Easy Ways to Learn and Remember Muscles of the Posterior Forearm

Overview

• 12 muscles in the posterior forearm divided into two layers:
  • Superficial layer: 7 muscles
  • Deep layer: 5 muscles

Superficial Layer

• All seven muscles originate on the humerus:
  • 2 originate above the lateral epicondyle
  • 4 originate on the lateral epicondyle
  • 1 originates behind the lateral epicondyle
• Mnemonic: "Beer Lifting Break Dancing Muscles Unless Atrophied" (Lateral → Medial)

Breakdown of Mnemonic

1. Beer (Brachioradialis)

   • Origin: Supracondylar ridge (above lateral epicondyle)
   • Insertion: Radial styloid process
   • Function: Elbow flexion, returns wrist to neutral position when supinated or pronated
   • Nickname: Beer drinking muscle

2. Lifting (Extensor Carpi Radialis Longus)

   • Origin: Supracondylar ridge (below brachioradialis)
   • Insertion: Base of the second metacarpal
   • Function: Radial deviation, wrist extension, weak elbow flexion

3. Break (Extensor Carpi Radialis Brevis)

   • Origin: Lateral epicondyle of humerus
   • Function: Similar to Extensor Carpi Radialis Longus but shorter

4. Dancing (Extensor Digitorum)

   • Origin: Lateral epicondyle
   • Insertion: Extensor hoods of the four fingers
   • Function: Extends fingers and wrist

5. Muscles (Extensor Digiti Minimi)

   • Origin: Lateral epicondyle
   • Insertion: Extensor hood of the fifth digit
   • Function: Extends the pinky finger

6. Unless (Extensor Carpi Ulnaris)

   • Origin: Lateral epicondyle
   • Insertion: Base of the fifth metacarpal
   • Function: Wrist extension and ulnar deviation
   • Note: Shares insertion with Flexor Carpi Ulnaris

7. Atrophied (Anconeus)

   • Origin: Back of the lateral epicondyle
   • Insertion: Ulna
   • Function: Smallest muscle in superficial layer, triangular in shape

Deep Layer

• Five muscles: 1 for the index finger, 3 for the thumb, 1 for wrist supination

Proximal Muscle: Supinator

• Origin: Lateral epicondyle and proximal ulna
• Function: Supinates the wrist

Distal Muscle: Extensor Indicis

• Function: Extends the index finger
• Origin: Ulna (line from index finger nail bed to ulna)

Thumb Muscles

1. Abductor Pollicis Longus

   • Origin: Mid-forearm
   • Insertion: Base of the first metacarpal

2. Extensor Pollicis Brevis

   • Origin: Mid-forearm
   • Insertion: Proximal phalanx of thumb

3. Extensor Pollicis Longus

   • Origin: Mid-forearm
   • Insertion: Distal phalanx of thumb

• Alphabetical order of insertions: Metacarpal (A - Abductor), Proximal phalanx (B - Brevis), Distal phalanx (L - Longus)

Summary

• Mnemonics and tricks to remember origins, insertions, and functions
• Prepared for upcoming discussions on the hand muscles

Good luck on your next test!