LETTER TO THE EDITOR
The ‘rectangular palm’ sign in ulnar nerve paralysis
Received: 2 January 2012 / Accepted: 7 March 2012 / Published online: 27 March 2012
The ulnar nerve supplies most of the intrinsic muscles of the
hand. The abductor pollicis brevis, the two radial lumbricals
and parts of the flexor pollicis brevis and opponens pollicis are
supplied by the median nerve. All remaining intrinsic muscles
are supplied by the ulnar nerve, including all interossei and the
two ulnar lumbricals, the hypothenar muscles and parts of
flexor pollicis brevis and opponens pollicis and the adductor
pollicis. The bulkiest individual muscles in this group are the
adductor pollicis and the first dorsal interosseous. Impairment
of function of the ulnar nerve at, or above, the level of the wrist
will result in dysfunction, wasting and eventual atrophy of the
group of intrinsic muscles it supplies.
Many clinical signs and tests are available for detection
of the presence and level of ulnar nerve impairment. These
can be grouped into:
1. Observational signs
2. Examination signs
3. Provocation signs
We are concerned here with the observational signs, and
these will be listed in detail.
1. Masse’s flat palm  secondary to the loss of muscle
tone that helps maintain the transverse arch of the palm.
The main protagonists are the opponens and flexor
digiti minimi on the ulnar side and the adductor pollicis
and the first dorsal interosseous on the radial side, all
supplied by the ulnar nerve.
2. Mannerfelt sign  in effect an exacerbation of the claw
hand secondary to extensor overactivity. Present at rest,
distinct from the Duchenne claw  or intrinsic minus
hand which is produced when the patient is invited to
extend the long digits. Both of these signs are secondary
to loss of the stabilising force of the lumbricals and
interossei on the MP joints, permitting hyperextension.
3. Wartenberg's sign [4–6], abduction of the little finger at
rest, secondary to interosseous loss.
4. Hypothenar wasting  produced by loss of bulk of the
hypothenar musculature. This produces a loss of convex
contour on the ulnar border of the hand.
5. Dorsal hand guttering/wasting [5–8] secondary to gen-
eral wasting of intrinsics. This is particularly manifested
as loss of bulk of the first dorsal interosseous muscle.
Guttering in the valleys between the metacarpals is also
Fig. 1 A normal right hand with a square palm, and a paralysed
wasted left hand, with a rectangular palm
D. Sammut (*)
The Circle Hand Clinic,
Windsor SL4 4LH, UK
Eur J Plast Surg (2012) 35:569–570