Muscles of the Hands Lecture Notes

Overview

• Focus on muscles of the hands.
• Utilize mnemonics and references to Nintendo for easier learning.
• Aim to condense an hour of study into a few minutes.

Main Areas of Muscles in the Hand

1. Thenar Eminence

   • Located beneath the thumb.

2. Hypothenar Eminence

   • Located beneath the pinky finger.

3. Middle of the Hand

   • Involves muscles around the metacarpals.

Mnemonic for Areas

• Triforce Representation: Visualize a triforce in the palm to remember the three muscle groups in each area.
• Triforce Plus One: There’s one additional muscle that doesn’t fit into the compartments.

Muscles of the Thenar and Hypothenar Eminences

• Similar Muscle Groups:
  • Each area has a flexor, abductor, and opponens muscle.

Mnemonic for Muscles

• One for All (Thenar):

  • Opponens Pollicis
  • Flexor Pollicis Brevis
  • Abductor Pollicis Brevis

• All for One (Hypothenar):

  • Abductor Digiti Minimi
  • Flexor Digiti Minimi Brevis
  • Opponens Digiti Minimi

Muscles in the Middle of the Hand

1. Adductor Pollicis

   • Two-headed triangular muscle.
   • Originates from metacarpals and inserts on proximal phalanx of the thumb.

2. Lumbricals

   • Originates from tendons of the Flexor Digitorum Profundus.
   • Helps flex the MCP joint while extending PIP and DIP joints (creates a "lumbrical grip").
   • Mnemonic: "If you dig deep, you’ll find worms" (for lumbricals).

3. Interossei Muscles

   • Palmar Interossei: Adducts fingers (P for Palmar = Adducts).
   • Dorsal Interossei: Abducts fingers (D for Dorsal = Abducts).
   • Function: Create "lumbrical grip" and finger ab/adduction.

The Triforce Plus One: Palmaris Brevis

• Small muscle, superficial.
• Originates from the palmar aponeurosis; inserts into skin.
• Possibly aids in grip and protects the ulnar nerve.

Innervations of the Muscles

• Ulnar Nerve: Innervates most hand muscles.
• Median Nerve: Innervates 4 muscles:
  • Lateral two lumbricals
  • Opponens Pollicis
  • Abductor Pollicis Brevis
  • Half of the Flexor Pollicis Brevis

Mnemonic for Innervations

• Half Loaf Half:
  • Half of the lumbricals (lateral) = Median nerve,
  • Other thenar muscles also associated with median nerve.

Conclusion

• Summary of hand muscle anatomy and innervation.
• Transition to lower extremity study.

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• Good luck with your studies and tests!