Theory question 102
Support and Movement(a) (i) What is a joint? (ii) List three types of movable joints and mention one location in the mammalian body of each type.
(b) (i) Make a labelled diagram, 8 - 10 cm long, of a typical movable joint.
(ii) Explain how the structure of the joint adapts it to its function.
Show the model answer
(a)(i) A joint is a place where two or more bones meet (articulate).
(ii) Any three: ball and socket joint – shoulder or hip; hinge joint – elbow or knee; gliding (sliding) joint – wrist, ankle or between vertebrae; pivot joint – between the atlas and axis in the neck.
(b)(i) Diagram of a synovial joint labelled: bone (e.g. humerus/femur), articular (hyaline) cartilage, synovial membrane, synovial fluid, synovial cavity, capsule (capsular ligament), ligaments, (tendon/muscle).
(ii) Smooth articular cartilage covers the bone ends, reducing friction and absorbing shock; synovial fluid lubricates the joint and nourishes the cartilage; the synovial membrane secretes the fluid; tough, slightly elastic ligaments hold the bones together but allow movement; the capsule encloses the joint and keeps the fluid in; tendons attach muscles to the bones so their contraction moves the joint; the shapes of the bone ends decide the direction of movement.
Link each structure in (b)(ii) to what it does for movement.