Saddle Joints

One of three types of joints found in the body, synovial joints are located in the synovial fluid. Synovial joints are distinct from other joints in that they possess a fibrous joint capsule filled with synovial fluid. Synovial joints include hinge joints and ball-and-socket joints, which are both types of joints. Saddle joints are a form of synovial joint that is distinct from the others.

The saddle joint got its name because one of the bones that makes up one of its parts is concave (bent inward) at one end, giving it the appearance of a saddle. The end of the other bone is convex (curved outward), and thus has the appearance of a rider in a saddle.

As a result of the concave-convex bone interaction being linked to the movement of a horse rider riding a horse, the term “saddle” is coined because both bone surfaces are saddle-shaped. The saddle joint, also known as the sellar joint, is a type of joint that connects two bones.

Movement

Adduction, abduction, and circumduction are all movements that saddle joints may perform, and they are comparable to those performed by the condyloid joint.  Axial rotation, on the other hand, is not permitted. Saddle joints are biaxial joints, meaning that they allow movement in both the sagittal and frontal planes.

The carpometacarpal joint of the thumb,the sternoclavicular joint of the thorax, the incudomalleolar joint of the middle ear and the calcaneocuboid joint of the heel are all examples of saddle joints in the human body.

Unlike hinge joints, such as those between the bones of your fingers, saddle joints have a far larger range of motion than a basic backward-and-forward movement. Saddle joints include two main forms of movement, known as flexion-extension and abduction-adduction.

Abduction and adduction are movements connected to the midline of a structure. For example, spreading your fingers wide sends them away from the midline down the centre of your hand.

Structure

A saddle joint is formed when one bone surface is concave and the other is convex.This has a big impact on stability.

Examples of saddle joints

• Trapeziometacarpal joint 

The trapeziometacarpal joint, which is located at the base of your thumb, is an excellent example of a saddle joint. The trapezium and the metacarpal bone of your thumb are connected by this ligament.

With its flexion-extension and abduction-adduction features, this joint allows your thumb to spread out wide to assist you hold large objects in your hands, while also moving inward, allowing it to snugly contact each of your other fingers.

A typical site for osteoarthritis is the thumb and inner wrist, which can cause discomfort, weakness, and stiffness in the thumb and inner wrist area.

• Sternoclavicular joint 

When your clavicle (collarbone) joins your manubrium (upper section of your sternum), you have a junction called the subclavian joint (breastbone). It allows you to perform a variety of activities, like raising your arm above your head, while also supporting your shoulder.

It is difficult to hurt the sternoclavicular joint because the ligaments that surround it are some of the strongest in your body, making it difficult to dislocate. High-impact collisions, falls, and automobile accidents, on the other hand, can all cause injury to your sternoclavicular joint.

• Incudomalleolar joint

 In the inner ear, this joint links two little bones known as the malleus and incus, which are connected by a short ligament. Each is critical to your capacity to hear. Main purpose of the incudomalleolar joint is to aid in the transfer of vibrations in your ear, which are then recognised as sounds by your brain.

Head injuries, long-term ear infections, and introducing foreign objects too deep into your ear canal can all result in damage to this joint and impair your ability to hear in the future.

Features of saddle joints

• Saddle joints are quite similar to condyloid joints in appearance and function.
• The word saddle joint is derived mostly from the shape or construction of the joint.
• This joint has a shape that is very similar to a saddle seat, which is why it is dubbed saddle joint.
• The connecting bones are fashioned like interlocking saddles, which helps to keep the bones together.
• In comparison to other joints, this joint has a higher range of motion.
• A saddle joint is less flexible than a ball and socket joint since it does not allow for complete rotation.
• When comparing saddle joints to other types of synovial joints, the flexibility and interlocking are greater in saddle joints.
• Saddle joints are a hybrid of the hinge joint and the ball and socket joint in terms of their structural design.

Conclusion

When the opposing surfaces of two opposing synovial joints are reciprocally concave and convex, the saddle joint (also known as sellar joint or articulation via reciprocal reception) is formed.The saddle joint got its name because one of the bones that makes up one of its parts is concave (bent inward) at one end, giving it the appearance of a saddle. As a result of the concave-convex bone interaction being linked to the movement of a horse rider riding a horse, the term “saddle” is coined because both bone surfaces are saddle-shaped. The saddle joint, also known as the sellar joint, is a type of joint that connects two bones.Flexion and extension are opposite actions, yet they’re easy to visualise. This is an example of flexion.A saddle joint is formed when one bone surface is concave and the other is convex.A saddle joint is less flexible than a ball and socket joint since it does not allow for complete rotation.When comparing saddle joints to other types of synovial joints, the flexibility and interlocking are greater in saddle joints.Saddle joints are a hybrid of the hinge joint and the ball and socket joint in terms of their structural design.