THE ARTERIAL SYSTEM.
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Tounderstand thoroughly the process of embalming as described in the preceding chapter, it will be necessary to give here a brief explanation of the circulatory system; also to explain the position of the different parts of the viscera, to which reference has been made.
The arteries commence from the great arterial trunk, called the aorta, and their branches are distributed to all parts of the system; they are dense in structure, and preserve for the most part their cylindrical form when emptied of their blood, which is their condition after death.
The aorta arises from the left ventricle, at the middle of the root of the heart; it ascends at first forwards and to the right, then curves backwards and to the left, and descends on the left side of the vertebral column, to the fourth lumbar vertebra; here it is divided into the arch and descending aorta.
It should be here remembered that most of the branches, which spring from the great artery and vein, are double, that is, each right branch has a corresponding one on the left side—so that there are, for instance,the right and left carotid arteries, the right and left jugular veins, etc. From the arch of the aorta are sent off those arteries which are distributed to the head and arms; the principal ones among these are named as follows:
The carotid artery, which ascends in the side of the neck and divides into the temporal artery which is distributed in the temple, and the facial artery which supplies the face, and also sends a branch called theinternal carotidto the parts within the skull. The sub-clavian artery, lying beneath the clavicle, or collar bone—that part of the continuation of this artery which passes through the axilla or arm-pit, is called the axillary artery; its continuation in the upper part of the arm, the brachial artery; and in the fore-arm it divides into the radial and ulnar arteries, which are distributed to the hands and fingers.
The principal branches of the descending aorta are as follows:
The iliac artery, which on passing into the thigh becomes the femoral artery, and, in the leg divides into the tibial and peroneal arteries, which form numerous branches for the supply of the leg and foot.
Before dividing into the iliac arteries the descending aorta gives off several important branches, as the cœliac artery, from which the stomach and liver are supplied; the renal artery, which goes to the kidneys, and the mesenteric artery to the intestines; besides many other sub-divisions in various parts of its course.
The veins are the vessels which return the blood to the heart, after it has been circulated by the arteries through the different tissues of the body; they are much thinner in structure than the arteries, so that when emptied of their blood they become flattened and collapsed.
The veins of the trunk may be divided into, the superior vena cava, with its formative branches, and the inferior vena cava with its formative branches.
The superior vena cava is formed by the junction of the right and left vena innominata; it is a short trunk about three inches in length; it descends perpendicularly on the right side of the arch of the aorta, and terminates in the upper part of the right auricle of the heart. The right vena innominata receives the veins of the neck, which return the blood from the head as follows: The internal, external and anterior jugular veins—the external jugular vein being the one which is ordinarily open to let out the extravasated blood from the head—it will not be amiss to describe its course; it descends the neck in the direction of a line drawn from the angle of the lower jaw to the middle of the clavicle or collar bone, and terminates into the sub-clavian vein; it is variable in size, and replaced by two veins. The sub-clavian vein becomes the axillary vein near the arm-pit, and opens into the brachial veins down to the bend of the elbow, where it is divided into several branches which supply the fore-arm and the hand.
The inferior vena cava is formed by the union of the two common iliac veins; it ascends along the front of the vertebral column or back bone, and, passing through the fissure in the posterior border of the liver, terminates into the inferior part of the right auricle of the heart. Its branches are the lumbar veins, three or four in number, which collect the blood from the muscles and integuments of the loins and spinal veins; the renal veins, which return the blood from the kidneys, and the hepatic veins in the liver.
The common iliac veins, which, by their union form the inferior vena cava, are in turn formed by the union of the internal and external iliac veins; the external iliac vein passing into the thigh becomes the femoral vein, and is found in the same sheath with the femoral artery; further below it becomes the popliteal vein; about one inch and a half below Poupart’s ligament in the upper part of the thigh, the femoral vein receives the internal saphenous vein, which commences at the inner side of the foot and great toe; it ascends in front of the inner ankle and along the inner side of the leg; it then passes behind, and along the inner side of the thigh to the saphenous opening, where it pierces the sheath of the femoral vessels and terminates as above stated, in the femoral vein.
The above explanation of the circulatory blood vessels is given only for one side of the body—the right side. The other vessels branching off from the two great trunks, the aorta and the vena cava, on the left side are the same, with very slight modifications.
The œsophagus is a slightly flexuous canal, inclining to the left in the neck, to the right in the upper part of the thorax; it commences at the termination of the pharynx, which is a musculo-membranous sac, about four inches in length, and communicating with the cavity of the nose and mouth; the œsophagus then passes behind the arch of the aorta to the œsophagal opening in the diaphragm, where it enters the abdomen, and terminates into the stomach.
The stomach in man is an oblong, membranous bag, placed obliquely across the abdomen and just below the diaphragm; its average capacity in the adult is about one quart; it has two openings, one towards the heart called thecardiac orifice, which receives the food from the œsophagus, and the other at the right or small end of the stomach, called the pyloric orifice, for the transmission of food to the small intestines.
The small intestines, about twenty-five feet in length, are coiled in various directions, and terminate into the large intestine, called the colon, which is about five feet in length, and resembles in appearance a long sac divided into numerous pouches.
The pancreas is a long narrow gland, situated partly behind the right side of the stomach, and within the first curve of the small intestine.
The liver is the largest gland in the body; it is situated on the right side, below, and in contact withthe diaphragm, and is divided into several lobes. At its lower side is the gall bladder, into which the bile is poured after being secreted. Its duct opens into a duct leading direct from the liver, and forms with it the common bile duct, through which the bile is poured into the small intestine, at the same point with the duct from the pancreas, until, at length, it is carried with the food into the larger intestine or colon, from whence it is excreted from the system, through the rectum.
The lungs are supplied with air through the larynx and the trachea.
The larynx is an irregular cartilaginous tube, forming the upper part of the windpipe, as the whole tube is commonly called.
The larynx is situated immediately below the root of the tongue, and forms the protuberance in the front part of the neck, called Adam’s apple.
The trachea, which is a continuation of the larynx, is composed of about eighteen cartilaginous rings, connected together so as to form a tube, which is capable of maintaining a uniform size. On entering the chest, the trachea divides into two trunks, called bronchi, one of which goes to the right, and the other to the left, lung. As soon as the bronchi enters the lungs they branch off into numerous divisions and sub-divisions; their ultimate extremities terminate in air cells.
The lungs occupy the greater part of the chest, the heart being the only organ of much volume, which it includes in it.
The chest, or thorax, is a cavity closed on all sides from the entrance of air, and its bony walls afford an admirable protection to the delicate organs included within it. The walls of the thorax are formed by the breast-bone in front, by the ribs and spine on the sides and back, and by the diaphragm below.
The diaphragm, as has been stated in a previous part of this chapter, is a large muscular partition, which separates the chest from the abdomen.
The explanations given in this chapter upon the arterial and venous circulation, also upon the names, places and relations of the abdominal and thoracic viscera, will be found of the utmost importance, to understand fully the process of embalming already given, and also the other methods which will be stated hereafter.
Although briefly enunciated, this review of the anatomy of the parts of the human body, which the embalmer must be conversant with, will be found quite sufficient for the purpose.
It will be seen, that even after the arterial and venous systems have been properly injected, there still remains a prolific source of putrefaction in the liquids contained in the intestines, and the thoracic viscera; for instance, the fecal matter contained in the intestines, and the undigested food in the stomach at thetime of death, must all be evacuated, and the organs containing them properly cleaned and injected, and unless this be done fermentation will set in, and be followed by rapid decay of the surrounding tissues. It is true the arteries and veins extend their branches to all parts, and to every organ of the body, but it is also an undeniable fact that the contents of those organs which are prone to putrefy will carry the infection to the vessels containing them.
The stomach and bowels are emptied of their contents for the mere reason that these same contents are already undergoing a process of fermentation, which will generate into rapid decay and the emission of noxious gases.
In certain cases of consumption, the lungs are gangrenous and decayed long before death takes place; it will then be found necessary to introduce through the trachea some antiseptic fluid which will stop the progress of decay.
It is also necessary that the names of the different organs mentioned in this work should be explained, so as to make the use of technical words comprehensive to every undertaker who is not supposed to be familiar with the terms of the dissecting room or the human organism in general.
Besides the knowledge of the information given in the preceding pages will enable the embalmer to follow the workings of the embalming process in all its details, and enable him to discover the causes of failure in certain cases; also to use the proper means in the achievement of success.