Here the humerus begins, which at both its ends is enlarged, soft, without marrow, and cartilaginous; in the middle round and hard, and containing marrow; is a little concave[(8)] in its fore and internal part; and convex in its posterior and external part. Now the fore part is next the breast; the posterior is toward the scapulæ; the internal next the side; and the external at the greatest distance from the side: which distinctions will afterwards appear applicable to all joints in the extremities. The upper end of the humerus is rounder than the other bones, which I have yet mentioned, and a small part of it is inserted into the vertex of the broad bone of the shoulder; the greatest part, standing out of it, is secured by ligaments. But the inferior head has two processes; the intermediate space between which, is even more depressed than its extremities.
This affords a reception to the fore-arm; which consists of two bones. The Radius, which the Greeks call cercis[ HY ], is the superior one and shorter, and at first being more slender, with its ends round, and a little concave, receives the small tubercle of the humerus, which is secured there by ligaments and a cartilage. The cubitus is the inferior and longer; it is at first larger in its upper end, and by two vertices, as it were, standing out, fixes itself into the sinus of the humerus, which I mentioned, betwixt its two processes. The two bones of the fore arm at first[(9)] are close together, then separate by degrees, and meet again at the hand, their former proportions being reversed: for there the radius is pretty large, and the cubitus very small. After that the radius rising to a cartilaginous head is inserted into its neck. The cubitus is round at its extremity, and projects a little on one part. And to save frequent repetition, this ought to be known, that most bones end in a cartilage, and that every articulation is thus terminated: for it could neither be moved, unless it pressed upon something smooth, nor be joined with flesh and ligaments, unless these were connected by some matter of a middle nature.
In the hand, the first part of the palm consists of many and small bones, the number of which is uncertain. But all of them are oblong and triangular, and connected together by a peculiar kind of structure, the plain of each one being higher than another alternately; whence it happens, that the whole makes up the appearance of one bone a little concave on the internal part. But from the hand two small processes are lodged in the cavity of the radius. Then at the other end five straight bones going to the fingers, compleat the palm; from which the fingers themselves have their origin. These consist each of three bones. The conformation of them all is the same. The more internal bone has a depression in its vertex, and receives the small tubercle of the external, and these are secured by ligaments. From them arise the nails, which grow hard: and thus they adhere by their roots, not to bone, but rather to flesh. This then is the construction of the superior parts.
But the lower part of the spine ends in the hip-bone, which is transverse, and far the strongest, and defends the womb, bladder, and intestine Rectum. And this in the external part is convex; at the spine inclined backward; on the sides, that is, at the hips themselves, it has round cavities; from whence arises the bone, which is called pecten; and that being situated transversely over the intestines under the pubes, strengthens the belly; it is straighter in men, but in women more bent externally, that it may not prevent the birth.
From these proceed the thigh bones; the heads of which are still rounder than those of the humeri; though the latter have more rotundity, than is found in any of the rest. A little lower they have two processes on the fore and posterior part. From that they descend hard and full of marrow, externally convex, and are again enlarged at the inferior heads. The superior ones are inserted into the cavities of the hip-bone, as the humeri into the bones of the scapulæ; then, lower down, they slope gently inward, that they may more equally sustain the superior parts. And their inferior heads have also depressions between them, that they may be the more easily received by the bones of the leg: which articulation is covered by a small, soft, and cartilaginous bone, which is called Patella. This floating above, and not being fixed to any bone, but bound down by flesh and tendons, and a little more inclined to the thigh bone, defends the joint in all flexures of the legs.
The leg consists of two bones; for in every thing the thigh resembles the arm, and the leg the fore-arm; so that the shape and elegance of the one may be known from the other; which beginning with the bones, answers also in the flesh. One of these bones is situated on the external part of the calf of the leg, and from that properly enough takes the name of Sura[(10)]. This is shorter and more slender above, but is enlarged at the ancles. The other, which is placed in the fore part, and has the name of Tibia, is longer and larger in the upper part, and is alone connected with the lower end of the thigh-bone, as the cubitus is with the humerus: and these bones too, being joined both below and above, separate in the middle, as those of the fore arm.
The leg bones are received below by a transverse bone in the ancle; and that is situated above the heel bone; which in one part has a depression and in another prominences, and it both receives the processes from the ancle-bone, and is inserted into its cavity. And this is hard, without marrow, and projecting more to the posterior part makes a round figure there. The other bones of the foot are constructed in a similar manner to those of the hand. The soles answer to the palms, the toes to the fingers, and the nails to the nails.