Pivot Joints

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What are Pivot Joints?

Pivot joints are joints that let the rotatory movement of bones around one axis. The pivot joint may be an articulatio synovialis during which the ends of two bones connect. In this joint, a cylinder-shaped bone rotates inside another ligament that forms a hoop round the joint. The joint between the atlas and therefore the axis which is true under the skull allows the turning of the top from side to side. The rotation of the skull is feasible due to pivot joints. The twisting movement of the bones of the forearm, against the upper arm, is owing to pivot joints.


Implications of Pivot Joints

  • The rotary joint located near the elbow, holds the 2 forearm bones, radius and ulna, together.

  • 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.

  • The rotary joint situated at the bottom of the skull connects the primary vertebrae of the spine to the second vertebrae. It helps in the side-to-side rotation of the head.

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

  • In the physical body, the joint of the wrist that lets the palm of the hand move up and down is feasible due to pivot joints.

  • 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.

Common Disorders

The rotary joint often suffers from subsequent disorders:

  1. Ankylosis:

It is the fusion of bones across a joint and is a complication of arthritis.

  1. Ankylosing Spondylitis:

This is often a disease that causes a number of bones within the spine to fuse.

  1. Capsulitis:

Improper foot mechanics, where the ball of the foot might experience excess pressure causes the disorder capsulitis.

  1. Dislocation:

When there is a displacement of the bone from its normal position, that is called Dislocation.

  1. Neoplasms:

It's an abnormal growth of tissue that may be classified as characteristics of cancer.

  1. Rheumatoid Arthritis:

This is often an autoimmune condition, which is caused by the system attacking healthy body tissue.

Joints within the physical body are where bones are connected. There are a variety of bones that can be found in the human body. Like joints in the vertebrates, some joints have limited motion. Some joints have more movement than others, like the joints in the toes and fingers. Such joints are known as hinge joints.

Synovial joints belong to the category of Hinge joints. An articulatio synovialis may be a quite joint which is found between two bones that move against one another, like joints of limbs. For example, shoulder, hip, elbow and knee. Therefore, a hinge joint is defined to be the joint between two bones that permits movement only in one plane. For instance, human fingers, toes, elbows, knees, and ankles are a part of hinge joints.


Implications of Hinge Joints

  • Unlike other joints, hinge joints help in the movement across one plane.

  • Hinge joints help in straightening, bending, and flexing joints.

  • The bones in hinge joints are covered with protective cartilage and a thick fluid referred to as synovia. This fluid helps in lubricating the bones, making them move without much friction.

  • All hinge joints include muscles, ligaments, and other forms of tissues that maintain the joint.

  • Hinge joints are considered more steady than ball-and-socket joints, like hips and shoulder joints. Ball and socket joints have a greater role in the movement.

  • Unlike the movement in hinge joints, the movement in ball-and-socket joints is along quite one plane.

  • Even though hinge joints are considered stable, there are chances of dislocating them. In the hinge joints, the most dislocated joints are hands and feet.

  • Performing some of the difficult sports activities usually create problems in the hinge joints. For example, runner’s knee.

  • By maintaining a healthy diet, reducing stress, frequent movement, and strengthening muscles around the joints, one can maintain a healthy hinge joint.

Conclusion

So far we've learnt how pivot joints help in flexibility and freedom of movement to the skeleton of the body. It allows movement of the top from side-to-side, the movement of wrists in up and down direction and twisting of the forearm bones against the upper arm. Therefore, the functioning of pivot joints is important for the smooth movement of joints.

FAQ (Frequently Asked Questions)

Q1. What Movements do Pivot Joints Allow?

Ans: Pivot joints allow rotation for both internal and external. External rotation is the rotation when we rotate an arm outward and internal rotation is when we rotate an arm inward.

Q2. What is the Function of a Pivot Joint?

Ans: The pivot joint allows rotational movement as the rounded bones move across their own axis.

Q3. Is the Wrist a Pivot Joint?

Ans: Yes, the wrist is a pivot joint that moves in relation to the forearm bones namely, radius and ulna.