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In common usage, the prefix dipolar, dative or coordinate merely serves to indicate the origin of the electrons used in creating the bond. For example, F 3 B ← O(C 2 H 5) 2 ("boron trifluoride (diethyl) etherate") is prepared from BF 3 and :O(C 2 H 5) 2, as opposed to the radical species [•BF 3] – and [•O(C 2 H 5) 2] +.
The proatlas is a paired bone in the skeleton of many vertebrates that occurs between the skull and the first cervical vertebra. It ossifies endochondrally. [1] Skull of the sauropod dinosaur Smitanosaurus in posterior view, with (left) and without (right) the proatlases in place. A number of different interpretations have been made of the ...
The appendicular skeleton, comprising the arms and legs, including the shoulder and pelvic girdles, contains 126 bones, bringing the total for the entire skeleton to 206 bones. Infants are born with about 270 bones [ 4 ] with most of it being cartilage, but will later fuse together and decrease over time to 206 bones.
The ectotympanic, or tympanicum, is a bony structure found in all mammals, located on the tympanic part of the temporal bone, which holds the tympanic membrane (eardrum) in place. In catarrhine primates (including humans), it takes a tube-shape.
A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces.
Anatomical terms of bone [ edit on Wikidata ] The posterior border of the ala of sacrum , shorter than the anterior, also presents two projections separated by a notch, the posterior superior iliac spine and the posterior inferior iliac spine .
A true endoskeleton is derived from mesodermal tissue. In three phyla of animals, Chordata, Echinodermata and Porifera (), endoskeletons of various complexity are found.An endoskeleton may function purely for structural support (as in the case of Porifera), but often also serves as an attachment site for muscles and a mechanism for transmitting muscular forces as in chordates and echinoderms ...
Cervical vertebra. The pars interarticularis, or pars for short, is the part of a vertebra located between the inferior and superior articular processes of the facet joint. [1] [2]