Not under flexor retinaculum -

Ans. is 'b' i.e., Ulnar nerve Structures deep to flexor retinaculumLateral compartment : Flexor carpi radialis tendon with its synovial sheath lodged in the groove on the palmar surface of trapezium.Medial compartment : (carpal tunnel proper).Median nerveFlexor pollicis longus with its synovia! sheath (radial bursa)4 tendons each of flexor digitorum superficialis and profundus enclosed by common flexor synovial sheath (ulnar bursa).Structures superficially to flexor retinaculumPalmaris longus tendon continuous with apex of palmar aponeurosis.Palmar cutaneous branch of median nerve.Palmar cutaneous branch of ulnar nerve.Ulnar nerve.Ulnar vessels protected superficially by volar carpal ligament (superficial part of the flexor retinaculum).