THE great characteristic of the Hand, as distinguished from the Foot, is the mobility of the first digit, or thumb. Accordingly when this digit stands out apart from the others, and can be moved independently of them, so as to be more or less completely opposed to them, in the upper or Mammalian Class of animals, at least, we call the member a Hand. When this digit is absent, or is fixed in the same manner as the others, which is the case in each of the four limbs of Quadrupeds, we call the member a Foot. In Monkeys, or in most of them, the thumb is present and is separate and moveable in each of the four limbs; and these animals are, therefore, called “quadrumanous” or “four-handed.” Man, having the moveable thumb upon each of the two upper limbs only, is “bimanous” or “two-handed.” By this peculiarity, perhaps more definitely than by any other, he is distinguished in structure from all the rest of the animal series; and naturalists have, accordingly, given the epithet “Bimanous” to the class in which he is placed, and in which he stands alone.

The hand is the executive or essential part of the upper limb. Without it the limb would be almost useless. The whole limb is, therefore, so made as to give play and strength to the hand; and, in ever so brief a description of the hand, it is necessary, even more than in the case of the foot, to give some idea of the manner in which the other parts of the limb are constructed, and to dwell a little upon such points as have relation to its movements.

The general plan of construction of the upper limb will readily be understood by means of the drawings (figs. 53 and 58, p. 122). It resembles very much that of the lower limb (see fig. 4, page 15). The one bone of the upper arm—the humerus—resembles the one bone of the thigh, and is jointed, above, with the shoulder-blade, which, with the collar-bone, corresponds with the pelvis. Below, it is connected with the two bones of the fore-arm—the radius and ulna; and these correspond with the two bones of the leg. In the wrist there are eight bones, called carpal bones, arranged in two rows. These are connected with five metacarpal bones; and these, like the metatarsals of the foot, are jointed with the phalanges. Of the latter there are three in each finger; but in the thumb, as in the great toe (page 10), there are only two.

The diagram shows how the bones of the hand are arranged in three divisions. Thus, the upper row of carpal bones (3, 4, 5) consists, practically, of three bones; the fourth (6), which is much smaller than the others, being rather an appendage to one of them than a distinct constituent of the wrist. (According to this view, the number of the wrist-bones corresponds exactly with that of the tarsal bones of the foot, viz. 7). The outer of these three carpal bones (3) bears the thumb‍7 and the fore-finger (I. and II.), and constitutes, with them, the outer division of the hand; the inner one (5) bears the ring-finger and the little finger (IV. and V.), and constitutes the inner division of the hand; and the middle one (4) bears the middle finger (III.), and is the middle division of the hand. The diagram shows, too, that the two outer bones (3 and 4), with the two outer divisions of the hand, are connected with the radius; whereas the inner bone (5) only, with the inner division of the hand, is connected with the ulna. Strictly speaking, even this bone is not directly connected with the ulna, but is separated from it, as will be shown presently, by a thick ligament.

You frequently hear ignorant persons (and the greater number of persons are lamentably ignorant of the structure of their own body) speaking of the small bones of the shoulder, or the small bones of the elbow. You may think this a matter of no importance, and that it does not concern you and people generally to have any knowledge of human anatomy. But I will tell you what is very often happening, and will leave you to judge whether such complete ignorance on this subject is not attended with some practical disadvantage. A man meets with an injury, falls and hurts his shoulder. The immediate effects of the injury subside; but he does not quickly recover the use of the part; he still cannot raise his elbow, or put his hand upon his head, or put it behind him. Soon he begins to think that something more is wrong than has been suspected; and the notion creeps over his mind, and gradually takes possession of it, that some small bone is displaced. Not content with the assurances of his medical man, he resorts to a quack, called a “bone-setter.” The latter, taking advantage of the popular fallacy, gratifies the patient with the information that his fears are correct, affirms that “a small bone is out,” and proceeds forthwith to employ the requisite forcible measures for putting the said “small bone” in. I need not say with what result. Every year, in this civilized country, many persons are maimed for life by these attempts to put imaginary small bones in. I beg you, therefore, particularly to observe that there is no small bone either at the shoulder or at the elbow. The only small bones are at the wrist; and these are so well fitted to one another, and so firmly bound together, that nothing short of a crushing force suffices to displace them. This remark respecting the small bones of the wrist is true of nearly all the small bones in other parts of the body. So that, in fact, small bones are very rarely dislocated; and when you hear it asserted that a small bone is out, you may pretty confidently conclude that the speaker does not know what he is talking about.

I have said that the upper limbs resemble the lower in their general construction. There are, however, some important differences; and one of the chief of these is the greater variety and freedom of the movements in the upper limbs. Strength, for the purpose of carrying the body, is the object in the lower limbs. Mobility is the requisite in the upper limbs. Of this one example has already been given in the instance of the thumb as compared with the great toe.

Movements at the Shoulder.

An equally striking example is afforded by the shoulder. In the first place, the “Shoulder-blade” itself can be moved in several directions—upwards, downwards, backwards and forwards;—whereas the “Pelvis,” i. e. the part which bears to the lower limb the same relation that the shoulder-blade does to the upper-limb, is immoveably fixed.

Secondly, the “Shoulder-joint” is so made as to permit a great variety and extensive range of movements to take place. We can move the arm forwards or backwards, as in throwing a ball, or, in sword exercise; we can raise it so that the limb points straight upwards; and we can swing it round in any direction. It is owing to the free movement in this joint that we are able to apply the hand to every part of the body, so as to remove sources of irritation. It is interesting to observe how other animals get on without hands, though they are much exposed to what we should consider great annoyance, as from flies, &c. The Cow, for instance, lashes its hide with its tail. The Cat licks itself with its tongue. The Sparrow dusts itself by the road-side. The Pig and the Donkey roll in the mud. And many of them, as the Horse and the Ox, have a thin muscle, called “panniculus carnosus,” spread out under the skin, which effects those sudden twitchings of the skin whereby they are enabled to jerk off anything that troubles them. In Man the hand answers better than all these methods combined; and it is necessary that it should do so, because his skin is more sensitive and less protected by natural covering than that of any other animal.

For this freedom of movement of the arms, so important to the usefulness of the hand, we are much indebted to the “Collar-bones.” These bones, so called because they are placed at the lower part of the collum or neck, extend, horizontally, from the upper edge of the breast-bone, to the processes of the blade-bones which overhang the shoulder-joint. Thus they hold the shoulders apart, and give width to the upper part of the chest. They also steady the shoulder-blades, and afford a point d’appui to the muscles which effect the lateral movements of the arms,—for instance, to the muscles which tend to draw the arms together, as when we hold anything, between the hands, in front of us; and to those which separate the arms from one another, as when we stretch them out at right angles with the body.

Many animals—the Elephant, the Rhinoceros, the Horse and the Ox—have no collar-bones; and they are only able to swing their fore limbs to and fro. They cannot execute any lateral movements. They cannot throw the limbs out sideways, nor press their fore feet together, so as to hold anything between them. If the horse wants to seize or hold any substance he must do it with his mouth. The Elephant has a special provision for the purpose of prehension in his trunk, which enables him to provide himself with food by pulling down the branches of trees. The Lion and the Tiger can press their fore paws together sufficiently to enable them to hold their prey, and fix it upon the ground, while they put the head down to it and pull at it and tear it with their teeth; and they are furnished with rudimentary, or half, collar-bones suspended in the flesh of the upper part of the chest; while the little Squirrel, which sits upon its hind legs, and holds up the nuts between its fore paws to be nibbled, has complete collar-bones. So has the flying Bat, the climbing Sloth and the digging Mole. In Birds the collar-bones (fig. 56, AA) are very large; and, for the purpose of giving them greater strength, they are united together in the middle line just above the breast-bone, forming what is commonly called the “merry-thought;” and, as this is not sufficiently strong to resist the force of the powerful muscles which flap the wings and sustain the animal in the air, there are, in addition, stout “side-bones,” called by anatomists “coracoid bones.” These (B) run, from the breast-bone (D), in the same direction as the collar-bones, one, on either side, to the shoulder-blades (C); and they afford even more efficient support to the shoulders than do the collar-bones. The coracoid bones are peculiar to oviparous animals, or nearly so. In some reptiles, as the Crocodile, they quite supersede the collar-bones.

These few examples are enough to show that freedom of movement of the arms, especially of lateral movement, is closely associated with, and, indeed, is dependent upon the shoulder-blades being supported and steadied by bones, which extend from the breast-bone to the shoulder-blades, and fasten the one to the other.

But, even the powers and advantages conferred by nature have often some drawbacks; and this free play of the arm at the shoulder in man, of which we are speaking, and the provision for it afforded by the collar-bone, are no exceptions to the remark. It is necessary for so great a range of movement that the socket in the shoulder-blade should be shallow, and that the ligaments which connect the arm-bone with the blade-bone should be loose. Hence the shoulder-joint is weak as regards its ability to resist injury. The collar-bone also causes the shoulder to project so much that it is greatly exposed to injury and often bears the brunt of a fall. A man is thrown from a horse or is knocked down upon the ground, and, if anything prevents the hand being stretched out, the chances are that he falls upon the shoulder. True, the head is saved thereby; but the shoulder suffers. Hence the shoulder-joint is more often dislocated than any other; and no bone is more frequently broken than the collar-bone. Even in little children, in whom, notwithstanding their many tumbles, the other bones usually contrive to escape, the collar-bones are often broken; and in grown-up persons the shoulder is sometimes dislocated by the mere action of the muscles, as in swimming, or throwing, or lifting a weight above the head.

That you may understand the movements of the shoulder a little more fully, I will ask you to contrast the drawing (fig. 58), which shows the position of the blade-bone upon the chest in Man, with the drawing (fig. 57) of the corresponding parts of the Rhinoceros; and you will at once recognise several important differences, besides the presence of the collar-bone in the one and its absence in the other.

In the Rhinoceros the chest is deep, from the back-bone to the breast-bone, and is flattened at the sides; and the depth of this part of the trunk is increased, slightly, by the breast-bone projecting, keel-like, underne1ath, and, much more, by the spines of the back-bone running up into a high ridge, above. The blade-bone and the arm-bone are applied against the flat side of the chest, and lie, lengthways, between the spine and the breast-bone, nearly parallel with the broad flat ribs. The blade-bone has no process overhanging the shoulder-joint, and, as before said, there is no collar-bone. The short thick arm-bone descends nearly in a line with the blade-bone, and has huge processes at its upper end for the attachment of muscles. The parts are designed to bear the great weight of the animal, and to carry its ponderous head and horn; but the only movement of which they admit is a sliding of the blade-bone and arm-bone, backwards and forwards, upon the side of the chest.

In animals of similar construction to the Rhinoceros, but of lighter frame, and of greater fleetness, the blade-bone is placed more obliquely, which gives freer and easier movement both to it and to the arm-bone. This, for instance, is the case with the well-bred horse, and if we want a quick-going horse, one that can lift his fore feet well, we should observe whether the shoulder-blade is oblique, and whether the spines of the back rise well above it. Such a horse is said to have “a good shoulder” and to be “well up.” He will carry a saddle well, and is not likely to trip.

In Man the chest has proportionately less depth and length, and greater breadth, than in any other animal; the breast-bone is quite flat; and the spines of the back are sloped downwards, so that they do not project beyond the level of the ribs and the blade-bones. Hence he can lie easily either upon the stomach or the back—a privilege which is shared with him by very few of the lower animals. Scarcely any of them can lie upon the back, or even upon the stomach without the help of the fore limbs. The donkey enjoys rolling over and over upon a dusty road, but he cannot poise himself for a minute upon his back.

The sides of Man’s chest, moreover, are not flat, as in the Rhinoceros and Horse, but rounded, so that the blade-bones can revolve upon them to and fro, as well as slide upwards and downwards; and the long arms—comparatively long, that is, from the shoulder to the elbow—hang quite free of the chest and form sharp angles with the blade-bones.

The blade-bones are accommodated to the shape of the chest; for, instead of being elongated in a direction parallel with the ribs, they are prolonged downwards, along the sides of the chest, at right angles with the ribs. This prolongation of the lower part of the blade-bone is very important, inasmuch as it enables the muscles to hold the bone steady upon the wall of the chest, and so gives greater power to those muscles which pass from the blade-bone to the arm and act upon the shoulder-joint. Were it not for this provision the contraction of the muscles intended to raise the arm would quite fail to produce the desired effect, and instead of it would simply cause the shoulder-blade to revolve upon a transverse axis. That is to say, when we endeavoured to raise the arm our effort would merely have the effect of raising the hinder part of the shoulder-blade.

In each of these particulars—in the form of the chest, and in the shape and direction of the shoulder-blade—the Monkey is intermediate between Man and the inferior animals. The Monkey’s chest is broad and round, in proportion to its length, if we compare it with other animals; but this is less marked than in the human chest. And you perceive that the Monkey’s back-bones project, as they do in other animals, beyond the level of the ribs. The blade-bones are also like those of Man in being prolonged downwards, and in being carried, to a certain extent, across the ribs; but their lower angles do not run so far in this direction as they do in the human skeleton.

The movement of raising the arm, as in carrying the hand outwards, or pointing upwards, or putting the hand upon the head, is rather a difficult one, and requires the combined action of many muscles. It is, therefore, to be avoided by persons to whom muscular straining is likely to be injurious; and the power of effecting this movement is easily impaired by accident or disease. A long time often elapses even after a slight bruise of the shoulder, before the person recovers the power of putting the hand upon the head.

The exercise of raising the arms above the head is a good one for those in health, and is much, and wisely, recommended by the directors of gymnastics. It brings many muscles into play, not only those of the shoulder, but the muscles all round about the chest, viz. those which pass from the spine and ribs, as well as from the breast-bone, head, and pelvis, to the shoulder-blade and arm; and, thus, it tends to strengthen the spine and the chest, as well as the shoulders and arms. There is, perhaps, no exercise so good as this; and it is much to be regretted that the dress of young ladies, with its paraphernalia of stays and shoulder-straps, interferes so greatly with it. The frequency among them of “pigeon-breast” and “crooked spine” must, partly, be attributed to the confinement of the arms, caused by the mode of dress and the customs of life. One of the few opportunities afforded to the arms of availing themselves of this exercise is in the dressing-room during the process of brushing the hair. I would by all means, therefore, recommend young ladies to give sufficient time and attention to this part of the toilette, and not to delegate it to the lady’s maid. If, in addition, I suggest that it be commonly done with open window, I feel sure that I shall have a deservedly great authority among them—Miss Nightingale—on my side.

The movement at the Elbow is, merely, that of bending and straightening, in a hinge-like manner; yet there is a slight obliquity in the direction in which it takes place, an obliquity resembling that in the movement at the knee (page 39).

Pronation and Supination of the Hand.

In the Forearm and Hand there is a movement with which we have nothing exactly corresponding in the leg. It is called “Pronation and Supination.” In pronation we turn the palm downwards, as in picking up any substance from a table; in supination we turn the palm upwards, as a boy does when he holds out his hand for a caning, or for the more agreeable purpose of having a shilling put into it.

Pronation and Supination take place in the following manner. Each of the two bones of the forearm extends from the elbow to the wrist (fig. 53); but one of them—the “ulna”—is chiefly connected with the elbow; and the other—the “radius”—is chiefly connected with the wrist, and, by means of the wrist, with the hand. The two bones are separate from one another, except at their ends. There they touch, and are jointed together in such a manner that the large lower end of the radius can play round, or partly round, the small, button-like, lower end of the ulna; and, in so doing, it carries the hand with it. In this movement the upper end of the radius (A, fig. 60) does not leave its place, but simply revolves, upon its own axis, on the surface of the arm-bone; and its edge turns in a notch cut for it in the upper end of the ulna (B), which remains still.

In the drawings (figs. 61 and 62) the relation of the parts in the supine and in the prone state is shown by the aid of a plumb-line falling from the part of the arm-bone upon which the upper end of the radius revolves. The line traverses the upper end of the radius, then passes along the interval between the two bones, then traverses the lower end of the ulna, and, finally, takes the course of the ring finger. And, provided the limb be held vertically, the line traverses the same parts whatever be the position of the forearm and hand. It does so in complete supination, as shown in fig. 61; it does so in complete pronation, as shown in fig. 62; and it does so in every intermediate position. We may call it, therefore, the axis upon which the radius and the hand turn in pronation and supination; and, according to this representation, the ring finger remains stationary during the movement, while the other fingers and the thumb perform their partial revolutions around it.

I have said there is no movement in the lower limb exactly like the pronation and supination of the forearm and hand. We have, it is true, a power of moving the leg upon the thigh in a somewhat similar manner; but this can only be done when the knee is bent. For instance, when sitting in a chair with the foot upon a fender, or with the toes upon the ground, we can make the foot revolve so as to turn the heel in or out. A little careful observation, however, will prove that this movement takes place, altogether, at the knee, and that both bones of the leg participate equally in it, the whole leg revolving with the foot. Whereas, in the case of the forearm, the movement takes place, partly, at the wrist, and, partly, at the elbow; and one bone (the ulna) remains still while the lower end of the other bone (the radius) revolves around it. Moreover, the pronation and supination of the hand and forearm are much more free than these movements of the foot and leg; and they take place with equal facility and freedom in any position of the limb. We can turn the palm up or down as easily when the elbow is straight as when it is bent.

The movement of which I am speaking is so important to the usefulness of the hand, that I will call your attention to three of the muscles by which it is effected.

And, let me remark, by the way, that all the movements in the solid parts of the body—probably all without exception, even the slight wrinklings of the skin that take place when it is exposed to cold—are the result of muscular action. Muscles are bundles of fibres which have usually a red colour and constitute what is commonly called the “flesh” or “lean meat” of animals. They are endued with the power of contracting or shortening themselves; and it is this property which gives rise to the various movements of animal bodies. At their ends muscles often dwindle into “tendons” or “sinews” which, though occupying much less space, and having no contractile power, are very strong, and serve to connect the muscles with the bones.

One of the three muscles just mentioned (A, fig. 61) passes from a projecting process on the inner side of the arm-bone, at its lower end, to the outer edge of the middle of the radius. Its contraction causes the radius to roll over, or in front of, the ulna. It thus pronates the hand, and is called a “Pronator” muscle. Another muscle (B, fig. 62) passes, from a projecting process on the outer side of the arm-bone, to the inner edge of the radius near its upper part. It runs, therefore, in an opposite direction to the former muscle and produces an opposite effect, rolling the radius and the hand back into the position of supination. Hence it is called a “Supinator” muscle.

The third is a very powerful muscle. It is called the “Biceps” muscle (fig. 63), because it has two points of attachment to the shoulder-blade. It descends along the front of the arm, and, bulging there, forms a conspicuous feature, to which athletic persons are proud to point in evidence of their muscular development. Its tendon crosses over the front of the elbow, and is inserted into the hinder edge of a stout tubercle which is seen on the inner side of the radius near its upper end. The chief effect of this muscle is to bend the elbow; but it also rotates the radius so as to supinate the hand; and it gives great power to that movement. When we turn a screw, or drive a gimlet, or draw a cork, we always employ the supinating movement of the hand for the purpose; and all screws, gimlets, and implements of the like kind, are made to turn in a manner suited to that movement of the right hand, because mechanicians have observed that we have more power to supinate the hand than to pronate it, though they are, probably, not aware that the preponderating influence of the biceps muscle is the cause of the difference.

The movement of which I am speaking is performed to its full extent only by Man. Monkeys cannot completely supinate the hand; and in most of the lower animals the part corresponding with the hand remains nearly, or quite, fixed in a state of pronation. Even in Man, complete supination is rather a constrained and awkward position. It is not a position which is habitual or natural to us. When we see any one sitting or walking with the palms turned forward it strikes us as strange, and the idea is suggested to us that the individual must be strange too, that, possibly, his head may be a little turned as well as his hands. In a state of ease the hand is naturally more or less prone; so that when it is desired to place the forearm or hand at rest, as in case of disease or injury, the prone position is usually selected. If the forearm be broken, for instance, the surgeon sets the fracture and fixes the limb with the hand prone or semiprone. This is, also, the position of greatest strength, as well as of most ease. Hence, in striking a blow, or carrying a weight, or making any strong muscular effort, the palm is always kept more or less inturned.

The Wrist.

This drawing (fig. 64) represents what is seen when a section has been made, from side to side, through the wrist and lower part of the forearm. It gives an idea of the mode in which the several bones of the wrist are adapted to one another and held together by ligaments. The upper three wrist-bones (C, E, D) are joined together, so as to present a convex surface, which is received into a wide cup, or socket, formed by the end of the radius (A) and a ligament passing from the radius to the ulna (B); and, in pronation and supination, the end of the radius, together with this ligament and the wrist-bones, revolves upon the end of the ulna.

All the bones here represented are so well fitted to one another, and so strongly bound together, that, as I have before said, displacement very rarely occurs among them. We sometimes hear of a dislocation of the wrist, but very seldom see one. The wrist is often bruised, or its ligaments strained, by falls upon the hand; or, what very often happens, especially after the middle period of life, the bones of the forearm are broken a little above the wrist.

You might think that, in such an accident, the radius only would suffer, inasmuch as it is especially connected with the wrist-bones, and so receives the force directly from the hand. But, if you observe the line of contact of the radius and ulna (running from F), you will see that it is oblique, and that its direction is such as to cause the ulna to support the radius, and to receive some of the force from it; and this disposition, which makes the ulna share the duties of the radius, makes it, also, share the dangers; hence, it is very frequently involved with the radius in fracture of the forearm.

By the joints of the wrist we are enabled to move the hand backwards and forwards, and also slightly sideways.

The Movements of the Hand.

I come now to speak more particularly of the movements that take place in the Hand. I have already said that the mobility of the thumb is the chief characteristic of the hand as distinguished from the foot. Another important distinction between the hand and the foot is the greater length and mobility of the fingers as compared with the toes. The toes are short; and our power of moving them is, under any circumstances, slight. They constitute a small, and, comparatively, unimportant, part of the foot. The fingers, on the contrary, are long; they form a half, and, including the thumb, the more important half, of the hand. Without them the rest of the hand, indeed the rest of the limb, would be comparatively useless. Their movements are varied and free, and take place with singular facility and rapidity. We can bend them quite down upon the palm, and can extend them beyond the straight line; we can separate them from one another to a considerable extent; and we can bring them together with some force, as a waiter does when he carries a number of wine-glasses between his fingers; and persons who have lost the thumb contrive to hold a pen, a knife or fork, or other things, between the fingers.

Let me endeavour to give you an idea of some of the muscles which are concerned in executing these movements.

The wrist and hand are bent forwards upon the forearm by means of three muscles (A, B, C, fig. 65). These all pass downwards from the inner side of the lower end of the armbone. The outer and inner ones (A and C) are connected, by tendons, with the wrist-bones; and the tendon of the middle one (B) runs over the wrist and becomes spread out in the palm like a fan, so as to support the skin of the palm and to protect the nerves and blood-vessels, which lie beneath it, from injurious pressure, when we grasp any substance firmly in the hand. The fan-like expansion of this tendon in the palm is called the “palmar fascia.” It is very strong, and is connected, below, with the ends of the metacarpal bones, and with the sheaths of the fingers. The bundle of muscles near D forms what is called the “ball of the thumb,” and serves to move the thumb in various directions.

Beneath these three muscles which bend the wrist and strengthen the palm lies another set of muscles (A, B, fig. 66) which bend the thumb and fingers. They pass from the bones of the forearm, and end in long tendons or “leaders” which run over the wrist and palm and along the fingers and are firmly connected with the last phalanges of the fingers. They lie close to the bones in their whole course, and are held in their places by sinewy cross bands and sheaths which are seen, both at the wrist and in the fingers, in fig. 65.

Fig. 67 represents the muscles on the back of the forearm. The tendons pass from them, and run, some to the wrist and extend, or bend backwards, the wrist upon the forearm, some to the thumb and extend the several joints of the thumb; and others run to the back of the fingers. These leaders lie nearer to the skin than do those on the palmar aspect; and most of those which go to the thumb and fingers may be distinguished through the skin. The short muscles (A, A) situated upon and between the metacarpal bones pass from them to the sides of the fingers; some of these serve to spread the fingers out from one another, while others have the effect of drawing them together. There are several such small muscles on both surfaces of the hand, but I must not detain you by a description of them; and there are other little muscles passing from the flexor tendons to the phalanges, which have been called fidicinales, from their assisting in performing the short quick motions of the fingers, and from their being, accordingly, called into action in playing upon the violin and other musical instruments.

Movements of the Thumb.

In its adaptation to the purposes of bearing the weight and ministering to the locomotion of the body the human foot excels that of any other animal; and, unquestionably, the human hand is not less preeminently distinguished by the nicety, the variety, and the freedom of its movements. This is shown by the manner in which it can be twisted about, by the exquisite play of the fingers; and it is shown, above all, by the mode in which the thumb can be moved to and fro, can be opposed to the other fingers, and to any part of them individually and collectively, and can be folded beneath them or clasped upon them as occasion may require.

The power which the thumb possesses, and gives to the hand, is signified by its name—“pollex,”—derived from the Latin word pollere, which means to have power. Some have supposed that the word “poltroon” is derived from pollice truncato, and signifies one so cowardly that he has submitted to have his thumb cut off in order that he may be incapacitated for fighting.

The faculty which we possess of moving the thumb in the way I have mentioned, athwart the other fingers, and of touching any part of the palmar surface of either of them depends, partly, upon its being set, not quite in the same plane with them, but, obliquely, so that when it is moved towards the palm it faces or opposes the other fingers; and, partly, upon the nature of the joint between its metacarpal bone and the bone of the wrist with which it is connected.

This joint is so constructed as to admit of three different movements. First, the thumb can be moved forwards or backwards, that is, towards, or, away from, the palm. Secondly, it can be “adducted” or “abducted,” that is, approximated to the forefinger or inclined away from it. Thirdly, it can be “circumducted,” that is, its extremity can be made to describe a circle, as in “twiddling the thumbs.” These several movements are effected with great power and rapidity by means of the bundle of muscles which forms the “ball of the thumb” (fig. 65. D), as well as by the long muscles and tendons which descend, from the forearm, to the thumb.

Movements of the metacarpal bones of the Fingers upon the Wrist.

The movements of the thumb, through the medium of its metacarpal bone, upon the wrist are much more free than those of any of the other fingers. The middle finger, indeed, has its metacarpal bone set upon the wrist so fixedly as to admit of scarcely any such movement. The forefinger can be thus moved a little; the ring finger more and the little finger still more.

You may easily prove this by taking the knuckles or heads of the respective metacarpal bones of one hand between the fingers and thumb of the other hand, when you will find that you can press the knuckle of the little finger backwards and forwards in a very perceptible manner. Then try the knuckle of the ring finger; the movement is distinct, though not so free as in the case of the little finger. The knuckle of the forefinger you will find to be almost fixed; and in that of the middle finger you will be unable to perceive any movement at all.

In fact the joints of the metacarpal bones of the fingers with the wrist resemble those of the outer four toes with the tarsus; and the drawings of these joints of the foot (figs. 22 to 25) will serve sufficiently well to illustrate those of the hand.

These movements of the metacarpal, or knuckle, bones upon the wrist enable us to increase or diminish the hollow of the palm by bringing its edges more or less forward. Thus, when we make a cup of the hand we bring forward the metacarpal bones of the thumb and the little finger, wrinkling the skin of the palm; and when we spread the hand open we carry those bones backwards, rendering the skin of the palm tense.

These movements, moreover, enable us to bring the little fingers and the thumb more easily into contact.

Have you ever wondered what advantage is gained by the fingers and thumb all differing from one another in length; or don’t you take the trouble to reflect upon little matters of this sort? If you have, I would ask you now to remark that there is, in the several fingers, a relation between their shortness, their position near the edge of the hand, and the amount of mobility of their metacarpal bones upon the wrist. Thus the finger which is in the middle of the hand is the longest, and its metacarpal is the most fixed. The fore-finger is not quite so long; and its metacarpal is rather less immovable. The ring-finger comes next in shortness and in the mobility of its metacarpal. Then the little finger; and the thumb which is much shorter than any other has also its metacarpal much more moveable.

Observe, further, that, when the fingers and thumb are separated from one another, and then bent, the middle knuckle-bone remains stationary, but the others are advanced a little forwards, each to an extent proportionate to its mobility upon the wrist, and to the shortness of the finger. The fore-finger is, by this means, advanced a little, the ring and the little fingers more, and the thumb most of all. And the result is, that the tips of the fingers and the thumb come all to a level, and form, with the palm, a great hollow in which we can grasp any substance, a cricket-ball, for instance, and hold it very firmly. The length of the several fingers and the thumb is, therefore, just so regulated, in relation to their mobility upon the wrist, as to give us this power.

You may observe, also, that when the fingers and the thumb are spread out the space between the thumb and the fore-finger is considerably greater than either of the spaces between the other fingers. Then, by a slight movement, the thumb takes up a position in front of, or opposite to, the fingers; and in grasping any substance it has to antagonise the pressure exerted by all the fingers. Hence it needs to be much stronger than they are, and to be wielded by more numerous and more powerful muscles.

The Middle Finger is not only the longest and the largest finger; it is also, to a certain extent, the centre about which the others move. Thus, when the fingers are bent down into the palm, their tips all converge towards the middle finger; and when they are spread out, they all diverge from it. Its greater length and the greater prominence of its knuckle, expose this finger to injury more than any of the others; which may account for the fact that Surgeons are called upon to amputate the middle finger more frequently than either of the other fingers or the thumb.

The Fore-finger has the greatest range of independent movement. Hence it is used to point with, and is called the “Index” or “Indicator” finger.

Writing.

In Writing the pen should be held between the pulps of the fore and middle fingers and the thumb, in contact with all three, and firmly lodged between them. The down-stroke is made by bending the phalanges of the fingers and the thumb inwards and the metacarpal bone of the thumb outwards; and the up-stroke is made by straightening all the joints of the fingers and thumb. The hand rests lightly, not upon its whole edge, but, upon the hindermost and foremost parts of the edge, that is, upon the pisiform bone of the wrist and upon the little finger near the end, so that it can be moved easily along the paper, and can be inclined, or rolled, a little to either side. The obliquity of the stroke is not imposed by mere arbitrary rule, but is in accordance with the direction in which there is the freest movement of the fingers and thumb when thus holding the pen. Make the experiment for yourselves of moving the pen in different directions, and you will soon be satisfied that the writing-master has nature on his side in insisting on a particular movement as well as a particular mode of holding the pen. Some persons make the strokes vertical, or slope them the wrong way; but in either case the writing is stiff and awkward; it is not natural.

The custom of writing from left to right may also be regarded as correct or natural, inasmuch as we can move the pen more freely upwards and outwards than upwards and inwards. Hence the light up or advancing stroke—that which connects a letter with the one which follows it—is most easily made outwards or to the right; and the letters are, consequently, made to follow one another in that direction. To understand this more clearly make a down-stroke upon paper in the usual manner; you will then find that you can make up-strokes from any part of it more easily to the right than to the left; and if you make a series of continuous up-and-down-strokes at a little distance from one another, the up-stroke is, not merely habitually, but naturally, made fine and inclined to the right, whereas the down-stroke is made heavier or thicker and is sloped to the left. Moreover, you will perceive that the hand slides along the paper more easily from left to right than from right to left.

It is worthy of remark that the writing of all that great class of languages called Indo-European, which includes Sanscrit, Greek, Latin, and many others, with our own, is from left to right; whereas nearly all the writing of another great class called the Semitic, which includes the Hebrew and Arabic, is in the opposite direction, viz. from right to left. Some nations write in perpendicular columns, the letters being placed under one another, of which the Chinese affords an example. But either of the two latter methods must be inferior to the Indo-European style in ease of execution and expedition.

Reason for the Ring being usually placed upon the Fourth finger.

The Ring-finger has less independent movement than either of the others. It cannot be bent or straightened much without being accompanied by one or both of those next it. This is, partly, because its extensor tendon is connected, by means of a band of fibres, with the tendon on either side of it. You may discern these connecting bands working up and down under the skin of the back of your hand when you move the fingers to and fro (they are represented in fig. 67). The ring-finger is, therefore, always, more or less, protected by the other fingers; and it owes to this circumstance a comparative immunity from injury, as well, probably, as the privilege of being especially selected to bear the ring in matrimony. The left hand is chosen for a similar reason; a ring placed upon it being less likely to be damaged than it would be upon the right hand.

Other reasons have been given for this preference. It has been attributed to a notion among the ancients that the ring-finger is connected with the heart by means of some particular nerve or vessel, which renders it a more favourable medium than the other fingers for the reception and transmission of sympathetic impressions; the left hand being selected, in preference to the right, because it lies rather nearer to the heart.