Summary Flexor Digitorum Profundus Origin Proximal 3/4 of medial and anterior surfaces of ulna and interosseous membrane Insertion Base of the distal phalanx of digits 2 - 5 Action Flexes distal phalanges at distal interphalangeal joints of medial four digits; assists with flexion of hand Innervation Medial part (slips to SF and RF): ulnar nerve (C8, T1); Lateral part (slips to MF and IF): anterior interosseous nerve (C8, T1) Arterial supply Ulnar and anterior interosseous arteries