330 



THE MUSCLES OF THE TRUNK. 



crest of the ilium and the outer margin of the erector spina? muscle. From these 

 attachments the fibres, spreading over the side of the abdomen, pass to be inserted 

 as follows : the most posterior fibres pass upwards and forwards to the lower margins 

 of the cartilages of the last three ribs, where they are inserted in the same plane with 

 the internal intercostal muscles ; those arising from the anterior part of the iliac 

 crest pass forwards, the upper more obliquely and the succeeding ones more hori- 

 zontally, to end in an aponeurosis on the front of the abdomen ; those from the 



Fig. 292. LATERAL VIEW OF THE MUSCLES OF THB 



ABDOMEN, THE INTERNAL OBLIQUE MUSCLE HAVING 

 BEEN EXPOSED BY THE REMOVAL OF THE EXTERNAL 



OBLIQUE. (Allen Thomson, after Henle.) 1 



a, anterior superior iliac spine ; b, great tro- 

 chanter ; c, pubic spine ; d, posterior layer of the 

 lumbar fascia ; VI and XII, sixth and twelfth ribs ; 

 1, lower part of pectoralis major, where it is attached 

 to the aponeurosis of the external oblique ; 2, 2, lower 

 digitations of serratus magnus ; 3, 3, costal attach- 

 ments of latissimus dorsi ; 3', its iliac attachment : 

 4, trapezius ; 5, 5, divided attachments of external 

 oblique, left in connection with the ribs ; 5', 5', 

 aponeurosis of external oblique divided in front of 

 the rectus, where it joins the sheath ; 6, internal 

 oblique at its middle ; 6', 6', line where its aponeu- 

 rosis divides to form the sheath of the rectus ; + + 

 XII, its attachment to the lowest ribs ; 6", conjoined 

 tendon ; 7, sartorius ; 8, rectus femoris ; 9, tensor 

 vaginae femoris ; 10, gluteus medius ; 11, glutens 

 maximus. 



anterior superior spine run horizontally to 

 the same aponeurosis ; while the fibres 

 from Poupart's ligament, usually paler than 

 the rest, incline downwards to the lower 

 portion of the aponeurosis ; and the lowest, 

 arching downwards and inwards over the 

 spermatic cord, or the round ligament of 

 the uterus, end in tendinous fibres com- 

 mon to them and the lower part of the 

 transversalis muscle, thus forming the 

 structure known as the conjoined tendon 

 of these muscles ; through the medium of 

 this tendon they are attached to the front 

 of the pubis, and to the inner part of the 

 ilio-pectineal line behind Gimbernat's 

 ligament. The spermatic cord, or round 

 ligament, passes under the arched lower 



borders of the transversalis and internal oblique muscles on its way from the 

 internal to the external abdominal ring. 



The aponeurosis of the internal oblique may be regarded as the expanded tendon 

 of the muscle continued forwards and inwards : it extends from the margin of the 

 thorax to the pubis, and is wider at the upper than at the lower end. At the outer 

 border of the rectus muscle the aponeurosis divides into two layers, one passing 

 before, the other behind that muscle ; and the two reunite at its inner border in the 

 linea alba, so as to enclose it in a sheath. The anterior layer, as already mentioned, 

 becomes inseparably united with the aponeurosis of the external oblique muscle, and 

 the posterior layer is similarly incorporated with that of the transversalis. The 



