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The function of some dermal bone is conserved throughout vertebrates, although there is variation in shape and in the number of bones in the skull roof and postcranial structures. In bony fish, dermal bone is found in the fin rays and scales. A special example of dermal bone is the clavicle. Some of the dermal bone functions regard ...
Osteoderms are composed of bone tissue, and are derived from a scleroblast neural crest cell population during embryonic development of the organism. The scleroblastic neural crest cell population shares some homologous characteristics associated with the dermis . [ 4 ]
Osteoderms are dermal bone structures that support the upper layer of skin and serve as protection against the elements in a large variety of extinct and extant organisms, especially reptiles. [1] This structure is commonly called "dermal armor" and serves to protect the organism, while also helping with temperature regulation.
The resulting compact bone is known as a periosteal collar. The collarbone has a medullary cavity (marrow cavity) in its medial two-thirds. [7] It is made up of spongy cancellous bone with a shell of compact bone. [8] It is a dermal bone derived from elements originally attached to the skull.
The dermatocranium is the portion of the cranium that is composed of dermal bone, as opposed to the endocranium and splanchnocranium, which are composed of endochondral bone. The dermatocranium comprises the skull roof, the facial skeleton (usually excluding the dentary), and—in fishes—the opercular bones. [1]
The bones are derived from dermal bone and are part of the dermatocranium. In comparative anatomy , the term is applied to the whole dermatocranium. [ 1 ] In general anatomy, the roofing bones may refer specifically to the bones that form above and alongside the brain and neurocranium (i.e., excluding the marginal upper jaw bones such as the ...
Euteleostomes originally all had an endochondral bone, fins with lepidotrichs (fin rays), jaws lined by maxillary, premaxillary, and dentary bones composed of dermal bone, and lungs. Many of these characters have since been lost by descendant groups, however, such as lepidotrichs lost in tetrapods , and bone lost among the chondrostean fishes.
It is homologous to the postparietal bones of other animals. In humans, it corresponds to the upper portion of the squama of the occipital bone that lies superior to the highest nuchal line and is completely fused to the supraoccipital. However, in some individuals this portion remains separate from the rest of the occipital bone throughout life.