Muscles that move wrist:hand:fingers

Intrinsic Muscles of the Hand

  • The intrinsic muscles of the hand are vital for the dexterity and precision of hand movements.

    • They originate and insert entirely within the hand.

    • Enable intricate actions such as typing and writing.

Categories of Intrinsic Muscles

1. Thenar Muscles

  • Located on the radial aspect of the palm.

    • Include:

      • Abductor pollicis brevis

      • Opponens pollicis

      • Flexor pollicis brevis

      • Adductor pollicis

  • Form the thenar eminence (base of the thumb).

  • Crucial for thumb movements, allowing precise hand functions.

2. Hypothenar Muscles

  • Located on the medial aspect of the palm.

    • Include:

      • Abductor digiti minimi

      • Flexor digiti minimi brevis

      • Opponens digiti minimi

  • Form the hypothenar eminence (base of the little finger).

  • Aid in the movements of the little finger.

3. Intermediate Muscles

  • Act on all fingers, contributing to complex finger movements.

    • Include:

      • Lumbricals

      • Palmar interossei

      • Dorsal interossei

  • Important for grip strength and manipulation.

Detailed Functions of Intrinsic Muscles

Thenar Muscles

  • Abductor pollicis brevis:

    • Movement: Abduction of the thumb.

    • Origin: Flexor retinaculum; lateral base of proximal phalanx of thumb.

  • Opponens pollicis:

    • Movement: Opposition of the thumb.

    • Origin: Flexor retinaculum; anterior of first metacarpal.

  • Flexor pollicis brevis:

    • Movement: Flexion of the thumb.

    • Origin: Flexor retinaculum; trapezium.

  • Adductor pollicis:

    • Movement: Adduction of the thumb.

    • Origin: Metacarpals 2-4.

Hypothenar Muscles

  • Abductor digiti minimi:

    • Movement: Abduction of the little finger.

    • Origin: Pisiform bone; hamate bone.

  • Flexor digiti minimi brevis:

    • Movement: Flexion of the little finger.

    • Origin: Hamate bone; flexor retinaculum.

  • Opponens digiti minimi:

    • Movement: Opposition of the little finger.

Intermediate Muscles

  • Lumbricals:

    • Function: Flex metacarpophalangeal joints; extend interphalangeal joints.

  • Palmar Interossei:

    • Function: Adduct and flex fingers at metacarpophalangeal joints.

  • Dorsal Interossei:

    • Function: Abduct and flex fingers at metacarpophalangeal joints; extend at interphalangeal joints.

Summary of Muscle Functions

  • Intrinsic muscles are essential for fine motor control, enabling various thumb and finger movements including:

    • Abduction

    • Adduction

    • Flexion

    • Extension

    • Opposition

  • They allow for the complex and nuanced dexterity needed for everyday tasks.