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1 The remaining part of my work relates to the bones; and to make this more easily understood, I will begin by pointing out their positions and shapes. First then comes the skull, concave internally, convex externally, on both aspects smooth, where it covers the cerebral membrane as well as where it is covered by the skin bearing hair; and it is in one layer from the back of the head to the temples, in two layers from the forehead to the vertex. Its bones are hard externally, but the inner parts which connect them together are softer, and between these run large blood-vessels which probably supply their nutrition. It is rare for the skull to be solid without sutures; in hot countries, however, this is more easily found; and that kind of head is the firmest and safest from headaches. As for the rest, the fewer the sutures, the better for the heads; and there is no certainty as to the number, or even as to the position of the sutures. Generally, however, there are two above the ears separating the temples from the upper part of the head: a third stretches to the ears across the vertex and separates the occiput from the top of the head. A fourth runs likewise from the vertex over the middle of the head[p. 477] to the forehead, sometimes ending at the hairy margin, sometimes dividing the forehead itself and ending between the eyebrows. Most of these are dovetailed, but those which cross over above the ears are bevelled off a little all along their margin so that the lower bones smoothly overlap the upper. Now the thickest bone in the head is behind the ear, where hair does not grow, probably on that very account. Under the muscles covering the temples is situated the middle bone which slopes outwards. But the face has the largest suture; it begins at one temple, passes across the middle of the orbits and nose to the other temple. From this suture two short sutures are directed downwards from the inner corners of the eyes; and the cheeks at their upper parts also have transverse sutures. From the middle of the nostrils or of the gums of the upper teeth, one suture runs back through the middle of the palate, another cuts the same palate transversely. These are the sutures found in most skulls. Now the largest passages leading into the head are those of the eyes, next the nostrils, then those of the ears. Those of the eyes lead direct and without branching into the brain. The two nasal passages are separated by an intermediate bone. These begin at the eyebrows and eye-corners, and their structure is for almost a third part bony, then changes into cartilage, and the nearer they get to the mouth the more soft and fleshy their structure becomes. Now these passages are single between the highest and lowest part of the nostrils, but there they each break up into two branches, one set from the nostrils to the throat for expiration and inspiration,[p. 479] the other leading to the brain and split up in its last part into numerous small channels through which we get our sense of smell. In the ear the passage is also at first straight and single, but as it goes further becomes tortuous. And close to the brain this too is divided into numerous fine passages which give the faculty of hearing. Adjacent to the passages there are two little pits, as it were, above which ends the bones which stretches across from the cheek, supported by deeper-seated bones: it may be called the yoke, from the same resemblance which led the Greeks to call it zygodes. But the lower jaw is a soft bone and a single one, of which the chin forms the middle and lowest portion, whence it is continued on the two sides to the temples; and it alone is movable, for the cheek-bones with all that bone which produces the upper teeth are immobile. Now the ends of the lower jaw itself form, as it were, two horns. One process broader below tapers to its tip, and as it passes higher, goes under the zygoma, and is fastened to the temporal muscles above it. The other is shorter and more rounded off, and in that pit which is adjacent to the auditory passages, it is set in a sort of hinge, and as it bends there forwards backwards supplies the power of movement to the lower jaw. The teeth are harder than bone, some are fixed in the lower jaw, some in the cheek-bones. Of the teeth, the four in front are named by the Greeks tomis because they cut. These are flanked at each side by four canine teeth. Behind these on either side is generally a set of four molars, except in those who[p. 481] have five one tooth on each side coming through later. There are some in whom the four last, which generally come through late, do not make their appearance. Of these teeth the front ones are fixed by single roots, the molars at least by two, sometimes even by three or four; and generally the longer root produces the shorter teeth; the straight tooth has a straight root; a crooked tooth a crooked root. From the same root in children a new tooth grows which general pushes out the former one, but sometimes shows itself behind or in front of it. Now the spine is the support of the head. It is composed of twenty-four vertebrae, seven in the neck, twelve belonging to the ribs; the remaining five are below the ribs. The vertebrae are bones rounded off and short; from each side they thrust out a transverse process; they are perforated in the middle where the spinal marrow which is connected with the brain passes downwards, and at the sides also through the two transverse processes they are traversed by fine channels, through which little membranes pass down resembling the cerebral membrane; with the exception of the three highest all the vertebrae have slight depressions in their articular processes on the upper side, on the lower side other articular processes grow downwards. The highest vertebra is therefore the immediate support of the head, receiving its small processes into two depressions, and this enables the head to move up and down. The second vertebra is made irregular by a protuberance and is attached to the lower side of the one above. To secure the rotation of the head the top of it ends in a narrower round process, so that the first vertebra[p. 483] encircling the top of this allows the head to turn sideways as well. After the same fashion the third vertebra supports the second, hence there is easy movement in the neck. And the neck could not even hold up the head were it not supported on each side by straight and powerful sinews which the Greeks call te/nontej; since whenever the head bends one of the sinews is always tense, and does not allow what is above to slip too far over. From the third vertebra in turn grow little protuberances which are inserted into the vertebra below; the remaining vertebrae are fastened into the ones below them by processes directed downwards and support the ones above them in the depression which they have on either side, and they are held together by many ligaments and cartilages. Thus by bending once in the required direction and avoiding moving in other directions man stands upright, or bends somewhat, to do anything that is required. Below the neck the highest rib is placed on a level with the shoulders; after that there are six lower ribs, reaching as far as the bottom of the thorax; the ribs, which in their first part are rounded and end in small heads, as it were, are lightly fixed to the transverse processes of the vertebrae, which themselves have slight depressions; then the ribs flatten out and after curving outwards gradually degenerate into cartilage, and here, after again bending slightly inwards, they become united to the breast-bone. This, a strong and hard bone, begins below the throat, is lunated on each side, and, when it becomes itself softened into cartilage, is bounded by the praecordia. Below the upper ribs, there are five called by the Greeks nothae; they are short, thinner, and after changing gradually into[p. 485] cartilage, they are embedded in the highest part of the abdomen. The lowest of these consists for the most part only of cartilage. Again, from the neck two wide bones extend to the shoulders on each side; we call them scutula operta, the Greeks omoplatae. These bones are curved at their highest point, and below these they are triangular, and become gradually wider as they approach the spine. As they become wider, they become blunter. And they too at the lowest part soften into cartilage at the back and float, as it were, since they are unconnected with any other bone except at the top, but there they held in place by very strong muscles and sinews. Now at the level of the first rib, and a little behind its middle, a bone grows out which at first is slight but as it comes nearer the broad bone of the shoulder-blades becomes thicker and broader, and curves slightly outwards; and this at its other upper end is enlarged somewhat to support the root of the neck. But this bone itself is curved, and must not be reckoned among the hardest or most solid, and it lies with one head fixed as just stated, the other in a small depression of the breast-bone; it moves a little with the movement of the arm, and is connected with the flat bone of the shoulder-blades by sinews and cartilage. From this point begins the humerus, which at both ends is swollen out, and is there soft, without marrow and cartilaginous; in the middle cylindrical, hard, contain in marrow; and slightly curved both forwards and outwards. Now its front part is that on the side of the chest, its back, that on the side of the shoulder-blades; its inner part that which faces the[p. 487] side, its outer away from the side. It will be clear in later chapters that this applies to all joints. Now the upper head of the humerus is more rounded than any other bone hitherto described and is inserted by a small excrescence into the top of the wide bone of the shoulder-blades, and the greater part of it is held fast by sinews outside its socket. The humerus at its lower end has two processes, between which the bone is hollowed out even more than at its extremities. This furnishes a seat for the forearm, which consists of two bones. The radius, which the Greeks call cercis, is the uppermost and shorter; at its beginning it is thinner, with a round and slightly hollowed head which receives a small protuberance of the humerus; and it is kept in place there by sinews and cartilage. The ulna is further back and longer and at first larger, and at its upper extremity is inserted by two outstanding prominences into the hollow of the humerus, which, as I said above, is between the two processes. At their upper ends the two bones of the forearm are bound together, then they gradually separate, to come together again at the wrist, but with an alteration in size; since there the radius is the larger whilst the ulna is quite small. Further, the radius as it enlarges into its cartilaginous extremity is hollowed out at its tip. The ulna is rounded at the extremity, and projects a little at one part. And, to avoid repetition, it should not be overlooked that most bones turn into cartilage at their ends, and that all joints are bounded by it, for movement would be impossible unless apposition were smooth, nor could they be united with flesh and sinews unless some such intermediary material formed the connection.[p. 489] Turning to the hand, the first part of the palm consists of many minute bones of which the number is uncertain, but all are oblong and triangular, and are connected together on some plan since the upper angle of one alternates with the base of another; therefore they appear like one bone which is slightly concave. Now two small bones project from the hand and are fitted into the hollow of the radius; and at the other end five straight bones directed towards the fingers complete the palm; from these spring the fingers themselves, each composed of three bones; and all are similarly formed. A lower bone is hollowed out at its top to admit a small protuberance from an upper bone, and sinews keep them in place; from them grow nails which become hard, and thus these adhere by their roots to flesh rather than to bone. And such are the arrangements for the upper limbs. Now the bottom of the spine is fixed between the bone of the hips, which lies crosswise and is very strong and so protects the womb, bladder and rectum; and the bone bulges out externally, is bent up towards the spin, and on the sides that is, the hips proper, it has rounded hollows; and from these start the bone they call the comb, situated crosswise above the intestines below the pubes, and this supports the belly; in men the bone is straight, in women more curved outwards so as not to hinder parturition. Next in order are the thigh-bones, the heads of which are even more globular than those of the arm-bones, although those are the most globular of the other bones; below there are two processes, one directed forward, the other backward; after this the bones are hard and marrowy and convex on the outer[p. 491] side, and they are again enlarged at their lower ends also. The upper ends are inserted into hollows of the hip-bones, as the arm-bones into the shoulder-bones; then these tend gently downwards and inwards in order that they may support the upper parts of the body more evenly. But the heads at the lower end have a hollow in between, that the leg-bones may be more easily fixed into them. Their juncture is covered by a small, soft, cartilaginous bone, called the knee-cap. This bone, which floats freely and is not attached to any other bone, but held in place by flesh and sinews, is turned slightly towards the thigh-bone and protects the joint in all movements of the legs. The leg itself is made up of two bones; for as the thigh-bone is throughout similar to the humerus, so is the leg like the forearm, hence the form and appearance of the one can be learnt from the other: and what holds good for the bones holds also for the soft parts. One bone lies outside, and this too itself is called the calf. It is the shorter, and is smaller in its upper part, but swells out just at the ankles. The other is placed more in front and is named tibia; it is the longer, and is larger at the upper end, and it alone joins with the lower head of the thigh-bone, as the ulna does with the humerus. These two bones, moreover, are joined together at the lower and upper ends, but in the middle as in the forearm they are separated. The leg below is received by the transverse bone of the ankles, which itself is set upon the heel-bone; the heel-bone is hollowed out in one part, and has excrescences at another part, so that it receives the excrescences of the ankle and is received itself into the hollow of the ankle. The [p. 493] heel-bone is without marrow, is hard, and projects somewhat backwards where it presents a rounded outline. The other bones of feet are constructed in a similar way to the bones of the hand; the sole corresponds to the palm, digits to digits, nails to nails.
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