fibrous joints

Examples of fibrous joints in the following topics:

• Fibrous Joints

  • Fibrous joints are also called fixed or immovable joints because they do not move.
  • Fibrous joints are connected by dense connective tissue consisting mainly of collagen.
  • Fibrous joints have no joint cavity and are connected via fibrous connective tissue.
  • The skull bones are connected by fibrous joints called sutures.
  • Syndesmoses of long bones and gomphoses of teeth are also types of fibrous joints.

• Structural Classification of Joints

  • There are three structural classifications of joints: fibrous, cartilaginous, and synovial.
  • There are three types of fibrous joints.
  • These moveable fibrous joints are also termed amphiarthrodial.
  • They allow more movement than fibrous joints but less than that of synovial joints.
  • Image demonstrating the three types of fibrous joints.

• Sutures

  • A suture is a type of fibrous joint (or synarthrosis) that only occurs in the skull (or cranium).
  • A suture is a type of fibrous joint (or synarthrosis) that only occurs in the skull.
  • The bones are bound together by Sharpey’s fibers, a matrix of connective tissue which provide a firm joint.
  • The joint between the mandible and the cranium, known as the temporomandibular joint, forms the only non-sutured joint in the skull.

• Synovial Joint Movements

  • A synovial joint, also known as a diarthrosis, is the most common and most movable type of joint in the body of a mammal.
  • Structural and functional differences distinguish synovial joints from cartilaginous joints (synchondroses and symphyses) and fibrous joints (sutures, gomphoses, and syndesmoses).
  • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).
  • The six types of joints include:
  • Saddle joints - permit the same movement as condyloid joints and combine with them to form compound joints

• Gomphoses

  • A gomphosis is a fibrous joint that binds the teeth to bony sockets in the bones of the maxilla mandible.
  • A gomphosis is a joint that anchors a tooth to its socket.
  • Disorders of the mouth sometimes involve these joints.
  • This particular joint is an example of a synarthrosis, a joint with limited to no movement.
  • The gomphosis is made up of fibrous tissue, a collection of tough ligaments that attach to the socket and base of the tooth.

• Functional Classification of Joints

  • This category includes fibrous joints such as suture joints (found in the cranium) and gomphosis joints (found between teeth and sockets of the maxilla and mandible).
  • Most joints in this category include cartilaginous joints such as those found between vertebrae and the pubic symphysis.
  • An example is the elbow joint.
  • Multiaxial – Includes the ball and socket joints.
  • An example is the hip joint.

• Syndesmoses

  • Like other joint tissue, it is designed to be able to deform and flex rather than shred or fracture on impact, allowing the joint to absorb considerable stress before damage occurs.
  • Along with symphysis joints, syndesmoses are classified as amphiarthrosis joints in that they allow slight movement.
  • Located directly above the ankle joint, which is a synovial hinge joint, the ankle syndesmosis is held together by four ligaments.
  • Due to the limited flexibility in these joint structures, ligament injuries in syndesmosis joints are common, particularly at the wrist and ankle.
  • Image of fibrous joints with the tibiofibular syndesmosis demonstration in figure (b).

• Cartilaginous Joints: Synchodroses

  • Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint.
  • The joint between the manubrium and the sternum is an example of a cartilaginous joint.
  • Where the connecting medium is hyaline cartilage, a cartilaginous joint is termed a synchondrosis or primary cartilaginous joint.
  • A synchondrosis joint is the first sternocostal joint (where the first rib meets the sternum).
  • The rest of the sternocostal joints are synovial plane joints.

• Structure of Synovial Joints

  • The joint may be divided, completely or incompletely, by an articular disk or meniscus, the periphery of which is continuous with the fibrous capsule while its free surfaces are covered by synovial membrane.
  • The articular capsule is fibrous and continuous with the periosteum of articulating bones, surrounding the diarthrosis and uniting the articulating bones.
  • The articular capsule also consists of two layers: (1) the outer fibrous membrane that may contain ligaments and (2) the inner synovial membrane that secretes the lubricating, shock-absorbing, and joint-nourishing synovial fluid.
  • The outer layer, or subintima, can be fibrous, fatty, or loosely areolar.
  • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).

• Bursae and Tendon Sheaths

  • Joints are cushioned by small fluid-filled sacs called bursae and stabilized by tough bands of fibrous connective tissue called tendons.
  • Elsewhere, the tendon lies in a bed of loose fibrous tissue.
  • A tendon or sinew is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension.
  • It provides a cushion between bones and tendons or muscles around a joint.
  • Bursae are found around most major joints of the body, such as the shoulder and the knee.