The flexor pollicis brevis is a muscle in the hand that flexes the thumb.

[4] The superficial head is usually innervated by the lateral terminal branch of the median nerve.

[2][3] The flexor pollicis brevis receives its blood supply from the superficial palmar branches of radial artery.

[3] Flexor pollicis brevis can, rarely, be completely absent at birth due to a congenital issue (as can the other muscles of the thenar eminence).

[6] This article incorporates text in the public domain from page 461 of the 20th edition of Gray's Anatomy (1918)