DIAPHRAGM (Lat., el ia phra grim. (tia_ paypa, partition, midriff, from pi rat, d ia ph ragnynai, to barricade, from (Yid, di,, through to fence in). A thin musculo-fibrons partition separating the cavity of the thorax from that of the abdomen. It is roughly elliptical, with the longest diameter from side to side and almost horizontal in its anterior part, while the posterior portion is nearly vertical. The diaphragm is attached in front to the ensiform cartilage of the breast-bone (stemum), and laterally to the inner surface of the eartilages and bony parts of the six or seven lower ribs: posteriorly the attachment is to two aponcurotie arches on each side (/iyameprnof (lima I um c,rtern u ni and internam), and to the second, third, and fourth lumbar vertebra' by means of firm fibrous tendons (the (Tura of the diaphragm). which terminate above in large fleshy bellies. The central portion of the dia phragm is tendinous and shaped like a trefoil leaf, the muscular fibres radiating from this to the points of attachment. There are three large and alley openim.fs in the diaphragm.
I 'trough the former pass the abdominal aorta, I lie :17? Ina it.1". I he t lioraeic duet. the tie nerves. and Vella eava.
es, above and is in relation mull the plelitir of the and pericardium: While flume is invested by the peri ton•al lining of the abd alien. During respira tion the 'eight of the diapliraglil constantly it deseciid, (luring inspiration and thus tbe I apaeity of the thorax. so that air rushes in to fill the vacuum formed. This eon t 1:1(.1i(Pn of the diaphragm also the and mot•l's the chest laterally. In expiration the diaphragm to former position. The descent of the diaphragm encroaches upon the abdomen and lessen- capacity. In all expul siNe net, the diaphragm by its tont raetion, gives increased power to the effort and is accordingly all important fat-tor in sneezing. coughing. laugh ing. and crying. as well as in the expulsion of urine and hiccoughing is due to spas modic contraction of the diaphragm.