Types of Diarthrodial Joints

According to Henry Gray's Anatomy of the Human Body, there are three types of joints in the body: synathroses or immovable joints, such as the joints in the skull; amphiarthrose or slightly movable joints, such as the disk spaces between vertebrae and diarthroses, or free-moving joints. This last classification covers almost every other joint in the body. Diarthrodial joints have a free range of movement around one axis or many, depending on how they are made.

Ginglymus

• The ginglymus or hinge joint moves uniaxially, meaning that it can only move in one direction. In this case, hinge joints can only move back and forth. Examples of ginglymus joints include the fingers, toes and elbows. The knee and ankle joints also fall into this category, although they do allow some side-to-side movement.

Trochoid

• The trochoid or pivot joint is also uniaxial. In this case, pivot joints can rotate but not bend. An example of a trochoid joint is the connection of the radius to the ulna, which allows you to turn your hand palm up or palm down. This same type of joint allows you to turn your head left or right.

Condyloid

• The condyloid joint is elliptical and biaxial, meaning that the joint can move both up and down as well as side to side but cannot rotate 360 degrees. An example of this type of joint would be the wrist. You may think you can turn you wrist in a complete circle. However, if you hold onto your arm below the wrist and just rotate the wrist joint, you will notice that it does not rotate smoothly but rather changes direction from backward to forward after shifting left or right.

Saddle Joints

• The saddle joint is extremely similar to a condyloid joint except that it is circular rather than elliptical. An example of a saddle joint is the joint located at the base of the thumb, which allows you to move your thumb toward the palm.

Enarthrosis

• The enarthrosis or ball-and-socket joint is an example of a polyaxial joint. This type of joint has a 360 degree range of rotation, as well as independent up/down and left/right movement. One bone has a rounded head fits into cup-like cavity on the adjoining bone. The hips and shoulders are examples of ball-and-socket joints.

Arthrodia

• Arthrodia or gliding joints are polyaxial but have a much narrower range of motion. These joints are strictly limited by ligaments that connect them. An example of this would be the movement of vertebrae along the spine. While you can twist and bend along the spine, you do not completely fold up or bend back at each vertebrae like you can with your shoulder.