A saddle joint is a type of synovial joint in which the articulating surfaces of both bones are shaped like a saddle — concave in one direction and convex in another. This allows movement in two planes. The best example of a saddle joint in the human body is the carpometacarpal (CMC) joint of the thumb, located at the base of the thumb.
Saddle joint is a biaxial synovial joint — allows movement in two planes.
Both articulating surfaces are concave in one direction and convex in the other.
Best example: Carpometacarpal (CMC) joint of the thumb.
Movements: flexion/extension, abduction/adduction, circumduction — but NO rotation.
The thumb's opposability is due to its saddle joint.
Sternoclavicular joint (sternum + clavicle) is also sometimes classified as a saddle joint.
• Both articulating bone surfaces are concave in one direction and convex in another (like a horse saddle) • One bone surface is convex; the complementary bone surface is concave, fitting together like a rider on a saddle • The joint is enclosed in a synovial capsule with synovial fluid for lubrication • It is a biaxial joint — movement occurs along two axes
Saddle joints allow:
Saddle joints do NOT allow: • Rotation (axial rotation is not possible)
This gives greater mobility than hinge joints but less than ball-and-socket joints.
The most important and commonly tested example:
Carpometacarpal (CMC) joint of the thumb: • Located at the base of the thumb • Between the trapezium (a carpal bone) and the first metacarpal bone • Allows the thumb to move in multiple directions — crucial for gripping objects • The thumb's opposability (ability to touch other fingers) is due to this joint
Other examples (less common): • Sternoclavicular joint: between the sternum (breastbone) and clavicle (collarbone) — sometimes classified as a saddle joint
Joint type | Movement | Example Hinge joint | One plane (flexion/extension only) | Elbow, knee, ankle, finger joints Saddle joint | Two planes (no rotation) | Base of thumb (CMC joint) Ball-and-socket | All directions + rotation | Shoulder, hip Gliding/Plane joint | Sliding | Between carpal bones, vertebrae Pivot joint | Rotation only | Atlas-axis (neck), radio-ulnar joint Condyloid joint | Two planes (no rotation) | Wrist joint (radiocarpal)
A saddle joint is a biaxial synovial joint where both articulating surfaces are concave in one direction and convex in another (like a saddle). It allows movement in two planes. Example: the carpometacarpal (CMC) joint of the thumb — between the trapezium and first metacarpal bone.
Saddle joints allow: flexion and extension, abduction and adduction, and circumduction. Rotation is NOT possible. This is why saddle joints are called biaxial — movement occurs along two axes.
Saddle joint: biaxial, allows movement in two planes, no rotation. Example: thumb CMC joint. Ball-and-socket joint: multiaxial, allows movement in all directions including rotation. Example: shoulder joint, hip joint.
Cuscuta (Amarbel) — Example of a Parasitic Plant
Cuscuta (Amarbel) is a classic example of a parasitic plant. Learn how it absorbs nutrients from a host plant using haustoria, and why it lacks chlorophyll.
Dangerous Dogs – Breeds and Temperament
Rottweiler, Pit Bull Terrier, American Bulldog, German Shepherd, and Doberman are considered dangerous dog breeds, but temperament depends largely on training.
What Is a Dangerous Level of Bilirubin in Adults?
Normal bilirubin in adults: 0.2–1.2 mg/dL. Jaundice appears above 2.5 mg/dL. Levels above 20–25 mg/dL indicate severe liver disease. Complete chart and FAQs.
Define Heredity and Its Mechanism
Define heredity and explain the mechanism of hereditary changes. Learn about DNA, genes, and Mendelian inheritance in Class 10 Biology.
What is the Dental Formula of a Human Being?
Learn the dental formula of an adult human (2123/2123) and a child. Understand the arrangement of Incisors, Canines, Premolars, and Molars.
Turn this guide into revision flashcards, a practice exam, or an AI-generated podcast — free, no signup required.