More images of nerve lesions; Note that the true ulnar claw as seen in the first and second pictures is caused by a distal ulnar lesion which paralyzes the medial two lumbricals and may cause thenar wasting due to loss of adductor pollicis. The "pope's blessing" or "Benedictine" sign looks the same but is only visible upon an active attempt to make a fist. It is due to a median nerve injury which paralyzes the lateral 2 lumbricals and weakens the flexor digitorum superficialis and deep. A total claw is visible in the infant's hand and is a result of Klumpke's palsy--damage to the lower roots affects the ulnar, median, and radial nerves--affecting all lumbricals and weakening extension of the digits.A sudden jerking of a child's arm or falling from a tree and grabbing a limb can cause it. Erb's palsy is a result of upper root damage and affects the suprascapular, musculocutaneous, and axillary nerves. The deltoid, brachialis, biceps, supraspinatus, and infraspinatus muscles may be affected contributing to the "waiter's tip" sign. Dystocia can cause both Klumpke's and Erb's palsies.
