 In this video, I will describe the six types of synovial joints based on their movements. So in A here, we see an example of a pivot joint. A pivot joint allows the action of rotation. This is a monoaxial joint, meaning it allows action only through one plane of motion. Specifically, it allows rotation, meaning that we can move around the long axis of the body, rotating to the right or rotating to the left. That's what we see. The example here is the atlantoaxial joint. The atlantoaxial joint is the joint between C1 and C2. The first two cervical vertebrae, atlas and axis, form a pivot joint, the atlantoaxial joint. The atlantoaxial joint enables you to rotate your head at the neck, rotate the atlantoaxial joint. If you are shaking your head to the left and the right, as to indicate no, you are rotating the atlantoaxial joint. Next in B, we can see an example of a hinge joint. What's commonly known as the elbow joint is technically known as the humeral ulnar joint. This is the articulation between the trochlea of the humerus and the trochlear notch of the ulnar. This allows angular motion only in the flexion or extension. It's a monoaxial joint that only allows the angular motion of flexion or extension. All hinge joints enable this flexion and extension. The humeral ulnar joint, commonly known as the elbow, is one example of a hinge joint. Another example of a hinge joint is commonly referred to as the knee. The tibiofemoral joint is also a hinge joint because it only allows that angular motion of flexion and extension. Similarly, the tallochrural joint, commonly referred to as the ankle joint, is a hinge joint. In C, we see an example of a saddle joint. The saddle joint example in the body is a joint between the trapezium and the first metacarpal. The saddle joint is a joint that enables motion through two different planes. It's a biaxial joint. There's a concave surface that fits around a convex surface of another bone and enables both a flexion of this joint as well as abduction of this joint. You can have flexion and extension, abduction and abduction, and a large motion to draw the polyx across to touch the fifth digit known as opposition is enabled by the flexible articulation of the saddle joint. Next, we have a plane joint, a type of joint that only allows a sliding motion, a little bit of gliding between bones. Typically, a plane joint does not allow a large amount of motion, but it's still a type of synovial joint. There's more motion than an amphiorthrosis. The bones do have articulating surfaces that glide along one another, and those articulating surfaces are separated by a fluid-filled synovial cavity. An example that we see here in the illustration is between the tarsal bones, there are the intertarsal joints that allow gliding of adjacent tarsal bones. Similarly, the articulations between adjacent carpal bones, the intercarpal joints are examples of plane joints. The articulation between the clavicle and the scapula, the acromial process of the scapula and the clavicle form, the acromioclavicular joint, another example of a plane joint that allows some gliding motion. Now, E, we see condyloid joint. A condyloid joint is another biaxial joint that enables motion through two planes, and so at the radiocarpal joint we can have the actions of flexion and extension. So the radiocarpal joint is the joint between the radius and the carpal bones, primarily the scaphoid, the lunate, the triquetrum are articulating with the distal end of the radius. And that forms what's commonly known as the wrist joint. So the radiocarpal joint, commonly known as the wrist joint, is a condyloid joint, a joint where we have an oval face in a depression, and that allows movement in two planes, so this will allow you to flex or extend the radiocarpal joint. But also you can abduct and adduct the radiocarpal joint. So another example of a condyloid joint would be the metacarpal phalangeal joints, the articulations between the distal end of our metacarpals and the proximal ends of the proximal phalanges. These joints enable flexion, extension, abduction, and adduction as well. And so then the last category of synovial joints that we see here in the illustration is the ball and socket joint, and a ball and socket joint is a joint that allows movement through three different planes. So the rotation of the shoulder joint, the glenohumeral joint, or the other example, aside from the glenohumeral joint, as we see here in the illustration, what's commonly known as the hip joint, the acetabulofemoral joint or hip joint, is another example of a ball and socket. Both the shoulder and the hip are ball and socket joints. The glenohumeral and acetabulofemoral joints are the only ball and socket joints in the human body. And so the name describes the structure of these joints. The head of the femur has a ball shape, and the head of the humerus has a ball shape, and that fits into a socket shape. The acetabulum is the socket shape for the acetabulofemoral joint, and the glenoid cavity is the socket shape for the glenohumeral joint. So these ball and socket joints enable rotation as well as flexion and extension and abduction and adduction. So a wide range of motions, rotation as well as flexion, extension, abduction, and adduction are possible at a ball and socket joint, like the acetabulofemoral joint, commonly known as the hip joint, or the glenohumeral joint, commonly known as the shoulder joint.