Suture (gastropod)

Suture
Details
Identifiers
Latin	sutura
TA	A03.0.00.008
FMA	7493
Anatomical terminology []

In anatomy, a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements.

Sutures are found in the skeletons or exoskeletons of a wide range of animals, in both invertebrates and vertebrates. Sutures are found in animals with hard parts from the Cambrian period to the present day. Sutures were and are formed by several different methods, and they exist between hard parts that are made from several different materials.

The skeletons of vertebrate animals (fish, amphibians, reptiles, birds, and mammals) are made of bone, in which the main rigid ingredient is calcium phosphate.

The skulls of most vertebrates consist of sets of bony plates held together by cranial sutures. These sutures are held together mainly by Sharpey's fibers which grow from each bone into the adjoining one.

In the type of crurotarsal ankle which is found in crocodilians and some other archosaurs, the astragalus is fixed to the tibia by a suture, and the joint bends around a peg on the astragalus, which fits into a socket in the calcaneum.

The shells of most molluscs are made of calcium carbonate (the main constituent of limestone and chalk), and of conchiolin, a protein. For more information, see Mollusc shell.

In cephalopod mollusks which have external shells (e.g. Nautilus, ammonites), the shell is divided into compartments by septa (partitions).

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