Types of Joints

To start I am going to talk about the types of joints in the body we find and how they move and all of their nerdy and scientific names. Most of the origins of our words come from the Greek and Latin languages so if you have a basic understanding of the roots of words, it will help paint a picture of what is going on just by hearing the names of the conditions. No need to go and get a Berlitz learning program but sometimes a medical dictionary is quite helpful.

Lets get started. After I get through this we will focus on the specific joints.

Some joints have cavities (spaces) and some do not. Joints range in definition from immovable to slightly movable to movable. I am going to move right into the movable joints since those are the ones that have the most problems and are the more common joint in the body. As I describe a joint I am going to go from the least mobile to the most mobile.

Gliding Joint (Arthrodia or plane joint) These joints only allow for a gliding or twisting motion. Very similar to a porch swing, it mostly glide and has a little bit of twist motion. An easy one to look at in your body is the joints in your hand (not the fingers). Grab the palm of your right or left hand near the knuckle and try pushing it up and down. If you want to feel it twist, take all four knuckles in one hand and squeeze, much like getting a hearty hand shake you can feel these bones give a little bit.

Hinge Joint (ginglymus or uni-axial) This is when a concave surface glides along a convex surface. This joint only allows for flexion (bending the joint) and extension (straightening the joint or locking it out), in terms of movement. The eblow is a hinge joint.

Pivot Joint (Trochoid or uni-axial) A rotation around a long axis. Much like the wheel of a car rotating around the axel. The top joint in our neck (C1 or atlas) rotates around the second cervical bone (axis). This type of joint generally has lots of rotation.

Condyloid Joint (Ellipsoid or Bi-axial) Condyle or ovoid in shape with an eliptical cavity to allow flexion, extension, adduction (motion towards the body), abduction (motion away from the body)and circumduction. The wrist is a condyloid joint. You can roll your wrist around but not rotate it. Don't believe me? Turn one hand palm down, with the other hand grip the wrist very firmly. Now that you are holding your own wrist, palm down try to turn it face up. It wont rotate to palm up, but you can move it in any other direction. The motion that allows the palm to turn face up comes from the joints in your forearm, which happen to be pivot joints.

Saddle Joint (bi-axial) Both joints have a saddle shape like a horse and its saddle. One side is concave and one side is convex. Really the only joint that has this is our thumb. We have mastered the art of jar opening with the saddle joint. Woo hoo, now can you hand me a pickle?

Last joint type... Ball and Socket (Spheroid, enarthrosis or poly-axial) These joints are the only joints that allow motion in all directions. This is like the shoulder and hip. While we lose some motion directions as we age, they are meant to move in all directions. Think babies who pull thier feet to thier head.