76 Neuroanatomy: Draw It to Know It
Sensory Map of the Hand
Here, we will create a diagram for the sensory coverage
of the hand. Begin with the median nerve’s sensory cover-
age. Trace both sides of your hand. On the palm-up trac-
ing , square off the ball of the thumb to indicate the sensory
coverage of the palmar cutaneous nerve. Th en, show that
the median nerve digital sensory branches cover the lat-
eral palm, lateral half of the ring fi nger, middle and index
fi ngers, and the palmar thumb. Next, on the dorsal sur-
face of the hand, show that the median nerve provides
sensory coverage to the dorsal tips of the thumb, index
and middle fi ngers, and lateral half of the ring fi nger.
Next, let’s show the ulnar nerve’s sensory coverage.
On the dorsal surface tracing, show that the dorsal ulnar
cutaneous nerve covers the medial one third of the hand
and the medial half of the fourth digit and fi ft h digit.
Th en, on the palm-up tracing, show that the palmar
ulnar cutaneous nerve covers the hypothenar eminence.
Remember that both of these sensory nerves branch
proximal to Guyon’s canal. Lastly, still on the palm-up
tracing, show that the superfi cial sensory division covers
the medial half of the fourth digit and the fi ft h digit.
Th is sensory branch passes through Guyon’s canal.
Now, to map the superfi cial sensory radial nerve cov-
erage, fi rst, on the dorsal surface tracing, show that the
superfi cial sensory radial nerve covers the lateral two
thirds of the dorsum of the hand, the proximal thumb,
proximal second and third digits, and proximal lateral
half of the fourth digit. And then on the palm-up trac-
ing, show that the radial nerve’s sensory coverage wraps
around to the proximal palmar thumb.^1 – 8