64 ANATOMY FOR NURSES. [CHAP. VI. 



layers. The abdominal muscles are covered and lined by sheets 

 of fasciae, some of which are very dense and strong, and serve 

 to strengthen weak points in the muscular walls. 



The strongest and most superficial of the abdominal muscles 

 is the external oblique, the fibres of which, arising from the lower 

 eight ribs, incline downwards and forwards and terminate in the 

 broad aponeurosis, which, meeting its fellow of the opposite side 

 in the linea alba, covers the whole of the front of the abdomen. 

 The lowest fibres of the aponeurosis are gathered together in 

 the shape of a thickened band, which extends from the superior 

 spinous process of the ilium to the pubis, and forms the well- 

 known and important landmark, called from the anatomist who 

 first described it, Poupart's ligament. Just above this ligament, 

 and near the pubic bone, is an oblique opening which transmits 

 the spermatic cord in the male, or the round ligament in the 

 female. This opening, called the external abdominal ring, is 

 often the seat of hernia. 



The internal oblique muscle lies just beneath the external 

 oblique. Its fibres run upwards and forwards, and end for the 

 most part in a broad aponeurosis. At the outer border of the 

 rectus muscle this aponeurosis divides into two layers, one pass- 

 ing before, the other behind, that muscle : they reunite at its 

 inner border in the linea alba, and thus form a sheath for the 

 rectus. 



The transversalis muscle lies beneath the internal oblique; 

 the greater part of its fibres have a horizontal direction, and 

 extend forward to a broad aponeurosis in front. 



The rectus is a long, flat muscle, consisting of vertical fibres 

 situated at the fore part of the abdomen, and enclosed in 

 the fibrous sheath formed by the aponeuroses of the internal 

 oblique. It arises from the pubis, and is inserted into the car- 

 tilages of the fifth, sixth, and seventh ribs ; it is separated from 

 the muscle of the other side by a narrow interval which is occu- 

 pied by the linea alba. 



The linea alba, or white line, is a tendinous band formed by 

 the union of the aponeuroses of the two oblique and transverse 

 muscles, the tendinous fibres crossing one another from side to 

 side. It extends perpendicularly, in the middle line, from the 

 ensiform portion of the sternum to the pubis. It is a little 

 broader above than below, and a little below the middle it is 



