Detailed Instructions: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Problem:Context: A joint is a point at which two or more bones meet. There are three main types of joints in the body: 1. Fixed joints do not allow any bone movement. Many of the joints in your skull are fixed ( Figure 1.1). There are eight bones that fuse together to form the cranium. The joints between these bones do not allow movement, which helps protect the brain. 2. Partly movable joints allow only a little movement. Your backbone has partly movable joints between the vertebrae ( Figure 1.2). The skull has fixed joints. Fixed joints do not allow any movement of the bones, which protects the brain from injury. 3. Movable joints allow the most movement. Movable joints are also the most common type of joint in your body. Your fingers, toes, hips, elbows, and knees all provide examples of movable joints. The surfaces of bones at movable joints are covered with a smooth layer of cartilage. The cartilage reduces friction between the bones. Ligaments often cross a joint, holding two nones together. For example, there are numerous ligaments connecting the leg bones across the knee joint. Four types of movable joints are discussed here. 1. In a ball-and-socket joint, the ball-shaped surface of one bone fits into the cup-like shape of another. Exam- ples of a ball-and-socket joint include the hip ( Figure 1.3) and the shoulder. 2. In a hinge joint, the ends of the bones are shaped in a way that allows motion in two directions, forward and backward. Examples of hinge joints are the knees ( Figure 1.4) and elbows. 3. The pivot joint ( Figure 1.5) only allows rotating movement. An example of a pivot joint is the joint between the radius and ulna that allows you to turn the palm of your hand up and down. 4. A gliding joint is a joint which allows only gliding movement. The gliding joint allows one bone to slide over the other. The gliding joint in your wrist allows you to flex your wrist. It also allows you to make very small side-to-side motions. There are also gliding joints in your ankles.
Question: what type of joint allows you to turn the palm of your hand?
Solution:
a pivot joint