310 



MUSCLES OF THE THOEAX. 



vertebra to the last rib, arching orer the front of the quadratus lumbo- 

 rum : it is the upper part of the fascia covering that muscle, somewhat 

 increased in thickness. From botli ligamenta arcuata diaphragmatic 

 muscular fibres take their origin, and are directed upwards to the 

 posterior part of the tendinous centre. 



FiS- 222. Fig. 222.— ViKw of the 



DiAl'HIlAGJI, FROM BE- 

 lOTT. (A. T.) I 



In the preparation from 

 wliicli this figure is dra'svii, 

 the lower ribs and sternum 

 are thrown upwards so as 

 to exiJose and stretch the 

 lower surface of the dia- 

 jilnagm, and tlie four 

 upper lumbar vertebra3 

 have been exposed by the 

 removal of all the muscles 

 on the right side, and the 

 dissection of the psoas mag- 

 nus and quadratus lumbo- 

 rum on the left side, a, 

 the aorta emerging in the 

 abdomen from between the 

 pillars on the first lumbar 

 vertebra ; b, the OBSojiha- 

 gus, in its aperture between 

 the muscular crura, repre- 

 sented too far to the right ; 

 c, the ajjerture for the 

 vena cava inferior situated 

 at the place of union of the 

 middle and right divisions 

 of the trefoil tendon; d, the 

 body of the fourth lumbar 

 vertebra ; e, c, the twelfth 

 ribs near their extremities ; 

 /,/,the ends of the eleventh 

 ribs ; 3, the tendinoiis part of the right crus ; 2, the left ; 3, the tendinous arch formed 

 by their union over the aorta, above which the decussation of muscular fibres is seen ; 

 4, second decussation of muscular fibres in front of the oesophageal opening ; 5, on the 

 right side, placed near the end of the transverse process of the first lumbar vertebra, 

 towards which, arching from above and from within, over the + , is seen the ligamentum 

 arcuatum internum ; and from which, passing towards c, is seen the ligamentum arcua- 

 tum externum ; 5', on the left side, is in a similar position, but here the quadratus 

 lumborum muscle is seen descending from the twelfth rib behind the ligamentum arcuatum 

 externum, and the upper part of the psoas muscle is within the ligamentum arcuatum 

 intenium ; 6, the middle division of the trefoil tendon, from which in front pass the 

 slips of attachment of the diaphragm to the ensiform process ; 7, the left, and 8, the 

 right divisions of the trefoil tendon ; from the outer and anterior margins of these the 

 costal slijis of the muscle are seen diverging, and from the posterior border of the tendon 

 the slips of origin proceeding from the ligamenta arcuata and the tendinous arch of the 

 crura ; 9, part of the quadratus lumborum ; 10, part of the psoas magnus. 



c. The fibres arising from the cartihigcs of the si.K lower ribs form a 

 series of serrated slips interdigitating -with the attachments of thetrans- 

 versalis nbdominis muscle. They sometimes arise also in part from the 

 osseous ribs. The fibres proceeding from the ensiform cartilage form 

 a narrow slip, sometimes divided into two, on each side of whicla there 

 occurs an interval, in which the lining membranes of the thorax and 



