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  • Joints are essential for all types of movements involving the bony parts of the body and classified according to their degree of movement. Joints vary from immovable to freely movable.
  • The three major structural forms are fibrous, cartilaginous and synovial joints.
  • The bones of a synovial joint are joined (fastened and stabilized) by ligaments that form a capsule. Capsule is lined with synovial membrane, which secretes synovial fluid to lubricate and cushion the joint.

SYNOVIAL JOINT

  • Synovial joints are most freely movable and flexible; contain a synovial fluid; helps in locomotion and allow for a variety of movement.
  • Characterized by having a fluid filled synovial cavity between the articulating surfaces of the two bones.
  • Synovial fluid is a complex mixture of polysaccharides, proteins, fats and cells, which forms a thin lubricating film covering the surfaces of a joint.
  • Some of the EXAMPLES of synovial joints are as stated below:
    • Ball and socket joint (between humerus and pectoral girdle and between the femur and the coxal bone; forms hip and shoulder)
    • Hinge joint (knee joint; construct knee and elbow; permit movement in one direction only, like the hinges on a door)
    • Pivot joint (between atlas and axis)
    • Gliding joint (between the carpals; as in the wrist and the ankle) and
    • Saddle joint (between carpal and metacarpal of thumb)
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