Recallab › Question bank › Anatomy › Histology › #50204
Classification of joints
Which feature is present in a synovial joint but absent from both fibrous and cartilaginous joints?
- correctA. A cavity lined by a membrane that secretes hyaluronan-rich fluid
- B. Continuity of the two bones by dense connective tissue
- C. The presence of a fibrous capsule
- D. A layer of hyaline cartilage covering the bone ends
Explanation
Key fact
The joint cavity is what defines a synovial joint. Fibrous and cartilaginous joints join bone to bone directly, with no space between.
A cavity lined by a membrane secreting hyaluronan-rich fluid. No other class of joint has a cavity at all.
Why
Joints are classified by what lies between the bones.
In a fibrous joint it is dense connective tissue - a suture or a syndesmosis.
In a cartilaginous joint it is cartilage - hyaline in a primary, fibrocartilage in a secondary.
In a synovial joint there is a fluid-filled space instead.
The synovial membrane lines everything except the articular surfaces and secretes hyaluronan, which is what makes the fluid viscous.
The three classes of joint, defined by what lies between the bones
Why not the others
- B. Continuity of the two bones by dense connective tissue — defines a fibrous joint - a suture, syndesmosis or gomphosis.
- C. The presence of a fibrous capsule — is characteristic of synovial joints but the surrounding fibrous tissue of other joints performs the same role. The cavity is the unambiguous feature.
- D. A layer of hyaline cartilage covering the bone ends — is present in a synovial joint, but also is the joining tissue of a primary cartilaginous joint such as the first sternocostal joint. It does not distinguish them.
Remember
No cavity, no synovium. Stability and mobility trade off against each other - the shoulder is the most mobile and the most dislocated joint in the body.
Go deeper
Hyaluronan gives synovial fluid its viscosity; lubricin provides boundary lubrication of the cartilage surfaces.
Articular cartilage has no perichondrium, no blood supply and no nerves, which is why it cannot heal and why early arthritis is painless.
The costal cartilages of ribs 6 to 9 articulate with each other by small synovial interchondral joints, which is the point the recall was making.
Gray's Anatomy for Students, 5th ed. (Elsevier, 2023); BD Chaurasia's Human Anatomy, 10th ed. (CBS Publishers, 2025).