SYNARTHROSIS (synarthrosis; Greek syn-together, with + arthron a joint + - osis) — continuous motionless or slow-moving connection of bones by means of a connecting, cartilaginous or bone tissue.
Pages meet where the corner of shift of bones concerning each other is small. In the course of S.'s ontogenesis form from mesenchymas (see), located between laying of bones, edges forms connecting or cartilaginous tissue (see. Connecting fabric , Cartilaginous tissue ).
Depending on a type of the fabric connecting bones among S. distinguish syndesmoses, synchondroses, synostoses.
Syndesmoses, or fibrous connections (syndesmoses, s. articulationes fibrosae), represent connection of bones by means of connecting fabric. Syndesmoses can have an appearance of interosseous membranes (e.g., between bones of a forearm or a shin), sheaves (in all joints), and also seams (between bones of a skull), at the same time distinguish a gear seam (sutura serrata), a scaly seam (sutura squamosa) and a flat seam (sutura plana). Connecting fabric in syndesmoses can be dense fibrous (interosseous membranes, sheaves) or elastic (yellow ligaments of a backbone). The direction of the course of fibers in syndesmoses is caused by the direction of shift of one bone in relation to another and depends on the function which is carried out by this or that department of the jointed bones. Refer to syndesmoses also connection of fangs with tooth sockets — a vkolachivaniye (gomphosis).
Synchondroses, or cartilaginous connections (synchondroses, s. articulationes cartilagineae) — a joint of bones by means of hyaline (e.g., between the I edge and a breast) or a fibrous cartilage (e.g., between bodies of vertebrae). Synchondroses differ in durability and elasticity that causes their spring function. On duration of existence distinguish the temporary synchondroses which at a certain age are replaced with synostoses and the constant synchondroses existing throughout all life.
Synostoses, or bone connections (synostosis), develop at adults on site of syndesmoses or temporary synchondroses, napr, a synostosis of the ileal, pubic and sciatic bones which are a part of a haunch bone (see. Synostosis ).
See also Syndesmologia .
E. A. Vorobyova.