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Examination of Peripheral Nervous System
https://t.me/med1917
A
B
Figs 8.3A and B: Wrist drop—due to radial nerve palsy.
Fig. 8.4: Wasting in the right hand
especially over thenar eminence.
Wound if present should be inspected for its depth,
site and other features. Similarly scar of old wound
should be inspected. Nerve related to this wound or
scar may be damaged.
Palpation
Temperature: Paralyzed limb is colder than normal.
201
Skin: Anaesthesia over the area of sensory supply of
that particular nerve is typical. In axillary nerve injury
paralysis of deltoid muscle will be present along with
loss of sensation over the lower part of the deltoid.
Often muscle paralysis or power cannot be assessed
due to traumatic fracture of the particular site like
shoulder dislocation or fracture neck of humerus in
axillary nerve injury . Shifting of hyperaesthesia along
the distribution of the peripheral nerve is the sign of
nerve regeneration.
Wound or scar should be palpated for tenderness.
Scar tenderness may signify nerve entrapment or
adhesion.
Palpation of affected muscles: Paralysed muscle is
soft, and flabby. It shows reduced muscle bulk and
texture.
Muscle power: Muscles which are exclusively supplied
by a particular nerve should be checked for altered
power. Muscle power of that particular muscle is
checked by the movement against resistance across
the joint it acts. Medical Research Council graded
the muscle power: 0—complete paralysis; 1—flicker
of contraction; 2—contraction of muscle with gravity
eliminated; 3—contractions against gravity alone; 4—
contraction against gravity and some resistance alone;
5—contraction against powerful resistance.
Trapezius is checked by shrugging the shoulder
against resistance. There will be wasting of trapezius
with flat shoulder. It suggests spinal accessory nerve
palsy. It is observed in advanced fixed neck lymph
node secondaries; after radical neck dissection; trauma.
In hypoglossal nerve palsy, patient is asked to
protrude the tongue. There will be wasting of tongue
on the side of the lesion; tongue will deviate towards
the same side of the injury. Hypoglossal nerve palsy
occurs in advanced secondaries in neck (upper nodes);
after submandibular salivary gland excision (1%);
surgery to submandibular salivary gland malignancy.
Serratus anterior muscle is checked by pushing
the outstretched hand against wall. Its paralysis causes
prominent vertebral border and inferior angle of the
scapula which will stand out of the chest wall. It is
called as ‘winging of scapula’. It is due to injury to
long thoracic nerve of Bell. It is derived from the C5,
C6, C7 nerve roots of brachial plexus. It may be injured
in brachial plexus injury or chest wall/breast surgeries.
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SRB’s Clinical Surgery
Deltoid muscle is checked with elbow flexed at
right angle and abducting the arm (through shoulder
joint) against resistance. Muscle contraction should
be checked by palpation with the other hand.
Brachioradialis muscle is checked by asking the
patient to flex the elbow against resistance keeping
forearm in midprone position. It originates from upper
2/3rd of lateral supracondylar ridge of the humerus
above the origin of the extensor carpi radialis longus
and inserted on to the lateral side of the radius just
above the styloid process. It is flexor of forearm in
midprone position; supinator of fully pronated forearm.
It is supplied by radial nerve C
It is paralysed
5, 6, 7.
in radial nerve injury but its action is intact in posterior
interosseus nerve injury (Fig. 8.5).
Fig. 8.5: Checking the brachioradialis muscle power in midprone position. It is paralysed in radial nerve injury. It is
intact in posterior interosseous nerve injury.
Fig. 8.6: Extension of the wrist should be checked
against resistance.
digital expansion. Intermediate slip attaches to middle
phalanx dorsally. Two side ward tendon slips later
join again to attach to dorsum of base of distal phalanx.
Interossei and lumbricals pass through the tunnel to
enter the dorsal expansion as wing tendons. Extensor
digitorum is extensor of metacarpophalangeal joint
and interphalangeal joints. Interossei and lumbrical
are also flexors of the interphalangeal joints.
Flexor pollicis longus: It originates from upper
3/4th of anterior surface of shaft of radius and anterior
surface of interosseous membrane; gets inserted into
the palmar surface of the distal phalanx of the thumb;
supplied by anterior interosseous nerve; flexor of
the distal phalanx of thumb. Its power is checked by
asking the patient to steady the proximal phalanx, and
to bend the terminal phalanx of thumb against
resistance (Figs 8.7A and B).
Extensor muscles of wrist: Extensors of the wrist are
supplied by posterior interosseous nerve except
extensor carpi radialis longus (supplied by radial
nerve). Injury to posterior interosseous nerve will cause
wrist drop with inability to extend the wrist. Wrist
is extended against resistance to check the power of
these muscles (Fig. 8.6). Patient can extend the fingers
using interossei. Brachioradialis is intact in posterior
interosseous nerve lesion but it will be paralysed in
above elbow injury of radial nerve Extensor carpi
radialis longus, extensor carpi radialis brevis, extensor
digiti minimi, extensor carpi ulnaris, extensor
digitorum and anconeus are common extensors of the
wrist. Extensor digitorum from its common extensor
origin in the dorsum of hand divides into four slips
of tendons one for each of medial four fingers. It
extends into the dorsum of proximal phalanx as dorsal
Figs 8.7A and B: Test for flexor pollicis longus. Flexion
of distal phalanx of thumb against resistance is checked.
Flexor digitorum superficialis (sublimus): Its
humeroulnar head originates from medial epicondyle
of humerus and tubercle on the medial border of the
Examination of Peripheral Nervous System
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coronoid process and ulnar collateral ligament; radial
head from anterior border of radius; it ends as four
tendons one each to medial four fingers; opposite the
proximal phalanx each splits into two and gets attached
to medial and lateral part of the base of middle phalanx.
It is the main flexor of the proximal interphalangeal
joint. It is supplied by median nerve.
Flexor digitorum profundus (FDP): It originates from
upper 3/4th of anterior and medial surface of ulnar
shaft, olecranon and coronoid process of ulna and
anterior surface of the interosseous membrane; it ends
as 4 tendons one for each medial 4 fingers; each after
passing through the split sublimes attaches to base
of the distal phalanx in front. It is the chief flexor
of the distal phalanx. It is a composite hybrid muscle
wherein medial two tendons are supplied by ulnar
nerve and lateral two tendons are supplied by anterior
interosseous nerve. Both sublimes and FDP has got
synovial folds called as vincula longa and vincula
brevia.
Ochsner’ s clasping test: If the patient is asked to clasp
the hands, index finger of the affected side fails to
flex and remains as pointing index. It suggests median
nerve injury (Figs 8.8A and B).
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pophalangeal joint and carpometacarpal joints with
associated medial rotation. Its power is tested by
moving the thumb upwards at right angle to the palm
of the hand with palm laid flat on the table. Patient
is asked to keep his hand flat supine on the table. A
pen tip is kept near thumb in front at higher level;
patient is asked to abduct his thumb to touch the pen
held. In normal functioning muscle patient can touch
the pen otherwise he cannot. It is called as ‘pen test’
(Figs 8.9 and 8.10).
Fig. 8.9: Pen test for abductor pollicis brevis—
median nerve.
Figs 8.8A and B: Ochsner’s clasping test: If the patient
is asked to clasp the hands, index finger of the affected
side fails to flex and remains as pointing index. It suggests
median nerve injury.
Abductor pollicis brevis: It originatese from the
tubercle of the scaphoid, crest of trapezium, flexor
retinaculum; gets inserted to lateral side of base of
proximal phalanx of thumb. Its nerve supply is median
nerve (C8, T1). It abducts the thumb at metacar-
Fig. 8.10: Abduction and adduction of thumb occurs in right
angle to the plane of flexion and extension of thumb.
Opponens pollicis: It originates from crest of trapezium
and flexor retinaculum; gets inserted to lateral half
of the palmar surface of the first metacarpal bone;
supplied by median nerve (C8, T1). It causes opposition
of thumb with combination of flexion and medial
rotation. It is checked by swinging the thumb across
the palm to touch tips of other fingers (Fig. 8.11) .
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Fig. 8.11: Checking opponens pollicis against
resistance.
SRB’s Clinical Surgery
Flexor carpi ulnaris: Its origins is from common flexor
origin –humoral head from medial epicondyle; ulnar
head from the medial margin of olecranon. It is inserted
into the pisiform bone, base of the 5th metacarpal
bone, hook of the hamate as pisometacarpal and
pisohamate ligaments. It is supplied by ulnar nerve.
Its action is flexion of wrist, adduction of wrist. Ulnar
nerve passes between two heads of this muscle. Ulnar
vessels and nerve are lateral its tendon just above the
wrist. Pisiform is a sesamoid bone of this muscle. Its
power is checked by flexing the wrist against resistance
and deviation of hand towards radial side is seen due
to defective wrist adduction (Fig. 8.12).
Lumbrical muscles: They are four small muscles
originating from tendons of the flexor digitorum
profundus numbering of which is done from lateral
to medial—1, 2, 3 and 4. Their origins are shown in
Figure 8.15. They are inserted into the 2nd, 3rd, 4th
and 5th dorsal digital expansions of the proximal
phalanges on their lateral sides. 1st and 2nd lumbricals
are supplied by median nerve (C
, T1); 3rd and 4th
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lumbricals are supplied by deep branch of ulnar nerve
(C8, T1). Along with interossei they extend to proximal
and distal interphalangeal joints; and also flex the
metacarpophalangeal joints.
Palmar interossei: They are 4 small muscles between
metacarpals numbered as 1st, 2nd, 3rd and 4th from
lateral to medial. 1st muscle originates from medial
side of the base of 1st metacarpal bone and gets inserted
to medial side of the proximal phalanx of thumb. 2nd
muscle originates from medial side of shaft of 2nd
metacarpal, gets inserted to medial side of proximal
phalanx and dorsal digital expansion of index finger.3rd
muscle has got its origin from lateral part of the shaft
of the 4th metacarpal inserting into the base of proximal
phalanx and dorsal digital expansion of the ring (4th)
finger. 4th muscle begins from lateral part of the shaft
of 5th metacarpal gets inserted into proximal phalanx
and dorsal expansion of little (5th) finger. There is
no palmar interosseous to middle finger. It is supplied
by deep branch of the ulnar nerve (C
, T1). Actions:
8
All palmar interossei adduct the finger (PAD) with
middle finger as the centre line. They also flex the
metacarpophalangeal joint and extend the interphalangeal joints along with lumbricals (Figs 8.13A
to 8.14B).
Fig. 8.12: Flexion of the wrist should be checked
against resistance.
Dorsal interossei: They are 4 small muscles between
metacarpals numbered from lateral to medial. 1st
originates from shafts of 1st and 2nd metacarpals; 2nd
from shafts of 2nd and 3rd bones; 3rd from shafts
of 3rd and 4th bones; 4th from shafts of 4th and 5th
bones. First is inserted to lateral aspect of dorsal digital
expansion and base of proximal phalanx of index
finger; second to lateral aspect of middle finger; third
to medial aspect of middle finger; fourth to medial
aspect of ring finger. Dorsal interossei is not inserted
to thumb and little fingers. Middle finger has got two
dorsal interossei insertions on either side. Dorsal
interossei are supplied by deep branch of ulnar nerve
Examination of Peripheral Nervous System
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A
B
Figs 8.13A and B: Card test: A card is placed between
the two fingers of the patient to grasp. In weak palmar
interossei, patient cannot grasp (palmar interossei are
adductors of the fingers—PAD).
(C8, T1). Actions: They are abductors (DAB) of the
fingers with middle finger as centre line of action.
Thumb and little finger has got their own abductors
and so they do not need dorsal interossei. Abduction
of fingers occurs in the plane of the palm whereas
abduction of thumb occurs in a plane right angle to
the plane of the palm (Figs 8.15 and 8.16).
205
Fig. 8.14: Extension of interphalangeal joint should be
checked against resistance by fixing.
Fig. 8.15: Figure showing attachments of lumbricals and interossei. Lumbricals after origin from FDP tendons get inserted
to lateral aspects of extensor hoods of medial four fingers. 1st and 2nd palmar interossei are attached to medial aspect
of the proximal phalanx of thumb and index; 3rd and 4th are inserted into the lateral side of the ring and little fingers;
no palmar interossei is attached to middle finger. 1st and 2nd dorsal interossei are inserted to lateral aspects of base
and dorsal expansion of proximal phalanges of index and middle fingers. 3rd and 4th interossei are inserted to medial
aspect of proximal phalanges of middle and ring fingers. Middle finger has got on either sides insertions of 2nd and
3rd dorsal interossei.
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Fig. 8.16: Plane of finger movements is along the middle
finger. Palmar interossei are adductors of the fingers (PAD);
dorsal interossei are abductors of the fingers (DAB).
SRB’s Clinical Surgery
Adductor pollicis: Oblique head has origin from
capitate bone and bases of 2nd and 3rd metacarpal
bones; transverse head from palmar part of 3rd
metacarpal bone. It is inserted into medial side of the
base of the thumb. It is supplied by deep branch of
ulnar nerve (C8, T1). It adducts the thumb from abducted
or flexed position assisted by first palmar interossei.
It helps in forceful gripping. Patient is given a book
to hold between extended thumb and fingers. If ulnar
nerve is normal, he can hold the book with extended
thumb using adductor pollicis and first palmar interossei. If there is ulnar paralysis, grip on book is assisted
by flexing the terminal phalanx using flexor pollicis
longus (supplied by median nerve). This book test
is called as Froment’s sign. It can also be confirmed
by holding the card firmly between extended thumb
and other fingers – card test (Figs 8.17A and B).
Sciatic nerve injury is rare. When it develops it
is complete paralysis of the hamstring muscles and
muscles below the knee. Incomplete lesion commonly
involves common peroneal nerve (lateral popliteal
Figs 8.17A and B: Froment’s test and card test for ulnar
nerve – adductor pollicis. Thumb has to be flexed in paralysed
adductor pollicis by over action of flexor pollicis longus to
have grip on book or card.
nerve). There is paralysis of extensor and peroneal
muscles of the leg causing talipes equino varus and
inability to dorsiflex and evert the foot with undue
lifting of the foot to clear ‘dropped foot’ high from
the ground – ‘foot drop’. Tibial nerve supplies the
plantar flexors of the ankle joint. Patient will not be
able to plantar flex the ankle joint causing ‘talipes
calcaneo valgus’ (Fig. 8.18).
Sensation: Light touch, pressure, localisation, two
point discrimination, pain, temperature, sense of
position, size, shape and form of the object recognition,
vibration sense – all should be checked in nerve injury/
diseases. Sensations are checked from impair ed ar ea
towards normal area. Light touch is epicritic sensation
used to locate accurate area of loss of sensation. It
is done using cotton. Gross touch is protopathic
sensation which is checked by fingertip. Sensation
Examination of Peripheral Nervous System
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207
Fig. 8.18: Foot drop with claw toes. It is due to
peroneal nerve injury (Lateral popliteal nerve).
of two point discrimination is checked using a compass
points. A 2 mm separation can be made out normally
which is impaired in a nerve injury. It is transmitted
by posterior column of spinal cord. Superficial pain
sensation from the skin is elicited using sharp pin.
Deep muscular or bone pain is elicited by gentle
pressure or squeezing. Temperature is checked using
warm and cold water in test tubes. Inability to recognise
the size, shape and form of the object is called as
astereognosis. Position sense is joint’s spatial
orientation. It is usually checked in great toe or other
toes; thumb or other fingers. Position sense is checked
with patient eyes closed and eliciting the joint
movements passively by holding its outer aspect
(laterally); and the patient is asked which position the
joint is held. Position sense is often lost with
astereognosis in posterior column lesions. Only
astereognosis with normal position sense and light
touch is seen in parietal lobe injury. Vibration sense
is checked using tuning fork 128 Hz by placing over
the surface (bony protuberance). Vibration sense is
lost in tabes dorsalis, peripheral neuritis, and posterior
column disorders (Figs 8.19A to 8.20D).
Reflexes like biceps, supinator, triceps, knee,
plantar, ankle should be checked for changes. Reflexes
A
B
Fig. 8.19: Upper limb and lower limb dermatomes.
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SRB’s Clinical Surgery
A
B
Figs 8.20A to D: Quick tests for motor and sensory nerves in the hand – ulnar, median and radial nerves.
are str etch reflexes and are indicators of the integrity
of the spinal segments. Tendon is stretched using a
rubber hammer. Often patient is asked to clench the
teeth or interlock fingers so that site to be tested is
relaxed properly. Biceps – C
jerk – C8; Supinator – C8; Knee jerk – L
jerk – S
; Plantar reflex – L5, S1, S2; Abdominal
1, 2
reflexes–T8, T9, 10 and T
L1 segment. In plantar reflex, lateral aspect of the
sole of the foot when scraped causes a withdrawal
reflex and flexion of the great toe. Great toe extension
; Triceps – C
5, 6
2, 3, 4
; Cremasteric reflex –
10, 11
C
A,B,C—Motor, D—Sensory
(upward) occurs in upper motor neuron lesion.
Abdominal reflexes are elicited by stroking upper
and lower abdomen which causes contraction of
rectus abdominis muscle. In cremasteric reflex
; Finger
6. 7
; Ankle
inner side of the thigh is stroked to contract cremaster
muscle.
Movements of the related joint should be checked.
Both active and passive movements should be checked.
In paralysed muscle passive movements are increased
more than active movements (Normally passive and
active movements are near equal; passive movement
D
Examination of Peripheral Nervous System
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is elicited by the examiner; active movement is done
by the patient himself).
Palpation of area of deformity and confirming it
is also necessary.
Palpation of injured area; scar; peripheral pulses;
regional lymph nodes should be done. Nerve
thickening, sensation over a skin patch may need to
check in case of leprosy . Gentle tapping over the course
of the peripheral nerve is done to elicit hyperaesthesia
or ‘pins and needles’ which is a sign of regeneration
of injured nerve—Tinel’s sign.
Systemic Examination
Examination of respiratory system; examination in
relation to features of alcoholism, diabetic neuropathy,
neuritis, syphilis, beriberi, lead poison, arsenic poison
are essential.
Examination of spinal cord and central nervous
system is essential.
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Peripheral Nerve Injuries
Figure 8.21 shows cross-section view of a peripheral
nerve.
Fig. 8.21: Cross-section of a nerve.
Relevant Investigations
Blood tests for diabetes; peripheral smear; haemoglobin. Urine analysis.
Nasal scraping, skin biopsy, nerve biopsy for
leprosy. Usually sural nerve biopsy is done. It is done
under local anaesthesia by making incision over the
lateral aspect of the leg or adjacent to latetral malleolus.
Nerve abscess and AFB staining will confirm the
Hansen’s disease.
Nerve conduction study: It is demonstration of nerve
potentials. It is used to find out nerve regeneration.
It is useful to differentiate from cervical spondylosis,
carpal tunnel syndrome or cervical rib syndrome with
neurological manifestations.
Electrical stimulation: It is to assess reaction of
degeneration. It begins in 4th day of nerve injury and
establishes in 2 weeks. It is seen in denervated muscle.
Normally cathodal/kathodal closure contraction
(KCC) is stronger than anodal closure contraction
(ACC). In muscle denervation, there is no response
to Faradic stimulation but weak galvanic response on
reverse – Anodal closure contraction has become
stronger than Kathodal closure contraction.
Other relevant investigations related to cause – MRI,
serum tests, etc.
Seddon’s Classification
Neuropraxia: It is temporary physiological paralysis
of nerve conduction. Here recovery is complete in
few hours to weeks. There is no reaction of degeneration. It is due to stretching/torsion/transmitted injury.
Axonotmesis: It is division of nerve fibres or axons
with intact nerve sheath. It is an incomplete nerve
injury. Wallerian degeneration occurs distally. It is
due to stress/compression/traction by fractures/
dislocations/exercises. There is reaction of degeneration distally with anodal closure contraction greater
than cathodal closure contraction with near complete
recovery. Position of axons and nerve is intact. Patient
can present with sensory loss, paralysis of muscles
or causalgia. There is loss of sensation, loss of muscle
tone and power, reduced reflex. Total area affected
is lesser than the area supplied by the affected nerve.
Disused atrophy of the affected area occurs with thin
skin, brittle nails, cold and blue tissues.
Neurotmesis: Here complete division of nerve fibres
with sheath occurs. Degeneration occurs proximally
up to the first node of Ranvier (retrograde degeneration)
as well as distal to the injury . Recovery is incomplete
even after nerve suturing. There is complete loss of
motor and sensory functions with loss of reflexes.
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SRB’s Clinical Surgery
Recovery is still poorer if the nerve is of mixed type
other than pure motor or sensory type. Example is
recovery of radial nerve injury at elbow is better than
recovery of median or ulnar nerves.
Injuries may be incised or lacerated or crushed one.
Cut end of the nerve forms proximally neuroma and
distally glioma.
Neuromas may be—True neuroma or False
neuroma; End neuroma or Side neuroma.
Sunderland’s Classification
I. Conduction block—temporary neuronal block.
II. Axonotmesis but endoneurium is preserved.
III. Axonotmesis with disruption of endoneurium but
perineurium is preserved.
IV . Here there is disruption of endo and perineurium
but epineurium is intact.
V. Neurotmesis with disruption of endo, peri and
epineurium.
Clinical Features
Loss of sensory , motor, autonomous and reflex functions; secondary changes in the skin and joints.
Prognostic Factors
Prognostic factors in healing of the nerve injury:
Higher the lesion worse the prognosis; more the gap
between the cut ends worse the prognosis; associated
injuries alter the prognosis; children do better with
nerve injury; type of the injury also decides the
prognosis.
completion of nerve degeneration). It is done by tapping
over the course of the nerve from distal to proximal
to elicit a sensation of ‘pins and needles’ or hyper-
aesthesia. If sensation is felt at the site as well as distally
along the distribution of the nerve that means good
recovery can be expected. If sensation is felt only at
the site of tapping, then result is equivocal. If no
sensation is felt it means no recovery.
Causes of Peripheral Nerve Lesions
Nerve injury/disease may be single nerve disease or
multiple nerve diseases.
Traumatic: Either closed or open injury.
Inflammatory: Leprosy, herpes zoster, diphtheria.
Compression neuropathies.
Lead and arsenic poisoning.
Alcoholism.
Metabolic: Diabetes mellitus, B
deficiency (Beriberi),
1
Porphyria.
Neurofibroma and other neural tumours.
Idiopathic.
Brachial Plexus Injury
It can be—Supraclavicular injury—65%; Infraclavicular injury—25%; Combined—10%.
It can be
• Pre-ganglionic injury like avulsion injury; more
dangerous; extends into the spinal cord.
• Post-ganglionic injury—usually less severe;
better recovery.
TINEL’S SIGN
It is the clinical sign (prognostic indicator) used to
assess the level of regeneration. It is elicited 3 weeks
after the nerve injury (Regeneration begins after the
Upper plexus injury (Erb-Duchenne paralysis) Lower plexus injury: ( Klumpke’s paralysis)
It is due to depression of shoulder by trauma Forcible hyperabduction causes this injury.
After difficult labour in newborn In newborn due to difficult breech delivery
Muscles affected are: Deltoid, Biceps, Brachioradialis, Here C
Supinator. Intrinsic muscles of the hand are involved
Elbow will be extended; pronated and upper limb is Effects are: Combined median and ulnar claw hand
internally rotated (Policeman receiving tip). Sensory Horner’s syndrome
deficit over the lateral aspect of arm and upper part Sensory deficit over the medial aspect
of the lateral forearm. of the forearm, hand and medial 1½
Causalgia
It is severe burning pain in the distribution of a
peripheral nerve due to incomplete injury to the
peripheral nerve. Sites: Common in upper limb, seen
and T1 are injured
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finger
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