Which muscle flexes the wrist and inserts on the palmar aponeurosis?

Which muscle flexes the wrist and inserts on the palmar aponeurosis?

• A. Teres Major
• B. Palmaris Longus
• C. Flexor Carpi Radialis
• D. Supraspinatus

Answer: (B)

The key idea is recognizing a wrist flexor whose tendon anchors into the palm’s fascia. The palmaris longus fits this exactly: its tendon travels across the wrist and inserts into the palmar aponeurosis, allowing the palm fascia to tense during gripping. It also acts to flex the wrist, though it is a relatively weak flexor compared with others. Teres major is a shoulder muscle that acts on the arm and does not attach near the palm. Supraspinatus is another shoulder/rotator cuff muscle with insertion on the greater tubercle of the humerus, not the palm. Flexor carpi radialis does flex the wrist but inserts on the bases of the second and third metacarpals, not the palmar aponeurosis. So the muscle that both flexes the wrist and inserts on the palmar aponeurosis is palmaris longus.

The key idea is recognizing a wrist flexor whose tendon anchors into the palm’s fascia. The palmaris longus fits this exactly: its tendon travels across the wrist and inserts into the palmar aponeurosis, allowing the palm fascia to tense during gripping. It also acts to flex the wrist, though it is a relatively weak flexor compared with others.

Teres major is a shoulder muscle that acts on the arm and does not attach near the palm. Supraspinatus is another shoulder/rotator cuff muscle with insertion on the greater tubercle of the humerus, not the palm. Flexor carpi radialis does flex the wrist but inserts on the bases of the second and third metacarpals, not the palmar aponeurosis. So the muscle that both flexes the wrist and inserts on the palmar aponeurosis is palmaris longus.