Radius and ulna are bones of the?

Step 1: Analyze the question The question asks which part of the skeleton contains the radius and ulna. This is a question on the appendicular skeleton (the limbs and girdles).

Step 2: Explain the concept The forelimb (arm) of a human has three regions:

• Upper arm: one bone, the humerus
• Lower arm (forearm): two bones, the radius and ulna
• Hand: carpals, metacarpals, and phalanges

The girdles are different:

• Pectoral girdle (shoulder): the scapula and clavicle
• Pelvic girdle (hip): the ilium, ischium, and pubis (fused hip bones)

Step 3: Work through the options

• A. Pectoral girdle: No. This holds the scapula and clavicle.
• B. Upper arm: No. This has only the humerus.
• C. Pelvic girdle: No. This belongs to the hip region.
• D. Lower arm: Yes. The radius (on the thumb side) and the ulna (on the little-finger side) make up the forearm.

Step 4: Answer The radius and ulna are bones of the lower arm, so the answer is D.

Exam tip: Remember the pattern "1-2-5" for the forelimb: 1 bone in the upper arm (humerus), 2 bones in the forearm (radius and ulna), and then the hand bones. The same pattern in the hind limb is femur (1) in the thigh, then tibia and fibula (2) in the lower leg.