Upload
pamela-agatha-puno
View
60
Download
0
Embed Size (px)
Citation preview
Reflexes
and
Special SensesSpecial Senses
REFLEXES
• Reflex
- a rapid, predictable and involuntary motor response to stimuli.
• Sources of Stimulus and Classification of Reflexes
A) internal environment
- Autonomic / Visceral reflex
B) external environment
- Somatic reflex
Reflex Arc Mechanism Components
• Receptor organ ( w/ Afferent / Sensory Neuron)
• Communication network (Interneurons / network (Interneurons / Association Neurons))
• Effector organ
(w/ Efferent / Motor Neuron)
Monosynaptic and Polysynaptic Reflex Arcs
Somatic: Spinal Stretch Reflexes
A. Patellar (or Knee-Jerk) Reflex:
Purpose: L2-L4 Assessment
Procedure:
B. Achilles (or Ankle-Jerk) Reflex:
Purpose: Assessment of sacral segments 1 and 2
Procedure:
Somatic: Spinal Stretch Reflexes
Results of Spinal (Stretch) Reflexes
• Hyperflaxia (exaggerated response) resulting
from damaged or diseased motor areas in the
CNS.
• Hypoflaxia (inhibited response) resulting from
the degeneration of the nerve pathways,
voluntary motor control, and other factors
A. Plantar Reflex:
Purpose: Assessment of corticospinal tract damage
Procedure:
Somatic: Superficial Cord Reflex
A. Corneal Reflex:
Purpose: Assessment of trigeminal nerve (cranial nerve V) or brain stem dysfunction
Procedure:
Somatic: Cranial Nerve Reflex
Autonomic Reflex: Pupillary ReflexesComponents:
a) Receptor: Retina of the eye
b) Afferent Fibers: Optic Nerve (Cranial nerve II)
c) Efferent Fibers: Oculomotor Nerve (Cranial nerve III)nerve III)
d) Effector: Smooth muscles of iris
A. Photopupillary (or Pupillary Light) Reflex:
Purpose: Assessment of optic nerve or brain stem
dysfunction
B. Consensual Reflex:
Purpose: Assessment of oculomotor nerve or brain
Autonomic : Pupillary Reflex
Purpose: Assessment of oculomotor nerve or brain
stem dysfunction
Procedure:
Results of Photopupillary and Consensual Reflex:
Autonomic : Pupillary Reflex
Special Senses
A. Visual Function Tests
Retina to Brain
retinaoptic nerve
lateral geniculate
nucleus
visual cortex
A.1. Blind Spot TestA.1. Blind Spot Test
Examples of Blind Spot Test Charts
Blind Spot Chart
A.2. Refraction,Visual Acuity and
Astigmatism TestsAstigmatism Tests
A.1.1. Near Point of Accommodation
• Definition:
• The ability of the eye to adjust its focus in
relation to changes in distance of an object
being viewed (less than 20 feet)being viewed (less than 20 feet)
• Procedure:
Principle of Near Point of Accommodation
Accommodation Test
Accommodation Test
• Interpretation of Results / Clinical Diagnosis:Normal vision – 10 cm; emmetropia
Abnormal:
a) Myopia (“Nearsightedness”) – failure of the parallel light rays to reach the retinal surface.
b) Hyperopia (“Farsightedness”) – the parallel light rays are b) Hyperopia (“Farsightedness”) – the parallel light rays are focused behind the retina.
Ageing Patients: presbyopia “old vison”
• Treatment:Myopia – concave lenses
Hyperopia – Convex lenses
A.1.2. Visual Acuity Test
• Definition:
• The clearness and sharpness of an image
• Procedure:• Procedure:
Visual Acuity Test
(Snellen’s Chart)
Visual Acuity Charts
Visual Acuity
• Interpretation of Results:Ratio is <1 = a person has greater than normal visual
acuity
Ratio is >1 = a person has less than normal visual acuity acuity
• Sample Problem: Patient 1: 20/20
Patient 2: 20/70
• Clinical Diagnosis:>1 Ratio (myopia = “nearsightedness”)
• Definition:
the abnormal curvature in some parts of the
lens and/or cornea
A.1.3. Astigmatism Test
• “Astigma” – not a point
• Procedure:
Astigmatism Test Chart
Astigmatism Test Chart
Test for Astigmatism
• Interpretation of Results:
Normal eyes – all radiating lines are equally dark and
distinct.
Astigmatic Eye – some lines are blurred or appear Astigmatic Eye – some lines are blurred or appear
less dark than the others
A.1.4. Color Blindness Test
Photoreceptors
• Rods – peripheral
region of retina; dim
light; black and white
• Cones – fovea; bright
light; colored; types
a) absorbs red
b) absorbs blue
c) absorbs green
Ishihara’s Color Blindness Test
• Purpose: test for deficiencies in the cones
(color photoreceptor cells)
Ischihara Test Kit
= collection of 38 plates filled with colored dots build the base of this test. The dots are colored in different shades of a color and a number or a line is hidden inside with different shades of an other color.other color.
= Distance from Subject:30 inches (75 cm)
Ishihara Test
Normal Color Vision Red-Green Color Blind
Left Right Left Right
Top 25 29 Top 25 Spots
Middle 45 56 Middle Spots 56
Bottom 6 8 Bottom Spots Spots
AMRWong
AMRWong
Interpretation of Results:
= Conditions:
a) Deuteranopia – absence of green-sensitive
receptors
b) Protanopia - absence of red-sensitive b) Protanopia - absence of red-sensitive
receptors
= These tests are never 100% accurate.
Color deficiency
AMRWong
Color deficiency
People who are "colorblind"
tend to be missing some of
the color-sensitive cones, so
these colors will appear
darker. Few people are
completely colorblind. For those that are color deficient, this is a
graph showing approximate proportions
of each type, based on a study of 5000
Swiss men who wanted to be pilots
BOYS VS. GIRLS
• Color deficiency is common in boys
Different books give different figures, from 5-8
% of boys, 1 boy in about 12-20, or an
average of one boy per classroom has some average of one boy per classroom has some
color deficiency, almost similar to the
percentage of people who are left-handed!
• Color deficiency is rare in girlsThe genes for color vision are on the X chromosome, and because females have 2 X chromosomes, if one is deficient, the other makes up for it. The result is that there are makes up for it. The result is that there are only about 1 in 200+ girls who have color deficiencies, or roughly only one girl in 16 classrooms
More common in Europeans:
It is inherited naturally through the mother,
who may pass on a defective X chromosome.
The actual ratios vary in different populations,
and one book reported that color deficiency is and one book reported that color deficiency is
more common in European stock, and much
less common in Asian and Native American.
(Perhaps northern dwellers during the ice ages
did not need color vision as much and lost it
during a mutation?)
A.1.5. Reflex Activity of the Intrinsic and Extrinsic Eye Musclesand Extrinsic Eye Muscles
1) Accommodation Pupillary Reflex2) Convergence Reflex
• Procedures:
B. Hearing and Equilibrium Tests
Hearing and Conduction Tests
B1. Rinne Test
• compares air conduction to bone-conduction hearing.
Results and Interpretation: • Normal - one will have greater air conduction than bone conduction and
therefore hear the vibration longer with the fork in the air. • Abnormal:
a) Conductive hearing impairment = Bone conduction is the same or greater than the air conduction.
b) Sensineuronal hearing loss = Vibration is heard substantially longer than usual in the air.
* It would also be prudent to perform an otoscopic examination of botheardrums to rule out a severe otitis media, perforation of the tympanicmembrane or even occlusion of the external auditory meatus, which allmay confuse the results of these tests. Furthermore, if hearing loss isnoted an audiogram is indicated to provide a baseline of hearing for future reference.
B2. Weber Test
• A test of lateralization –
Conductive and
Sensorineural Deafness
• Evaluates whether the • Evaluates whether the
sound remains centralized
(normal) or lateralized to
one side (indicative of some
degree of conductive or
sensorineural deafness)
Results and Observations
• The sound is heard in the center of the head or equally in both ears = equal hearing or equal loss of hearing.
Sensorineural deafness of L ear = tone is heard in R ear
Conduction deafness = tone is louder in ear with hearing lossConduction deafness = tone is louder in ear with hearing loss
NOTE: If the patient doesn't hear the vibration at all, attempt again, but press the butt harder on the patient's head.
B3. Romberg Test• Equilibrium is a result of:
1. visual confirmation of position, 2. non-visual confirmation of position (including proprioceptive and vestibular input)
3. a normally functioning 3. a normally functioning cerebellum.
Result: (+) result means that there is pathology in the proprioceptive pathway if a patient loses their balance after standing still with their eyes closed, but is able to maintain balance with their eyes open.
C. Chemical Senses: Taste and
SmellSmell
C.1. Sense of Taste
• Taste buds are found on the – Tongue
– Palate
– Lips– Throat– Throat
Sense of Smell (Olfaction)
Olfactory Epithelium and Bulb
C.1. Sense of Taste and Smell
• Factors affecting taste and smell:
• A) Presence/Absence of moisture
• B) Texture
• C) Olfactory stimulation• D) Temperature• D) Temperature