Joint: A joint is an attachment between bones in the body which link the skeletal system. They are constructed to permit for different degrees and types of movement. Some joints, such as the elbow, knee, and shoulder, are self-lubricating, almost frictionless, and are able to execute smooth and precise movements. Other joints such as sutures between the bones of the skull allow very little movement (only during birth) in order to protect the brain. The connection between a tooth and the jawbone is described as a fibrous joint.
Types of Joints
- Fibrous Joints
- Cartilaginous Joints
- Synovial Joints
Fibrous joints-Fibrous joints are formed of tough collagen fibers and include the sutures of the skull and the syndesmosis joint that holds the ulna and radius of the forearm together, the middle tibiofibular joint is examples of syndesmosis joints. Teeth articulate among their sockets in the maxillae (upper teeth) or the mandible (lower teeth) is known as gomphosis a type of fibrous joints.
Cartilaginous joints-Cartilaginous joints are formed by a band of cartilage that binds bones together. There are two main types – primary cartilaginous and cartilaginous secondary joints. Some examples of cartilaginous joints include joints within the ribs and costal cartilage and the intervertebral disks of the spine. Pubic symphysis joints are slightly movable an example of cartilaginous secondary joints.
Synovial joints-A synovial joint is a joint filled with synovial fluid. They allow a huge range of movements, which are defined by the arrangement of their surfaces and the supporting ligaments and muscles. There are many different classes of synovial joints in the body, including gliding-
Permits flexion and extension. e.gElbow joint
Concave and convex surfaces unite at saddle joints, e.g. Metatarsophalangeal joint (toes).
Permit gliding or sliding movements, e.g. Acromioclavicular joint.
Permits rotation; a round bony process fits into a bony ligamentous socket. e.g the atlantoaxial joint & proximal radio-ulnar joint.
Allows flexion, extension, adduction, abduction, and circumduction e.g. Metacarpophalangeal joint.
Ball & Socket
Allows movement in several axis; a rounded head fits into a concavity. e.g. glenohumeral joint (shoulder).