In a complete section of the ulnar nerve at the wrist, disability of the hand results from the paralysis of
Interossei involve all digits hence produce complete disability. Hypothenar muscles are paralyzed but affect only the muscles of the little finger. Branches to FDP and FCU are given off in the forearm and hence intact in a wrist lesion.** Both interossei, hypothenar effected, question asks which causes more disability hence interosseiReference: Chaurasia; 6th edition
Flexor carpi ulnaris
Flexor digitorum profundus
Interossei
Hypothenar muscles
Upper limb