Synovial Joint Diagram – Capsule, Cartilage, Fluid, Ligament

All 8 parts on the diagram

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Start here: 5 main parts 5

Articular cartilage A thin, smooth layer of hyaline cartilage. It covers the end of each bone, so the bones glide without damage.
Joint cavity The space between the bones, enclosed by the articular capsule. Only synovial joints have one.
Synovial fluid A thick, slippery fluid in the joint cavity. It cuts friction and feeds the articular cartilage.
Articular capsule A tough fibrous wall, also called the joint capsule. It is joined to each bone just outside its joint surface.
Ligament A ligament: a strong band of fibrous tissue joining the bones. It lets the joint move normally but stops it moving too far.

Other 3

Synovial membrane The synovial membrane: a thin lining on the inside of the capsule. Its cells make the synovial fluid.
Periosteum The tough covering on the outside of each bone. The capsule joins it.
Bursa A small sac of fluid near a joint. It keeps skin, muscle or tendon from rubbing on the bone.

How this list was compiled: Read 2026-09-27. OpenStax, Anatomy and Physiology 2e, section 9.4 Synovial Joints, https://openstax.org/books/anatomy-and-physiology-2e/pages/9-4-synovial-joints : a synovial joint has a joint cavity, which fibrous and cartilaginous joints lack; the articular capsule, a fibrous connective tissue attached to each bone just outside its articulating surface, forms the walls of the cavity; the articulating surfaces are covered by articular cartilage, a thin layer of hyaline cartilage; a thin synovial membrane lines the inside of the capsule and its cells secrete synovial fluid, which lubricates the joint and nourishes the avascular cartilage; ligaments, strong bands of fibrous connective tissue, hold the bones together and limit movement, and may be extrinsic, intrinsic or intracapsular; some joints have an articular disc or meniscus, or a fat pad; bursae are thin sacs of lubricating fluid that stop skin, muscle or tendon rubbing on bone. Licence: own work

The drawing: Drawn for this site on 2026-10-05 by script. Our own drawing, nothing traced. The layout of the layers (cartilage, cavity, lining and capsule) is laid out by eye after one public domain plate in Henry Gray, Anatomy of the Human Body (20th US edition, 1918), fig. 299, diagrammatic section of a diarthrodial joint (https://commons.wikimedia.org/wiki/File:Gray299.png). A plan, not to scale and of no one joint: the recess on each side of the cavity is drawn apart from the pool of fluid by a line, though in a joint they are one space, and the lining carries the same tint as the fluid. Licence: own work

How it works

Asked to correctly identify the following parts of a synovial joint? This diagram shows a generic synovial joint cut through, with all 8 parts numbered. Start with the 5 main parts.

Read the full guide

Inside the joint

The ends of the two bones are capped with smooth articular cartilage. Between them is the joint cavity, filled with slippery synovial fluid, so the bones glide with little friction.

Around the joint

The articular capsule wraps the joint and joins the periosteum on each bone. Its inner lining, the synovial membrane, makes the fluid. Ligaments outside hold the bones together, and a bursa nearby stops tissues rubbing.

Only synovial joints have a joint cavity; fibrous and cartilaginous joints join the bones directly, with no space between them.

Questions and answers

What produces synovial fluid?

The synovial membrane, the thin lining on the inside of the articular capsule. The fluid lubricates the joint and feeds the articular cartilage, which has no blood vessels.

What is the difference between the capsule and a ligament?

The articular capsule is the wall that encloses the whole joint. Ligaments are separate strong bands, often outside the capsule, that hold the bones together and limit movement.

What does a bursa do?

It is a small sac of fluid near a joint that lets skin, muscles or tendons slide over the bone without rubbing.