The laws and mechanics of circulation, with the principle involved in animal movement . t in the stomach and abdomenas well. Thus, all this mechanics is easily understood. Theseveral openings in the diaphragm involve a number of verypretty adjustments, well worthy of undivided attention—aresimply wonderful. Thus, taking the powerful muscular bun-dles that embrace the oesophagus, and looking from theirpoints of origin in the tendinous centre of the diaphragm totheir points of insertion in the lumbar vertebrae, it will be seenthat they form two arcs around the oesophagus and aorta (), much
The laws and mechanics of circulation, with the principle involved in animal movement . t in the stomach and abdomenas well. Thus, all this mechanics is easily understood. Theseveral openings in the diaphragm involve a number of verypretty adjustments, well worthy of undivided attention—aresimply wonderful. Thus, taking the powerful muscular bun-dles that embrace the oesophagus, and looking from theirpoints of origin in the tendinous centre of the diaphragm totheir points of insertion in the lumbar vertebrae, it will be seenthat they form two arcs around the oesophagus and aorta (), much in the form of the figure 8, so as to form the elliptical openings, or the oesophageal and aortal , then, since the muscles contract upon a line between THE ACTION- I]ST THE PILLAES OF TIIK DIAPHRAGM. 2ll their origin and insertion, both openings would be occludedduring inspiration but for the following disposition of thefibres; notably : 1st. The arc upon the left side of the aorta isbounded by a tendon, which is the point of insertion for the t^flfom , Cartilo-t. • for tenser S/Janebtc Pig. 92.—The Diaphragm as Viewed from Below.—Oray. The letters A, B, C, D, E, N, O, are added. thick layers of muscular fibres proceeding from the left leafletof the central tendon of the diaphragm (A, B), so that duringinspiration this is pulled away from the aorta at the same timethat it compresses the oesophagus upon the right in the upperarc. 2d. The arc upon the right of the aorta is also boundedby a tendon, which is the point of insertion for the thick mus- 242 PHYSIOLOGICAL ANAIOMT IX THE DIAPHEAGM. cular layers proceeding from the right leaflet of the centraltendon (C, i>), so that during inspiration this is pulled awayfrom the aorta at the same time that it compresses theoesophagus upon the left in the upper arc. It results from thisarrangement, therefore, that the aorta is relieved from pressureduring inspiration, while there is progressive increase of pres
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