ANSWERS

1. Define a joint.
   A joint occurs wherever 2 or more bones meet. The degree of movement varies considerably between different types of joint, and some joints allow little or no movement at all.
2. List 2 other names for a joint.
   • Arthrosis.
   • Articulation.
3. List the 3 types of joint. Give an example of each.
   • Synovial - stifle.
   • Cartilaginous - pelvic symphysis.
   • Fibrous - the sutures between the flat bones of the skull.
4. List 5 properties of synovial joints.
   • Articular surfaces covered with hyaline cartilage.
   • Surrounded by a continuation of the periosteum known as the joint capsule.
   • Joint cavity lined with synovial fluid for lubrication, nutrition and removal of waste products.
   • Often stabilised by collateral ligaments.
   • May have 1 or more fibrocartilage menisci which increase range of movement and reduce wear and tear on the articular surfaces.
5. As the name suggests, in cartilaginous joints the bones are connected by cartilage, and may or may not allow a degree of movement. Name the 2 types of cartilaginous joint and give 1 example of each.
   • Synarthroses - allow little or no movement (e.g. the pelvic symphysis between the 2 pelvic bones).
   • Amphiarthroses - allow a reasonable degree of movement (e.g. the intervertebral joints).
6. The changes in position between the bones of a joint can be complex, and usually occurs by means of a combination of movements. List the 4 types of movement and briefly describe each.
   • Gliding/sliding - 1 articular surface slides over another.
   • Angular - altering the angle between 2 bones; flexion decreases the angle between 2 bones, whilst extension increases it (over-extension occurs when the movement continues past the straight line).
   • Rotation - 1 bone rotates around its longitudinal axis; may be described as inward or outward rotation depending upon whether the movement is directed towards or away from the body.
   • Circumduction - one end of the bone is involved in the articulation whilst the other describes a circle or arc.
7. What is a sesamoid bone? Give an example.
   A small bone that develops within a tendon to ease the passage over the joint. An example is the patella which protects the tendon of the quadriceps femoris muscle as it passes over the stifle.
8. What is the difference between abduction and adduction?
   Abduction describes a movement of the limb away from the body (as in cocking a leg), whilst adduction describes a movement towards or beneath the body.
9. What is the name of the joint which allows movement in 1 direction only? Give an example.
   A hinge joint (e.g. the elbow).
10. What is the name of the joint which allows flexion, extension to the straight line, then over-extension? Give an example.
    A condylar joint (e.g. the carpal joint).
11. What is the name of the joint which allows rotation? Give an example.
    A pivot joint (e.g. the radio-humeral joint in cats).
12. What is the name of the joint which is the most freely moveable of all, allowing flexion, extension, rotation, adduction and abduction? Give an example.
    A ball and socket joint (e.g. the hip).
13. What is the name of the joint which allows a restricted amount of gliding movement of 1 bone over another. Give an example.
    A plane joint (e.g. the small bones in the carpus and tarsus.)