Flexor Pollicis Brevis (FPB) Anatomy
- Origin: Flexor retinaculum and trapezium bone.
- Insertion: Lateral side of the base of the proximal phalanx of the thumb.
- Innervation: Both the median nerve (superficial head) and the ulnar nerve (deep head).
- Nerve: Median nerve (for the superficial head) and ulnar nerve (for the deep head)
Diagrams & Photos
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Flexor Pollicis Brevis (FPB)
Key Points
- Superficial head of the flexor pollicis brevis is innervated by the median nerve and deep head innervated by the ulnar nerve.
- With the hand palm down on a flat surface, the median innervated thenar muscles are at risk for injury during a deep laceration into thenar muscles radial to the metacarpal of the dorsal thumb the anatomic structures at risk section.
- The flexor pollicis longus divides the thenar muscles into the group innervated by the median nerve and the ulnar nerve innervated group. The ulnar nerve innervated group includes the adductor pollicis and the deep head of the flexor pollicis brevis.