is kept in the head. Thus, then, apoplexy supervenes in drowning, and this view is supported by the consideration of the means, by which recovery has sometimes been induced when the individuals have not been too long a period in the water; inflation of the lungs, warmth applied externally, and the passing of stimuli, by means of tubes, into the stomach. In these processes the great object is to nutrify the blood, and unless this is done by means of inflation of the lungs with new air, the apoplexy cannot be overcome. It is true that the lungs thus inflated must act partly in transmitting the blood through them, but we have no evidence whatever that the systemic ventricle can be stimulated to action by the presence of blood in the pulmonary auricle. Therefore, we must either suppose that the contractions of the ventricles remain with the vie organique, or, that they are excited through nervous communications either from the impressions of warmth, or, of those derived from the stimuli. Thus blood, renewed blood is received from the lungs, although not much reenwed at first. The moment this renewed blood is forced against the arterial column of the aorta, the heart is stimulated by the regurgitation of the latest renewed blood into the coronary arteries, and thus raises the pulse slowly and feebly. At first this action is induced merely by mechanical agents, and afterwards by the hearts deriving sufficient strength, from the nutrified blood thus mechanically forced into it, to enable it to dilate the arterial coats sufficiently to excite general contraction, and thus to renew the vis a tergo, necessary to expel from the veins of the encephalon, the blood which was kept there by the atmospheric pressure. From a consideration of these particulars it appears that the views here taken of this mode of death is at least highly probable, and nothing can be more desirable in the absence of real evidence. There is no doubt that it is possible that in drowning, the fear and the violent efforts for delivery from the danger, may rapidly increase the action of the heart, so as to stimulate it to send an increased quantity of blood, with an increased momentum towards the head, and thus produce the arterial mode of apoplexy. But, it must also be remembered, that the exertions soon overcome the force of the vis a tergo, and thus allow of the action of the coats of the encephalic arteries being excited: so that previous to death, this case would seem to resolve itself into the same as has been considered probable above. The principal difficulties seem then to be removed; and it does appear that this theory of apoplectic seizures may stand the test of inquiry. But still it is remarkable that in coma, although the powers of sensation are more or less destroyed, and, of course, those of consciousness and of voluntary motion, there are certain motions of voluntary muscles of the existence of which the patient is unconscious. At one time these actions are convulsive, rapid, and violent, and affecting all the muscles of the spine. At another, they are confined to the ale of the nose, and to the various muscles more particularly connected with the organs of respiration, and, of this class, to convulsive motions of the muscles of respiration. At other times, however, these motions appear to affect all orders of muscles with irregular action. whatever be the different affection of the muscles, whatever be the degree of that affection, in syncope, epilepsy, coma, apoplexy, one set of symptoms are invariable, namely, temporary absence of consciousness both of external impressions and of objects of reflexion, and a conse But quent absence of desire to induce volition. By these symptoms, they may be associated into one species of complaint, and the symptoms by which they are thus associated may be fairly explained on the principles laid down. That difference in constitution, strength, integrity of nervous communication, should produce different consequences from the same antecedent, the cutting off the nutriment from the encephalon, and thus from the nervous system, is not wonderful. That these consequences should exhibit themselves in the form of twitchings, spasms, convulsions of the muscles, may, perhaps, be explained by the fact that at first there is not only an increased quantity of blood sent to the organs of sense, but by two roads through the medulla oblongata; for the vertebral arteries send considerable twigs both from the parts of them within and without the brain, to the medulla oblongata and superior part of the spinal marrow, and certainly to the respiratory column of the medulla oblongata. As soon therefore as the transit of arterial blood through the encephalic part of the vertebrals is stopped, the blood must tend to find a vent through the branches without the cranium, and thus to add an unusual stimulus to the medulla oblongata. As might be conjectured these involuntary actions are far more violent at the first part of the fit than towards its close. The consequences of these various affections in producing lesions of the apparatus of the senses, and in destroying the power of volition over one or more muscles, or over a whole class, depend not improbably upon the changes of structure, or of the calibre of the vessels produced in these organs of sense, and in the medulla oblongata where the nervous fibres interlace, or in a manner partly change sides, by the sudden diversion into these canals of the quantity of arterial blood destined to have past through the cavity of the head. Such a diversion, particularly in the weakened and debilitated subjects, among whom apoplectic affections are most common, to organs weakened either by local or by constitutional disease, must like every increase of the vis a tergo prove dangerous and sometimes fatal to their integrity. You must now be satisfied as to the influence of rupture of the vessels of the head, where it produces an extravasation, and as to that of the fluid sometimes so plentifully secreted within the cavity of the cranium. It is manifest that the effect of the extravasated or secreted matters must be to occupy part of that space, which under ordinary circumstances, is devoted to the transmission of fluid blood through the head. These matters, inasmuch as they have no connection with the circulating canals, must act in the same manner as the masses of the brain, or of solid matter: the space therefore occupied by these masses must be taken either equally from the venous and arterial columns of the head, or more or less from one of these. But as these masses are similar in effect to masses of brain, and as the powers of the circulation remain the same, they will produce no more effort on the veins than on the arteries. But the actual, or total space to be occupied by the blood past through the arteries being diminished, the quantity of blood sent to these vessels remaining the same, has an increased power, and thence can more easily produce such a congestion of these as shall obliterate the space due to the remainder of the encephalic venous system. Further than this it would appear, that these extravasations have no immediate effect, although they may, and undoubtedly do produce, when long left in the encephalon, such irritation as to induce various changes destructive, more or less, of the directing power of the organ, by unfitting it for being benefitted by the nutrient blood circulated through its vessels. It must certainly be admitted that exhaustion of a portion of the accumulated nervous energy may take place from the separation of structure produced by the dilacerations of the arteries opposed by these mechanical obstructions. It may also happen that such lacerations may cut off a part of the influence, which might have been transmitted along the entire fibres. But, these are only a part of that host of circumstances, which tend, more or less in every case, to render inanition of the brain more fatal, by exhausting a part of its previously accumulated power. The most important part of these views, however, is, that from them may be deduced a very simple explanation of death in most cases. Inanition of the fountain head of the nervous system, namely the encephalon, is then the CAUSE OF DEATH; this inanition must be produced by some change or changes in the quality of the blood transmitted through the systemic part of the circulation, or by some obstruction to the free transmission of a part of this blood through the nutrient vessels of the encephalon. But, as the vis a tergo is diminished by a rapid and sudden diminution of the nutrient power, and so diminished as not to be able to overcome the atmospheric pressure keeping the veins full, so, it is highly probable, that apoplexy would always take place from the interruption of the encephalic circulation previous to the entire exhaustion of the nutrient particles of the blood. Yet, this interruption to the encephalic circulation acts more or less rapidly, according to the power of the system at the time, and, when that is at a very low point, will, perhaps, act more suddenly, and carry off the patient at once. Under this point of view, no disease has the specific power of producing death, but, every derangement of function, produced by alteration of structure, or lesion of continuity, however small, tends to prevent the full assimilation of nervous nutriment or stimulus: greater derangements, and irregular actions of the body, or operations of the mind, all tend towards that state of the system, in which inanition of its helmsman may more easily supervene, and, in which that inanition may have lasted so long, that no efforts at resuscitation, no skill of the medical attendant can possibly afford relief. DEATH, then, is a continuation of apoplexy, or rather of coma, to a period when the structures engaged have ceased to be obedient to the laws, which guided them while under the influence of the brain. Nothing can be more interesting than this view of the subject, because it accounts for the extinction of the demonstrations of life on precisely the same principles as the extinction of the powers of any mechanical contrivance depending for its power on a supply of food. Diminish the quantity of water supplied to the boiler of a steam engine, by any means, whether by a total or partial obstruction of the pipes, or irregular action of their valves, and the action of the steam engine will be impaired ; cut it off altogether and its actions cease: impair the machine in other respects, or diminish the power of the fire at the same time, and the action ceases so much the sooner. [17] VOL: I. G BONES OF THE CRANIUM AND FACE. HOW TO FIND THEIR POSITIONS. Nos. referred to in the Analytical index. IN the adult head, those are called individual bones, which can be separated by art, so as to be distinct, without displaying any fracture of their substance. } 1 In this demonstration it will be useful to begin from a given point, and, proceeding along a given line, to name all the bones crossed by the line. Those bones, not crossed by the given line, may afterwards be found by observation of the boundaries of the bones already named. Take a piece of thread, and, placing one extremity of it on the centre of the anterior lower extremity of the chin bone, pass it along the surface of the face and head, taking care to keep it in a vertical plane passing through the middle of the longitudinal course of the head, and, bring it back to the same point. A line will thus be made along the face and the head, which may be as well made in the imagination as with the thread, and which, for convenience, may be called the mesial line of the head. } 2 Divide the thread, or the mesial line of the head, into five equal parts, marking the points of division, 1, 2, 3, 4, 5. 1. Rests upon the centre of the lower anterior base of the chin bone 3 1st. 2nd. The middle of a bone called submaxillary; 4 3rd. The line, proceeding up A space between two teeth called front in- 6 wards from No. 1, runs along and terminates at No. 2, which will be found to lie at the upper extremity of the line of the junction of the nasal bones. The line 2 to 3 runs upwards and backwards along the convex surface of a bone, which terminates posteriorly at 3, and is called the frontal bone. The zigzag line crossed by the mesial at 3, and running laterally from it, is called the coronal suture. The line 3 to 4 runs along the pointed productions made by a zigzag line, separating two bones called the parietal bones. The zigzag line is called the sagittal suture. At 4, the mesial line crosses another zigzag line, transverse to itself, which is called the lambdoidal suture, and proceeds backwards and downwards along a convex bone called the occipital bone, and terminates at 5, which lies upon the posterior margin of a large orifice called the foramen magnum, or great hole of the occipital bone. The line 5 to 1 running forwards, passes along The sharp edge of a bone that divides two 15 and terminates at No. 1, from whence the mesial line began. We now proceed to fill up the list of the bones of the head, we have given, by pointing out the sphoenoid, temporal, malar, ethmoid, and lachrymal, by means of the boundaries of those, whose position has been already determined. |