74 MUSCLES OF THE ABDOMEN. 



the chest. Or. from the ensiform cartilage, and second bone of the 

 sternum. In. into the third, fourth, fifth, and sixtti ribs. Use. To 

 depress the ribs. 



MUSCLES OF THE ABDOMEN. 



Beneath the skin of the abdomen is the fascia superjicialis abdo- 

 mi?iis, a layer of condensed cellular substance, varying in thickness 

 in different individuals, and containing more or less tat. Its lami- 

 nated character admits of its being dissected into several layers. In 

 the groin it incloses the lymphatic glands, and is traversed at its 

 lower part by the arteria ad cutem abdominis; it is thickened over 

 the symphysis pubis, and constitutes the 7no?is veneris. 



Obliquus externus.^^ — Origin from the eight inferior ribs, the 

 first head being covered by the pectoralis major ; five superior heads 

 interdigitate with those of the serratus anticus, and three inferior, 

 with those of the latissimus dorsi. The fibres pass obliquely down- 

 wards and forwards. Insertion, into the whole length of the linea 

 alba, tendinously ; into the anterior half or two-thirds of the crest of 

 the ilium, by muscular and tendinous fibres ; and into the body and 

 crest of the pubis, forming thereby Poupart's ligament. As the ten- 

 dinous fibres approach the pubes, they split, forming a triangular 

 opening called the external abdominal ring ;*^ through which passes 

 in the male the spermatic cord, and in the female the round ligament 

 of the uterus; a portion of the tendon being inserted into the spinous 

 process and body of the pubes ; the external or posterior edge of this 

 part constitutes the anterior or internal column of the ring. The 

 other portion is inserted into the crest of the pubes ; the internal 

 edge of which constitutes the external or posterior column of the 

 ring. The external edge of this portion of the tendon is called Gim- 

 bernat's ligament. This ring is prevented from splitting still further, 

 by some transverse tendinous fibres. i* (Fig. 59.) 



Use. — It compresses the viscera of the abdomen, and approximates 

 the pelvis and thorax. 



Obliquus internus.^^ — Origin, from the three inferior spinous pro- 

 cesses of the lumbar vertebrse, and from all those of the sacrum, 

 the whole length of the crest of the ilium, and from the outer half of 

 Poupart's ligament. Insertion, into the six inferior ribs, into the 

 ensiform cartilage, into the whole length of the linea alba, and also 

 tendinously into the pubes behind the external abdominal ring. At the 

 linea semilunaris, the tendon splits into two laminse, which thereby 

 form a sheath for the rectus muscle ; in the lower third or fourth of 

 the muscle, both laminae, however, pass in front, and include between 

 them the pyramidalis. 



Transversalis abdominis. — Is beneath the last. Origin, from 

 the transverse processes of the last dorsal and four upper lumbar 

 vertebras, from the crest of the ilium, and from the external half of 



