The endosteum (plural endostea) is a thin vascular membrane of
connective tissue
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
that lines the inner surface of the bony tissue that forms the
medullary cavity of long
bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...
s.
This endosteal surface is usually resorbed during long periods of
malnutrition
Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
, resulting in less
cortical thickness.
The outer surface of a bone is lined by a thin layer of connective tissue that is very similar in
morphology and function to endosteum. It is called the
periosteum, or the periosteal surface. During
bone growth, the width of the bone increases as
osteoblasts
Osteoblasts (from the Greek combining forms for " bone", ὀστέο-, ''osteo-'' and βλαστάνω, ''blastanō'' "germinate") are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts functi ...
lay new bone tissue at the periosteum. To prevent the bone from becoming unnecessarily thick,
osteoclasts resorb the bone from the endosteal side.
Additional images
File:Illu long bone.jpg , Long bone
References
External links
* – "Bone, structure (LM, High)"
Image at dal.ca
Musculoskeletal system
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