Overview
This lecture explains the organization, names, actions, and nerve supply of the muscles in the anterior forearm, using mnemonics and memory tricks.
Organization of Anterior Forearm Muscles
- The anterior forearm contains 8 muscles in three layers: superficial (4), intermediate (1), and deep (3).
- All superficial and intermediate layer muscles originate at the medial epicondyle.
Superficial Layer Muscles (Mnemonic: Pass, Fail, Pass, Fail)
- Index finger: Pronator teres — pronates the wrist.
- Middle finger: Flexor carpi radialis — flexes the wrist, runs along the radial side, inserts at base of 2nd/3rd metacarpals.
- Ring finger: Palmaris longus — flexes the wrist, inserts into palmar aponeurosis.
- Pinky finger: Flexor carpi ulnaris — flexes the wrist on ulnar side, inserts at pisiform, hook of hamate, and base of 5th metacarpal.
Intermediate Layer Muscle
- Flexor digitorum superficialis — flexes fingers (excluding distal tips); inserts on sides of middle phalanges.
Deep Layer Muscles (Mnemonic: Punching Muscles, all contain "P")
- Flexor digitorum profundus — flexes all finger joints, inserts at distal phalanges.
- Flexor pollicis longus — flexes thumb, inserts on distal phalanx of thumb.
- Pronator quadratus — pronates wrist by pulling radius over ulna.
Innervation of Anterior Forearm Muscles
- Median nerve supplies most anterior forearm muscles.
- Flexor carpi ulnaris is innervated by the ulnar nerve.
- Flexor digitorum profundus is innervated by both median and ulnar nerves (lateral half: median, medial half: ulnar).
Key Terms & Definitions
- Medial epicondyle — bony projection at elbow, origin for many forearm flexors.
- Flexion — bending movement decreasing joint angle.
- Pronation — turning the palm downward.
- Metacarpal — long hand bones between wrist and fingers.
- Phalanges — finger bones.
- Carpal tunnel — passage in wrist for tendons and nerves.
- Aponeurosis — flat broad tendon.
Action Items / Next Steps
- Review muscle names, actions, and insertions using hand mnemonics.
- Memorize nerve supply to each muscle.
- Prepare for upcoming lecture on the rest of the arm.