TION. flated; 2, the inspiration must be repeated sufficiently often, and con- CHAP. IV. tinuously; 3, the air is to be allowed a free exit from the lungs, so that SECT. IV. the same air shall not be transmitted more than once; 4, the method of RESPIRAinflating the lungs must be simple and easy of adoption, for as the interval of time during which the artificial respiration can possibly be of any service, is very limited (not in general exceeding five minutes after the last respiration,) (y) it is important to avoid whatever may occasion the least delay.(z) The proximity of the lungs to the ribs, explains the effect of fracture Other injuof those bones in producing the tumour called Emphysema. The broken ries, &c. end of the rib, piercing the pleura costalis, tears also the pleura pulmonalis, and breaks the surface of the lungs, and opens the bronchial cells, and the injury proceeds and increases. (a) Wounds in the diaphragm or thorax in general terminate fatally, though not always so.(b) Pulmonary apoplexy arises from the rupture or bursting of a blood vessel in the lungs, and generally from obstruction to the circulation in the heart.(c) Wounds of and injuries to the throat are often attended with considerable danger on account of the great number of important parts which are intersected; but mere cuts of the integuments of the throat and neck are not, generally speaking, dangerous, and do not materially differ from common incised wounds of the skin in any other part of the body. (d) Wounds of the lungs are not necessarily fatal, though for the most part extremely dangerous.(e) Immediate hemorrhage may produce suffocation; extravasation into the thorax may also give rise to fatal consequences, and with rapidity; or the foundation of an ulcerative process in the lungs itself may be laid, which will ultimately terminate life. But sometimes a patient may escape with the loss of a lung absorbed in this manner.(ƒ) and transu Besides respiration through the lungs, a species of invisible vapour is of transpidischarged as well from the lungs as from the surface of the body, ration, evathrough the skin, and called Transpiration, and which discharge from poration, the surface of the body is connected with some of the most important ope- dation. (g) rations of the system.(g) It has been supposed, that the average quantity of vapour carried off by cutaneous transpiration in twenty-four hours, is thirty ounces, while that by respiration, including, as it appears, the pulmonary transpiration, is said to be fifteen ounces.(h) But it has been observed that so far as regards the generation of water in the lungs, the hypothesis is without foundation.(i) (y) 2 Par. & Fonb. 33, 34. (z) Id. 80, 81; see farther, id. 86 to 89; and 2 Bost. 141 to 145. (a) 1 Bell, 567 to 569; G. Smith, 278; El. Blum. 123; 1 Gibson, Surg. 137. (b) G. Smith, 279. (c) Coop. Surg. Dict. tit. Pulmonary Apoplexy; see Brous. Pathol. 290. (d) Id. tit. Throat; and id. tit. Wounds; CHAPTER V. THE FUNCTION OF CIRCULATION; and, first, of ITS ORGANS, (NAMELY, CHAP. V. TION. SECT. I. Section I. The Organs and Parts of the First. The Heart. 1. Its External Appearance, Size 2. Its Situation and Posture. 3. Its component Parts. 4. The two Auricles and two Ven- 5. The Valves of the Ventricles 6. The Arteries, Veins, and Nerves 1. The Coronary Arteries 2. The Coronary Veins there- 3. The Nerves of the Heart. 6. Rapidity of Circulation 7. Cause of the Action of the SECTION I. 8. State of Circulation at different Ages. 9. Harvey's discovery of the Double Course of Circulation. 10. Use thereof. 7. Pericardium. 8. Defects and Diseases of the Heart. 9. Rupture, or broken Heart. 10. Injuries to, by Wounds, &c. Secondly. The Arteries. 1. Description, &c. 3. Injuries to. 4. Number and Names of. Thirdly. The Capillaries. And of Pulse-feeling, and 1. Description of Veins. 2. Diseases. 3. Injuries. 4. Number and Names. Section II. THE BLOOD. Section III. The Function of Circulation and its incidents. THE Function of Circulation of the Blood stands next to Respiration in importance. (a) We will arrange the subject under several sections, namely, I. The Organs and Parts concerned in circulation. II. The Blood, and, III. The manner in which the Function of Circulation is performed, and its incidents. Section I.-The Organs and Parts concerned in the Function of CirTHE OR- culation are principally the HEART, with its PERICARDIUM, and the ArGANS OF teries, Capillaries and Veins. CIRCULA TION IN GENERAL. The Heart is the central and principal organ of the function of CirculaThe heart. tion, and, indeed, the main spring of all the other functions, for if the due (a) Some physiologists even consider this Function superior to, and more important than any other, especially those physiologists who consider that diseases and their remedies are principally connected with the state of the blood, Park's Inquiries, 42 and 335, to the end. But as life cannot continue for five minutes without Respiration, and without its perpetually renovating qualities, the blood would not circulate; I have therefore treated respiration as the superior, ante, 92 to 123. action of the Heart be suspended for five minutes, or even less, all CHAP. V. the functions immediately feel the effect and cease to act, and death, ensues. (b) In order that Blood may be properly renovated, and afterwards circulated through the arteries, veins, and capillaries into and throughout every part of the Human Frame, the HEART is placed nearly in the centre of the Trunk, and constitutes the grand mover of the mass of Blood, with a constant unvarying and truly wonderful power to the last moment of existence. (c) In the foetus the heart is discernible, and is supposed to be formed before the brain or spinal cord. (d) SECT. I. CIRCULA- On a superficial view, the heart appears as if it were one entire cone- The exterlike figure, but when stripped of the Pericardium and more minutely ex- nal appearamined, there are obviously two parts and distinct apparatus belonging ance, size and weight to each.(e) Its external appearance much resembles the heart of a calf, of the and is about five inches and a half diameter in the upper or widest part, heart. and somewhat resembles the base of a cone reversed.(f) the heart. Anatomists state that there is great difference in the size of the heart Size and in different individuals, even to the variation of double the size, and this weight of without any relative proportion to the general bulk of the body.(g) With respect to the weight and size of the heart, Professor Meckel, in his work on Anatomy, gives the following account:-"The weight of the heart in the male adult is in general about ten ounces, and bears a propor (b) 1 Bost. 265; Jackson, Prin. Med. 457. (c) El. Blum. 85; 1 Bell, Anat. 447; 1 Bost. 268; and see as to the Heart, 2 Horn. Anat. 185 to 198; 2 Dungl. Phy. 117 to 123; Jackson, Prin. Med. 468 to 470; 2 Paris & Fonb. 17, 18; Smith, For. Med. 37, 51, 277. (d) 1 Bost. 267; 2 Horn. Anat. 282. (f) See representation. CHAP. V. CIRCULA TION. Situation heart. tion to the whole body of 1 to 200. Its whole length, measured from the space between the auricles, varies between five and six inches; the mean length is five and a half inches, of which four belong to the ventricles, and one and a half to the auricles. The breadth of the ventricles united, is three inches at their base, and that of the auricles three and a half inches."(h) Laennec, in his work on Diseases of the Chest, thus speaks of the heart: (i)-"The heart, comprising the auricles, ought to have a size equal to or a little less, or a very little larger than the fist of the subject. The walls of the left ventricle ought to have a thickness a little more than double that of the walls of the right; they ought not to collapse when an incision is made into the cavity, and the right ventricle is a little larger than the left. Reason indicates, and observation proves, that in a sound and well-built subject the four cavities of the heart, containing each nearly the same quantity of blood, namely; between two and three ounces, so as to equalize the circulation, are within very little equal to each other. But as the walls of the auricles are very thin, and those of the ventricles have much thickness, it results that the auricles form scarcely a third of the total volume of the organ, or half of that of the ventricles."(k) But in one of the latest works upon descriptive anatomy, it is observed that Laennec's statement, that the heart is about the same size as the closed hand of the individual, cannot be considered a good standard of comparison, because no part of the entire frame is so liable to be influenced by incidental circumstances as the hand, and it is more accurate to consider its usual weight to be about ten ounces, and that in other respects the above description of Meckel is accurate. (1) It was formerly a vulgar error that the degree of courage depends on the size of the heart. (m) The ancients, and indeed even the most eminent physiologists, erroneously supposed the heart to be the seat of the soul or mind, and that all the attributes of good or bad disposition proceeded from that organ, as good, bad, base, tender, cold-hearted, &c., and hence the innumerable inaccuracies in our English terms continued even in the best dictionaries. (n) It is supposed that the heart of old persons, especially of those who are lean, generally diminishes in size and beats more slowly. (0) The Position of the heart is singular. It is suspended in its natural and pos- position with its base, or largest part upwards, and by the great blood ture of the vessels which form the main trunks of the sanguiferous system. It is placed in the left side of the fore part of the thorax, resting upon the diaphragm, (p) between the lobes of the lungs, nearly in the centre of the cavity of the thorax, but inclining towards the left, in a line obliquely from the second rib of the right side, to the sixth rib of the left side, and it is on the left side of the mediastinum (or the space between the membranes which pass directly across and through the breast from the sternum, or breast bone, to the spine, and which separate and support the cavity of one side of the chest from the other, and separate the two lungs from each other.) It lightly rests upon the diaphragm as upon a floor, and by which it is in part supported.(g) The com ponent. The heart has been described as a hollow muscle, composed of masses of strong longitudinal fibres, forming an irregular cone, and having an (h) Meckel, vol. ii. 252. (n) It is singular that even in such a Dic (i) Laennec, Traité des Maladies du tionary as Walker's, courage is still supCœur. (k) Id. ibid. (1) See 2 Horn. Anat. 185. (m) 1 Bell, Anat. 501. Hence we know that one of our kings, from his courage, was named Richard Cœur de Lion. posed to be seated in, and depend upon TION. internal cavity.(s) Its texture is peculiarly fleshy, or muscular, dense CHAP. V. and compact, and very different from common muscularity. It is com- SECT. I. posed of fasciculi of fibres more or less oblique, here and there singularly CIRCULAbranching out variously and curiously contorted and verticose in their direction, lying upon each other in strata closely interwoven between the parts of th heart.(r) cavities, and bound by four somewhat tendinous bands at the basis of the ventricle, which thus are supported, and are distinguished from the fibres of the auricles. These fibres arise from a sort of tendinous line, which unites the two auricles to their cavities, and by which the two parts of the heart are joined and united, whereby they mutually strengthen the effect of each other.(t) It has been observed, with respect to the muscular fibres of the heart, that both in their form and their mode of connexion with each other, they greatly differ from the ordinary voluntary muscles. Instead of an assemblage of long and comparatively straight fibres, disposed in the form of separate bundles, each of them enclosed in a sheath of cellular substance, and the whole furnished with a coating of the same, the muscular fibres of the heart are disposed in an irregular manner, and they are not divided into distinct parcels, and they have but little cellular substance attached to them.(u) The long and the straight lacerti of the muscles of voluntary motion are fitted to produce the contraction of those parts in one direction only, whereas, the irregular interlacing of the fibres of the heart obviously serves to promote the contraction of this organ in every direction, so as to diminish its size in all its dimensions. There is no muscular part which is possessed of the same kind of action with the heart.(x) 1. 1. The two Subclavian Veins or Venæ Innominatæ. 2. 2. The two Internal Jugular 3. The Superior Cava. 6. A Flap of the Pulmonary 7.7. The Tricuspid Valve, des- 9. 9. 9. The Semilunar Valves 10. 11. The Pulmonary Artery 12. 12. Its two Branches passing 13. The Ductus Arteriosus,- (t) 1 Bell, Anat. 449, 454, 496; 2 Horn. (u) Soemmering, Hum. Corp. Fab. |