is strengthened by a 

 band of fibrous tissue, which is only loosely connected to Poupart's ligament, and 

 is specialized as the deep femoral arch. The spermatic cord in the male and the 

 round ligament in the female pass through this fascia; the point where they pass 

 through is called the internal abdominal ring. This opening is not visible exter- 

 nally, owing to a prolongation of the transversalis fascia on these structures, 

 which forms the infundibuliform fascia. 



