The Skeleton : Limbs, Part 2

Hygienic Physiology: with Special Reference to the Use of Alcoholic Drinks and Narcotics
by Joel Dorman Steele, Ph.D.

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1. The Upper Limbs. - The Shoulder. - The bones of the shoulder are the collar bone (clavicle), and the shoulder blade (scapula). The clavicle (clavis, a key) is a long, slender bone, shaped like the Italic f. It is fastened at one end to the breastbone and the first rib, and, at the other, to the shoulder blade. I. Therefore holds the shoulder joint out from the chest, and gives the arm greater play. If it be removed or broken, the head of the arm bone will fall, and the motions of the arm be greatly restricted.

The Shoulder Blade is a thin, flat, triangular bone, fitted to the top and back of the chest, and designed to give a foundation for the muscles of the shoulder.

The Shoulder Joint. - The arm bone, or humerus, articulates with the shoulder blade by a ball-and-socket joint. This consists of a cup-like cavity in the latter bone, and a rounded head in the former, to fit it,-. Therefore affording a free rotary motion. The shallowness of the socket accounts for the frequent dislocation of this joint, but a deeper one would diminish the easy swing of the arm.

The Elbow. - At the elbow, the humerus articulates with the ulna - a slender bone on the inner side of the forearm - by a hinge joint which admits of motion in only two directions, i. e., backward and forward. The ulna is small at its lower end; the radius, or large bone of the forearm, on the contrary, is small at its upper end, while it is large at its lower end, where it forms the wrist joint. At the elbow, the head of the radius is convex and fits into a shallow cavity in the ulna, while at the wrist the ulna plays in a similar socket in the radius. Therefore the radius may roll over and even cross the ulna.

The Wrist, or carpus, consists of two rows of very irregular bones, one of which articulates with the forearm; the other, with the hand. They are placed side to side, and so firmly fastened as to admit of only a gliding motion. This gives little play, but great strength, elasticity, and power of resisting shocks.

The Hand. - The metacarpal (meta, beyond; karpos, wrist), or bones of the palm, support each a thumb or a finger. Each finger has three bones, while the thumb has only two. The first bone of the thumb, standing apart from the rest, enjoys a special freedom of motion, and adds greatly to the usefulness of the hand.

The first bone of each finger is so attached to the corresponding metacarpal bone as to move in several directions upon it, but the other phalanges form hinge joints.

The fingers are named in order: the thumb, the index, the middle, the ring, and the little finger. Their different lengths cause them to fit the hollow of the hand when it is closed, and probably enable us more easily to grasp objects of varying size. If the hand clasps a ball, the tips of the fingers will be in a straight line.

The hand in its perfection belongs only to man. Its elegance of outline, delicacy of mold, and beauty of color have made it the study of artists; while its exquisite mobility and adaptation as a perfect instrument have led many philosophers to attribute man's superiority even more to the hand than to the mind.

2. The Lower Limbs. - The Hip - The thigh bone, or femur, is the largest and necessarily the strongest in the skeleton, since at every step it has to bear the weight of the whole body. It articulates with the hip bone by a ball-and-socket joint. Unlike the shoulder joint, the cup here is deep. Therefore affording less play, but greater strength. It fits so tightly that the pressure of the air largely aids in keeping the bones in place. Indeed, when the muscles are cut away, great force is required to detach the limbs.

The Knee is strengthened by the patella, or kneepan (patella, little dish), a chestnut-shaped bone firmly fastened over the joint.

The shin bone, or tibia, the large, triangular bone on the inner side of the leg, articulates both with the femur and the foot by hinge joints. The knee joint is so made, however, as to admit of a slight rotary motion when the limb is not extended.

The fibula (fibula, a clasp), the small, outside bone of the leg, is firmly bound at each end to the tibia. It is immovable, and, as the tibia bears the principal weight of the body, the chief use of this second bone seems to be to give more surface to which the muscles may be attached.

The Foot. - The general arrangement of the foot is strikingly like that of the hand. The several parts are the tarsus, the metatarsus, and the phalanges. The graceful arch of the foot, and the numerous bones joined by cartilages, give an elasticity to the step that could never be attained by a single, flat bone. The toes naturally lie straight forward in the line of the foot. Few persons in civilized nations, however, have naturally formed feet. The big toe is crowded upon the others, while crossed toes, nails grown-in, enormous joints, corns, and bunions abound.

The Cause of these Deformities is found in the shape and size of fashionable boots and shoes. The sole ought to be large enough for full play of motion, the uppers should not crowd the toes, and the heels should be low, flat, and broad. As it is, there is a constant warfare between Nature and our shoemakers, and we are the victims. The narrow point in front pinches our toes, and compels them to override one another; the narrow sole compresses the arch; while the high heel, by throwing all the weight forward on the toes, strains the ankle, and, by sending the pressure where Nature did not design it to fall, causes that joint to become enlarged. The body bends forward to meet the demand of this new motion, an. Therefore loses its uprightness and beauty, making our gait stiff and ungraceful.