Which of the following joints is classified as a biaxial diarthrosis?

• A. Shoulder joint
• B. Metacarpophalangeal joint
• C. Suture joint
• D. Elbow joint

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the classification of joints based on their movement. Diarthrosis refers to freely movable joints, and biaxial diarthrosis specifically allows movement in two planes or axes.
2. Step 2: Review the characteristics of each joint option provided: - Shoulder joint: This is a ball-and-socket joint, classified as a multiaxial diarthrosis, allowing movement in multiple planes. - Metacarpophalangeal joint: This is a condyloid joint, classified as a biaxial diarthrosis, allowing movement in two planes (flexion/extension and abduction/adduction). - Suture joint: This is a fibrous joint, classified as synarthrosis, meaning it is immovable. - Elbow joint: This is a hinge joint, classified as a uniaxial diarthrosis, allowing movement in one plane (flexion/extension).
3. Step 3: Focus on the definition of biaxial diarthrosis and identify which joint fits this classification. A biaxial joint must allow movement in two distinct planes.
4. Step 4: Compare the movement capabilities of the metacarpophalangeal joint with the other options. The metacarpophalangeal joint allows flexion/extension and abduction/adduction, making it biaxial.
5. Step 5: Conclude that the metacarpophalangeal joint is the correct answer based on its classification as a biaxial diarthrosis, while the other joints do not meet this specific criterion.