When exploring just posterior to the clavicle, which muscle must you palpate through to access the first rib?

When exploring just posterior to the clavicle, which muscle must you palpate through to access the first rib?

• A. Scalene
• B. Pectoralis minor
• C. Serratus anterior
• D. Levator scapulae

Answer: (A)

The first rib lies just beneath the scalene muscles in the region behind the clavicle, so to reach it you palpate through the scalene group. The anterior scalene, in particular, runs from the cervical vertebrae to the first rib and sits directly over it as you move laterally from the neck toward the shoulder. That overlying layer is why palpating the first rib from that location requires going through the scalene muscles. The other muscles—pectoralis minor, serratus anterior, and levator scapulae—do not overlay the first rib in this area, so they aren’t the structures you would palpate through to access the rib.

The first rib lies just beneath the scalene muscles in the region behind the clavicle, so to reach it you palpate through the scalene group. The anterior scalene, in particular, runs from the cervical vertebrae to the first rib and sits directly over it as you move laterally from the neck toward the shoulder. That overlying layer is why palpating the first rib from that location requires going through the scalene muscles. The other muscles—pectoralis minor, serratus anterior, and levator scapulae—do not overlay the first rib in this area, so they aren’t the structures you would palpate through to access the rib.