Reflexes

Examination of Reflexes
Dr. Sai Sailesh Kumar G
Associate Professor
Department of Physiology
RDGMC

Contents
 Reflex
 Purpose of examination
 Superficial reflexes (Cranial and spinal reflexes)
 Deep or tendon reflexes (Cranial and spinal
reflexes)

Reflex
 Reflex is defined as an involuntary response to a
stimulus.
 It depends on integrity of reflex arc, which consists
of receptor, afferent nerve, center, efferent nerve
and effector organ.
 Reflex can be Monosynaptic or polysynaptic.

Types of reflexes
Mono synaptic reflexes
or Deep reflexes
 Knee jerk
 Ankle jerk
 Biceps jerk.
 Triceps jerk
 Supinator jerk
 Jaw jerk
Poly synaptic reflexes
or superficial reflexes
 Abdominal reflex
 Plantar reflex
 Conjunctival reflex
 Corneal reflex
 Pupillary reflexes
 Cilio spinal reflex

Purpose of examination
 Whether the reflex is present or absent.
 If present whether its normal or showing signs that influences
from higher centres are defective.
 If absent, whether the arc is breached on the motor or
sensory side.
 Whether any abnormalities are unilateral, bilateral, affecting all
reflexes or whether a definite level can be detected in the nervous
system at which abnormalities first appear because reflex
‘levels’ may be helpful as sensory level.

Superficial reflexes
Cranial reflexes
 Corneal reflex
 Conjunctival reflex
 Cilio spinal reflex
 Pupillary reflexes
Spinal reflexes
 Abdominal reflex
 Plantar reflex
 Cremastric reflex

Cranial reflexes

Corneal reflex
 Mediated by opthalmic division of trigeminal nerve
 Make the subject to sit comfortably
 Ask the subject to fix his gaze at a distant object or the ceiling
 Bring the cotton wisp from the side of the subject and touch the
lateral edge of the cornea at its conjunctival margin
 Observe that the subject blinks his eyes
 Elicit the corneal reflex on the other side and compare.

Conjunctival reflex
 Mediated by opthalmic division of trigeminal nerve
 Ask the subject to fix his gaze at a distant object or the ceiling
 Bring the cotton wisp from the side of the subject and touch the
bulbar part of conjunctiva
 Observe that the subject blinks his eyes
 Elicit the corneal reflex on the other side and compare.

Pupillary reflexes
 Mediated by third cranial nerve
 Light reflex- direct, indirect and Accommodation reflex
Light reflex- direct
 Ask the subject to fix his gaze at a distant object
 Shine a bright light in one eye with the torch
 Observe immediate constriction of pupil in the same eye
 Elicit the light reflex on the other side and compare

Pupillary reflexes
Light reflex- in direct
 Hold the cardboard on the forehead and bridge of the nose
 Shine a bright light in one eye with the torch
 Observe immediate constriction of pupil of both eyes
 Elicit the light reflex on the other side and compare

Pupillary reflexes
Accommodation reflex
 Bring your index finger midway between and near the eyes of the subject
 Ask the subject to look at the tip of the index finger
 Observe the constriction of pupil and convergence of eyes.

Ciliospinal reflex
 The ciliospinal reflex (pupillary-skin reflex) consists of dilation of
the ipsilateral pupil in response to pain applied to the neck, face,
and upper trunk.
 If the right side of the neck is subjected to a painful stimulus, the
right pupil dilates (increases in size 1-2mm from baseline).

Spinal reflexes

Plantar reflex
 Position the patient so that knee is slightly flexed, and thigh externally
rotated.
 The foot is rest on the couch. Ask the patient to let the foot remain closed.
 The outer aspect of sole is then firmly stroked with the blunt point end of
knee hammer.
 Then curve the stimulus towards the middle metatersophalengeal joint.
 Do the stimulation slowly and allow yourself time to see what is
happening.
 Normally great toe flex at the metatersophalengeal joint.
 At the same time other toe will flex and close together.

Babinski’s sign
 Extension of the great toe at the interphalengeal joint, and the
other toes open in a fanwise manner and are dorsiflexed.
 It indicates UMN lesion above L5 segment.

Babinski sign
Babinski sign negative Babinski sign positive

Abdominal reflexes
 The patient should first lie flat. Palpate gently to asses the degree of
relaxation and the sensitivity of the skin. Explain the patient the
procedure.
 Lightly stroke the abdomen with a pencil, key or with the end of the
hammer in all quadrants of abdomen and lower margin of the thoracic
case.
 Normal resultthe muscle contract and umbilicus moves in that direction.
 Segmental innervation- Epigastric-T7-T9, Upper abdominal T9-T11,
Lower abdomen T11-T12

Abdominal reflexes
 Abnormal response- Exaggerated abdominal reflexes occur in
psychoneurosis, nervousness.
 Absent of reflex- UMN lesion above the level of reflex arc, LMN
lesion at
 corresponding reflex arc, obesity, rigid abdomen.

Deep reflexes
Cranial reflexes
 Jaw jerk
Spinal reflexes
 Biceps jerk
 Triceps jerk
 Supinator jerk
 Knee jerk
 Ankle jerk

Biceps Jerk (C5, C6)
 Relax the forearm on examiners hand
 Place the forefinger gently on the biceps tendon and then strike
the finger with hammer
 Normal response – flexion of elbow and visible contraction of
biceps

Supinator Jerk (C5, C6)
 Relax the forearm on patient’s body at pronation state. Strike the
lower end of radius about 5 cm above the wrist
 Watch the movement of forearm and finger.
 Contraction of brachioradialis and flexion of elbow results.
 Also slight flexion of finger may occur.

Triceps Jerk (C6,C7)
 By holding the patients hand, draw the arm across the trunk and
allow it to lie loosely in the new position.
 Then strike the triceps tendon 5 cm above elbow.
 Extension of elbow and visible contraction of triceps seen.

Knee Jerk (L2,L3,L4)
 Patient supine, flex the knee 60ᵒ by placing the forearm under the
knee to be tested.
 Strike the patellar tendon midway between its origin and insertion.
 Extension of knee and visible contraction of quadriceps seen.
 It can also be done with patient in high sitting on bed and leg
hanging at edge.

Ankle Jerk (S1, S2)
 Patient in supine position, hip externally rotated, slightly flex the knee
(medial malleolus facing upward), dorsiflex the ankle by examiner as to
stretch the achillis tendon.
 Strike the tendon on posterior surface.
 The calf contracts and moves ankle.
 The plantar flexion of foot can be felt by the hand of examiner.
 Alternative method:- ask the patient to kneel on the chair so that the ankle
are hanging loose over the edge. Then strikes the achillis tendon.
 Normal response – plantar flexion of the foot and the contraction of
gastrocnemius muscle.

Jaw Jerk
 Ask the person to partially open the mouth.
 Place a finger firmly on his chin.
 Strike the finger with the help of knee hammer
 Use the narrow end of knee hammer
 Observe the immediate closure of the mouth.
 This response is due to contraction of the elevators of the jaw.

Jendrassik’s Maneuver
 This is performed by asking the subject to make a strong voluntary
muscular effort using following methods.
 While testing the reflexes of the lower limb, ask the subject to hook
the fingers of two hands together and pull them apart (against one
another) as hard as possible.
 While testing the reflexes of the upper limb, ask the subject to
clench his teeth or to make a fist in the other hand.

Abnormalities in tendon reflexes
Exaggeration
 Reflex may be excessively brisk, the movement being a sudden,
short lived jerk. This type of reflex is seen of UMN lesion. Also seen
in fright, anxiety, after violent exercise but then return to normal on
rest.
 .A reflex may be clonic :- the muscle that has been stretched goes
into clonic contraction until the stretch is relieved. It is seen in
pyramidal disease, and in tensed individual.

Abnormalities in tendon reflexes
Reduction or absent
 Defective technique application
 When there is breach of ant part of reflex system.E.g.- sensory
nerve(polyneuropathy), sensory root (tabes dorsalis), anterior horn
cell(poliomyelitis), the anterior root(spinal compression), the
peripheral nerve (trauma), the terminal nerve
ending(polyneuropathy) or the muscle itself(myopathy)
 During cerebral or spinal shock phase which can be of some hour
to some days

Reflexes

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Reflexes