Download laboratory 5: cranial nerve and reflex testing

CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
LABORATORY 5: CRANIAL NERVE AND REFLEX TESTING
REMINDER:
bring a calculator to class
AND
wear clean socks!!
PART 1 : CRANIAL NERVES
Purpose
1. review the general functions of the cranial nerves
2. describe a clinical test for the function of each cranial nerve (see lab manual p 2 and 3)
Review of cranial nerve functions:
NAME
FUNCTION
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
TESTS OF CRANIAL NERVE FUNCTION
One method of assessing neurological damage is to test cranial nerve function. Working with a
partner, perform the following tests as instructed that demonstrate cranial nerve function. Your
assignment involves determining which cranial nerve(s) is/are assessed by which test.
Test A. cranial nerve tested = __________________________________________
Ask the subject to: wrinkle the forehead by looking upward, close the eyelids forcefully while you
try to pry them open, show the teeth and to whistle or purse the lips, draw the lower lip and mouth
downward while tensing the surface of the skin of the neck, similar to the action that men use
while shaving.
Test B. cranial nerve tested = __________________________________________
Ask the subject to gaze at a distant point, and compare the size of the two pupils. Gazing far
away is important to avoid the pupillary constriction that occurs during the accommodation reflex.
As the subject gazes into the distance, move a bright flashlight in from the sides to illuminate
each eye separately. The eye into which the light is shining should demonstrate a prompt
pupillary constriction. This is the direct pupillary response. The opposite eye should show an
equal constriction. This is the consensual pupillary response. Each eye should be tested
separately.
Test C. cranial nerve tested = __________________________________________
Ask the subject to close their eyes and occlude one nostril. Present to the non-occluded nostril
the test stimulus, and ask the subject to sniff and identify the odor if possible. Non-irritating odors
such as a stick of gum, ground coffee or tobacco may be used. The other nostril is tested in a
similar fashion.
Test D. cranial nerve tested = __________________________________________
Ask the subject to look downwards without changing the position of their head.
Test E. cranial nerve tested = __________________________________________
Ask the subject to look to the side without changing the position of their head (move eyes
laterally).
Test F. cranial nerve tested = __________________________________________
Ask the subject to protrude their tongue on the midline past the teeth, and to wiggle it from side to
side. In the normal case, the patient will be able to move the tongue on the midline without any
deviation.
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
Test G. cranial nerve tested = __________________________________________
Have the subject close his/her eyes. Lightly whisk a piece of dry cotton over the mandibular,
maxillary and ocular areas of the face. Check both sides of the face. Have the subject clench
his/her teeth and hold one hand firmly under his/her chin, then open their mouth. This tests the
motor function of the mandibular branch of this nerve.
Test H. cranial nerve tested = __________________________________________
Ask the subject to close his/her eyes and snap your fingers about 1 meter away from the left or
right side of the head. Ask her/him to identify the direction from which the sound is coming.
Test I. cranial nerve tested = __________________________________________
Ask the subject to cover their right eye and look at your right eye with their left eye. You should be
positioned at about an arm's length away from the patient. Utilize your finger as a target by
wiggling it and moving it from outside your peripheral visual field to inside. Ask the subject to
report when she/he sees it. All four quadrants should be tested (it is most efficient to test at about
45° above and below the horizontal meridian). Essentially, you are testing the patient's peripheral
fields against your own. You should be observing for defects that involve one-half of the visual
field or one-quarter of the visual field and whether the defect is the same or different in both eyes.
Test J. cranial nerve tested = __________________________________________
Ask the subject to dip a swab in quinine solution and apply it to the back of the tongue. Ask the
subject to describe the taste
Test K. cranial nerve tested = __________________________________________
Place your hands on your partner’s shoulders and ask him/her to raise them against your
resistance. Place your hands on each side of your partner’s head and ask him/her to turn the
head to each side against your resistance.
Test L. cranial nerve tested = __________________________________________
DO NOT DO THIS TEST but see if you can figure out what nerve is involved. In this test, the
posterior wall of the pharynx is touched with a tongue depressor. The normal response is
contraction of pharyngeal muscles, and elevating the soft palate. The response is called the gag
reflex, although gagging may or may not occur. Each side of the pharynx needs to be tested
separately.
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
PART 2. REFLEXES
Purpose:
1.
2.
3.
4.
To identify and describe the functions of the basic elements of the reflex arc.
To explain why reflex testing is an important part of a physical examination.
To describe and discuss several types of reflex activities observed in this laboratory.
To identify the spinal nerves involved for each of the spinal reflexes investigated in the
laboratory.
Clinical reflexes are automatic, predictable muscle movements brought on through known neural
circuits when the appropriate receptor is stimulated. They can be used to assess neural
development or health. Relexes are initiated when sensory receptors are stimulated and occur
when an effector (eg. muscle) responds.
SOMATIC REFLEXES
Somatic reflexes terminate with the excitation of skeletal (voluntary) muscle. The stimulus for
such a reflex may be initiated through excitation of receptors in the skin or mucosae, and are
therefore called superficial reflexes, or through excitation of receptors in tendons or in the
muscles themselves, and are therefore called deep reflexes.
Somatic reflexes may involve turn around (integration) centers in the spinal cord and would
therefore be called spinal reflexes or in the brain itself and would therefore be called cranial
reflexes.
Procedure:
For each reflex tested, classify the location of the stimulus (superficial, deep) the location of
integration (spinal, cranial) the type of effector excited (somatic, autonomic) Also, describe the
observed responses for each reflex and name the muscles and neural pathways involved as
much as possible.
Work in pairs, taking turns performing each of the tests.
1. Patellar (knee jerk) reflex
Have the subject seated on the laboratory bench with legs hanging free or with knees
crossed. Locate the patellar ligament by palpation of the patella. The patellar ligament is
located just below the kneecap. Tap the patellar ligament sharply with the reflex hammer to
elicit the reflexive response. Test both knees and observe the responses.
Response: ________________________________________________________
2. Achilles reflex (ankle-jerk response)
Have the subject remove shoes. Ask the subject to dorsiflex the foot slightly to increase the
tension of the gastrocnemius muscle. Sharply tap the calcaneal tendon and note the results.
Response: ___________________________________________________________
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
3. Plantar reflex
Have the subject remove a shoe and lie on the laboratory bench with knees slightly bent.
The lateral side of the foot should rest on the bench. Draw the handle of the reflex hammer
firmly down the lateral side of the exposed sole from the heel to the base of the great toe.
Note the response.
Response: __________________________________________________________
NOTE: This reflex is commonly tested in infants. Infants will typically show an extensor
response. A baby's smaller toes will fan out, and their big toe will dorsiflex slowly. This is
known as ‘Babinski’s sign’ and occurs because the corticospinal pathways that run from
the brain down the spinal cord are not fully myelinated at this age, The extensor response
disappears and gives way to the flexor response around 12-18 months of age.
The Babinski’s sign in adults can indicate motor neuron damage to the spinal cord in the
thoracic or lumbar region, or brain disease constituting damage to the corticospinal tract.
Complete the following table.
Reflex
Receptor
stimulated
Site of
Integration
Effector
Superficial
or Deep
Nerve
Patellar
Reflex
Achilles
reflex
Plantar
reflex
VISCERAL (AUTONOMIC) REFLEXES
Smooth muscle, cardiac muscle and glands are innervated by autonomic nerves. Innervation
may be either sympathetic or parasympathetic and may result in excitation or inhibition of action.
Autonomic reflexes may be cranial or spinal, superficial or deep. The pupillary reflex that was
examined as an assessment of cranial nerve function is an visceral reflex.
Reflex
Receptor
Afferent nerve
Site of
Integration
Effector
Efferent
Nerve
Pupillary
Reflex
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PART 3: REACTION TIME
Purpose:
Unlike the other activities, this lab exercise does not test a simple reflex. Rather, this activity is
designed to measure your response time to something that you see. The time required for a
person to react to a stimulus depends on several factors:
•
•
•
•
•
•
•
responsiveness of the sensory receptor
nerve conduction velocity
synaptic delay
number of neurons and synapses involved
distance nerve action potential must travel
efficiency of neuromuscular transmission
speed of muscle contraction
Procedure:
1. Working in groups of two students, get a ruler marked into cm
2. One partner will hold the ruler near the end (highest number) and let it hang down.
3.
Have the other student place his or her hand at the bottom of the ruler (over the 0
measurement) and have them ready to grab the ruler (they should place their fingers
approximately 5 mm away from the ruler).
4.
Tell the other person that you will drop the ruler sometime within the next 5 seconds and that
they are supposed to catch the ruler as fast as they can after it is dropped. Record the level
(in centimeters) at which they catch the ruler. This represents the distance the ruler fell
before it was caught. You can convert this distance into reaction time using a graph of data
on the following page.
5.
Test the same person 4 times (vary the time of dropping the ruler within the 5 second "dropzone" so the other person cannot guess when you will drop the ruler). Calculate the
average distance.
6.
Repeat the test using the test subject’s other hand (eg. if they are right handed, now
evaluate distance using the left hand)
7.
Determine reaction time by looking up the average values on the graph generated from data
on the following page.
Table 1. Distance ruler traveled in a test of reaction time
distance ruler traveled (cm)
1
dominant
hand
2
3
4
mean
reaction
time
(msec)
subject 1
subject 2
nondominant
hand
subject 1
subject 2
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
8. Plot a “standard curve”. This is a reference curve generated using known values. An
accurate standard curve can be used to extrapolate unknown values. Graph the known
relationship between time and the distance a falling object travels using the following data
set. Table 2. Relationship between distance an object falls and time
Distance(cm)
5
10
15
20
30
40
60
80
Time (msec)
100
140
170
200
240
285
350
405
9. The reaction times for the dominant and non-dominant hands can then be determined by
looking up the mean distance that the ruler traveled (as calculated in table 1) and reading the
reaction time off your standard curve above. Put these values in table 1.
10. Did reaction time seem to improve with ‘practice’
th
(eg. was it less on the 4 trial than the first)?
Is this a reflex you are testing?
_______________
_______________
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
Table 4 Class reaction time data (msec) in the ruler-drop test
Dominant hand
Non-dominant hand
mean
males
females
mean
11. What is the range of reaction times for the class? range = ________________
12. Using the class data, calculate the mean reaction time for the
dominant hand =
__________________
non-dominant hand =
__________________
What is the independent variable in this analysis? ________________________
13. Based on your observations, does reaction time
vary on the dominant vs non-dominant side? _______________
13. Using the class data, calculate mean reaction time (dominant hand) for males and females
Mean reaction time (males)
_________________
Mean reaction time (females)
_________________
What is the independent variable in this analysis? ___________________
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14. Let’s assume you want to publish the results of this study.
Graph the reaction time data in some meaningful way!
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
PART 4. ‘MUSCLE MEMORY’?
Performance of a motor skill will improve with practice. Repetition of a motor skill (eg. throwing a
javelin, doing a flip-turn in the pool, typing, piano playing, etc.) results in progressive
improvement. The term ‘muscle memory’ is sometimes used to describe this effect. Muscle
memory is fashioned over time through repetition of a given suite of motor skills until they become
automatic. Even everyday activities such as brushing the teeth, combing the hair, or chewing food
involve a complex series of neuromuscular events that must be learned. As these movements
are reinforced neurologically through repetition, the nervous system ‘learns’ these fine and gross
motor skills to the degree that one no longer needs to think about them, but merely to react and
perform appropriately. Repeated use of a particular neural pathway is thought to reinforce
neuromuscular communication through physiological changes involving the cerebellum and
neuromuscular junctions.
Read the abstract below which summarizes the results of a study which illustrates this principle.
The Impact of Video Games on Training Surgeons in the 21st Century
James C. Rosser, Jr, MD; Paul J. Lynch, MD; Laurie Cuddihy, MD; Douglas A. Gentile, PhD;
Jonathan Klonsky, MD; Ronald Merrell, MD
Arch Surg. 2007;142:181-186.
Background Video games have become extensively integrated into popular culture.
Anecdotal observations of young surgeons suggest that video game play contributes to
performance excellence in laparoscopic surgery. Training benefits for surgeons who play
video games should be quantifiable.
Hypothesis There is a potential link between video game play and laparoscopic surgical skill
and suturing.
Design Cross-sectional analysis of the performance of surgical residents and attending
physicians participating in the Rosser Top Gun Laparoscopic Skills and Suturing Program
(Top Gun). Three different video game exercises were performed, and surveys were
completed to assess past experience with video games and current level of play, and each
subject's level of surgical training, number of laparoscopic cases performed, and number of
years in medical practice.
Setting Academic medical center and surgical training program.
Participants Thirty-three residents and attending physicians participating in Top Gun from
May 10 to August 24, 2002.
Main Outcome Measures The primary outcome measures were compared between
participants' laparoscopic skills and suturing capability, video game scores, and video game
experience.
Results Past video game play in excess of 3 h/wk correlated with 37% fewer errors (P<.02)
and 27% faster completion (P<.03). Overall Top Gun score (time and errors) was 33% better
(P<.005) for video game players and 42% better (P<.01) if they played more than 3 h/wk.
Current video game players made 32% fewer errors (P=.04), performed 24% faster (P<.04),
and scored 26% better overall (time and errors) (P<.005) than their nonplaying colleagues.
When comparing demonstrated video gaming skills, those in the top tertile made 47% fewer
errors, performed 39% faster, and scored 41% better (P<.001 for all) on the overall Top Gun
score. Regression analysis also indicated that video game skill and past video game
experience are significant predictors of demonstrated laparoscopic skills.
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CAMOSUN COLLEGE BIOLOGY 144 (2010) LABS
Author Affiliations: Department of Surgery, Beth Israel Medical Center (Drs Rosser and
Lynch), and Department of Anesthesiology, New York University Medical Center (Dr Lynch),
Department of Orthopedic Surgery, Montefiore Medical Center (Dr Cuddihy), and Department
of Surgery, Brookdale University Hospital and Medical Center (Dr Klonsky), New York, NY;
Department of Psychology, Iowa State University, Ames (Dr Gentile); and Department of
Surgery, Virginia Commonwealth University, Richmond (Dr Merrell).
The conclusion component of this scientific abstract has been omitted. The conclusion is
a concise written summary of results which explains the potential importance or relevance
of the results.
Write a conclusion section for this abstract:
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