Other Name: Abductor digiti quinti (ADQ).
• Abducts the small finger.
• Hypothenar eminence muscle (an intrinsic hand muscle).
• Abducts metacarpal-phalangeal and carpal-metacarpal joints of small finger.
• Assists in opposition of small finger.
• Metacarpal phalangeal joint flexion of small finger.
• Interphalangeal joint extension of small finger.
Palpation: Palpate ulnar aspect of hypothenar muscles while resisting small finger abduction.
Strength Testing: Position – the palmar side up. Stabilize – the hand. Resist – the small finger abduction (in the direction of adduction).
Possible Substitutions: Extensor digiti minimi – keep the small finger in neutral to prevent substitution and in respect to flexion and extension. Avoid small finger extension.
• Roots: C8, T1.
• Nerve: Ulnar nerve; deep motor branch.
• Innervation Route: C8, T1 → ulnar nerve → deep motor branch → abductor digiti minimi branch.
Origin: Distal pisiform, flexor carpi ulnaris tendon, and connective tissue lying between hook of hamate and pisiform.
Insertion: Splits into two tendon slips going to proximal phalanx base (at ulnar tubercle) of small finger, and ulnar aspect of extensor hood of small finger.