Describe the different classifications of joints and range movement at each?
Joints are the points where two or more bones meet. They allow for movement and provide stability to the body. There are three main types of joints:
1. Synovial joints are the most common type of joint. They are characterized by a joint cavity that is filled with synovial fluid, which reduces friction and allows for smooth movement. Synovial joints allow for a wide range of motion, including:
* Flexion: bending a joint
* Extension: straightening a joint
* Abduction: moving a limb away from the midline of the body
* Adduction: moving a limb towards the midline of the body
* Rotation: turning a limb around its long axis
* Circumduction: moving a limb in a circular motion
2. Cartilaginous joints are connected by cartilage, which is a tough, flexible tissue. Cartilaginous joints allow for some movement, but not as much as synovial joints. There are two types of cartilaginous joints:
* Synchondroses are joints between bones that are still growing. The cartilage in synchondroses gradually turns into bone, so these joints become less mobile as a person ages.
* Symphyses are joints between bones that have stopped growing. The cartilage in symphyses is more flexible than the cartilage in synchondroses, so these joints allow for more movement.
3. Fibrous joints are connected by dense connective tissue. Fibrous joints do not allow for any movement. There are two types of fibrous joints:
* Sutures are joints between the bones of the skull. The sutures are filled with a dense connective tissue called dura mater.
* Syndesmoses are joints between the bones of the limbs. The syndesmoses are filled with a dense connective tissue called interosseous membrane.
Range of Motion
The range of motion of a joint is determined by the shape of the joint, the muscles that surround it, and the ligaments that hold it together. The following are the average ranges of motion for some of the major joints of the body:
* Shoulder joint: Flexion: 180 degrees, Extension: 45 degrees, Abduction: 90 degrees, Adduction: 45 degrees, Rotation: 180 degrees
* Elbow joint: Flexion: 140 degrees, Extension: 0 degrees
* Wrist joint: Flexion: 80 degrees, Extension: 70 degrees, Abduction: 20 degrees, Adduction: 20 degrees, Rotation: 80 degrees
* Hip joint: Flexion: 120 degrees, Extension: 0 degrees, Abduction: 45 degrees, Adduction: 30 degrees, Rotation: 50 degrees
* Knee joint: Flexion: 135 degrees, Extension: 0 degrees
* Ankle joint: Dorsiflexion: 20 degrees, Plantar flexion: 50 degrees, Inversion: 20 degrees, Eversion: 20 degrees