Anatomy
Origin:
Oblique head: capitates and bases of the second and third metacarpals.
Transverse head: ulnar aspect of third metacarpal.
Insertion:
Base of proximal phalanx of the thumb.
Key relations:
The radial artery passes between the two heads on its course from the dorsal aspect to the palmar aspect of the hand where it forms the deep palmar arch.
Functions
Adducts the thumb at the carpometacarpal and metacarpophalageal joint.
Supply
Nerve Supply:
Deep branch of the ulnar nerve (C8, T1).
Blood Supply:
Arteria princeps pollicis from radial artery.
Clinical
An ulnar nerve palsy will give a positive Froment’s sign whereby the patient will be unable to keep a grip on a sheet of paper between their thumb and index finger. It is due to compromising of the action of adductor pollicis primarily.
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