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.
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.
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.
Act on all fingers, contributing to complex finger movements.
Include:
Lumbricals
Palmar interossei
Dorsal interossei
Important for grip strength and manipulation.
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.
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.
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.
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.