Synovial Joints

Synovial Joints

Definition of Synovial Joints

Highly mobile joints formed by the articulation of bones enclosed in a capsule containing synovial fluid in the human body
Examples of synovialjoints are joints present in knee, wrists and elbow.

More About Synovial Joints

• It is also known as “mobile joints” or “diarthrosis joint” with regards to the functional mobility of the joints
• It is very different from the cartilaginous and the fibrous joints when the structural and functional aspects are considered
• The main difference lies in the presence of the capsule and synovial fluid around the surface of the articulating bones in synovial joints
• A typical synovial joint consists of the two articulating bones separated by a narrow cavity known as articular cavity
• This cavity is filled with a slippery fluid known as synovial fluid produced by the synovial membrane
• Synovial fluid lubricates the joint and provides protection against the shocks, preventing friction and damage during movement
• It also provides nourishment and removes the wastes from the articular cartilage
• A capsule like structure is formed around the articulating bones and it is known as articular capsule
• The periosteum of the two bones of the joints are externally connected by ligament
• The inner surface epiphyses of the two bones have hyaline cartilage or articular cartilagethat absorbs shock and reduces friction
• The inner articular capsule surrounding the synovial cavity is lined by the synovial membrane that contains the synovial fluid
• The synovial joints are of three types based on the plane of the movement of the bones
• They are monoaxial joints having one plane of movement. E.g: Hinge joints(Ginglymus joints)
• Biaxial joints having two planes of movement. E.g: Condyloid joint (Ellipsoidal joint)
• Multiaxial joints having three or more than three planes of movement. E.g: Ball and socket(Spheroid joints)
• Basically there are six types of synovial joints as follows:
  • i) Ball and socket joints – joints in the shoulder and the hip bones
    ii) Hinge joints - joint in the elbow, knee joint, interpharyngeal joints
    iii) Gliding joints - joints in the bones of the wrist, intertarsal joints, articular processes between vertebrae
    iv) Pivot joints - atlanto-axial joint in the upper part of neck
    v) Saddle joints - joint present at the base of the thumb
    vi) Condylar joints - mandible to the temporal joint