SUBLUMBAR BEGION. 205 



Action. — To support and compress the abdominal viscera and 

 assist in respiration. It is the chief flexor of the spinal column. 



TRANSVERSALIS ABDOMINIS. 

 (Lumho-dbdominalis.) 



Placed on the infero-lateral aspect of the abdomen, imme- 

 ttately outside the peritoneum, this muscle is broad, flat, and 

 [uadrilateral, its fibres extending downwards. It is fleshy 

 rom its origin to the linea semilunaris, where it becomes 

 Iponeurotic. 



Attachments. — To the transverse processes of the lumbar 

 rertebrse, and the inner surface of the cartilages of the false ribs, 

 iterdigitating with the attachments of the diaphragm, and by 



aponeurosis to the xiphoid cartilage and linea alba, becoming 

 idimentary posteriorly. 



Relations. — Anteriorly with the diaphragm ; externally with 

 bhe cartilages of the false ribs, the obliquus internus and rectus ; 

 iternally with a thin layer of fascia (the fascia transversalis) 

 rhich connects it with the peritoneum. 



Action. — To assist the oblique muscles, and raise the viscera. 



SUBLUMBAR REGION. 



The muscles of this region, a single group, connect the lumbar 

 md last dorsal vertebrae with the pelvis or the posterior limb. They 

 ire covered by the iliac fascia, and this by the peritoneum, a 

 jerous membrane lining the abdominal cavity. In this group we 

 >lace four muscles : — 



Psoas magnus. I Iliacus. 



Psoas parvus. | Quadratus lumborum^ 



PSOAS MAGNUS. 



(Suhlumho-trochantineus.) 



(Fig. 76. c.) 



Situated below the transverse processes of the lumbar vertebrae, 

 it is elongated and fusiform, flattened anteriorly, conical posteriorly, 

 its - fibres extending downwards and backwards ; it is almost 

 entirely fleshy, except at its insertion. 



Origin. — From the inferior surfaces of the last two ribs, the 



