Joint

Joint. Although the bones are rigid and hard, they cannot move because they are not glued together, but separated by the joints that act with the muscles and are the point of union between two or more bones. This allows normal movements to be performed and those that cannot or should not be performed are prevented.

Summary

[ hide ]

  • 1 Description
  • 2 Types of joints
  • 3 Components of a Joint
  • 4 Cartilage wear
  • 5 External Links
  • 6 Sources

Description

The human skeleton has more than 100 joints that connect many bones and thanks to them there can be adjustment and mobility between the bones. Their movements depend on the needs of each part, they can make large movements such as the extremities, be fixed without movement like the skull sutures or have little movement like those of the vertebrae . Movement is also due to ligaments, the strength of the muscles that move them, and the shape of the joints. Each joint allows some type of movement and we do not have any that allows stretching, bending and turning everywhere. The movements depend on the type of joint that exists in that part of the body.

Types of joints

  • Hinge like those of the elbow, knee and between the fingers that allow to stretch and bend the legs, arms and hands.
  • Saddle, like the thumb of the hand and that allows movement in 2 directions.
  • Spheroidal like that of the femur, its almost round shape allows it to perform movements forward, back and sideways.
  • Slippery, like that of the foot bones, which can withstand large loads, even if they do not move much.

To protect bones from natural wear and tear and friction with each other, between each bone there are “cushions” that contain a slippery, firm and elastic substance called cartilage. There is also between the bones a lubricating liquid called synovial fluid that together with cartilage , cushions the blows and prevents friction and wear of the bones. When this fluid is spilled, it causes severe pain and swelling in the joints.

Components of a Joint

  • Cartilage: In the joint, the bones are covered with cartilage (a type of connective tissue), which is made of cells and fibers and is resistant to wear. Cartilage helps reduce friction caused by movements.
  • The Synovial Membrane: It is a tissue that covers the joint and encloses it in the joint capsule. The synovial membrane secretes synovial fluid (a clear, sticky fluid) around the joint to lubricate it.
  • The Ligaments: Strong ligaments (bands of hard and elastic connective tissue) surround the joint to support it and limit its movements.
  • Tendons: Tendons (another type of hard connective tissue), located on both sides of the joint, are attached to the muscles that control the movements of the joint.
  • Bursae: Fluid-filled pockets, called bursae, located between the bones, ligaments, or other adjacent structures, help cushion friction in a joint.
  • Synovial Fluid: A clear, sticky liquid secreted by the synovial membrane.
  • The Bone: Examples:
    • The tibia – shin bone.
    • The patella – knee cap.
    • The Meniscus: – semilunar cartilage found in the knee and other joints.

Cartilage wear

The wear of the cartilage due to osteoarthritis , develops gradually, giving no symptoms in its early stages.

  • First, the cartilage structure gradually loses elasticity and is more prone to injury from shock or overuse.
  • The synovium, which is the lining of the joints, becomes inflamed as a result of cartilage wear, and the inflammation produces cytosine, which are inflammatory proteins and enzymes that cause further damage to cartilage.
  • With cartilage wear, the bone is exposed and the joint loses its natural shape, forming bone buds or spurs.
  • Finally, liquid-filled cysts and sometimes bits of bone or cartilage float in the joint space, causing bone inflammation along the joint, causing further inflammation of the synovium.

 

by Abdullah Sam
I’m a teacher, researcher and writer. I write about study subjects to improve the learning of college and university students. I write top Quality study notes Mostly, Tech, Games, Education, And Solutions/Tips and Tricks. I am a person who helps students to acquire knowledge, competence or virtue.

Leave a Comment