- Origin:
- superficial head: distal border of the flexor retinaculum;
- greater multangular bone tuberosity of the trapezium bone deep head;
- trapezoid and capitate bones;
- Insertion: base of the proximal phalanx of the thumb;
- Action:
- flexes proximal phalanx of the thumb; continued action flexes first
metacarpal and rotates it medially;
- Synergists:
FPL,
adductor pollicis;
- Nerve supply: superficial head:
Median,
C8,
T1
deep head:
Ulnar,
C8,
T1;
- Discussion:
- FPB is on volar surface of metacarpal and under
abductor brevis;
- one head of the flexor brevis originates from volar carpla ligament
and in the region of the
Flexor Carpi Radialis tendon;
- other originates from trapezium and from capitate tendon that inserts
into radial sesamoid & radial tubercle of proximal phalanx;
- this muscle also attaches to an expansion into the extensor mech.
and assists in extending the distal phalanx of the thumb;
