What are examples of a fibrous joint?

Fibrous joints are a type of joint where the bones are joined by strong fibrous tissue rich in collagen. These joints allow for very little movement (if any) and are often referred to as synarthroses.

Examples

Fibrous joints are connections between bones that are held together by fibrous connective tissue that includes many collagen fibres.

The definition of a fibrous joint may be clearer with information about how fibrous joints compare with the other types of joints.

Types of fibrous joints

There are three types of fibrous joints in the human body :

• Sutures (plural, the singular is suture)
• Syndesmoses (plural, the singular is syndesmosis)
• Gomphoses (plural, the singular is gomphosis)

Sutures (plural, the singular is suture) A suture is an immovable joint (synarthrosis) consisting of a thin layer of dense fibrous connective tissue (definition of a fibrous joint) attaching certain bones of the skull. The irregular (roughly wave-shaped) interlocking edges of the cranial bones that are attached together by suture joints contribute to the strength of the joint Sutures between the skull bones There are many sutures in the skull, prominent examples incl. the coronal suture the sagittal suture the lambdoid suture the squamous suture Syndesmoses (plural, the singular is syndesmosis) A syndesmosis is an immovable joint (synarthrosis) at which the bones are attached by fibrous connective tissue (definition of a fibrous joint) which is neither a suture nor a gomphosis. Distal articulation of tibia and fibula The articulation between the bases (i.e. the "distal articulation", at he ankle-end) of the tibia and fibula bones. Gomphoses (plural, the singular is gomphosis) A gomphosis is an immovable joint (synarthrosis) in the shape of a socket at which one solid structure in an animal's body is firmly attached to another. Articulations of teeth in jaw bones The only gomphoses in the human body are the attachment of the roots of the teeth within the sockets of the alveolar processes of the lower-jaw (mandible) and upper-jaw (maxillae).

Examples of fibrous joints include:

• sutures between skull bones,
• syndesmoses between certain long bones e.g. the tibia and fibula
• gomphoses that attach the roots of human teeth to the upper- and lower- jaw bones.

For specific examples of different types of fibrous joints see the table above.

See also types of joints, cartilaginous joints and synovial joints.

A joint is defined as a connection between two bones in the skeletal system.

Joints can be classified by the type of the tissue present (fibrous, cartilaginous or synovial), or by the degree of movement permitted (synarthrosis, amphiarthrosis or diarthrosis).

In this article, we shall look at the classification of joints in the human body.

Fibrous Joints

A fibrous joint is where the bones are bound by a tough, fibrous tissue. These are typically joints that require strength and stability over range of movement.

Fibrous joints can be further sub-classified into sutures, gomphoses and syndesmoses.

Sutures

Sutures are immovable joints (synarthrosis), and are only found between the flat, plate-like bones of the skull.

There is limited movement until about 20 years of age, after which they become fixed and immobile. They are most important in birth, as at that stage the joints are not fused, allowing deformation of the skull as it passes through the birth canal.

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Gomphoses

Gomphoses are also immovable joints. They are found where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth).

The tooth is bound into its socket by the strong periodontal ligament.

Syndesmoses

Syndesmoses are slightly movable joints (amphiarthroses).

They are comprised of bones held together by an interosseous membrane. The middle radioulnar joint and middle tibiofibular joint are examples of a syndesmosis joint.

Cartilaginous

In a cartilaginous joint, the bones are united by fibrocartilage or hyaline cartilage.

There are two main types: synchondroses (primary cartilaginous) and symphyses (secondary cartilaginous).

Synchondroses

In a synchondrosis, the bones are connected by hyaline cartilage. These joints are immovable (synarthrosis).

An example of a synchondrosis is the joint between the diaphysis and epiphysis of a growing long bone.

Symphyses

Symphysial joints are where the bones are united by a layer of fibrocartilage. They are slightly movable (amphiarthrosis).

Examples include the pubic symphysis, and the joints between vertebral bodies.

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Synovial

A synovial joint is defined by the presence of a fluid-filled joint cavity contained within a fibrous capsule.

They are freely movable (diarthrosis) and are the most common type of joint found in the body.

Synovial joints can be sub-classified into several different types, depending on the shape of their articular surfaces and the movements permitted:

• Hinge - permits movement in one plane - usually flexion and extension.
  • E.g. elbow joint, ankle joint, knee joint.
• Saddle - named due to its resemblance to a saddle on a horse's back. It is characterised by opposing articular surfaces with a reciprocal concave-convex shape.
  • E.g. carpometacarpal joints.
• Plane - the articular surfaces are relatively flat, allowing the bones to glide over one another.
  • E.g. acromioclavicular joint, subtalar joint.
• Pivot - allows for rotation only. It is formed by a central bony pivot, which is surrounded by a bony-ligamentous ring
  • E.g. proximal and distal radioulnar joints, atlantoaxial joint.
• Condyloid - contains a convex surface which articulates with a concave elliptical cavity. They are also known as ellipsoid joints.
  • E.g. wrist joint, metacarpophalangeal joint, metatarsophalangeal joint.
• Ball and Socket - where the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. It permits free movement in numerous axes.
  • E.g. hip joint, shoulder joint.

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