300 ELEMENTARY ANATOMY. [LESS. 



tion, as explained in the Fourth Lesson of " Elementary 

 Physiology." It is a partly fibrous, partly muscular partition 

 between the thorax and abdomen, perforated for the passage 

 of certain organs namely, the oesophagus, or swallow, and 

 two great blood-vessels named aorta and vena cava. The 

 diaphragm is strongly convex upwards and concave down- 

 wards, and is attached to the ensiform cartilage and several 

 ribs, to the centra of the lumbar vertebras, and to fibrous 

 structure binding down the quadratus lumborum and other 

 muscles. Muscular towards its circumference, the diaphragm 

 has a tendinous central portion. 



FIG. 276. DEEP MUSCLES WITHIN THE LUMBAR AND PELVIC REGIONS. 



i, psoas parvus; 2, psoas ma^nus ; 3, quadratus lumborum; 4, inter-trans- 

 versarii ; 5, iliacus ; 6, obturator externus ; 7, pyriformis. 



12. The MUSCLES OF THE INFERIOR EXTREMITY, though 

 mainly taking origin from the pelvis and leg-bones, yet 

 partly arise from the loins. Thus \hepsoas magnus springs 

 from the centra of the lumbar and last dorsal vertebrae, and 

 from the transverse processes of the former. Passing out 

 over the brim of the pelvis, it is inserted into the lesser 

 trochanter of the femur. 



The iliacus occupies the iliac fossa of the pelvis, whence it 

 descends and joins the psoas magrius. 



T\\Q. psoas parvus springs from the bodies of the last dorsal 

 and first lumbar vertebrae, and is inserted into the ilio-pecti- 

 neal eminence. 



The glutens maximus is a very large muscular mass which 

 arises from the posterior part of the crest of the ilium, the 



