Hind leg

“ The bones of the column meet and form articulations that are held together by ligaments, and attached to their faces, borders and extremities are muscles and tendons. In the superior portion of the limb the muscles are heavy, tapering inferiorly, and terminating in the region of the foot in long tendons. Each limb is divided into four regions. The regions of the fore-limb are the shoulder, arm, forearm and forefoot. In the hind limb are the regions of the pelvis, haunch, thigh, leg and hind-foot. ”

“ Inasmuch, now, as no weeding out of the weaker determinants of the hind leg [or eye] by personal selection takes place on our hypothesis, inevitably the average strength of this determinant must slowly but constantly diminish—that is, the hind leg [or eye] must grow smaller and smaller until it finally disappears altogether. ”

“ It is comparatively seldom that navicular disease is found to exist in the hind feet, and the preference which it shows for the fore ones may possibly be found in the difference which exists in the conformation of the limbs. The straight fore-leg allows the weight to fall directly on to the feet, while in the hind one it is first broken and diffused in passing through the angle forming the hock, so that by the time it reaches the foot the sharp edge of concussion is removed and the foot escapes the injury which is inflicted through the straighter column in front. ”

“ The fore legs are obviously in no way affected as to the direction of the hair in the sitting posture, and the hind legs, being doubled up and subject to the direct downward weight of the body, are also free from the sliding pressure, which we shall see affects the fore limb when the dog lies prone. Thus of the three supports, fore legs, hind legs and tuberosities of the ischium, two are necessarily unaffected in their patterns of hair. ”

“ The right hind foot continues its onward motion until it is sometimes much in advance of its lateral fore foot, the former, however, being gradually lowered, while the latter is being raised. The right hind and both fore legs are now much flexed, while the left hind is stretched backwards to its greatest extent with the bottom of the foot turned upwards, the left fore leg is being thrust forwards and gradually straightened, with the toe raised as the foot approaches the ground ”

“ Its front limbs, which it uses very little, resting on them only in the instant during which it quits its erect posture, have never acquired a development in proportion to the other parts; they have remained thin, little, and weak.
(2) The hind legs, almost continually in action, whether to bear the weight of the whole body or to execute its leaps, have, on the contrary, obtained a considerable development; they are very big and very strong. ”

“ The fore-legs, but oftener the hind ones, and especially in coarse horses, are sometimes subject to considerable enlargement. Occasionally, when the horse does not seem to labor under any other disease, and sometimes from an apparent shifting of disease from other parts, the hind legs suddenly swell to an enormous degree from the hock, and almost from the stifle to the fetlock, attended by a greater or less degree of heat, and tenderness of the skin, and sometimes excessive and very peculiar lameness. ”

“ It was formerly almost universally believed that the fore legs were longer than the hinder ones, but in fact the hind legs are the longer by about one inch, the error having been caused by the great development and height of the withers, to give a proper base to the long neck and towering head. ”

“ It is also more frequent in the hind foot than the fore, because, from the violent action of the hind legs in propelling the horse forward, the pasterns are more subject to ligamentary injury behind than before; yet the lameness is not so great there, because the disease is confined principally to the ligaments, and the bones have not been injured by concussion; while, from the position of the fore limbs, there will generally be in them injury of the bones to be added to that of the ligaments. ”

“ Hence any deviation from this line, one way or the other, indicates more or less dislocation of the tibia. There is a pellet of fat under the ligament, which answers a ‘packing’ purpose—sinking in when the knee is bent; rising when the knee is extended, and bulging on either side of the tendon, almost enough to give the feel of fluctuation.
In a well-formed leg the ligamentum patellæ, the tubercle [Pg 51] of the tibia, and the middle of the ankle should be in the same straight line. ”

“ The gliding joints which twist upon each other; they are composed of small, square bones, forming arches, the simplest form of which is found in eels and snakes; they are found in the back bone, the arch of the foot and wrist. The next is the hinge, or swing joint, which moves to and fro, but has no side motion, the simplest illustration of which is the hinge of a door which moves only two ways, to and fro, swinging; these are usually the second and third joints of each member, thus, the second and third joints of the leg would be the knee and ankle; the second of the arm is the elbow ”

“ As one fore limb—the right, to particularize—moves forward, that side of his body—the right shoulder, moves forward, too; while approximately at the same time the left hind limb moves forward and carries with it that side or the left pelvic regions. This causes an alternating obliquity of the transverse axes of the shoulder and the hind regions of the body of the reptile as he walks on the ground. ”

“ Other persons present a peculiarity which I am at a loss to account for. Where the leg, for instance, has been lost, they feel as if the foot were present, but as though the leg were shortened. Thus, if the thigh has been taken off, there seems to them to be a foot at the knee; if the arm, a hand seems to be at the elbow, or attached to the stump itself.
Before leaving Nashville I had begun to suffer the most acute pain in my left hand, especially the little finger ”

“ Innervation.—The lateral division of the tibial nerve sends twigs into the posteromedial edge of the posterior head.
[Pg 429]
Individual Variation.—In one leg, the fleshy part of the anterior head is unusually long. In another leg, the anterior head is entirely tendinous. In one leg, a bundle of fibers of the posterior head attaches to the deep surface of the distal part of the patellar tendon. ”

“ It served originally for the origin of the ambiens muscle (see Muscular System below) ; shifting or disappearance of this muscle, of course, influences the process.
The Hind Limb.—The femur often possesses a well visible pneumatic foramen on the median side of the proximal end of its shaft. The inner condyle, the intercondylar sulcus, and a portion only of its outer condyle, articulate with corresponding facets of the tibia. The outer condyle articulates mainly with the fibula. There is a patella, intercalated in the tendon of the femori-tibialis or extensor cruris muscle. ”

“ The cartilages enjoy a limited range of movement within the joint, passing backwards during flexion, and forwards again when the limb is extended; under normal conditions the lateral moves more freely than the medial. While the limb is partly flexed, a slight degree of rotation of the leg at the knee is possible, and during this movement the cartilages glide from side to side, and the tibia rotates below them. ”

“ Experiment 29. To show the ligamentous action of the muscles. Standing with the back fixed against a wall to steady the pelvis, the knee can be flexed so as to almost touch the abdomen. Take the same position and keep the knee rigid. When the heel has been but slightly raised a sharp pain in the back of the thigh follows any effort to carry it higher. Flexion of the leg to a right angle, increases the distance from the lines of insertion on the pelvic bones to the tuberosities of the tibia by two or three inches—an amount of stretching these muscle cannot undergo. ”

“ When the eversion is more pronounced, the sole looks laterally and the tendons of the peronei stand out in relief. The anterior part of the foot is displaced laterally. Flat-foot is frequently associated with stiff great toe; the patient having lost the power of dorsiflexing the toe, the first phalanx and first metatarsal are in a straight line, instead of forming an angle open towards the dorsum.
The muscles of the leg are flabby and poorly developed. ”

“ If a joint is left permanently stiff in an awkward and useless position, the limb may be greatly improved by excision of the joint. Thus, if the knee is left bent and the joint is excised a useful, straight limb may be obtained, somewhat shortened, and, of course, permanently stiff. If after disease of the hip-joint the thigh remains fixed in a faulty position, it may be brought down straight by dividing the bone near the upper end. A stiff shoulder or elbow may be converted into a useful, movable joint by excision of the articular ends of the bones. ”

“ The reason, of course, is that the hind-feet are carried forward in order to be placed upon the heels, while the fore are taken backwards to relieve the hind of the body-weight.
In like manner the movements of the animal will vary with the feet affected. With only the front-feet diseased the animal is, comparatively speaking, comfortable. The hind-feet take the weight, and the animal stands for long periods together, resting alternately first one fore-foot and then the other, moving often in a circle of which his body is the radius, and his hind-limbs the centre. ”

“ These ligatures are worn extremely tight, and result not in atrophy of the limb, as might be expected, [79] but in an enormous swelling of the muscles above or below them. The ankle ligatures sometimes reach half-way up the leg. ”

“ When standing in the erect position, the hip-joint only permits the limb to move forwards, the knee-joint backwards, and the ankle-joint neither backwards nor forwards. When the body or limbs are inclined obliquely, or slightly flexed, the range of motion is increased. The greatest angle made at the knee-joint is equal to the sums of the angles made by the hip and ankle joints when these joints are simultaneously flexed, and when the angle of inclination made by the foot with the ground equals 30°. ”

“ In the production of opposition changes took place in the hind limbs first and most generally, since all species in which the thumb is opposed possess opposable great toes also—except in the single case of man—while many species occur in which opposition is presented by the hind limbs alone. In this adaptation of the foot to climbing three structural changes were effected—the parts of the limb became more flexible, the joints more widely separable, and the great toe, as has been said, opposed to the group formed by the remaining digits. ”

“ On the backs of the hands and fingers nodules are very frequently, and on the extensor surfaces of the thighs and the front of the legs almost always, found. The calves are often also infiltrated as a whole, especially on the fibular side close above the ankle, and this infiltration reaches as high as the middle of the leg ”

“ Tendons in front of ankle.—Over the front of the ankle, when the muscles are in action, we can see and feel, beginning [Pg 55] on the inner side, the tendons of the tibialis anticus, the extensor longus pollicis, the extensor longus digitorum, and the peroneus tertius. They start up like cords when the foot is raised, and are kept in their proper relative position by strong pulleys formed by the anterior annular ligament. Of these pulleys the strongest is that of the extensor communis digitorum. ”

“ The leg fails to grow, the deformity becomes more pronounced, and the toes become pointed. If the tibia is markedly bent, it may be straightened by osteotomy; and the tendons, Achillis and peronei, may require to be lengthened. If the ankle is unstable as a result of the absence of the lateral malleolus, it may be artificially ankylosed, or the lower end of the tibia may be split vertically so as to make a socket for the talus. In either case, the foot is placed in the equinus attitude to compensate for the shortening of the leg. ”