![]() ![]() This fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. The cells of this membrane secrete synovial fluid (synovia = “a thick fluid”), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. Lining the inner surface of the articular capsule is a thin synovial membrane. Instead, the articular cartilage acts like a Teflon ® coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue. However, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. The bones of the joint articulate with each other within the joint cavity.įriction between the bones at a synovial joint is prevented by the presence of the articular cartilage, a thin layer of hyaline cartilage that covers the entire articulating surface of each bone. The walls of this space are formed by the articular capsule, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone’s articulating surface. Six Types of Synovial Joints: Image demonstrating the six different types of synovial joints.Synovial joints are characterized by the presence of a joint cavity. Ball and socket joints: allow all movements except gliding.Saddle joints: permit the same movement as condyloid joints and combine with them to form compound joints.Condyloid joints: perform flexion, extension, abduction, and adduction movements.Pivot joints: allow bone rotation about another bone.Hinge joints: allow flexion and extension in one plane.Gliding joints: only allow sliding movement.Others have multiple degrees of freedom, but at the expense of greater risk of injury. ![]() Some are relatively immobile but more stable than mobile joints. Rotation is a circular movement around a fixed point.īody Movements I: Image demonstrating the various joint movements. ![]() Flexion is bending the limbs (reduction of angle) at a joint. ![]() Extension is the straightening of limbs (increase in angle) at a joint. Adduction is the movement toward the middle line of the body. Abduction is the movement away from the midline of the body. Several movements may be performed by synovial joints. 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). Structural and functional differences distinguish synovial joints from cartilaginous joints (synchondroses and symphyses) and fibrous joints (sutures, gomphoses, and syndesmoses). Synovial joints achieve movement at the point of contact of the articulating bones. adduction: The action by which the parts of the body are drawn toward its axis.Ī synovial joint, also known as a diarthrosis, is the most common and most movable type of joint in the body of a mammal.abduction: The movement that separates a limb or other part from the axis, or middle line, of the body.synovial joint: Also known as a diarthrosis, the most common and most movable type of joint in the body of a mammal. ![]()
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