Ossa temporum are situated below the parietal bones at the middle and lower parts of the sides of the scull.

Bones of the Face.

The face is that irregular pile of bones, which compose the fore and under part of the head. These are divided by authors into the upper and lower maxilla, or jaws, and the several parts of which they consist, we shall now proceed to describe.

Ossa nasi make the upper part of the nose, and form that kind of arch, which is fitted to sustain such injuries as the nose is most exposed to, as blows, bruises, &c.

The ossa malarum compose the anterior, lower, and outer parts of the orbits of the eyes.

Ossa ungues are situated immediately below the os frontis, towards the nose, and within the orbits of the eyes, whose anterior and inner parts they help to compose. Between each of these and

the

upper jaw is a foramen as large as a goose-quill, for the passage of the lachrymal duct into the nose. Through this the puncta lachrymalia carry off any superfluous moisture from the eyes.

Ossa plana are seated immediately beyond the foregoing bones, in the orbits of the eyes, and are near thrice as big.

Maxilla superior is always described single, though it is manifestly divided by a suture, which is scarce ever obliterated. It has two processes, which join the os frontis, and make part of the nose; and a third, which joins to the cartilage of the septum nasi. Its upper and outer parts compose the lower portions of the orbits of the eyes; its lower side, all that part of the face under the cheeks, eyes, aud nose, to the mouth, and two thirds of the roof of the mouth. The ossa palati are two small bones that form the back part of the roof of the mouth, and a small part of the bottom of each orbit.

The vomer, so called from its resemblance to a plough-share, is seated between the bones of the palate, and the sphenoidal bone. It is also joined to the process of the ethmoides, and part of the lower jaw.

There are many more bones in the head, which we must pass

over.

The trunk consists of the spine, pelvis, and thorax.

The spine is composed of twenty-four vertebræ, besides those of the os sacrum and coccygis. Seven of these belong to the neck, and the first of them is called atlas, because it immediately supports the head. Its upper side has two cavities, into which the apophyses of the os occipitis are received; but these two cavities together, unlike all other joints, are laterally portions of concentric circles, by which means they are but as one joint, and so suffer the head to move easily side-ways, which otherwise it could no more do than the knee, which also has two heads and two cavities. The under side of this bone has a very flat articulation with the next; by which means it is fitted for a rotatory motion. The second vertebra is called dentata, or axis, from a process which passes through the former bone, and is the axis upon which it turns; nevertheless, all the ver tebræ of the neck contribute something to the rotatory motion of the head. The processus dentatus is strongly tied to the os occipitis and to the atlas by ligaments, to prevent its hurting the spinal mar. row. Twelve vertebræ belong to the back, and five to the loins, The ribs are twelve in number on each side. The seven uppermost are called true ribs, because their cartilages reach the sternum; and the five lowest are named false ribs. They are articulated to the bodies of the twelve vertebræ of the back, and all, except the two or three last, are articulated to their transverse processes, and the under side of the middle ribs are hollowed for the passage of the intercostal vessels. They defend the parts contained in the breast, and when they are drawn upwards, the cavity of the breast is enlarged for inspiration, and vice versa.

The sternum or breast-bone, is generally made up of three spongy bones, sometimes more. To this the two ribs are articulated by their cartilages, which sometimes, in robust men, have moveable joints, such as are seen in oxen and other quadrupeds.

Bones of the upper Extremity.

In speaking of these we shall begin with the clavicula or collarbone, which is connected at one end to the sternum by a loose carti

lage, and at the other to the processus acromion or the scapula. Its chief use is to keep the scapula a sufficient distance from the breast, and by that means to prevent the shoulders from coming too near together.

The scapula is united to the sternum by the clavicle. Its chief Connection, however, is to the ribs and spine, by means of the same muscles that direct its motions. On the outside of the scapula rises a large spine, the fore part of which is called the processus acromeon, and to which the clavicle is fixed. Near this process is another called coracoides, from whose extremity arise two muscles of the arm. The side opposite to the socket is called the basis of the sca◄ pula, and the lower edge costa inferior, from its figure, which is thick, and like a rib to the scapula.

The scapula is connected to the head, os hyoides, vertebræ, ribs, and arm-bone, by muscles, that have one end fastened to these bones, and the other to the scapula, so as to move it upwards, downwards, backwards, or forwards.

The os humeri, at its upper end or head, where it is joined to the scapula, is somewhat flat, and much larger than the socket which receives it. That part to which is attached the upper end of the radius, is fitted not only for the motion of the elbow, but also for the rotatory motion of the radius. The rest of the elbow-joint is made of portions of unequal, but concentric circles, like the shanks of quadrupeds; and this inequality prevents the ulna from dislocating sideways, which so small a joint, with so considerable a share of motion, would otherwise be very liable to.

The ulna, at its upper end, has one large process called olecranon, and a small process on the fore part; and on one side, between these, is also a small cavity, which receives the upper end of the radius for its rotatory motion. At the lower end is a process, called styliformis, and a round head, which is received into the radius, and adapted to the rotatory motion of the elbow.

The upper end of the radius is received into the ulna, and joined to the humeris, in a manner chiefly favourable to its rotatory motion. A little below its head is a large tubercle, into which the biceps muscle is inserted. At the lower end, which is thicker, is a

socket to receive the carpus, and at the side next the ulna a small one to receive that bone. There is likewise a thin edge, into which the transverse ligament, which arises from the ulna, is inserted. By this ligament these bones are tied conveniently and firmly together; for the ulna being chiefly articulated to the os humeri, and the radius to the carpus, a weight at the end would be liable to pull these bones asunder, were it not prevented by this ligament.

Bones of the Hand.

The carpus, or wrist, is composed of eight bones of very irregular forms, undoubtedly the properest that can be; yet why in these forms, rather than any other, no anatomist has been able to show. They have all obscure motions one with another, and with those of the metacarpus; but the motion of those of the first rank, or order, with those of the second, is more considerable, and is directed by the same muscles, which move the carpus on the radius.

The metacarpus consists of four bones, which sustain the fingers; that of the fore-finger having the least motion, and that of the little one the most. The other ends of these bones have round heads for the articulations of the fingers; but the other joints of the fingers have double heads and sockets. The thumb is shorter and stronger than any of the fingers, because in its actions it is to resist them all. The first joint is very singular, each bone receiving, and being equally received.

Bones of the lower Extremity

Of the bones of the lower limb, the principal is the os femoris, column, or thigh-bone, which, at its upper end, has a round head, that is received into the socket of the os innominatum.

The rotula, or knee-pan, is situated on the fore part of the knee. It has the appearance of being buried, as it were, in the centre of the tendon, through which, however, it soon extends, until the tendinous fibres are lost, and appear to be converted into bone.

The tibia, so called from its resemblance to an old musical pipe, or flute, is the long thick triangular bone, situated at the internal

part of the leg, and continued in almost a strait line from the thighbone. At its upper end are two shallow sockets, which receive the thigh-bone, and between these, a rough process, to which the crucial ligaments of the knee-joint are connected.

Fibula is the small long bone, placed on the outside of the leg, opposite to the external angle of the tibia; the shape of it is irregularly triangular.

Bones of the Foot.

The tarsus is composed of seven bones, the first of which, called astralagus, supports the tibia, and is supported by the os calcis, which being projected backwards, makes a long lever for the muscles to act with, that extend the ancle, and raise the body upon the toes. These two bones have a considerable motion between themselves, and the astragalus also with the os naviculare. All the rest have an obscure motion one with another, and with the bones of the metatarsus, the principal share of these motions falling towards the great toe, where lies the greatest stress of action. These bones, by yielding in this manner, are less liable to be broken; and acting as a kind of spring under the leg, render the motions of the body in walking more easy and graceful, and the bones to which they give support less subject to be fractured in any violent exertion.

To these bones are joined five others, called metatarsal bones. That which supports the great toe is much the largest; because of there being the greatest stress laid on it in walking. Under its end lie the two sesamoid bones, which are of the same use as the rotula. The great toe has two bones; the lesser three each. The little toe, and frequently that next to it, have the second and third bones intimately united into one; which may be owing to their little motion, and the great pressure they are subject to from the weight of the body.

Having now described the Bones, or the timbers of the temple, we shall, in the next place, describe its covering. "Thou hast clothed me with skin and flesh, and hast fenced me with bones and sinews," Job x. 11.

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