ABDOMINAL MUSCLES 95 



border is curved from the seventh rib down to the pubes. This is 

 indicated in the fascia over the muscle by a distinct line called 

 the semilunar line (linea semilunaris). 



Action. It compresses the abdominal organs. 



Nerves. Lower thoracic and first lumbar. 



Quadratus lumborum. This is the vertical' ^muscle at the 

 back (Fig. 74). Origin. The crest of the ilium. Insertion. 

 The lowest rib and transverse processes of the upper lumbar 

 vertebrae. It occupies the space at the back of the trunk between 

 the thorax and pelvis, being covered by the erector spinae and 

 latissimus dorsi muscles. 



m 



FIG. 80. INTERNAL OBLIQUE AND TRANSVERSE MUSCLES. 

 i, Rectus abdominis; 2, 2, 3, 3, internal oblique and cut edge of its aponeurosis; 

 4, 4, cut edge external oblique; 5, 5, spermatic cords; 6, aponeurosis ext. oblique 

 turned down; 7, rectus, upper part removed; 8, 8, 9, transversus muscle; 10, umbilicus; 

 n, 12, linea alba; 13, serratus anterior; 14, 15, cut edge latissimus dorsi; 17, 17, 

 external intercostal; 19, cut edge external oblique. (Sappey.) 



Action. It draws the rib down and the spine to one side 

 lateral flexion of the trunk . 



Nerves. Lower Thoracic. 



The three layers at the side and front consist of the obliquus 

 externus or external oblique; the obliquus internus, or internal 



