Страница 12 из 53
12. Bones
Bone is the type of co
The bones of women are generally lighter than those of men, while children's bones are more resilient than those of adults Bones also respond to certain physical physiological changes: atrophy, or waste away.
Bones are generally classified in two ways. When classified on the basis of their shape, they fall into four categories: flat bones, such as the ribs; long bones, such as the thigh bone; short bones, such as the wrist bones; and irregular bones, such as the vertebrae. When classified on the basis of how they develop, bones are divided into two groups: endochondral bones and intramembraneous bones. Endochondral bones, such as the long bones and the bones at the base of the skull, develop from cartilage tissue Intramembraneous bones, such as the flat bones of the roof of the skull, are not formed from cartilage but develop under or within a co
The formation of bone tissue (ossification) begins early in embryological development. The bones reach their full size when the person is about 25.
Most adult bone is composed of two types of tissue: anouter layer of compact bone and an i
Surrounding every bone, except at the surface where it meets another bone, is a fibrous membrane called the periosteum. The outer layer of the periosteum consists of a network of densely packed collagen fibres and blood vessels. This layer serves for the attachment of tendons, ligaments, and muscles to the bone and is also important in bone repair.
The i
In addition to the periosteum, all bones have another membrane, the endosteum. It lines the marrow cavity as well as the smaller cavities within the bone. This membrane, like the i