![]() ![]() Similarly, at a cartilaginous joint, the adjacent bones are united by cartilage. At fibrous joints, the adjacent bones are directly united to each other by fibrous connective tissue. Structural classifications of the body joints are based on how the bones are held together and articulate with each other. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body. In addition, the limb can also be rotated around its long axis. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. The shoulder and hip joints are multiaxial joints. This type of diarthrotic joint allows for movement along three axes ( ). A joint that allows for the several directions of movement is called a multiaxial joint (polyaxial or triaxial joint). The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together. ![]() An example of a biaxial joint is a metacarpophalangeal joint (knuckle joint) of the hand. ![]() A biaxial joint allows for motions within two planes. The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. Thus, diarthroses are classified as uniaxial (for movement in one plane), biaxial (for movement in two planes), or multiaxial joints (for movement in all three anatomical planes).Ī uniaxial joint only allows for a motion in a single plane (around a single axis). An axis in anatomy is described as the movements in reference to the three anatomical planes: transverse, frontal, and sagittal. These joints are divided into three categories, based on the number of axes of motion provided by each. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion. These types of joints include all synovial joints of the body, which provide the majority of body movements. ![]() In contrast, freely moveable joints allow for much more extensive movements of the body and limbs.Ī freely mobile joint is classified as a diarthrosis. Thus immobile or slightly moveable joints serve to protect internal organs, give stability to the body, and allow for limited body movement. The amount of movement available at a particular joint of the body is related to the functional requirements for that joint. Functional classifications describe the degree of movement available between the bones, ranging from immobile, to slightly mobile, to freely moveable joints. Structural classifications of joints take into account whether the adjacent bones are strongly anchored to each other by fibrous connective tissue or cartilage, or whether the adjacent bones articulate with each other within a fluid-filled space called a joint cavity. Joints are classified both structurally and functionally. List the three types of diarthrodial jointsĪ joint, also called an articulation, is any place where adjacent bones or bone and cartilage come together (articulate with each other) to form a connection.Describe the three functional types of joints and give an example of each.Distinguish between the functional and structural classifications for joints.By the end of this section, you will be able to: ![]()
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