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 282 A N A T O M Y. Part VI. being at the fame time, and by the fame means, lefs re- is wanting above the thorax and the neck, where the iifted or preffed upon ; the ambient air yields to the ex- outer coat of the cefophagus is only a continuation of ternal prefl'ure, and infinuates itfelf into all the places the cellular fubftance belonging to the neighbouring parts. where the preffure is diminifhed, that is, into the afpera. The fecond coat is mufcular, being made up of feveral arteria, and into all the ramifications of the bronchia all ftrata of flelhy fibres. the way'to the veficles. This is what is called infpiration. The third is termed the nervous coat, and is like that This motion of infpiration is inflantaneous, and ceafes of the ftomach and inteftines. in a moment by the relaxation of the intercoftal mufcles ; The fourth 9r innermoft coat refembles in fome meathe elaftic ligaments and cartilages of the ribs bringing fure that of the inteftines, except that inftead of the them back at the fame time to their former fituation. villi it has fmall and very fliort papillas. Through the This motion, by which the ribs are deprelfed and brought pores of this coat, a vifcid lympha is continually difcharged. nearer each othet*, is termed expiratic/n. The pulmonary arteries and veins which accompany The cefophagus from its very beginning, turns a little the bronchia through all their ramifications, and fur- to the left hand, and naturally runs along the left exround the veficles, tranfmit the blood through their nar- tremities of the cartilages of the afpera arteria. The row capillary extremities, and thereby change or modify thyroid gland, pharynx and larynx, /hall be defcribed in another place. it, at leaft in three different manners. The firft change or modification which the blood undergoes in the lungs, is to have the cohefionS of its parts DUCTUS THORACICUS. broken, to be attenuated, pounded, and, as it were, .reduced to powder. The fecond is, to be deprived of a The thoracic dudl is a thin tranfpareilt canal, which from the receptaculum chyli, along the fpina certain quantity of ferum, which tranfpires through the <- runs upbetween the vena azygos and aorta, as high as the kings, and is what we commonly call the breath. The dorfi, vertebra of the back, or higher. From thence it third is to be in a manner reanimated by the imprdlionof fifth paffes behind the aorta toward the left hand, and afcends the air. behind the left fubclavian vein, where it terminates in OESOPHAGUS. fome fubje<5ts by a kind of veficula, in others by feveral branches united together, and opens into the backThe oefophagus is a canal partly mufcular, and partly fide of the fubclavian vein near the outfide of the intermembranous, fituated behind the trachea arteria, and nal jugular. before the. vertebrae of the back, from near the middle This canal is plentifully furnilhed with femilunar of the neck, down to the lower part of the thorax; from valves turned upward. Its opening into the fubclavian whence it paffes into the abdomen through a particular vein in the human body, is, in the place of valves, cohole of the fmall or inferior mufcle of the diaphragm, vered by feveral pellicula:, fo difpofed as to permit the and ends at the upper orifice of the ftomach. It is made up of feveral coats, almoft in the fame entrance of the chyle into the vein, and hinder the from running into the dudt. Tt is fometimes double, manner as the ftomach, of which it is the continuation. bloodlying on each fide, and fometimes it is accompanied The firft coat, while in the thorax, is formed only by the one duplicature of the pofterior part of the mediaftinum, and by appendices called pampiniformes. EXPLANATION Figure i. fhews the contents of the thorax and abdomen, in fitu. 3, Top of the trachea, or wind-pipe. 2 2, The internal jugular veins. 3 3, The fubclavian veins. 4, The vena cava defcendens. 5, The right auricle of the heart. 6, The right ventricle. 7, Pait of the left ventricle. 8, The aorta afcendens. 9, The pulmonary artery. 10, The right lung, part of which is cut off to Ihewthe great blood-veflels. ny The left lung entire. 1212, The anterior edge of the diaphragm. 1313* The two great lobes of the liver. $4, The ligamentum rotundum. 15, The gall bladder. 16, The ftomaeh. 17 17, The jejunum and ilium. 18, The fpleen. Fig. 2. Shews the organs fubfervient to the chylo* poetic vifcera,—with thole of urine, and generation. j 1, The under fide of the two great lobes of the liver. Lobulus Spigelii. 2,. The ligamentum rotundum.

of PLATE XIX. 3, The gall-bladder. 4, The pancreas. 5, The fpleen. 6 6, The kidneys. 7, The aorta defcendens. 8, Vena cava afcendens. 9 9, The renal veins covering the arteries. 10, A probe under the fpermatic veffels and a bit of the inferior mefenteric artery, and over the ureters. 11 11, The ureters^ 12 12, Tire iliac arteries and veins. 13 The reftam inteftinum. 14; The bladder of urine. Fig. 3. Shews the chylopcetic vifcera, and organs fubfervient to them, taken out of the body intire.. A A, The under fide of the two great lobes of the liver. B, Ligamentum rotundum. C, The gall-bladder. D, Dudlus cyfticus. E,.Du<ftus hepaticus^ E, Ductus communis choledochus. G, Vena portarum. H, Arteria hepatica. II, The ftomach. KK, Venae & aijtgrise gaftro-epiploicas, dextrae & finiftrae. L L, Venae & arteriae coronariae ventriculi, M, The, fpleen. NN, Mefocolon, with its veffels, QOO, Inteftinum