patella

...rounded ends, or condyles, of the femur and tibia that meet at the knee are massive. The rounded ends of the tibia move forward and backward on the corresponding ends of the femur; the kneecap, or patella, rests upon the ends of the femur and serves to prevent the tibia from moving too far forward when the leg is bent. The articulating (meeting) surfaces of the femur and tibia condyles are...

rare hereditary (autosomal dominant) disorder characterized by small fingernails and toenails that show a tendency to split; small or absent kneecaps (patellae); underdevelopment of parts of the knee, elbow joint, and shoulder blade; spurs of bone on the inside of the pelvis; and kidney insufficiency. Nail-patella syndrome is apparent at birth or appears during early childhood. The mutated gene in persons with the disorder has been identified. Affected persons often experience dislocations, limited joint mobility, and early onset of osteoarthritis. Eye abnormalities, particularly glaucoma, may also occur. Treatment includes prevention or management of renal disorders; orthopedic care also may be necessary.

any of various snails having a flattened shell; those of subclass Prosobranchia (class Gastropoda) are marine, clinging to rocks near shore; Atlantic plate limpet (Acmaea testudinalis) common to America; Patella vulgata common species of Britain and N. Europe; keyhole limpets, of prosobranch family Fissurellidae, have slit or hole at apex of shell; those of subclass Pulmonata live in brackish and fresh water.

Two large bones, the femur and the tibia, meet at the knee. The femur is the thigh bone, and the tibia is the shin bone. Ligaments, or tough strands of tissue, connect the bones to each other. A layer of springy tissue called cartilage cushions the ends of the bones. A smaller bone called the patella, or kneecap, sits at the end of the femur. The patella protects the front of the knee joint.