302 Abdominal Muscles 



of one or two intercostal spaces, is herpes zoster (fao-T^p, a girdle),, 

 or shingles (cingulum, a belt). 



Muscles. The external oblique arises from the eight lower ribs 

 by as many digitations. The anterior part of this fleshy mass ends 

 on a wide aponeurosis which passes over the rectus to join the 

 aponeurosis of the opposite external oblique in the linea alba. The 

 hindermost part is muscular, and descends from the last rib, in a free 

 border, to be inserted into the anterior half of the outer lip of the iliac 

 crest. The shining aponeurosis is recognised during the operation of 

 ligation of an iliac artery. The fleshy part of the muscle extends very 

 slightly in front of a line running from the outer part of Poupart's 

 ligament vertically to the eighth costal cartilage. 



Poupart's ligament is that part of the aponeurosis which stretches 

 over the iliacus and psoas, and over the femoral vessels, from the front 

 of the iliac crest to the pubic spine, and to which the fascia lata of 

 the thigh is fixed. It is imperfectly marked in women, but in man it 

 forms an important seam between the deep layer of the superficial 

 fasciae of the abdomen and of the front of the thigh, and between the 

 transversalis and iliac fasciae (see crural sheath, p. 313) and the fascia 

 lata. It also gives origin to the internal oblique and transversalis. 

 The direction of the ligament shows, of course, the direction of the 

 fibres of the muscle itself downwards and outwards. Its inner end 

 is firmly attached to the pectineal line through the medium of Gim- 

 bernafs ligament, which is a triangular septum extending, in the erect 

 posture, almost horizontally between the pelvis and thigh.* Its base 

 is concave and free, and extends outwards as far as the crural 

 sheath. 



Femoral hernia passes below Poupart's ligament, inguinal comes 

 out above it ; the neck of a femoral hernia is placed below and to the 

 outer side of the spine of the pubes, while an inguinal hernia is above 

 it, and to its inner side. The spine of the pubes is an important 

 landmark in the differentiation of the two herniae, and is specially 

 valuable in the case of a fat subject. 



The structures beneath Poupart's ligament are the external 

 cutaneous nerve, iliacus, anterior crural nerve, psoas ; external iliac 

 vessels in crural sheath ; crural branch of genito-crural nerve, and 

 lymphatics passing from the thigh towards the pelvic glands. 



Between those fibres of the aponeurosis of the external oblique 

 which are incorporated with the inner half of Poupart's ligament and 

 those which blend with the linea alba there is a triangular or oval gap, 

 the external abdominal ringr. The base of the opening is at the 

 pubic crest ; the outer, and lower, side is formed by Poupart's 

 ligament ; and the inner boundary is made by those fibres which run 

 downwards and inwards to the pubic symphysis. Certain transverse 

 fibres which stretch as a kind of lacing across the opening constitute the 

 inter-columnar fascia, a prolongation from which descends as a cover- 



