updated ppt of examination of sensosry nervous system.pptx

The Rawalpindi Medical University
1

CNS MODULE
SKILL LAB /Physiology PRACTICAL
SECOND YEAR MBBS( BATCH 49 )
EXAMINATION OF THE SENSORY NERVOUS SYSTEM
2
Dr.Afsheen Batool
25th May ,2023

Table of Contents
Sr # Content Slide #
1 Motto, Vision 4
2 Professor Umar Model of Integrated Lecture 5
3 Bloom’s Taxonomy(Domains of learning) 6
4 Diagrammatic Representation of Blooms Taxonomy 7
5 Learning Objectives 8
6 Horizontal Integration 19
7 Core Concept 10 - 43
8 Vertical Integration 45,46
9 Biomedical Ethics(lesson of the day) 48,49
10 Suggested Research Article 50
11 Brainstorming(SEQ relevant with lecture) 52-55
12 Promoting IT and research culture(Digital Library) 56
13 References of this lecture 57

Motto Vision; The Dream/Tomorrow
• To impart evidence based
research oriented medical
education
• To provide best possible
patient care
• To inculcate the values of
mutual respect and ethical
practice of medicine
4

ProfessorUmarModel of Integrated Lecture
5
60%
CORE SUBJECT
20%
HORIZONTAL
INTEGRATION
Physiology
biochemistry
8%
VERTICAL
INTEGRATION
Pathology
pharmacology
7%
VERTICAL
INTEGRATION
Clinical
integration
5%
VERTICAL
INTEGRATION
Research,
professionalism
Ethics
Digital library

BLOOM'S TAXONOMY : DOMAINS OF LEARNING
Sr.
#
Domain of
learning
Abbreviat
ion
Levels of
the
domain
Meaning
1 cognition C C1 Recall / Remembering
2 C2 Understanding
3 C3 Applying / Problem solving
4 Psychomotor P P1 Imitation / copying
5 P2 Manipulation / Follows
instructions
6 P3 Precision / Can perform
accurately
7 Attitude A A1 Receiving / Learning
8 A2 Respond / Starts responding to
the learned attitude
9 A3 Valuing / starts behaving
according to the learned
attitude

Diagrammatic representation of
Blooms taxonomy
7

LEARNING OBJECTIVES
8
Sr. # Learning Objective Domain of
Learning
1 To list key points regarding the sensory system C1
2 To explain different receptors and their function C2
3 To describe various sensory modalities C2
4 To describe the dermatomes and their
importance in sensory examination
C2
5 To perform sensory examination. C3/P3

Core concept
9

1. Separate sensory pathways carry
information about each of the special
senses of vision, taste, olfaction and
equilibrium and about the general
somatosensory sensations of:
TOUCH
PROPRIOCEPTION,
PAIN
TEMPERATURE.
KEY POINTS REGARDING SENSORY SYSTEM
Core Concept
10

CONTD…
2. Somatosensory mechanoreceptors display
distinct physiologic properties based on :
• RECEPTIVE FIELD SIZE
• ABILITY TO ADOPT STIMULUS WITH TIME
• STIMULUS THRESHOLD
• RESPONSE TIME
11

CONTD….
. The propagation rate of action potentials varies
with the diameter of nerve fiber and the degree
of myelination.
4. Pacinian corpuscles are rapidly adapting
mechanoreceptors that act as rate detectors
with large receptive fields.
5.Ruffini’s endings are mechanoreceptors with
large receptive fields and sustained
responses.Rapidly adapting cell.
12

CONTD….
6.Meissner’s corpuscles and Merkel’s disks are
mechanoreceptors with small receptive fields.
Former is rapidly adapting cell ,the later is slowly
adapting.
7. Nociceptors contribute to the perception of
pain by transmitting information about high
intensities of mechanical, thermal, or chemical
stimulation.
13

CONTD…
. Thermoreceptors in the skin are rapidly adapting
and have a limited response range.
9. Thermoreceptors within central nervous system
exibit acute sensitivity and allow the body to
maintain the temperature of the nervous system
within its narrow functional range.
10. Proprioceptors in muscles and joints send
information about body position and movement
to cerebellum and other motor
14

CONTD…
in order to maintain posture and aid in muscle
reflexes.
11. Visceral sensory fibers provide general
information about mechanical, chemical and
thermal stimuli, but the sensation is not well
localized and is often referred or perceived as
emerging from some unstimulated part of the
body.
15

TRANSMISSION OF SENSORY
INFORMATION.
• Transmission of sensory information to the central
nervous system is triggered when receptors reach the
threshold required to initiate action potentials; the
number of action potentials reflect the srength of the
triggering stimulus.
1. Somatic sensory neurons release glutamate at their
axon terminals in order to stimulate postsynaptic
neurons within the central somatosensory pathway.
2. Different modalities and submodalities of
somatosensory sensation project in discrete
pathways within the dorsal and lateral portions of the
spinal cord.
16

3. Somatosensory information from head region is
carried by trigeminal nerve.
4. Nerve impulses for touch ,pressure ,vibration and
conscious proprioception from the limbs,
trunk,neck and posterior head ascend to the
cerebral cortex along the posterior column
medial lemniscus
5. Nerve impulses for pain,temperature,itch and
tickle from the limbs, trunk,neck and posterior
head ascend to the cerebral cortex along the
anterolateral or spinothalamic pathway.
17

6. Subcortical regions that receive
somatosensory information include:
a) The cerebellum ,which uses proprioceptive
information to coordinate movements and
posture.
b) . Motor nuclei in the spinal cord and brain
stem ,which control protective motor reflexes
in response to potentially harmful stimuli.
18

Horizontal integration (Anatomy)
DERMATOMES OF UPPER AND LOWERLIMB
Reference:/www.google.com/search?q=lower+limb+dermatome&s
ource=lnms&tbm=isch&sa=X&ved=2a 19

Assessment of sensory function
• For the assessment of sensory system ,six main
sensory modalities that can be tested at the
bedside include:
1. Pain
2. Temperature
3. Tactile sensibility
4. Vibration
5. Position
6. stereognosis
Core
concept
20

Pain testing
• Demonstrate the procedure to the patient.
• Ask the patient to say whether the pinprick feels
sharp or dull.
• Begin proximally on the upper arm and test in
each dermatome-the area of skin supplied by a
vertebral spinal segment.
• Compare right with left in the same dermatome.
• Map out the extent of any area of dullness.
• Do this by going from the area of dullness to the
area of normal sensation
21

Reference:https://www.google.com/search?q=pain+testing+for+sensory
+nervous+system&tbm=isch&ved=2ah
22

Temperature testing
• This can be done by using test tubes filled with hot (40
to 45 degrees) and cold(5 to 10 degrees) water.
• Cold sensation can also be tested with a metal object
such as tunning fork.
• Absence of ability to feel heat is almost always
associated with inability to feel cold.
• Temperature differences of 2 to 5 degrees can usually
be distinguished.
• These tests are performed only in special
circumstances for example, for suspected
syringomyelia.
23

Reference:https://www.google.com/search?q=examination+of+sensory+nerv
ous+system&source=lnms&tbm=isch&
24

VIBRATION TESTING
• Use a 128Hz tuning fork(not a 256Hz fork).
• Ask the patient to close the eyes,and then place
the vibrating tuning fork on one of the distal
interphalangeal joints.
• The patient should be able to describe feeling of
vibration.
• If vibration sense is reduced or absent ,test over
the ulnar head at the wrist,then the elbows (over
the olecranon)and then the shoulders to
determine the level of abnormality.
25

Reference:https://www.google.com/search?q=vibration+testing+sen
sory+system&tbm=isch&ved=2ahUKEwiKk7CL_
26

LIGHT TOUCH TESTING
• Some fibers travel in the posterior
columns(ipsilateral)and rest cross the middle
line to travel in the anterior spinothalamic
tract(contralaterally).
• For this reason light touch is of the least
discriminating value.irritation of light touch
receptors is probably responsible for
paraesthesiae-for example following
ischaemia of limb.
27

• Test light touch by touching the skin with a
wisp of cotton wool. Ask the patient to to shut
the eyes and say yes when the touch is felt
.Don’t stroke the skin because this moves hair
fibers test each dermatome comparing light
and left side.
28

29

PROPRIOCEPTION/POSITION TESTING
• Use the distal interphalangeal joint of the
patient’s little finger.
• When the patient has his/her eyes open
,grasp the little finger from sides and move it
up and down to demonstrate these positions.
• Then ask the patient to close eyes while these
manoeuvers are repeated randomly.
30

CONTD…
• Normally movement through even a few
degrees is detectable and should be reported
correctly.
• If there is abnormality,proceed to test the
wrists and elbows similarly.
• As a rule, sense of position is lost before sense
of movement,and the little finger is affected
before the thumb
31

Reference:https://www.google.com/search?q=proprioception+test&tbm=isch&ved=2
ahUKEwjR76_1-or_AhU3HLcAHaI9Bq4
32

Two point discrimination
• This is a useful, sensitive,quantitative test of
fingertip sensory discrimination that requires
intact distal sensory function and also intact
dorsal columns and primary sensory cortex
function.
• Use a pair of blunt dividers(two point
discriminator)and ask whether one or both
points can be felt.
33

CONTD…
• Normally 2mm separation of the points can be
recognized as two separate stimuli on the
figertips, and rather wider separation about
1cm on the pulps of the toes.
34

Reference:https://www.google.com/search?q=examination+of+sensory+nervou
s+system&source=lnms&tbm=isch&
35

STEREOGNOSIS AND GRAPHAESTHESIA
• Ask the patient to close the eyes. place
familiar small object, e.g coin ,key and
matchstick,in the patient’s hand
• Ask patient to identify object.
• Use the blunt end of a pencil and trace letters
or digits on the patients palm.
• Ask the patient to identify the figure.
36

37

Examination of lower limb
PAIN(pinprick)testing:
• Explain and demonstrate that the ability to
feel a sharp pinprick is being tested.
• Use a fresh neurological pin or sterilized pin.
Dispose off the pin after each patient to avoid
transmitting infection.
• Check sensation in each dermatome.
• Map out the boundaries of any area of
reduced ,absent or increased sensation.
38

TEMPERATURE TESTING
• Like upper limb this can also be carried out by
using test tube filled with hot or cold water
• Absence of ability to feel heat is almost always
associated with inability to feel cold.
• Temperature difference of 2 to 5 degrees can
usually be distinguished.
39

VIBRATION TESTING
• Test vibration sensation over the ankle first
and if necessary ,on the knees and the
anterior superior iliac spines by using tuning
fork.
• Use 128Hz tuning fork
• Ask the patient to tell when vibration feels
and when it stops.
40

PROPRIOCEPTION/POSITION TESTING
• With the patients eyes open, demonstrate the
procedure.
• Hold the distal phalanx of the patient’s great toe at the
sides to avoid giving information from pressure and
move it up and down.
• Ask the patient to respond with up or down as you
make these movements without him/her assisting or
resisting.
• Now ask the patient to close eyes and repeat the
procedure.
• Test both great toes .If impaired move to more
proximal joints in each limb.
41

LIGHT TOUCH TESTING
• While the patient looks away or closes his
eyes, use a wisp of cotton wool and ask the
patient to respond to each touch.
• Time the stimuli irregularly and make a
dabbing rather than a stroking or tickling
stimulus.
• Compare each side for symmetry.
42

TWO POINT DISCRIMINATION
• Use a two point discriminator
• Ask the patient to look away or close the eyes.
• Apply either one or two points to the pulp of
the patient’s forefinger and ask whether one
or two stimuli were felt.
• Adjust the distance between the two points to
determine the minimum separation at which
they are felt separately.
• Test both fingers and thumbs.
43

Vertical Integration
(Clinical and paraclinical sciences)
44

Reference:https://www.google.com/search?q=gangrenous+foot&sour
ce=lnms&tbm=isch&sa=X&ved=2ahUKE 45

Reference:https://www.google.com/search?q=brown+sequard+syndrome&
tbm=isch&ved=2ahUKEwjtx_mL_Yr_AhU 46

Bioethics
47

The four principles of Beauchamp and Childress
• The four principles of Beauchamp and Childress have been extremely
influential in the field of medical ethics, and are fundamental for
understanding the current approach to ethical assessment in health care.
48

Lesson of the day
Beneficence
• More commonly in medical ethics, beneficence is understood as a principle
requiring that physicians provide, and to the best of their ability, positive
benefits such as good health, prevent and remove harmful conditions from
patients.
49

Suggested research article
Reference:https://journals.lww.com/pain/Fulltext/2019/05001/The_role_
of_quantit
50

Brainstorming
51

Structured essay question related to
topic
• A 55 years old male known case of
diabetes mellitis ,on insulin therapy
presented in surgical emergency with
complaint of wound on his right foot. On
examination wound is dry,
black(gangrenous)and loss of sensations.
What is the probable cause of this
condition?
52

ANSWER
DIABETIC PERIPHERAL NEUROPATHY.
53

Structured essay question related to
topic
A 25 years old boy presented in medical out
patient department with complaints of
paralysis of left side of body and loss of
sensations on both sides.On examination he
has decrease power in both left arm and leg
and loss of vibration and touch on same side,
while loss of pain and temperature on
opposite side. History reveals he had gunshot
injury one month back .what is the probable
diagnosis?
54

Answer
Brown sequard syndrome
55

• Steps to Access HEC Digital Library
1. Go to the website of HEC National Digital Library.
2. On Home Page, click on the INSTITUTES.
3. A page will appear showing the universities from Public
and Private Sector and other Institutes which have access
to HEC National Digital Library HNDL.
4. Select your desired Institute.
5. A page will appear showing the resources of the
institution
6. Journals and Researches will appear
7. You can find a Journal by clicking on JOURNALS AND
DATABASE and enter a keyword to search for your desired
journal.
Promoting IT and Research Culture
How To Access Digital Library
56

REFERENCES
•Guyton And Hall textbook of Medical Physiology 14th
Edition
•Ganong’s Review of Medical Physiology 25th Edition
•Sherwood, 9th edition.
•Silverthorn Physiology,6th edition
•Vander’s Human Physiology,14th edition
•Google images.
57

58

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