<prompt> Insertion of extensor carpi ulnarisBase of proximal phalanx of thumbBase of Distal phalanx of thumbBase of 5th MetacarpalScaphoid base  <response>: Ans. is c i.e., Base of 5th MetacarpalExtensor carpi ulnariso Origin : Lateral epicondyle of humerus and posterior border ulnao Insertion : Base of 5th metacarpalo Nerve supply : Posterior interosseus nerveo Action : Extension dorsiflexion and adduction of hand. 