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Bone is broken down by osteoclasts, and rebuilt by osteoblasts, both of which communicate through cytokine (TGF-β, IGF) signalling. Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. [1]
The following bones develop in humans via Intramembranous ossification: [3] Flat bones of the face; Most of the bones of the skull; Clavicles; Other bone that formed by intramembranous ossification are: cortices of tubular and flat bones as well as the calvaria, upper facial bones, tympanic temporal bone, vomer, and medial pterygoid process. [4]
Endochondral ossification is responsible for development of most bones including long and short bones, [4] the bones of the axial (ribs and vertebrae) and the appendicular skeleton (e.g. upper and lower limbs), [5] the bones of the skull base (including the ethmoid and sphenoid bones) [6] and the medial end of the clavicle. [7]
The flat bones are: the occipital, parietal, frontal, nasal, lacrimal, vomer, sternum, ribs, and scapulae. [1] These bones are composed of two thin layers of compact bone enclosing between them a variable quantity of cancellous bone, [1] which is the location of red bone marrow. In an adult, most red blood cells are formed in flat
This form of bone development is the more complex form: it follows the formation of a first skeleton of cartilage made by chondrocytes, which is then removed and replaced by bone, made by osteoblasts. Intramembranous ossification is the direct ossification of mesenchyme as happens during the formation of the membrane bones of the skull and ...
The neurocranium is formed by the combination of the endocranium, the lower portions of the cranial vault, and the skull roof. Through the course of evolution, the human neurocranium has expanded from comprising the back part of the mammalian skull to being also the upper part: during the evolutionary expansion of the brain, the neurocranium ...
At birth, the skull features a small posterior fontanelle with an open area covered by a tough membrane, where the two parietal bones adjoin the occipital bone (at the lambda). The posterior fontanelles ossify within 6–8 weeks after birth. This is called intramembranous ossification. The mesenchymal connective tissue turns into bone tissue.
Intramembranous ossification involves the formation of bone from connective tissue whereas endochondral ossification involves the formation of bone from cartilage. Intramembranous ossification mainly occurs during formation of the flat bones of the skull but also the mandible, maxilla, and clavicles; the bone is formed from connective tissue ...