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- The Complete Bridgman Part 4
- THE HAND
- MUSCLES OF THE HAND
- Back View
- THE HAND—BACK VIEW
- THE HAND—PALMAR VIEW
- Construction of the Hand
- Thumb Side of the Hand
- Little Finger Side of the Hand
- THE THUMB
- Anatomy of the Thumb
- Saddle Joint of the Thumb
- Masses of the Thumb
- Muscles of the Thumb Palmar View, above
- The Fingers
- Bones, tendons and sheathing of the fingers, palm side
- ANATOMY OF THE FINGERS
- The Fist
- Knuckles of the Hand
- Hand of the Baby
- THE PELVIS
- THE LOWER LIMBS
- THE FOOT
The Complete Bridgman Part 4
Link to Illustrations on Picasa
Nature standardizes all hands to laws of mechanics and dynamics. The hands of the mummies of ancient Egypt, thousands of years old, are not different from those of today. The bones of prehistoric man are the same. Ninety per cent and more of the hand is standardized by its use to the unchanging laws of its use.
But the hand as drawn and sculptured has varied markedly in different ages. Cave dwellers marked the walls and roofs of their dwellings and their implements with signs and figures, and among them, hands. The hands they drew or carved had a general character distinctly of that age. The Peruvian, the Aztec, the American Indians in their written sign languages, the Alaskan on his totem pole, each of these—whether the hand was carved out or cut in, drawn or painted, in red or blue, wherever a hand was shown—adhered to a certain style of hand whose character marked it as belonging to that age or that tribe or that race, and all distinctly different from other periods or races or tribes. The Assyrians graved hands on their palace walls and carved them in stone; and they were Assyrian hands, distinguishable easily from those of any other race or age. The Egyptians told stories by means of carved and painted hands, as individual as those of any other place or time. When we come to the ages of a more studied art, the same psychological law is in evidence. There is an early Gothic hand, distinctly different from that of any other period. There is a Renaissance hand with a character of its own; so much so that it can be picked out and classified, not only as a Renaissance hand, but as an early or a late Renaissance hand.
No one questions the sincerity of Ghirlandajo, or of Lippi, or of Botticelli. Not only were they great masters, but close students, and yet each drew a different style of hand. Of later schools the same thing may be said; as of the Venetian and the Dutch schools, and of the schools of Jordaens, Rubens and Van Dyck. Of Van Dyck it has been said that he could not draw the hand of a laborer, and of Millet that he could not draw a gentleman’s hand. Indeed, it is very far from accurate to say that we see with our eyes. The eye is blind but for the idea behind the eye. It is the idea behind the eye that makes it different from a photographic plate—that pricks out some parts with emphasis and censors other parts. We see with the idea, and only through the eye. Michelangelo, Leonardo da Vinci and Raphael, all of the same period, all had the same style of models, and yet they produced hands of three very distinct types. Albert Diirer, Holbein the younger, Rembrandt, all made hands that, because of their individuality, are classed as a Holbein or a Diirer or a Rembrandt hand by the art world. Reasons for this change and flux in character and style of hands are no doubt familiar to every one. Briefly, the hand as pictured is not subject to the automatic forces that standardize the actual hand to the laws of its use. The pictured hand is standardized to no laws except those of perception; which means to the current concepts and to individual taste. The business of the artist in such a connection is to standardize his concepts of the hand to those of nature—to see it as nature sees its purpose, methods and laws.
It may be reflected that the science of anatomy is a comparatively recent acquisition of the race. It is not many decades since the cutting up of the human body was forbidden by law and abhorred in religion. Even after such a study is well developed, it takes a certain time for its significance to penetrate to other domains of thought and effort, and a much longer time for it to be assimilated there. It has taken man centuries to learn to look under the form for the mechanisms in the human body; and he is only now learning to look under the mechanisms for the reasons that underlie them. The world of art is beginning to appropriate these things to itself, and the improvement in one man’s technic by this means compels others to seek improvement in the same school—the school of nature, her reasons and her purposes. If this tendency to fluctuations, to styles and fashions is more marked in the hand than in other parts of the body, it is probably because the importance of the hand as an avenue of expression has not been understood. The hand is thought of as the slave of action. But the slave of action is the master of expression.
Expressions of the Hand
The face is well schooled to self-control as a rule, and may become an aid in dissimulation of thought and feeling. Rarely is the hand so trained; and responding unconsciously to the mental states, it may reveal what the face would conceal. Like any other living thing, the hand is modified to its use. The total modification in any individual is less than one per cent; but in a succession of generations it may be cumulative. Also it happens that it is the more superficial and conspicuous parts that are thus modified. On the background of the mechanics, then, which is older than the human race, we may have racial variations; then on this basis, accumulated hereditary or family modifications, and on them in turn expressions of individual history and character. The hand of the child is almost unmodified. With its creases and dimples and its tapering fingers, it represents almost the pure symmetry that is the natural heritage of all created things. The hand of age represents the opposite extreme, the end product, the insanity of over-modification; furrowed, wrinkled with the scars of time, with enlarged squared joints, and shaky. On the background then of mechanics and racial variations, we have many variations, such as those of youth or age; male or female; healthy or unsound; laboring or aristocratic; strong or weak. Types of hands may be classified as: square, round, compact; long or short; thick or thin. The relative length of fingers varies, both among themselves and in comparison with the hand. The relative thickness of joint and shaft and finger tip varies. The thumb may be short, thick or thin, may lie close or spread far from the hand. The hand that is inured to heavy labor shows very definite changes. It is larger and heavier. The muscles are of course developed, but these lie for the most part above the hand in the forearm. Those of the palmar (thenar) and hypothenar eminences are somewhat larger and more square. Chiefly, the joints become enlarged, square, rugged and irregular in appearance. The tendons are more in evidence. The skin is hardened, so that creases are deeper, especially the skin pads are heavier and may overhang the borders. The skin hairs may stand up like bristles. In repose it assumes a more crooked position. Clenched, with the aggressive thumb twisted around the fingers, it becomes a squared, knobbed and formidable looking weapon. The converse of this is true in the hand not inured to labor. The muscles of the palm present a softly rounded appearance, the skin is smooth and silky, the skin pads not clearly demarked; the joints are not only not rugged, but may be unduly flexible, small and weakly angled. The bones of the hand and fingers will have less of the spring curve, that is, they will be straighter and slighter. The hand will on the whole be much more symmetrical and expressionless.
When the hand is employed in what may by contrast be called the intelligent uses, in which flexibility is necessary, it will have as a consequence greater freedom of movement, will assume much more varied positions, and will express much more readily the mental states. In proportion as this habitual exercise is free and intelligent, will the symmetries assumed be free and expressive. Certain typical positions are due not so much to the mental states as to the mechanics of the hand. For instance, the little finger side is always more flexible than the thumb side, because it is opposite to the powerful thumb. The middle finger is always inclined to bend farther forward, or to bend forward first; this on account of its relatively greater power. All fingers bend forward first at the knuckles, then at each joint in turn. The thumb is habitually carried somewhat extended, out of the way of the fingers. Modern psychology, studying the dynamics of the nervous system, informs us in regard to many of the instinctive positions and actions of the body (including the hand) and the things expressed by them. For instance, there is a wholly involuntary opening out movement of the whole body, limbs and features, in pleasant emotions, honesty, courage, understanding, etc.; and conversely, there is a closing up, a drawing in, a turning away, in unpleasant emotions, in mental dishonesty, etc. In states of self-consciousness, and the effort at self-control, there is a tendency to express the same by clasping one’s self; as clasping the thumb with the fingers; clasping or twisting the other hand, or some part of the body.
The Wrist and the Hand
The bones of the wrist are mortised with those of the hand, making one mass, the hand moving with the wrist. The width of the wrist is twice its thickness and where it joins the arm it diminishes in both width and thickness. There is always a step-down from the back of the arm, over the wrist, to the hand. The wrist moves with the hand on the forearm, and in combination with these has some rotary movement, but no twisting movement. The twisting movement is accomplished by the forearm. The hand has two masses: that of the hand proper, and that of the thumb. The first of these masses is beveled from knuckles to wrist on the edge, from wrist to knuckles on the flat side, and from first to little finger from side to side. It is slightly arched across the back.
The knuckles are somewhat more arched. They are concentric around the base of the thumb, the second knuckle larger and higher than the rest, the first knuckle lower on its thumb side, where it has an overhang, as has also the knuckle of the little finger, due to their exposed positions. On the little finger side, the form of the hand is given by the abductor muscle and the overhang of the knuckle, by which the curve of that side is carried well up to the middle of the first segment of the little finger. On the back of the hand, nearly flat except in the clenched fist, the tendons of the long extensors are superficial, and may be raised sharply under the skin. The hand had four primal uses: weapon, scoop, hook and tongs.
Bones of the Wrist Palm side
1 Trapezium—No two sides parallel 2 Trapezoid—Two sides parallel 3 Os magnum—Great bone 4 Unciform—Hook-like 5 Scaphoid—Boat-shaped 6 Semi-Lunar—Half-moon 7 Cuneiform—Wedge-shaped 8 Pisiform—Pea-shaped
Mechanism of the Hand and Arm
Turning movement as distinguished from rotary movement (flexion to each corner in rotation) is not present in the wrist, but is produced by the radius or turning bone of the forearm. Movement in the wrist is confined to flexion and extension (about one right angle) and side-bending (a little more than half a right angle, in the average hand); these two combined produce some rotary movement. In movements of the wrist to extreme positions, the hand and fingers almost always participate, on account of association of tendons and muscular action; and in these positions it is practically always separation and hooking of the fingers that is produced.
The movement of the hand reflects itself as far as the shoulder, through the biceps muscle, which aids in turning the radius. In all movement but turning, the wrist can act alone. Turning, to nearly two right angles, is carried out by the radius. Further movement of any kind must be performed by elbow or shoulder. At the elbow it is the hinge movement that is important, wherefore the large size of the ulna or hinge bone, and the small size of the radius. At the wrist it is the turning movement that is important, wherefore the radius forms two-thirds of the joint, the ulna one-third.
Anatomy of the Hand
In the hand are four bones, continuous with those of the fingers, called metacarpals (meta, beyond, carpus, wrist). They are covered by tendons on the back, and on the front by tendons, the muscles of the thumb and little finger, and skin pads. There is a very slight movement like opening a fan between these bones. They converge on the wrist bones and are mortised almost solidly to them. The hand moves with the wrist. The dorsal tendons converge more sharply than the bones. The short muscles of the hand, crossing only one joint, the knuckle, and moving the fingers individually, lie deep between the metcarpal bones and so are called interossei. They are in two sets, back and front, or dorsal and palmar. The palmar interossei are collectors, drawing the fingers toward the middle finger, and so are fastened to the inner side of each joint except that of the middle finger itself. The dorsal interossei are spreaders, drawing away from the centre, and so are fastened to both sides of the middle finger and to the outside of the other joints. In the thumb and little fingers the muscles of this set are called abductors, and being in exposed positions, are larger. That of the first finger forms a prominent bulge between it and the thumb; that of the little finger forms a long fleshy mass reaching to the wrist.
2 Palmar interossei
Muscles of the Hand
To the four corners of the wrist are fastened four muscles, one of them doubled (that on the back of the first finger side).
1 Extensor carpi ulnaris 2 Extensor digitorum communis 3 Extensor metacarpi pollicis ossis 4 Extensor pollicis brevis 5 Extensor carpi radialis brevis 6 Extensor carpi radialis longus
7 Supinator longus 8 Flexor carpi radialis 9 Tendon of the palmaris longus 10 Flexor carpi ulnaris 11 Palmar fascia
The Hand—Back View
The wrist bones are collectively smaller than the end of the forearm, so there is a constriction at the sides. The wrist bones are in two transverse layers with an angle between, forming in profile view a hook, point backward; over this is a step-down to the back of the hand. A little to the outer side, this is bridged by the extensor tendons. The rows of wrist bones are arched toward the back. The two pillars of this arch in front far overhang the anterior line of the arm. From them arise the thenar and hypothenar eminences, and the palm of the hand.
Except for the thumb and the extensor tendons, the back of the hand is smooth. It is slightly arched from side to side. It is beveled from knuckles to wrist, and is narrower on the back than on the palmar surface. There is a slight fan-like movement among the bones of the hand. The general mass of the back flows from the wrist toward the first and second knuckles, and is flattened and thinned toward the little finger side.
MUSCLES OF THE HAND
1 Extensor digitorum communis 2 Abductor digiti minimi 3 Dorsal interosseous 4 Adductor pollicis 5 Extensor carpi ulnaris 6 Extensor digiti minimi 7 Extensor pollicis longus 8 Extensor pollicis brevis 9 Extensor metacarpi ossis pollicis
Distributed over the back are seen the extensor tendons. These represent two sets which have become blended, so have duplications and various connecting bands. Those to the thumb and little finger remain separate.
THE HAND—BACK VIEW
The tendons on the back of the hand pass quite high over the wrist. It is clearly impossible to arch the wrist both ways; and flexion being so much more important a function, the extensor tendons are forced far from the centre of movement backward and outward. They converge on the low outer part of the wrist arch. Thus placed they are taut in extreme flexion, so that the fingers cannot be tightly closed. The thumb side of the wrist arch is larger, higher and projects farther forward, carrying the thumb; it has a deeper inset at the wrist and is square compared with the heel inside, which ends in a ball—the pisiform bone. On the little finger side of the wrist, between the end of the ulna and the pisiform bone, may be seen a “rocker”—the cuneiform bone. This is the part of the arch of the wrist immediately above the pisiform— its outer end. It is prominent when the hand is bent to the opposite side or in the act of pulling. It almost blends with the ulna when the hand is carried to that side.
THE HAND—PALMAR VIEW
The palm slightly overlies the wrist, and extends to the middle of the first joint of the fingers. It is made of three portions, with the hollow of the palm between them. On the thumb side is the largest of these portions, the thenar eminence; opposite it is the hypothenar eminence, and across under the knuckles is the third portion, the mounds of the palm. The thenar eminence is high, fat and soft; it contains the short muscles of the thumb and forms with the bone the pyramidal first segment of it. The hypothenar eminence is longer, lower, harder and more triangular. It contains some muscles of the little finger, large on account of the exposed position of that digit, and part of the palmaris brevis. It reaches as far as the base of the little finger, blending there with the row of mounds. At the wrist it covers the pisiform bone, with a heavy fibrous pad like that of the heel.
Construction of the Hand
In the hand, as in the figure, there is an action and an inaction side. The side with the greatest angle is the action side, the opposite is the inaction or straight side. With the hand turned down (prone) and drawn toward the body, the thumb side is the action side, the little finger the inaction side. The inaction side is straight with the arm, while the thumb is almost at right angles with it. The inaction construction line runs straight down the arm to the base of the little finger. The action construction line runs down the arm to the base of the thumb at the wrist, from there out to the middle joint, at the widest part of the hand; thence to the knuckle of the first finger, then to that of the second finger, and then joins the inaction line at the little finger. With the hand still prone, but drawn from the body, the thumb side is the inaction side, and is straight with the arm, while the little finger is at almost right angles with it. The inaction construction line now runs straight to the middle joint of the thumb, while the action line runs to the wrist on the little finger side, thence to the first joint, etc., etc. These construction lines, six in number, are the same with the palm turned up, according as it is drawn in or out. They place the fingers and indicate the action and proportions of the hand. 1 Abductor pollicis 2 Flexor pollicis brevis 3 Adductor pollicis trans-versus 4 Lumbricales 5 Annular ligament 6 Abductor digiti minimi 7 Flexor digiti minimi
Thumb Side of the Hand
Between the knuckle of the first finger and the thumb is a bulging mass. This is the first interosseous muscle, large here on account of the exposed position of the finger, also because it aids the thumb. In clasping, it is perpendicular to the thumb and diagonal to the knuckle. It attaches to the phalanx at the knuckle, to the whole side of the thumb (first segment) and to the base of the metacarpal bone of the finger itself. Beyond its edge is a fold of skin, alternately drawn into a half-moon blade, and dimpled and wrinkled, as the thumb changes its position. Running the length of the thumb to the last joint, on its back, is seen the extensor tendon, pointing always to the top of the wrist. At the root of the thumb is seen another tendon, that of the short extensor, pointing always to the bottom of the wrist; the two converging on the second joint.. Between them at the wrist is a depression, quite deep when the thumb is extended. This latter tendon marks the front border of the metacarpal bone of the thumb. Bulging in front of it are, first, the trapezium, marking the radial end of the wrist arch, then the thenar eminence, to the big joint of the thumb. Sometimes the basal joint of the thumb still farther bulges this eminence. The mass of the hand sets an an angle across the end of the forearm; the mass of the thumb sets at an angle across the base of the hand.
The Muscles of the Thumb
1 Long extensor of the thumb 2 Short extensor of the thumb 3 Long abductor of the thumb
The power of the thumb depends chiefly on its short muscles. Muscles must be long in proportion to the distance they have to contract. Muscles to the ends of fingers and thumb are therefore long reaching to the elbow. Those of the first and middle segments of the thumb (the latter with very little movement) are short and are developed about the segment and across the palm, where they act in direct line with the movement of the bone. The power produced by muscular action depends on the leverage and the angle at which it is applied. The long muscles act at an acute angle, with rapid movement but little power.
These short muscles being in direct line produce great power but are relatively slow. The fastest movement of the thumb is therefore slow compared to that of the fingers; its power is proportionately greater.
Thumb Side of the Hand
Distinguishable under the skin of the thumb (palmar side) are three muscles, sometimes a fourth. These, from the back forward, are the fat opponens, hugging the bone; the broad abductor, forming the bulk of the mass; and the thin flexor brevis, inside. Deeper and reaching transversely across the hand is the adductor muscle, which throws the skin of the palm into a bulging wrinkle when the thumb is flattened back.
2 Abductor pollicis 3 Adductor transversus
Little Finger Side of the Hand
The little finger side of the hand is the pushing side; the little finger side of the wrist is the heel side. The thumb side of the hand is the pulling side. Since pulling is so much more important a function of the hand, the thumb side of hand and wrist and all the bones of that side, with the first two fingers, are larger. The little finger side of the hand sets across the end of the forearm at a sharper angle than does the thumb side. It is narrower and never wholly conceals the rest of the hand. The pisiform bone, or heel of the hand, is always conspicuous on the lower side of the wrist. To it attaches the flexor carpi ulnaris muscle, corresponding with the tendon of Achilles.
2 Flexor carpi ulnaris In resting the wrist on a table, the weight should rest on the pisiform bone. Instinct protects the more sensitive unciform bone, on the thumb end of the wrist arch. In this position the fingers are always curled up or arched, on account of the shortness of the flexor tendons.
1 Pisiform bone
1 Abductor digiti minimi 2 Annular ligament 3 Flexor carpi ulnaris 4 Pisiform bone
Drill master to the fingers, the hand and the forearm, is the thumb. The fingers, gathered together, form a corona around its tip. Spread out, they radiate from a common centre at its base; and a line connecting their tips forms a curve whose centre is this same point. This is true of the rows of joints (knuckles) also. Bent, in any position, or closed as in clasping, the fingers form arches, each one concentric on this same basal joint of the thumb. Clenched, each circle of knuckles forms an arch with the same common centre. The mass of the thumb dominates the hand. The design and movement of even the forearm is to give the freest sweep to the thumb; while, through the biceps muscle, its movement is seen to begin really at the shoulder.
The thumb, extended, faces half frontways; flexed it faces across the palm, and may by pressure be bent slightly toward it. It may touch the side of the first finger, but otherwise cannot touch the palm. It is the fingers that are brought down to touch it.
Anatomy of the Thumb
The thumb has three segments and as many joints. Its bones are heavier than those of the fingers, its joints more rugged. Its last segment has a nail and a heavy skin pad. The middle segment has only tendons. The basal segment is a pyramidal mass of muscle reaching to the wrist, the “line of life” of the palm, and the base of the first finger. The superficial muscles of this mass are a fat one, a broad one, and a thin one. The fat muscle hugs the bone (opponens), the broad one forms the bulk of the pyramid (abductor) and the thin one lies inside, toward the index finger (flexor brevis). Between the thumb and first finger the skin is raised into a web, which is bulged, especially when the thumb is flattened, by the abductor pollicis muscle.
Saddle Joint of the Thumb
The range of movement of the thumb is slight—half a right angle at the base, much less at the middle joint, a right angle at the last joint. The basal joint is a saddle joint permitting half a right angle of movement sideways, and very much less fore and aft. The middle joint is extra large in proportion to others on account of its exposed position, permitting slight flexion and very slight torsion. It is built for strength rather than movement. The last joint with its long muscle reaching to the elbow has a right angle of movement (this long muscle must take up the slack of the other joints, including the wrist, also).
Masses of the Thumb
The thumb is pyramidal at the base, narrow in the middle, pear-shaped at the end. The ball faces to the front more than sideways. It reaches to the middle joint of the first finger. The last segment bends sharply back, carrying the nail. Its skin pad, broad at the base, gives it an appearance not unlike a foot, expressing its pressure-bearing function. The middle segment is square with rounded edges, smaller than the other two, with a small pad. The basal segment is rounded and bulged on all sides except where the one is superficial at the back.
Muscles of the Thumb Palmar View, above
1 Flexor pollicis brevis 2 Abductor pollicis 3 Opponens pollicis
From the centre of the arch of the wrist radiate the tendons of the long muscles to the fingers; and the fingers must be in line with their power, to prevent warping, so radiate from this point. But the power of the thumb has drawn the centre of radiation a trifle to its side of the wrist, so that the mechanisms of the hand are grouped around a point near its base. The clenched fingers all point to this centre, as far as crowding will permit. Half closed, as in clasping, they form arches converging there. In any position except a strained one the rows of knuckles form arches whose common centre is this point.
Bones, tendons and sheathing of the fingers, palm side
ANATOMY OF THE FINGERS
Each of the four fingers has three bones (phalanges, soldiers). Each phalanx turns on the one above, leaving exposed the end of the higher bone. There are no muscles below the knuckles; but the fingers are traversed by tendons on the back, and are covered on the front by tendons and skin pads. The middle finger is the longest and largest, because in the clasped hand it is opposite the thumb and with it bears the chief burden. The little finger is the smallest and shortest and most freely movable for the opposite reason. It may move farther back than the other fingers, and is usually held so, for two reasons; one is that the hand often “sits” on the base of the little finger; the other is that being diagonally opposite the thumb it is twisted farther backward in any outward twisting movement, and so tends to assume that position.
1 First finger between knuckle and second joint 2 Between second and third joint 3 Last joint at nail
The skin pads are of approximately the same length, as necessary when the finger is tightly closed, but the segments are of different lengths; so the creases are not opposite the joints. In the first finger the creases are beyond the knuckle, opposite the middle joint, and short of the last; in the second finger they are beyond the knuckle, beyond the second joint, about opposite the last; in the third finger they are beyond the knuckle, beyond the second. The other positions vary in different individuals.
The joints of the fingers are built like shallow saddle joints; that is, one reaches up on the sides, the other reaches down on the front and back. In every case it is the more distant bone that turns on the convex end of the nearer bone, leaving the end of the latter exposed in flexion.
On the palmar surface, when the fingers are straight, the palm extends beyond the knuckles half way to the next joint; but when the fingers are bent, a portion bends with them, and belongs with them; so that when bent the fingers on the palmar side start from the knuckle. Thus when straight the fingers have three pads; when bent they have four.
When curled close, the ends of the fingers just cover the heads of their first phalanges; that is, they he with their tips against the knuckles, supporting them. This is a mechanical necessity in fitting the fingers into the fist. Thus the two outer segments are longer than the first, but when measured from the back of the knuckle, the first segment is equal in length to the latter two.
Opposite the three bones of the finger are four skin pads; the pads therefore smaller. The first joint is about equal to the last two, measuring from back of the knuckle (though the bone itself is shorter). When the three joints are bent to form three sides of a square, the four pads fill in the quarters of it. Three of the grooves between them are diagonals, with two other grooves irregularly placed.
The blow with the fist falls on the knuckle of the second finger, which is the longest, strongest, and in line with the radius. The more tightly it is clenched, the more it is arched across the knuckles. The bones of the second row lie in the same plane. The thumb lies against the first finger, or across the second.
The hand, open, is an implement. The hand, closed, is a weapon. When driven forward, the second knuckle, as the most prominent, becomes the point of impact; but in clenching it is braced by the entire fist, bone, tendon and knuckle. When driven directly forward, the second knuckle is in line with the wrist and the radius, making a straight battering ram.
Knuckles of the Hand
There is no muscular covering for the knuckles; only the tendons, which are half blended with them, and roughened skin. In clenching, this skin is tightly stretched, and by contact with objects is hardened, so that in other positions it is wrinkled. The end of the metacarpal bone is a round dome, over which fits the socket of the first phalanx. The dome is protected on the sides by square projecting flanges, which are matched by the sides of the socket. They are in the first finger set at a slight diagonal, so that there is an overhang of the phalanx, serving to protect the joint in lateral blows.
1 Tendons of the extensor digitorum communis 2 Dorsal interosseous muscles
Hand of the Baby
In the hand of the baby, neither anatomical nor mechanical features are in evidence, but are alike concealed under the soft flesh and smooth skin. In fact, neither anatomical nor mechanical features are sharply defined as yet; the bone is still partly cartilage, the joints still small, the muscles have not taken shape nor given shape to the skin.
The wrist is quite large in comparison with its size in mature hands, and the fingers quite short and symmetrically tapering in the same comparison. Instead of expanded joints we find constrictions in the flesh; instead of wrinkles over on the backs of knuckles and joints we find dimples. The wrist is marked by a double wrinkle. The first segment of the fingers, on account of the bulging and dimpling of the flesh, looks quite short. On the other hand, the middle joint of the thumb being, like the other joints, small, the last joint appears quite long, and the whole thumb has flowing lines.
Three bones make the pelvis; two innominate (without a name) bones and one sacrum (sacrificial) bone. The sacrum is a wedge about the size of the hand but more perfectly shaped, like a half-bent hand, and carrying a very small tip (coccyx) about as big as the last joint of the thumb. It forms the central piece in the back, curving first back and down and then down and in. The two innominate bones are formed like two propellers, with triangular blades twisted in opposite directions. The rear corners of the top blades meet the sacrum in the back, and the front corners of the lower blades meet in front to form the symphysis pubis. The hip socket itself forms the central point for the shaft. The two blades stand at right angles to each other. The upper blade is called the ilium, the lower is called the pubis in front and the ischium behind, with an opening between. The only superficial parts are the top of the upper blade (iliac crest) and the front tip of the lower (symphysis pubis). Masses and Markings The size of the pelvis is due to its position as the mechanical axis of the body; it is the fulcrum for the muscles of the trunk and legs, and is large in proportion. Its mass inclines a little forward, and is somewhat square as compared with the trunk above. At the sides the ridge is called the iliac crest. It is the fulcrum for the lateral muscles and flares out widely for that purpose, rather more widely in front than behind. Above the rim is a roll of muscle belonging to the abdominal wall; immediately below it a groove or depression, made by the sag of the hip muscles, obliterated when these are contracted in action.
1 Ilium 2 Pubis 3 Ischium 4 Sacrum
The greater part of the movement of a figure is based on the pelvis. Its bony basin in front supports the fleshy mass of the abdomen. Behind, a circle of bones forms the extreme lateral part, of which the sacrum is the keystone. The muscles that are visible are all situated at the back to form the gluteal region. Only two of these are prominent; they are, the gluteus maximus and the gluteus medius. With the pelvis as a base, these two act on the femur, which acts as a crank shaft. The upper end of the femur is in the shape of a bent lever on which the whole body rests.
The Pelvis and Hip
1 Tensor vaginae femoris 2 Sartorius 3 Rectus femoris 4 Gluteus medius 5 Gluteus maximus Gluteus Medius: From ilium, outer surface, to femur, greater trochanter. Action: Abducts and rotates inward thigh. Gluteus Maximus: From crest of ilium, rear portion, sacrum and coccyx to femur. Action: Extends, rotates and turns out thigh.
So great are the changes in surface form of the muscles in different positions of the hip that the iliac crest remains as the one stable landmark. It is a curvc, but being beveled backward, it presents to the side view two lines and almost an angle between them at the top. The posterior line is marked by two dimples where it joins the sacrum, and the line continues downward into the fold of the buttocks. From this whole line the gluteus maximus muscle passes down and forward, to just below the head of the thigh bone, making the mass of the buttocks and hip. Just in front of this, from the top of the crest, descends the gluteus medius muscle, forming a wedge whose apex is at the head of the thigh bone. Between these two muscles is the dimple of the thigh. Only part of the medius is superficial; its front portion is overlaid by the tensor fasciae femoris muscle, which rises from the edge of the front line of the crest and descends to form with the gluteus maximus the wedge filled in by the medius. The two fasten to the dense plate of fascia that guards the outside of the thigh (ilio-tibial band). This muscle is always prominent and changes its appearance greatly in different positions of the hip, forming a U-shaped wrinkle when the thigh is completely flexed. On the front end of the crest is a small knob, from which descends the sartorius (tailor’s) muscle, longest in the body. It forms a graceful curve as it lies in the groove of the inner side of the thigh, passing to under the knee. From just below the knob, overlaid therefore by the sartorius, descends the rectus femoris muscle, straight to the knee cap. From the knob, the line continues down and in to the symphysis, marking the boundary between abdomen and thigh.
Muscles of the Hip
Nature has provided a perfect system of columns, levers and pulleys to which cords and muscles are attached. When contraction takes place, these muscles and their tendons pull, twist or turn, the movable bones. The hip joint is a strictly machine-like contrivance. It has at its connection with the hip, a ball and socket joint and a hinge joint at the knee. The muscles at the hip give a wheel-like movement. Those muscles that pass to the knee parallel the thigh bones to bend the knee.
1 Gluteus medius 2 Gluteus maximus 3 Tensor vaginae femoris
THE LOWER LIMBS
The lower limbs are divided into three parts—the thigh, the leg, and the foot. These parts correspond to the arm, the forearm, and the hand of the upper limb. The thigh extends from the pelvis to the knee, and the leg from the knee to the foot. The longest and strongest bone of the body is the femur (thigh bone). It is joined to the bones of the pelvis at the hip socket by a long neck, which carries the shaft itself out beyond the widest part of the crest. From there the femora (thigh bones) converge as they approach the knees, bringing the knee under the hip socket. At the knee, the femur rests on the tibia (shin bone), the main bone of the leg, and makes a hinge joint. The tibia descends to form the inner ankle. Beside it, not reaching quite to the knee, is the fibula, the second bone of the leg, which descends to form the outer ankle. It is located on the outside, and is attached to the tibia at the top and bottom. These two bones are almost parallel. Above the juncture of the femur and tibia lies the patella (knee cap). This is a small bone almost triangular in shape. It is flat on its under side, and convex on the surface. The great trochanter of the femur is the upper tip of the shaft which reaches up slightly beyond where the neck joins. The lower portion of the femur widens to form two great hinge processes, known as tuberosities. They are on the outer and inner sides, and they are both visible.
The Thigh and the Leg
From the head of the femur (trochanter) to the outside of the knee runs a band of tendon called the ilio-tibial band. It makes a straight line from the head of the thigh bone to the outside of the knee. The rectus femoris muscle makes a slightly bulging straight line from just below the iliac crest to the knee cap. On either side of the latter is a twin mass of muscles. That of the outside (vastus externus) makes one mass with it, and slightly overhangs the ilio-tibial band outside. That of the inside (vastus internus) bulges only in the lower third of the thigh, and overhangs the knee on the inside. Behind and inside of this is the groove of the thigh occupied by the sartorius muscle, passing from the ilium above to the back of the knee below. Behind the groove is the heavy mass of the adductors, reaching two-thirds of the way down the thigh. Behind groove and adductors, around the back of the thigh and to the ilio-tibial band outside, is the mass of the ham-string muscles whose tendons are found on either side of the knee at the back. It is a dual mass of muscle, dividing above the diamond-shaped popliteal space at the back of the knee, whose lower corner is formed by the gastrocnemius muscle, similarly divided. Of the same width as the end of the thigh bone is the head of the tibia, or shin bone. Immediately below the head the shaft narrows on both sides, but on the outside and a little to the rear is the head of the fibula (which corresponds with the ulna of the forearm) more than filling out the narrowing on that side. The ridge of the shin bone descends straight down the front of the leg, a sharp edge toward the outside, a flat surface toward the inside, which at the ankle bends in to become the inner ankle bone. The outer bone of the foreleg (fibula) soon overlaid by a gracefully bulging muscular mass, emerges again to become the outer ankle bone. On the back of the leg are two muscles. Beneath is the low, flat and broad soleus (sole fish) muscle; on top of it is the double-bellied calf muscle (gastrocnemius, frog’s belly), covering its upper half, but crossing the knee joint above and helping to make the two knobs there. These two muscles unite to form the tendon of Achilles at the heel.
Muscles, Front View
1 Tensor fasciae latae 2 Sartorius 3 Rectus femoris 4 Vastus externus 5 Vastus internus 6 Tibialis anticus 7 Peroneus longus 8 Extensor digitorum longus Tensor Fasciae Latae (tensor fasciae femoris): From crest of ilium, front end, to fascia lata, or ilio-tibial band. Action: Tenses fascia and rotates inward thigh. Sartorius: From spine to ilium in front to tibia inside. Action: Flexes, abducts and rotates inward thigh. Rectus Femoris: From anterior inferior spine of ilium to common tendon of patella. Action: Extends leg. Vastus Externus: From outer side of femur to common tendon of patella. Action: Extends and rotates outward leg. Vastus Internus: From inner side of femur to common tendon of patella. Action: Extends and rotates inward leg.
THE LOWER LIMBS
1 Rectus femoris 2 Vastus internus 3 Sartorius 4 Gracilis 5 Semi-tendinosus 6 Semi-membranosus 7 Gastrocnemius 8 Soleus
Below the Knee
Soleus: From upper part of fibula and back of tibia to tendon of Achilles. Action: Extends foot and lifts body in walking. Extensor Digitorum Communis (extensor longus digitorum pedis): From tibia and front of fibula to second and third phalanges of toes. Action: Extends toes.
Muscles of the Lower Limbs
1 Gluteus maximus 2 Gluteus medius 3 Biceps femoris 4 Vastus externus 5 Gastrocnemius 6 Peroneuslongus 7 Tibialis anticus
THIGH AND LEG
The column of the thigh and leg diminishes in thickness as it descends to the foot. From any view it also has a reverse curve that extends its entire length. On either side a descending wedge overlaps the rounded form of the thighs and this again overlaps the square form above and below the knee joint, which is also square. The leg at the calf is triangular; at the ankle it is square.
Muscles Below the Knee
Gastrocnemius: From tuberosities of femur to tendon of Achilles. Action: Extends foot, raises body in walking. Peroneus Longus: From head and upper part of fibula passes beneath foot from outside, to base of big toe. Action: Extends ankle and raises outer side of foot. Tibialis Anticus: From upper and outer two-thirds of tibia to inner side of foot. Action: Flexes ankle and raises inner side of foot.
Muscles of the Lower Limbs
1 Gluteus medius 2 Gluteus maximus 3 Semi-tendinosus 4 Semi-membranosus 5 Biceps femoris 6 Gastrocnemius 7 Soleus Semi-tendinosus From ischial tuberosity to tibia. Action: Flexes knee and rotates inward leg. Semi-membranosus From ischial tuberosity to tibia. Action: Flexes knee and rotates leg inward. Biceps Femoris Long head from ischial tuberosity; short head from femur, to head of fibula. Action: Flexes knee and rotates thigh outward.
Ham-strings, gastrocnemius and popliteal space
I. Bones 1 Pubis: of the pelvis 2 Femur: thigh bone 3 The head of the femur 4 The neck of the femur 5 The great trochanter II. Muscles 1 The rectus femoris: arises by two tendons from the pelvis to join the common tendon of the triceps femoris a short distance above the knee. 2 The adductor muscles, longus and magnus: arise from the pubic and ischium portions of the pelvis to be inserted into the whole length of the femur on its inner side. 3 Vastus externus: from the femur at the great trochanter; following a rough line at the back of the shaft to join the common tendon a little above the knee. 4 The vastus internus: arises from the front and inner side of the femur to nearly the whole length of the shaft to be inserted into the side of the patella and common tendon.
III. The triceps of the thigh comprise the rectus, vastus externus and internus, adding the crureus, a deep seated muscle, which makes four in all. These four are together called the quadriceps extensor. They all meet above and around the knee to a common tendon that is inserted into the patella and continued by a ligament to the tubercle of the tibia. The rectus is seen above as it emerges from between the tensor vaginae femoris and the sartorius. From here it descends vertically on the surface of the thigh to join to its tendon above the knee. The rectus muscle bulges out at a much higher level than the muscles on either side. The outer muscle ends as a triangular tendon to enter the patella above the knee. The inner is placed quite low on the thigh and seen distinctly at its lower margin. It passes round the inner side of the knee to its insertion into the patella. IV. The human body is provided with a system of levers and pulleys by which muscles pull on the movable bones. The thigh swings backward as well as forward. When in action, all the muscles that surround the hip joint are geared and set in motion. The triceps of the thigh like the triceps of the arm is composed of three muscles that act together. When they pull they extend the leg on the thigh.
The thigh bone is the most perfect of all levers, it is balanced by the muscles that pass up from the “crank shaft” of the thigh bone to the pelvis. These muscles work against one another in turning the round slippery head of the thigh bone in the socket. The muscles parallel the shaft to control the action of the knee joint. The extensors of the leg are in front or on top when the thigh is drawn upward, while those that flex the leg on the thigh are at the back. The sartorius arises from the crest of the ilium. It sweeps downward in a sinuous curve across the thigh, in a flattened tendon as it wraps around the inner surface of the knee to its insertion on the tibia. INNER VIEW 1 Rectus 2 Vastus internus 3 Sartorius 4 Adductor 5 Hamstrings OUTER VIEW 1 Hamstrings 2 Rectus femoris 3 Biceps femoris 4 Vastus externus
Think of the knee as a square with sides beveled forward, slightly hollowed in back and carrying the kneecap in front. When the knee is straight its bursa, or water mattress, forms a bulge on either side in the corner between the cap and its tendon, exactly opposite the joint itself. The kneecap is always above the level of the joint. The back of the knee, when bent, is hollowed by the hamstring tendons on either side. When straight, the bone becomes prominent between them, making, with these tendons, three knobs. The inside of the knee is larger, and the knee as a whole is bent convex toward its fellow. The hip socket, the knee and the ankle are all in line when the leg is straight, but the shaft of the thigh bone is carried some distance out by a long neck, so that the thigh is set at an angle with the leg.
1 Pad or sack 2 Common tendon 3 Patella or knee-pan 4 Ligament of the patella
The Knee Outer View
The Knee Inner View
As the little finger side is the heel side of the hand, so the outside of the foot is the heel side. It is flat upon the ground, continuous with the heel; it is lower than the inside—even the outer ankle bone is lower—and it is shorter. The inside, as though raised by the greater power of the great toe and the tendons of all the toes, is higher. To the front of the ankle is the knob that corresponds with the base of the thumb. Opposite it, on the outside, is a similar knob corresponding with the base of the little finger. In the foot this symmetry is adapted to the function of weight-bearing and has developed into a wonderful series of arches. The five arches of the foot converge on the heel; the toes being flying buttresses to them. The balls of the foot form a transverse arch. The inner arches of the foot are successively higher, forming half of a transverse arch whose completion is in the opposite foot. Opening gradually toward the ankle, this arching movement finally culminates in the two columns of the leg and the arch between; wherefore the leg is placed somewhat to the inside of the central fine of the foot.
In all positions, the foot tends to keep itself flat with the ground, the arches of the foot changing accordingly. In action, the foot comes almost into straight line with the leg, but when settling upon the ground, the outer or heel side strikes first and the whole foot settles toward the inside.
Abduction and Adduction
Turning the foot inward toward the body is called adduction. Abduction means turning away. Abduction and adduction are controlled by the tendons that pass round the inner and outer ankles. The tendons that pass round the outer ankle bone pull the foot in an outward direction. The tendons that pass round the inner ankle bone turn the foot in. The foot is also capable of turning and elevating its inner border. The muscle that causes this movement passes from the outer to the inner side of the leg. The tendon passes over the arch of the foot to the base of the metatarsal of the great toe and is called the tibialis anticus. 1 The extensors as they pass under the annular ligament. 2 Tendons of both the long and short peroneals pass round the outer ankle to the outer side of the foot. 3 The tibialis anticus passes in front of the inner ankle to be inserted into the base of the great toe.
The Foot Inner View
The Foot Outer View
Interlocking of the ankle with the foot
Bones and Muscles of the Foot
Their Pads and Wedging
Toes are placed on the top of the foot and descend downward by steps tending to keep flat on the ground. The little toe is an exception. The big toe, as well as the little toe, has but two steps down. The other toes have three steps to reach the ground.
The mechanical contrivance used to move the toes, is a slit in one tendon to let another tendon pass through it. A long tendon in the foot bends the first joint of the toe and passes through the short tendon which bends the second joint.
The foot has strength to support the weight of the body. It also has flexibility, elasticity and beauty of form. Its construction is the envy of the bridge builders. The arrangement of its tendons and ligaments as they bind, pass round and through slits is akin with the belt, straps and ropes of the machine.
The arch of the foot is curved from heel to toe. The arch plays freely between two bones, the inner and outer ankle. From the two ends of this arch at its base, a strong elastic ligament extends that sinks or rises as the weight of the body bears upon the arch. The foot is also arched from side to side as well as forward, across and horizontally. The bones of the foot are wedged together and bound by ligaments. The leg bones rest on the arch where it articulates with the astragalus, the key-bone or keystone of the arch. This keystone is not fixed as in masonry, but moves freely between the inner and outer condyle. The heel is on the outside of the foot. The ball of the large toe is on the inside, giving it the rotary and transverse movement already mentioned.