ABDOMINAL MUSCLES 



337 



Trans versalis AbdominiS (Transverse Muscle of the Abdomen). 

 The innermost of the abdominal muscles. Like those already referred to, 

 it consists of a flat fleshy portion and a broad aponeurotic tendon. 



Origin. From the lower extremities of the false ribs, and from the, 

 transverse processes of the lumbar vertebrae. 



Insertion. Into the linea alba and the ensiform cartilage. The 

 internal surface of this muscle is covered by peritoneum. 



Action. The same as the oblique muscles. 



Diaphragm or Midriff. The diaphragm is the muscular and ten- 

 dinous partition which divides the chest from the abdomen (fig. 377). 



20 



19 



'18 



Fig. 377. The Diaphragm and Sub-lumbar Muscles, seen from below 



1, Fleshy periphery of Diaphragm. 2, Tendinous centre of Diaphragm. 3, Right Pillar. 4, Left 

 Pillar. 5, Psoas Magnus. 6, Psoas Parvus. 7, Iliacus Internus. 8, Tensor Fasciae Latae. 9, 9, Rectus 

 Femoris. 10, Adductor Longus. 11, Sartorius (cut to show underlying muscle). 12, Gracilis. 13, 

 Obturator Externus. 14, Quadratus Femoris. 15, Crureus. 16, Quadratus Lumborum. 17, Hiatus 

 Aorticus and posterior aorta. 18, Foramen Sinistrum and (Esophagus. 19, Foramen Dextrum and Vena 

 Cava. 20, Ensiform Cartilage. 



It passes obliquely downward and forward from the spine above to the 

 sternum below. It is convex in front and concave behind. The muscular 

 portion is situated around the circumference, and encircles a broad, flat, 

 glistening tendon. Connected with the latter are two fleshy bundles 

 situated in the centre towards the spine; these are known as the pillars 

 of the diaphragm, and are united with the tendinous portion in the centre. 

 Three openings are observed in this partition. 1. The Foramen sinistrum, 

 through which the oesophagus or gullet passes from the chest into the 

 abdomen. This is situated above, a little to the left of the middle line. 

 2. The Foramen dextrum, by which the posterior vena cava reaches the 

 chest. It passes through the middle of the central tendon. 3. The 



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