Joints in the human body is where bones are connected. Human body consists of a variety of joints. Some joints have limited motion, like joints in vertebrates. Some joints have more movement than others, like the joints in toes and fingers. Such joints are known as hinge joints.
Hinge joints are classified into the category of synovial joints. A synovial joint is a kind of joint which is found between two bones that move against each other, like joints of limbs. For example, shoulder, hip, elbow and knee. Therefore, a hinge joint is defined as the joint between two bones that allows movement only in one plane. For instance, human fingers, toes, elbows, knees, and ankles contain hinge joints.
Implications of Hinge Joints
- Unlike other joints, hinge joints permit movement across one plane.
- Hinge joints allow straightening, bending and flexing of joints. For example, flexing of a finger or a toe.
- The bones in hinge joints are covered with a protective cartilage and a thick fluid known as synovial fluid. This fluid helps in lubricating the bones, making them move without much friction.
- All hinge joints include muscles, ligaments and other kinds of tissues that maintain the joint.
- Hinge joints are considered more steady than ball-and-socket joints, such as hips and shoulder joints. But there is greater movement in ball-and-socket joints.
- Unlike the movement in hinge joints, the movement in ball-and-socket joints is along more than one plane.
- Even though hinge joints are considered stable, there are chances of dislocating them. The most commonly dislocated hinge joints occur in parts of hands and feet.
- Performing regressive sport activities usually affect 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.
Types of Hinge Joints
- The Elbow: The elbow joint connects the upper part of the arm known as humerus, to the two bones in the lower part of the arm known as radius and ulna respectively. This is called the humeroulnar joint. The humeroulnar joint is situated between a notch in the ulna and a notch in the humerus.
- The Jaw: The jaw is a hinge joint that allows one to open and close their mouth. The jaw can also move from side to side. Although the jawbone is not a hinge joint, the jawbone moves as a result of the hinge joint.
- The Hand: The interphalangeal joints are the joints that all the fingers together. As human beings utilize hands for daily activities, it is considered to be the most important hinge joint. There are three sets of joints namely, metatarsophalangeal joints, proximal interphalangeal joints and distal interphalangeal joints.
- The Foot: Just like the hands, the feet also consist of three interphalangeal joints. They have two planters, tendons and other ligaments. Even though toes appear different than fingers, they show two similar movements namely flexion and extension.
- The Knee: The knee joint connects the thighs to the lower part of the leg. The knee joint is the largest joint in the human body and is different from the other hinge joints. It is different because it not only allows movement like flexion and extension, but also side-to-side movement.
- The Ankle: The ankle joint is called the talocrural region. This joint is responsible for the movement of feet and ankles. This joint permits side-to-side movement. The hinge joint of the ankle is made of three separate joints namely, talocrural joint, subtler joint and tibiofibular joint.
After learning the meaning of hinge joints, their importance and the types of hinge joints, one can see the significance of hinge joints in our body. The hinge joints are integral components of complex biomechanics of the human body. The hinge joints might undergo degradation of articular cartilage, which results in osteoarthritis, in joints of the knee, hand and feet. Aspects like stress, trauma, daily activities, weight, lifestyle and genes play a major role in forming osteoarthritis.
Frequently Asked Questions on Hinge joints
What movements do hinge joints permit?
The hinge joint movement is across one axis that permits for flexion and extension. While flexion is for bending, the extension is for straightening of a hinge joint.
Is the shoulder a hinge joint?
No, the shoulder is not a hinge joint but is a ball-and-socket joint.
What are the examples of hinge joints?
The hinge joint includes ankle, elbow, knee and interphalangeal joints.
>Why do hinge joints only bend in one direction?
Hinge joints bend only in one direction because of their form and this concept is explained as ‘form dictates function’.
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