THE VENTRAL MUSCLES. 



521 



XII rib 



Quadratus luniborum 



thickened somewhat to form the deep crural arch (Fig. 1496). More medially still it 

 is attached to the free edge of Gimbernat's ligament and to the upper surface of the 

 superior ramus and body of the pubis. 



• A little over i cm. above Poupart's ligament, and about half-way between the 

 anterior superior iliac spine and the symphysis pubis, the transversalis fascia is per- 

 forated by the spermatic cord in the male and'by the ligamentum teres of the uterus in 

 the female. The fascia is continued downward and forward over the cord or ligament 

 to form a somewhat funnel-like investment for it termed^ the infiindibuliform fascia, the 

 inner margin of the funnel marking the position of the internal abdominal ring. 



5. Quadratus Lumborum (Fig. 527). 



Attachments. — The quadratus lumborum is a flat quadrilateral muscle which 

 lies towards the back part of the ab- 



dopiinal wall, extending between the Fig. 527. 



crest of the ilium and the lower bor- 

 der of the twelfth rib. It consists of 

 two layers of fibres which frequently 

 are distinguishable from each other 

 only with difficulty. The anterior 

 layer, which arises from the trans- 

 verse processes of the lower four lum- 

 bar vertebrae and from the posterior 

 part of the iliac crest, is iyiserted into 

 the lower border of the twelfth rib ; 

 the posterior layer (Fig. 527) arises 

 from the crest of the ilium and is in- 

 serted into the lower border of the 

 twelfth rib and into the transverse 

 processes of the upper four lumbar 

 vertebrae. 



Nerve-Supply. — By branches 

 from the lumbar plexus. 



Action. — To draw downward the 

 last rib and to bend the lumbar por- 

 tion of the spinal column laterally. 



Relations. — The quadratus lum- 

 borum rests behind upon the deep 

 layer of the fascia lumbo-dorsalis ( Fig. 

 519), which separates it from the spino- 

 sacral muscle. Its anterior surface is 

 in relation to the kidney and the as- 

 cending or descending colon, is. crossed 

 by the lumbar arteries, and is covered towards its inner margin by the psoas major. 



6. Intertransversales Laterales (Fig. 521). 



Attachments. — The lateral intertransversales are a series of small quadrilateral 

 muscles which extend between successive transverse processes of the lumbar vertebrae. 



Nerve-Supply. — Probably from the anterior rami of the lumbar nerves. 



Action. — To bend laterallv the lumbar portion of the spinal column. 



The Ventral Abdominal Aponeurosis (Fig. 528). — The bVoad aponeurotic 

 sheets into which the oblique and transverse muscles of the abdomen are continued 

 at their anterior (medial) edges unite more or less -intimately with one another and 

 with the fascia transversalis to form the ventral abdominal aponeia^osis. Laterally the 

 various layers of which this aponeurosis is composed are to a certain extent discerni- 

 ble, since the lines along which the fibres of the three muscles pass into the apo- 

 neurosis do not coincide, that of the external oblique extending from the outer border 

 of the rectus muscle above obliquely downward and laterally to the anterior superior 

 spine of the ilium, while those of the internal oblique and transversus follow essen- 



Iliac crest 



Dorsal 

 surface 

 of ilium 



1- 



Quadratus lumborum muscle of right side, seen from behind, 



