Continuous bone connections

Continuous bone connections are formed by different types of connective tissue located between the connecting bones. Among them are fibrous, cartilaginous and bone connections.

Fibrous connections include sutures, dentoalveolar connections (impacts) and syndesmoses. Sutures (suturae) are connections in the form of a thin connective tissue layer between adjacent bones of the skull. Depending on the shape of the connecting bone edges, there are three types of sutures. Flat (harmonious) sutures (sutura plana) are found between the bones of the facial part of the skull, where the smooth edges of the bones are connected. Serrated sutures (sutura serrata) are characterized by jaggedness of the connecting bone edges and are located between the bones of the cranial part of the skull. An example of squamous sutures (sutura squamosa) is the connection of the squama of the temporal bone with the parietal bone. Sutures are shock absorption zones for shocks and vibrations when walking and jumping. Sutures also serve as growth zones for the bones of the skull. After 40-50 years, many sutures grow together (synostose). Premature fusion of sutures leads to skull deformation. Asynchrony of suture fusion, especially paired ones, is the leading cause of skull asymmetry. Dentoalveolar junction, or impaction (articulatio dentoalveolaris, s. gomphosis), is the connection of the tooth root with the walls of the dental alveolus, between which there is a thin connective tissue layer (periodontium).

Syndesmoses (syndesmosis) are connections of bones by means of ligaments and interosseous membranes. Ligaments (ligamenta) in the form of thick bundles of dense fibrous connective tissue connect adjacent bones. At the same time, ligaments strengthen joints, direct and limit bone movements. Most ligaments are formed by collagen fibers. Yellow ligaments, built of elastic fibers, connect the arches of adjacent vertebrae. Collagen fibers of ligaments are slightly elastic, have great strength. Interosseous membranes (membranae interosseae) are stretched, as a rule, between the diaphyses of tubular bones. They firmly hold tubular bones near each other, often serve as the origin of muscles.

The connections of bones using cartilaginous tissue are called cartilaginous connections, or synchondroses. This type of connection is characterized by great strength and elasticity, which is due to the high elastic qualities of cartilage. A distinction is made between permanent synchondroses, which exist throughout life (for example, intervertebral discs), and temporary ones. Temporary synchondroses are replaced by bone tissue at a certain age (for example, epiphyseal cartilages of tubular bones).

Cartilaginous joints also include symphyses (half-joints), which have a narrow slit-like cavity in the cartilaginous layer between the bones. Symphyses (symphysis) occupy an intermediate position between continuous and discontinuous joints. An example of a half-joint is the pubic symphysis.

Bone joints (fusions, or synostoses) are formed as a result of the replacement of synchondroses with bone tissue. An example of synostosis is the replacement of cartilage between the pubic, ilium and ischium with bone tissue, resulting in the formation of a single pelvic bone.

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