Identifying the Radius Bone in a Dog's Forelimb Skeleton

Steps:

• Locate the forelimb in the diagram, as the radius is part of the lower front leg.
• Identify the paired bones in the forearm: the radius (lateral, thumb side) and ulna (medial).
• Distinguish the radius by its position parallel to the ulna, connecting elbow to wrist.
• Match the labeled option to the thinner, outer forearm bone.

Why B is correct:

• The radius is defined as the lateral bone of the antebrachium (forearm) in quadrupeds like dogs, articulating with the humerus proximally and carpus distally.

Why the others are wrong:

• A is the ulna, the medial forearm bone supporting elbow extension.
• C is the humerus, the upper arm bone from shoulder to elbow.
• D is the metacarpal, a paw bone distal to the radius.

Final answer: B