Fibrous Joints

Joints are points in the body where two or more bones meet. Arthrology studies joint types, structures, functions, disorders, and treatments.

Joints are classified based on mobility into three types:

  1. Fibrous Joints: Bones are connected by fibrous tissue like collagen.
  2. Synovial Joints: Bone ends are protected by the synovial membrane and fluid.
  3. Cartilaginous Joints: Bones are connected by cartilage.

Fibrous Joint Definition

A fibrous joint, also known as a "synarthrosis," is a type of joint where the bones are connected by fibrous connective tissue. These joints do not allow significant movement and provide stability and strength to the skeletal system. Examples include sutures in the skull and syndesmosis joints in the leg.

What is a Fibrous Joint?

Fibrous joints are those where bones are connected by fibrous tissue, known as fixed or immovable joints as they allow no movement. They lack a joint cavity, and the connecting tissue is collagen fibers. The skull is a prime example of a fibrous joint, where bones are fused together, forming a fixed structure.

Types of Fibrous Joints

 

There are three types of fibrous joints: sutures, Gomphosis, and Syndesmoses. Sutures are between skull bones, Gomphosis connects teeth to bone cavities, and Syndesmoses are in forearms (radius and ulna) and legs (tibia and fibula).

Suture joints

Suture joints are immovable joints composed of dense fibrous connective tissue, found between all skull bones except the mandible. They provide strength by attaching irregular interlocking edges of cranial bones and are sites of active bone growth.

Types of sutures based on articulating surfaces and mode of fusion:

  1. Serrate sutures: Found between parietal bones.
  2. Denticulate sutures: Between parietal and occipital bones.
  3. Squamous sutures: Example, Temporo-parietal suture between temporal and parietal bones.
  4. Limbous sutures: Slightly modified squamous suture, like Modified Temporo-parietal suture.
  5. Plane sutures: Between horizontal plates of two palatine bones.
  6. Wedge and groove sutures: Between vomer bone and rostrum of sphenoid bone.

Gomphosis

It's a specialized fibrous joint that offers individual and strong support for each tooth, fitting them into sockets in the maxilla and mandible. Gomphosis fibrous joints are also known as peg and socket joints.

Syndesmosis

It is a fibrous joint where two parallel bones are connected by an interosseous membrane or ligaments. This joint is found in the forearm and leg. In the forearm, the radius and ulna shafts are joined by an interosseous membrane, allowing flexibility. In the leg, the tibia and fibula shafts are connected by a strong interosseous membrane, forming the distal tibiofibular joint. This joint, along with ligaments, forms the Syndesmosis, providing stability to the ankle joint for weight-bearing.

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