Fibrous joints are described as fixed or immovable joints, which can be mainly restricted to a few components of the human body. They shape a connection between bones and are held collectively by fibrous connective tissues, such as collagen fibres.
One common example of a fibrous joint is the cranium. On this form of immovable joint, the bones are fused together in this sort of manner that they remain constant to that part to give a proper shape and structure. Apart from the cranium, spine, pelvic bone, rib cage and upper jaw are all examples of fibrous joints. On this page, we will provide information on the types of fibrous joints. Students can also refer to this page to know about gomphosis and suture joint for their exam preparation.
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Types of Fibrous Joints
The fibrous joints are categorised into three types on the basis of their location. These three types are:
1. Suture Joint
The sutures are a type of fibrous joints which are only found in the human skull and hence are also known as cranial sutures. The suture joints consist of a thin layer of dense fibrous connective tissue and is a site for active bone growth. The immovable and fixed suture joints can be found attached to the certain bones of the skull providing compliance and elasticity. Formation of a suture occurs through the fibrous protecting, or periosteum, of two bones passing between them. Within the adult, sutures are seen inside the roof and facets of the braincase and within the upper portion of the face. They are again further divided into six types depending on the shape and fusion mode of articulating bones:
Wave and groove
2. Gomphosis Joint
A gomphosis is a fibrous joint that binds the enamel to bony sockets inside the bones of the maxilla mandible. A gomphosis joint helps in anchoring a tooth to its socket. The upper and lower jaws in the teeth are lined by these joints and as such the gomphosis joints are also known as peg and socket joints. They also have a very limited mobility and therefore, the teeth are held firmly. Each tooth has bony protrusions or pegs that latch into the socket with the assistance of the gomphosis. Most of the disorders that occur in the mouth mostly involve these joints. These kind of joints are an example of synarthrosis joints due to restricted movements.
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The gomphosis is made from fibrous tissue, a set of tough ligaments that attach to the socket and base of the enamel. As human beings age and lose their preliminary set of baby teeth, the new teeth develop gomphosis to anchor them within the jaw. It is the only type of joint that does not join two bones, as teeth are technically not considered a bone. According to the modern anatomical and joint classification, a gomphosis falls under a type of fibrous joints due to the ligamentous tissues which link the structures.
A syndesmosis is a kind of articulation, or joint, in which adjoining bones are joined through an interosseous membrane. Alongside symphysis joints, syndesmoses are categorised as amphiarthrosis joints in that they permit moderate motion. Joints of this kind are found at several points inside the human body, such as the intermediate radioulnar joint (where the radius and ulna meet) above the wrist and above the ankle joint in which the tibia and fibula converge.
Some other common examples of syndesmosis fibrous joints are the coracoclavicular and old Sacroiliac joints.