Other Name: Flexor digiti minimi brevis, flexor digiti quniti, flexor digiti quinti brevis.
• Flexes the small finger at metacarpal-phalangeal joint.
• Hypothenar eminence muscle (an intrinsic hand muscle).
Primary: Flexion at the metacarpal-phalangeal joint of the small finger.
Secondary: Assists in small finger opposition towards thumb.
Palpation: Within in the hypothenar eminence during small finger flexion at the metacarpal-phalangeal joint.
Strength Testing: Position – hand in supination. Stabilize – the hand. Resist – small finger metacarpal-phalangeal flexion by applying force over palmar proximal phalanx (in the direction of extension).
Possible Substitutions: Opponens digiti minimi and the lumbricals.
• Roots: C8, T1.
• Nerve: Ulnar, deep motor branch.
• Innervation Route: C8, T1 → ulnar nerve → deep motor branch → flexor digiti minimi branch.
Origins: Hook of the hamate and flexor retinaculum.
Insertion: Small finger ulnar tubercle at base of proximal phalanx, ulnar side of metacarpal phalangeal joint palmar plate, and sesamoid (if present).