bility to deep touch. The areas of epicritic and of
protopathic insensibility are illustrated in Fig. 91. The division of
the nerve at the elbow, or even at the axilla, does not increase the
extent of the loss of epicritic or protopathic sensibility, but usually
affects deep sensibility.

[Illustration: FIG. 92.--To illustrate Loss of Sensation produced by
complete Division of Ulnar Nerve. Loss of all forms of cutaneous
sensibility is represented by the shaded area. The parts insensitive to
light touch and to intermediate degrees of heat and cold are enclosed
within the dotted line.

(Head and Sherren.)]

#The Ulnar Nerve.#--The most common injury of this nerve is its division
in transverse accidental wounds just above the wrist. In the arm it may
be contused, along with the radial, in crutch paralysis; in the region
of the elbow it may be injured in fractures or dislocations, or it may
be accidentally divided in the operation for excising the elbow-joint.

When it is injured _at or above the elbow_, there is paralysis of the
flexor carpi ulnaris, the ulnar half of the flexor digitorum profundus,
all the interossei, the two medial lumbricals, and the adductors of the
thumb. The hand assumes a characteristic attitude: the index and middle
fingers are extended at the metacarpo-phalangeal joints owing to
paralysis of the interosseous muscles attached to them; the little and
ring fingers are hyper-extended at these joints in consequence of the
paralysis of the lumbricals; all the fingers are flexed at the
inter-phalangeal joints, the flexion being most marked in the little and
ring fingers--claw-hand or _main en griffe_. On flexing the wrist, the
hand is tilted to the radial side, but the paralysis of the flexor carpi
ulnaris is often compensated for by the action of the palmaris longus.
The little and ring fingers can be flexed to a slight degree by the
slips of the flexor sublimis attached to them and supplied by the median
nerve; flexion of the terminal phalanx of the little finger is almost
impossible. Adduction and abduction movements of the fingers are lost.
Adduction of the thumb is carried out, not by the paralysed adductor
pollicis, but the movement may be simulated by the long flexor and
extensor muscles of the thumb. Epicritic sensibility is lost over the
little finger, the ulnar half of the ring finger, and that part of the
palm and dorsum of the hand to the ulnar side of a line drawn
longitudinally through