Regarding synovial flexor sheaths in the hand and wrist, which one of the following is INCORRECT?

• A. they surround flexor tendons in the carpal tunnel
• B. the superficial and deep flexors are invested with a common synovial sheath
• C. the common flexor sheaths can communicate with flexor pollicis longus sheath in some people
• D. for the index, ring and middle finger, a separate synovial sheath lines the fibrous sheath over the phalanges
• E. the sheath is the origin of the lumbricals