Skeleton
Aiton's Encyclopedia (1910)
in physiology, the framework of the body. The lower animals, as jellyfishes and worms, have no hard matter in their bodies that can be called a skeleton. Other animals, as the snail, starfish, crayfish, and the whole horde of insects, have a crusty protective outside covering, but it is an inconvenient arrangement. In order to grow, an animal of this sort must either burst its covering and produce a new one, or else, as in case of the snail, enlarge the free end and abandon the part first occupied. The chief uses of a skeleton are three: 1. It gives shape and proper stiffness to the body. 2. It protects the delicate organs and the soft parts of the body. 3. Its parts act as levers to which the tendons of the muscles may be attached to produce motion. The skeleton, or want of one, serves as a basis in the classification of animals. The human skeleton consists of over 200 distinct bones. Two of these, the hyoid to which the root of the tongue and the palate are attached, and the knee-cap, are not joined to any other bones. The human skeleton, being upright, is considered the most highly developed of all. The following outline is convenient: 1. Head or Skull. A. Cranium (8). 1 frontal. 2 parietal. 2 temporal. 1 occipital. 1 sphenoid. 1 ethnoid. B. Face (14) 2 upper jaw. 2 nasal. 2 lachrymal. 2 palate. 2 turbinated. 2 malar. 1 vomer. 1 lower jaw. II. Trunk. A. Hyoid bone. B. Spinal Column (26). 7 cervical vertebrae. 12 dorsal vertebrae. 5 lumbar vertebrae. 1 sacrum. 1 coccyx. C. Ribs (24) 14 true ribs. 6 false ribs. 4 floating ribs. D. Sternum (1). E. Hip Bones (2). III. Limbs. A. Arms (32 each). a. Upper Arm. 1 scapula or shoulder-blade. 1 clavicle or collar bone. 1 humerus or arm bone. b. Fore-arm. 1 ulna. 1 radius. c. Hand. 8 wrist bones. 5 metacarpal bones. 14 finger bones. B. Legs (30 each). a. Thigh. 1 femur. b. Lower leg. 1 scutella or knee-cap. 1 tibia. 1 fibula. c. Foot. 7 ankle bones. 5 instep bones. 14 toe bones. See Animals; Vertebrates; Horse; Tortoise; Bone; URANG-UTAN.
What Has Changed in the Last Century
The bone-by-bone tally Aiton's gave in 1910 still holds up: anatomists today count 206 bones in the adult skeleton, and the same three uses -- support, protection, leverage for muscles -- are still how the subject is taught. Two things have moved. Modern anatomy treats the hyoid, not the hyoid and the kneecap, as the one bone joined to no other, since the patella is a sesamoid bone riding in the tendon over the femur; and bone itself is no longer seen as inert framework but as living tissue constantly torn down and rebuilt by osteoclasts and osteoblasts, housing the marrow that makes all blood and immune cells and secreting hormones such as osteocalcin and FGF23 that act on the kidney and elsewhere. The claim that the upright human skeleton is the most highly developed of all belongs to a ladder-of-nature view of evolution that biologists abandoned: fossils such as the 1974 Lucy skeleton show upright walking as one specialised adaptation among many, not a summit.
Written for this edition, 2026.