A joint is a point in the body where two or more bones connect. Joints are made up of different components. Some of these components are
Meniscus: This is a part of the cartilage that is curved in the knee, as well as in other joints
Synovial Fluid: This is a sticky and clear fluid that the synovial membrane secretes.
Bursas: These play a major role in ensuring that the movements that take place between the joints are cushioned. They are sacs filled with fluids. They exist between ligaments, bones, etc.
Tendons: Tendons are tough connective tissues that are located on both sides of a joint that attach muscles to bones and play a crucial role in the movement of joints.
Ligaments: Ligaments exist to put a check on the movement of joints. They ensure that joints do not move beyond their range. Also, they help the bones that meet at joints connect better.
Synovial Membrane: Synovial membrane releases a fluid that is sticky and clear. This fluid helps in lubricating the joint. Ultimately making movement around the joint paint-free. A reduction in this fluid leads to arthritis and pain around the joint.
There are various types of joints in the body and one of them is synovial joints. Synovial joints are of various types and one of them is saddle joints.
Saddle joints go by their name because one of the bones that makes up a saddle joint is directed inwards at one part of the joint and has the appearance of a saddle. Also, the second bone which makes up the joint is turned outwards and has the appearance of someone riding a saddle. Although popularly known as saddle joints, these joints are also called sellar joints. They are very flexible and can be found in the inner ear, the thumb, and the shoulder.
How do Saddle Joints Move
Saddle joints have some similarities with hinge joints. They are, however, a lot different from hinge joints because they have a variety of range of motions. They do not just move forward and backward. Their movements involve abduction-adduction and flexion-extension.
The movement involving flexion and extension are in opposition to each other. Flexion involves reducing the angle between the bones. An example of this is bending the elbow. Extension, on the other hand, involves increasing the angle between two bones that are fused at a joint. An example of this is stretching the elbow.
Abduction and adduction, on the other hand, are joint movements that are either away from a structure’s midline or towards its midline. In adduction, a movement is made towards a midline, however, in abduction, a movement is made away from a midline.
While there are saddle joints that can carry out abduction- adduction movements and other saddle joints that can carry out flexion-extension movements separately, there are some saddle joints that have the ability to carry-out both abduction-adduction movements and flexion-extension movements.
Examples of Saddle Joints
It is good to know what saddle joints are. That, however, is not enough. It is vital that you know some examples of saddle joints. That being said, some examples of saddle joints are;
The sternoclavicular joint is a perfect example of a saddle joint. It is the point where the manubrium meets with the clavicle. This joint is responsible for making the movement of the arm over the head possible. It also plays a major role in supporting the shoulder.
The sternoclavicular joint is surrounded by very strong ligaments. As a matter of fact, the ligaments holding the sternoclavicular joints are considered to be some of the strongest ligaments in the body. This is one reason it is difficult for injuries to occur to this joint.
Trapeziometacarpal joint is a good example of a saddle joint. It is a joint that links the thumb’s metacarpal bone to the trapezium. This joint is capable of abduction-adduction and flexion-extension movements. These movements make it possible for the thumb to be able to hold objects. Furthermore, it allows the thumb to move towards the other fingers on the palm.
That’s not all. The trapeziometacarpal joint is also a point that is prone to arthritis. When this occurs, there is stiffness, weakness, and pain in the inner wrist, as well as the thumb.
The incudomalleolar joint exists in the inner ear. It is a joint that links the incus to the malleolus and plays a major role in your ability to hear as the incus and malleolus are very important for hearing. This joint basically functions in the transfer of vibrations in the ear. These vibrations, when transferred are interpreted by the brain as sounds.
Significance of Saddle Joints
- The saddle joints in the body’s most flexible joints
- They help the hand grasp better
- They help the hand carry out activities such as drawing, painting, writing, etc.