What are my joints made up of?

There are joints in the body, and they fall into three categories, fibrous, cartilaginous, and synovial. Fibrous joints, like that of the skull have zero movements. Cartilaginous joints, such as those found in the pelvis or the spine have very little movement. The most common joints are synovial joints, which make up about 80% of all joints in the body. The elbow, knee, hip, and shoulder are all examples of synovial joints.

Joints have the following parts:

Joint Capsule: Connective tissue which surrounds the entire joint.

Synovial membrane: The inner layer of the capsule that secretes lubrication.

Hyaline Cartilage: A slick dense cartilage that covers the ends of bone.

Synovial Fluid: A slippery substance secreted by the synovial membrane which allows for smooth joint motion.

Ligaments: Bands of connective tissue that connect bone to bone and work with the joint capsule to prevent against an extreme or awkward motion.

Tendons: Connective tissue which connects muscle to bone and also aids in supporting the joint.

Dr. Michael Roizen, MD
Internal Medicine

Here are the parts that make up your joints:

Collagen: a type of tissue that serves as the scaffolding upon which everything else is built.

Tendons: collagen fibers that attach muscles to bones.

Ligaments: soft tissues that connect bone to bone. Joints with few or weak ligaments, such as the shoulder, allow more motion, while joints with strong support structures, such as the hip joint, are more stable, but have a smaller range of motion. We like to call these biological trade-offs. For more mobility, you get less stability--and vice versa.

Cartilage: gives our bodies form before our bones are mineralized after birth, and continues to give structure to our ears and noses. In the rest of the body, it serves as the plate of soft tissue at the ends of bones that prevents bone-on-bone clanking.

The cartilage between bones acts as the internal shock absorber for your joints, while muscles are the external shock absorbers. As an example, the meniscus--cartilage that’s especially vulnerable to injury--works as a key shock absorber in the knee. Since it does not have a blood supply of its own, cartilage needs to get nutrients from the surrounding synovial fluid. 

Synovial fluid: joint oil, if you will. In a normal, healthy joint, the cartilage is smooth, and the synovial fluid is as pure as spring water. If a joint becomes injured, infected, or inflamed, you can produce too much synovial fluid, which leads to painful swelling.

YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

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YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

A few years ago, we wrote YOU: The Owner’s Manual, which taught people about the inner workings of their bodies—and how to keep them running strong. But you know what? There’s a big difference...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.