Pivot Joints: Definition, Diagram, & its Examples

Pivot joints are those joints that show movement in a single direction. Joints are points of contact between bones. The joint acts as a fulcrum that helps in dispersing the force generated by the muscles. The Pivot joint is a type of Synovial joint that is characterized by the presence of synovial fluid. Other types of Synovial joints are Ball and Socket Joints, Hinge Joints, and Gliding Joints. One example of the pivot joint is the joint between the atlas and the axis. Another Pivot joint in the human body is made of the bones in the wrist.

What is a Pivot Joint?

Pivot joints are part of synovial joints. They are described in two words “Pivot” and “joints”. Therefore, “Pivot” means a point of an object on which another object is moving in an up-and-down position. E.g. In the neck, the Skull moves on the upper point of the neck bone in the position of left, right, or up and down. “Joints” are the places where two bones meet that allow us to move and give flexibility to our body.

Types of Pivot Joints

There is just one axis of rotation possible with a pivot joint. It is also known as the “monaxial joint”. In this joint, the rounded bone fits into a shallow depression in another bone and one bone rotates around another within a concave ring formed in the second bone. A ligament lines this ring to provide smooth motion. There are two major types of Pivot Joints- Radioulnar Joint and Atlas-axis joint. These are explained below:

Proximal Radioulnar Joint

It is located near the elbow and is located within the same articular capsule. It is created by the articulation of the radial notch of the ulna and the head of the radius. The annular radial ligament, which surrounds the joint like a collar, secures the radial head like a cap. The synovial membrane, which lines this ligament, ensures that movement is fluid and free from excessive wear and tear. The movement allowed by these joints is; “Pronation” which is formed by the pronator quadratus and pronator teres, and another one is “Supination” which is formed by the supinator and biceps brachii.

Distal Radioulnar Joint

It is located just proximally to the wrist joint. It is created by the articulation between the ulnar notch of the radius, and the ulnar head. The articular disk, a fibrocartilaginous ligament, is present in the anterior and posterior ligament that support the joint and their function is to bind the radius and ulna together or separate the distal radioulnar joint from the wrist joint.

Median Atlantoaxial Joint

This joint lies between the two cervical vertebrae of the spine. The first vertebra is called atlas and the second one is called the Axis. It is located between first and second vertebra in the spine. It is created by the articulation between the odontoid process (dens) of the axis and the anterior arch of the atlas, and their function is to allow rotational movement of the head, particularly the ability to turn the head from side to side.

Pivot Joints Diagram

Below are the diagrams explaining the different types of Pivot Joints:

Pivot Joints Examples

In addition to the atlas-axis joint and radioulnar joints, there are a few other examples of pivot joints in the human body, including:

• The rotation of the skull is feasible due to pivot joints. The twisting movements of the bones of the forearm, against the upper arm, is due to pivot joints.
• The two bones are connected to each other, namely the radius and ulna that is located near the wrist by another pivot joint. With the help of two bones, they twist around each other by using a pivot joint.
• Without pivot joints, the skeleton of the physical body would lack flexibility and freedom of movement thus, making the movement of the skeleton quite stiff and rigid.
• Atlantooccipital joint: This joint is located between the skull and the atlas (C1). It allows for the nodding motion of the head.
• Intercarpal joints: These joints are located between the carpal bones in the wrist. They allow for a small amount of rotation of the wrist.

Functions of Pivot Joints

It plays a role of movements in the body’s functions, Let’s see the pivot joints’ functions as follows:

1. It allows movement where a cylinder-shaped bone is rotating inside the ring-shaped bone on a single axis. Like; In the neck, Skull moves on the upper point of the neck bone in the position of left, right, or up and down.
2. They are quite stable in nature, For example, a thick syndesmosis holding the ulna and radius together supports the radioulnar joints that are inversely in relationship to joint stability and movement.
3. They mostly coordinate with other joints, and muscles for creating movements. E.g. In this process, forearm works with the elbow joint and muscles to get movements such as holding, pushing, or pulling.
4. Pivot joints are adapted to adjust various loads and pressures. It is crucial for joint-stressing exercises like weightlifting and athletics, where the joints must endure high degrees of strain and stress.

Implications of Pivot joints

1. Forearm rotation: Rotation of the forearm is referred to as pronation and supination. Supination extends the hand’s palm whereas pronation reduces it. In this activities movements are essential like; turning as a screwdriver, turning as a doorknob.
2. Head movement: In this joint movement allows in the position of left, right, or up and down. Although, neck is connected to head. Here, the atlantoaxial joint is a type of pivot joint which is between the first and second cervical vertebrae.
3. Main purpose: Pivot joint function is to allow a body part to rotate around a single point, very similar to the rotation of a wheel because a pivot joint rotates around a single axis, it is often known as a ”rotary joint”. 
4. Muscles work: The muscles that link to the bones that comprise the pivot joints provide rotational movement.Their coordination is must So, that proper muscle control is essential to prevent injury and ensure smooth, controlled rotation around the joint.
5. Damage Tendency: Excessive power, quick blows, and repeated tension can cause damage to pivot joints. These joints are particularly vulnerable to injury from disorders like inflammation, imbalanced muscles, and improper body mechanics.

Disorders of Pivot Joints

Pivot joints are a type of there synovial joint that allows for rotation around a single axis. Pivot Joints sometimes get damaged due to physical stress or can get infected with infection or other disease. The major illnesses are listed below: 

1. Twists and pulls: Tendons and Ligaments are important components of the skeletal and muscular system. These support pivot joints and any damage to these causes a strain or sprain. If tendons get stretched or ripped, it results in a Strain. On the other hand, breakage of ligaments leads to a Sprain. Unexpected trauma or overuse are frequently the culprits of sprains and strains.
2. Dislocation: Sometimes while playing or when in an accident, the joint’s bones move out of their usual alignment. This is known as Dislocation.  If left untreated, dislocations can be extremely painful and lead to joint injury.
3. Arthritis: Sometimes the joints get inflamed due to infections or autoimmune diseases. This joint inflammation is known as Arthritis. Rheumatoid Arthritis is the most common type that affects Pivot Joints.
4. Fractures: Two bones join together to form a joint. If there are cracks in the bone, then these are called Fractures.They can be caused by trauma, such as a fall or a car accident.
5. Instability: If a pivot joint is loose and may dislocate, it causes instablity. Instability can make it difficult to perform everyday activities and can increase the risk of further injury.
6. Articular surfaces could over time decay due to constant movement and joint stress.

FAQs on Pivot joints

1. How many Pivot Joints are in the Human Body?

Pivot joints allow rotations, and although you have many joints in your body, there are only three pivot joints. They are located in your neck, your wrist, and your elbow.

2. What will Happen if there is no Pivot Joint in our Body?

Without pivot joints, the skeleton of the human body would lack flexibility and freedom of movement thus, making the movement of the skeleton quite stiff and rigid.

3. What are the Benefits of a Pivot Joint?

A pivot joint permits movement of the bones in one plane, such as rotation around a single axis. In the human body, the joint of the wrist that lets the plam of the hand move up and down is possible because of pivot joints.

4. How many Planes does a Pivot Joint move in?

A pivot joint permits movement of the bones in one plane, such as rotation around a single axis.

5. What are Real Life Examples of Pivot Joints?

Two real life examples of Pivot Joints are: Pivot joints present in the neck which allow its rotation and the ones present in the forearm between radius and ulna.