Part 8

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 ofthe 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 _out_wards than upwards and _in_wards. Hence the light _up_ or advancing stroke--that which connects a letter with the one which follows it--is most easily made _out_wards 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.

Some slight foundation for such a notion might be imagined to exist in the fact (supposing the ancients to have been acquainted with it) that the distribution of the nerves to the ring-finger is rather peculiar. The peculiarity will be readily understood by reference to the accompanying drawing (fig. 69). Two chief nerves are seen descending, in their course from the brain, along the arm and forearm, to supply sensation to the palmar surface of the hand. One (A), the larger of the two, passes in front of the middle of the wrist, and divides into branches which are distributed to the skin of the thumb, of the fore and middle fingers, and of the _out_er side of the ring-finger. The other nerve (B) lies on the _in_ner side of the forearm and wrist, and its branches go to the skin of the little finger, and of the inner side of the ring-finger. You see, therefore, that there is, in this finger, a meeting of the branches of the two nerves; the two sides of the finger being supplied by different nerves. It would be a mistake, however, to suppose that it gains any superiority in sensitiveness or sympathetic relations by this arrangement; and this distribution of the nerves certainly does not offer so probable an explanation of the selection of that finger for the honourable office of ring-bearer as the one I have suggested.

I must remark, here, that the nerve (B), in passing from the arm to the forearm, lies on the inner side of the back of the elbow, and is popularly known by the misnomer of the “funny-bone[8].” It lies, pretty much out of harm’s way, in a well-protected channel between two bones. Nevertheless, it is now and then hurt; and you know that when the “funny-bone” is struck, a peculiar pain, or tingling, is experienced along the little finger and the adjacent side of the ring-finger.

[8] It has been suggested, probably by _Punch_, that it is called the “_funny-bone_” because it lies near the “_humerus_.”

The practice of wearing rings upon the hand is a very ancient one. In some instances they were badges of slavery. More generally they were marks of high esteem or authority; as when “Pharaoh took off his ring from his hand and put it upon Joseph’s hand,” and when “Ahasuerus took off his ring, which he had taken from Haman, and gave it to Mordecai.” The Roman knights also wore rings of gold. Sometimes rings were worn as charms against diseases; a practice which has been revived in our own day. They were placed upon any of the fingers, and upon the right hand as well as the left. Thus we read in Jeremiah, “though Coniah the son of Jehoiakim king of Judah were the signet upon my right hand.” The preference of the left hand and of the ring-finger seems to be comparatively modern, originating, probably, when the ring was made lighter and more fragile, and was, at the same time, adorned with precious stones, and when it became, therefore, desirable to place it upon the part of the hand where it is least exposed to injury.

_The Monkey’s Hand._

Most of you have spent some time in watching the inmates of that interesting part of a zoological collection, the MONKEYS’ cage, and have observed how nearly the hand of that animal resembles the human hand, in the presence of a thumb, in the variety and celerity of its movements, in the facility with which it can catch and pick up objects and hold them up to the mouth, and in some other points. A little closer observation, however, will show that there are some differences between the two. The several parts do not bear the same relation to one another in the Monkey’s hand which they do in the human hand; neither have they quite so great variety or range of movement. The hand is altogether narrower, and straighter. The thumb is shorter and less strong, scarcely reaching beyond the knuckle of the fore-finger. The fingers, on the contrary, are longer and of more uniform length; they do not admit of being separated so widely from each other in a fan-like manner; and the metacarpal bones at the edges of the hand, i. e. the metacarpal bones of the thumb and of the ring and little fingers, have not the same amount of play upon the wrist. Hence the thumb and the fingers of the Monkey cannot be opposed to one another so easily as in man; neither can they be so advanced in front of the middle finger as to form a hollow or cup, in the way I described when speaking of the hollow of the palm and the different lengths of the fingers in the Human hand. When you throw a Monkey a nut he usually picks it up and holds it between the thumb and the _side_ of the bent fore-finger, not between the tips of the thumb and fingers. The length of the fingers adapts the Monkey’s hand well for clasping firmly the branches of trees, and assisting the animal to climb about in its native forests, or to hold on to the bars of its cage; and so the part answers the requirements of the creature better than if these qualities had been sacrificed to a greater regard for variety and range of movement.

_The Hand the Organ of the Will._

The human hand is peculiarly an organ devoted to the will, being more directly and completely under its influence than is any other part of the body. The WILL, remember, is that self-directing faculty which can be said to exist, definitely and decidedly, in Man alone, which is associated in him with the responsibility attaching to the selection between good and evil, and which is given to him to fit him to be the reasonable servant of his Maker, and upon which, therefore, his dignity, and his capability for occupying a position between the low animal and the high spiritual world, so much depend. How appropriate is it, then, that the will should have a special organ assigned as its more peculiar minister. It is to the complete subjection of the hand to the will, no less than to the combination of strength with variety and delicacy in its movements, that Man is indebted for his dominion over the rest of the animal world, and for the ability to execute the wonderful works which his genius designs.

When we reflect how essential is the hand to Man’s well-being, power, and progress, and upon the infinite variety of purposes which it serves in obedience to the will, we are not surprised that the construction of the foot, indeed of every part of the frame, should have reference to the object of liberating the hand from the subordinate work of locomotion to a degree which we find in no other animal, and of leaving it free to execute its higher offices in a ready and efficient manner.

But, after all, notwithstanding the excellence of its mechanism and its intimate relation to the will, what would the hand be without the reflecting and designing MIND--the mind that can build upon the past and prepare for the future, and so carry on the ever-advancing work of human civilization and progress. Without it Man would remain stationary, like the other animals; and, as age succeeded age, the hand would only suffice to provide the necessary requirements of the body. Nay, even this is saying too much; for without the mind, without, at least, some higher instinctive or reflective faculty than the other animals possess, Man would, in reality, be inferior to them. He would be absolutely unable to maintain his existence, and would be a miserable victim to the fineness of his organisation. His hand would fail to supply him with food, or to defend him against his numerous enemies, or to provide for the protection of his delicate and sensitive frame from the inclemency of the elements.

The real excellence of the human hand--and the remark applies equally to the whole human body--consists, not in the admirable construction of its several parts, nor in their well-adjusted relation to one another, so much as in the adaptation of the whole to the mind that presides over it. This it is that renders Man the lord of the creation, that enables him to subdue all his foes, and gives him, in some measure, power over the elements, so that land and water, fire and air, are made to serve his purpose. By this harmonious co-aptation of mind and body Man is rendered cosmopolitan, being able to thrive in every clime, from the regions of continual snow to those burning equatorial plains where even reptiles perish from the heat and drought, and being able to convert the barren plain into a fertile field, and to draw water out of the stony rock.

At the late meeting of the British Association at Oxford, a gentleman related that he had a monkey which was very partial to oysters, and was very fond of playing with a hammer; but he never could be taught to use the hammer for the purpose of breaking the oyster-shells to gratify his appetite. How wide a gulf does the absence of intelligence in this simple matter indicate between ourselves and the animal that approaches nearest to us!

_The Hand an Organ of Expression._

Further, we cannot fail to recognise and admire the adaptation of the hand to the mind at all ages, and under various circumstances; in its weakness and suppleness, and in its purposeless and playful movements in infancy and childhood; in its gradually increasing strength and steadiness as the intellect ripens; in the stiffness and shakiness of declining years; in the iron grasp of the artizan; in the light delicate touch of the lady; in the twirlings, fumblings, and contortions of the idiot; in the stealthy movements of the thief; in the tremulousness of the drunkard; in the open-handedness of the liberal man; and in the close-fistedness of the niggard.