Flexor digitorum profundus is innervated by the median and ulnar nerves. The medial aspect of the muscle (which flexes the 4th and 5th digit) is supplied by the ulnar nerve (C8, T1) The lateral aspect (which flexes the 2nd, 3rd and 4th digit) by the median nerve (via its anterior interosseous branch) (C8, T1). It is one of two flexor muscles that is not exclusively supplied by the median nerve (the other is flexor carpi ulnaris). | 
