2nd year ospe ( sensory motor - special sense )

Sensory Examinati

on

Crude TouchName of test: cotton wool test.Receptors: Free nerve endings & hair end organs.

Afferents: A delta and C fibers.

Pathway (tract): ventral spinothalamic tract (anterolateral system).

Perception: thalamus (protopathic).

Localization: not sharply localized.

Lost in: Tabes dorsalis, peripheral nerve lesion, brain stem lesion.Better felt in: hairy skin than non hairy skin (dorsum than palm of hands).Adaptation: rapidly adapting (phasic)= decrease or stop discharge upon maintained stimulation.

Fast cutaneous painName of test: pin prick test.Receptors: polymodal Free nerve endings (Nociceptors).

Afferents: A delta.

Pathway (tract): Neo-lateral spinothalamic tract (anterolateral system).

Perception: sensory cortex (epicritic).

Localization: sharply localized.

Lost in: peripheral nerve lesion, syringomyelia.Adaptation: slowly or non adapting (tonic).

Slow painReceptors: polymodal Free nerve endings (Nociceptors).

Afferents: C.

Pathway (tract): Paleo-lateral spinothalamic tract (anterolateral system).

Perception: thalamus (protopathic).

Localization: not sharply localized.

Lost in: peripheral nerve lesion, syringomyelia.Adaptation: slowly or non adapting (tonic).Occurs in: Skin, deep structures and in viscera.

painReceptors: polymodal Free nerve endings (Nociceptors).

Afferents: A delta & C.

Pathway (tract): lateral spinothalamic tract (anterolateral system).

Perception: thalamus & cortex.

Its Loss is termed: Analgesia.Its exaggeration is termed: Hyperalgesia.Adaptation: slowly or non adapting (tonic).Lesion in sensory cortex: loss of fast pain only.Lesion in thalamus: loss of fast & slow pain, then return of slow pain only.Lesion in peripheral nerve & syringomylia: loss of fast & slow pain.

Tactile discriminationName of test: Weber’s compass 2 point discrimination test.Receptors: Missner’s corpuscles, Merckle’s discs, paccinian corpuscles & Ruffini end organ.

Afferents: A beta.

Pathway (tract): Dorsal column tract = gracile & cuneate tract (medial lemniscus).



Lost in: peripheral nerve lesion, tabes dorsalis, thalamic lesion, brain stem & cortical lesions.Adaptation: rapidly adapting (phasic).

Tactile discriminationThreshold distance: minimal distance between 2 points to be felt as 2 separate points.Threshold distance : 2-3 mm at lips & finger tips, 3-5 mm at dorsum of hands, 50-60 mm at the back.

Areas with less threshold distance have: Large number of receptors, large number of afferents, less convergence of afferents, large cortical areas of representation.Areas with more threshold distance have: less number of receptors, less number of afferents, more convergence of afferents, less cortical areas of representation.

Tactile localizationName of test: 2 marker test.Receptors: Missner’s corpuscles, Merckle’s discs, paccinian corpuscles & Ruffini end organ.

Afferents: A beta.




Lost in: peripheral nerve lesion, tabes dorsalis, brain stem & cortical lesions.Adaptation: rapidly adapting (phasic).

Vibration sensationName of test: tunning fork test.Receptors: Missner’s corpuscles (respond to frequency up to 80 cycles/sec) & paccinian corpuscles (up to 500 cycles/sec).

Afferents: A beta.




Lost in: peripheral nerve lesion, tabes dorsalis, brain stem & cortical lesions.Adaptation: rapidly adapting receptors (phasic).

Vibration sensationMixed sensations: vibration & stereognosis.

Vibration= touch & pressure.

Uses of tunning fork: - vibration test - hearing tests (Rinne & Weber tests).

Sites of vibration sensation: all body areas.

Tunning fork is placed over bones: for magnification of stimulus.

proprioception (kinesthetic sensations)

Name of test: test for sense of position & test for sense of movement.

Receptors: Muscle spindle, golgi tendon organ, Ruffini end organ, in capsules and ligaments of joints ( and Paccinian corpuscles for sense of movements only).

Afferents: A beta.




Lost in: peripheral nerve lesion, tabes dorsalis, brain stem & cortical lesions.

Adaptation: slowly adapting receptors (tonic).

proprioception (kinesthetic sensations)

Static proprioception: sense of position.Dynamic proprioception: sense of movement.

Loss of these sensation in lower limbs: sensory ataxia.Ataxia: incoordination of voluntary movements in absence of paralysis.

Types of ataxia: - sensory (loss of proprioveption).- motor (cerebellar syndrome).

StereognosisName of test: test for stereognosis.Receptors: all receptors.



Lost in: peripheral nerve lesion, tabes dorsalis, brain stem & cortical lesions.

Center: sensory association cortex (area 5,7).This sensation requires: - Intact sensory association cortex (area 5,7).- Intact all sensations.- Previous cortical experience.

Examination for ataxiaName of test: Romberg’s test.Result: +ve in sensory ataxia (falling down upon closure of ayes).

Sensory ataxia Motor ataxiaTabes dorsalis Cerebellar lesion

+ve Romberg’s test no Romber’s test

Incoordination when eyes close

Incoordination even with open eyes

No tremors Kinetic tremors

Normal speech Staccato speech

Stamping gait Drunken gait

No nystagmus Nystagmus

Gloves & stockings sensory loss

Site of lesion: All peripheral nerves in upper & lower limbs.(peripheral neuritis = polyneuropathy)Affected sensations: loss of all sensations in peripheral parts of the body.

Jacket sensory loss

Site of lesion: around central canal of cervico-thoracic segments of spinal cord.Affected sensations: loss of pain & thermal sensations bilaterally in upper limbs & upper parts of chest & back.

Name of the disease: Syringomyelia.

Pattern of sensory loss: Dissociated sensory loss, because all dorsal column sensations + crude touch are not lost.

Hemisection of spinal cord

(Brown-sequard syndrome)Below level of lesion on the same side:

- Sensory effects: loss of dorsal column sensations only

- Motor effects: upper motor neuron lesion, with spastic paralysis, hyperreflexia, clonus & +ve Babiniski sign.

Below level of lesion on the opposite side: - Sensory effects: loss of spinothalamic

sensations only- Motor effects: noneAt level of lesion on the same side: - Sensory effects: loss of all sensations

(complete sensory loss).- Motor effects: lower motor neuron lesion, with

flaccid paralysis, hyporeflexia & atrophy.

HemianaesthesiaSite of lesion: brain stem of opposite side.Affected sensations: loss of all sensation in half the body.

Lesion in thalamus: - Loss of all sensation on opposite side.- Return of crude sensations after some time.Lesion in Sensory cortex: - Loss of fine sensations only on opposite side.- No loss of crude sensations.Lesion in Sensory association cortex: - Loss of stereognosis (Astereognosis).- Amorphosynthesis (forgets & ignores half of

his body).

DermatomesC2: skin over angle of mandible.T2: skin over angle of sternum.T4: skin over nipples.T7: skin over xyphoid process.T10: skin over umbilicus.T12: skin over symphysis pubis.C5: skin over deltoid muscle.C6: skin over lateral forearm, arm & hand anteriorly and posteriorly.C7: skin over middle forearm, arm & hand anteriorly and posteriorly.C8: skin over medial forearm, arm & hand anteriorly and posteriorly.

Spinothalamic sensations: - Pain.- Temperature.- Crude touch.Any of these sensations can be used to examine integrity of anterolateral system (spinal lemniscus).

Dorsal column sensations: - Fine touch.- Vibration.- Proprioception.- Deep pressure.Any of these sensations can be used to examine integrity of Gracile & Cuneate pathway (medial lemniscus)

Uses of cotton: - Crude touch examination.- Corneal reflex.

Examples of slow pain: - Ischaemic pain.- Pain due to spasm.- Pain due to overdistention.

1ry hyperalgesia 2ry hyperalgesiaAt site of injury Healyhy skin around

injury

Receptors are facilitated

Facilitation in spinal cord

Pain threshold is lowered

Pain threshold is normal

Increased chemicals at site of injury

Convergence-facilitation theory

Fast pain Slow painAcute, sharp, immediate

Chronic, burning, aching

Felt after 0.1 sec Felt after 1-2 sec

Lasts for 1 sec Lasts for a long period

Occurs in skin onlyCarried by A deltaDue to stimulation of mechano & thermo sensitive pain receptors

Neospinothalamic tractPerceived at cortex

In skin, deep tissues & visceraCarried by CDue to stimulation of all pain receptors mainly the chemosensitivePaleospinothalamic tractPerceived at thalamus & reticular formation

Protopathic (thalamic) sensations: - Slow pain.- Extremes of temperature.- Crude touch.

Epicritic (cortical) sensations: - Fine touch.- Fast pain.- Vibration.- Proprioception.- Deep pressure.- Fine degrees of temperature.- Stereognosis.

Motor Examinati

on

Muscle stateNormal: - Normal person.- Acute stage of UMNL.Atrophy: - LMNL: marked, localized & flaccid.- Chronic UMNL: minimal, generalized & spastic.

Hypertrophy: - Physiological: in athletes, associated with

increased power.- Pathological: in myopathy, associated with

decreased power.

Muscle PowerNormal: - Normal person.Paralysis: (loss of voluntary movements). - LMNL: localized, flaccid & ipsilateral.- UMNL: generalized, spastic & contralateral.

Pariesis: (weakness of voluntary movements) - Cortical lesions.Muscle power tests: - Hand grip test.Grades of muscle power tests: - Normal (5/5), voluntary movements without

resistance (4/5), voluntary movements against gravity (3/5), voluntary movements without gravity (2/5), flicker (1/5), paralysis (0/5).

Muscle ToneNormal: - Normal person.Hypotonia: (decrease muscle tone). - LMNL: localized, flaccid & ipsilateral.- Acute UMNL: generalized, flaccid &

contralateral.- Area 4 lesion.- Chorea (lesion in caudate nucleus).- Neocerebellar lesion

Hypertonia: (increase muscle tone) - Spasticity.- Rigidity.

Spasticity Rigidity- Chronic UMNL.- Area 6 lesion.

- Parkinsonism.- Other B.G. lesions

Affects antigravity muscles

Affects all muscles

Clasp knife (initial resistance followed by sudden release)

- Cog wheel (interrupted).- Lead pipe (continuous).

ClonusHyperreflexiaIncrease gamma activityNo tremors

No clonusNormoreflexiaIncrease alpha & gamma activityStatic tremors

Medical reflex hammer

Uses: - Examination of reflexes (tendon jerks).

Knee (patellar) jerk examination

Stimulus: Tapping tendon of quadriceps (sudden stretch).Receptors: Muscle spindle, central part of nuclear bag intrafusal fibers.

Afferents: A alpha (primary = annulospiral afferent).Center: AHCs of spinal segments L2, 3, 4. monosynaptic.

Efferent: Alpha motor neuron (LMN).

Effector: Contractile extrafusal skeletal muscle fibers.

Ankle jerk examination

Stimulus: sudden stretch of tendon achilis.Receptors: Muscle spindle, central part of nuclear bag intrafusal fibers.

Afferents: A alpha (primary = annulospiral afferent).Center: AHCs of spinal segments S1, 2. monosynaptic.



Tricepsexamination

Stimulus: sudden stretch of triceps tendon.Receptors: Muscle spindle, central part of nuclear bag intrafusal fibers.

Afferents: A alpha (primary = annulospiral afferent).Center: AHCs of spinal segments C6,7. monosynaptic.



Biceps jerk examination

Stimulus: sudden stretch of biceps tendon.Receptors: Muscle spindle, central part of nuclear bag intrafusal fibers.

Afferents: A alpha (primary = annulospiral afferent).Center: AHCs of spinal segments C5, 6. monosynaptic.



Planter reflex examination

Stimulus: deep scratch to sole from below upwards.Receptors: Superficial receptors

Afferents: afferents enter the spinal cord through posterior horn.Center: AHCs of spinal segments S1, 2.


Effector: Planter flexion of all toes.

Planter reflexNormal: - Normal person.

+ve Babiniski sign: = Dorsiflexion of big toe & fanning of lateral 4 toes.- UMNLArea 4 lesion.

Lost planter reflex:- LMNL in S1-2.

Pseudo +ve Babiniski sign: - Deep sleep & deep coma.- Hypoglycemia & general anaesthesia.- Infants below 1 year (pyramidal tract not

mylinated).

Partial +ve Babiniski sign: - Area 4 lesion (dorsiflexion of big toe), Area 6 lesion

(fanning of lateral toes).

Superficial reflexesStimulus: scratch to skin.Receptors: Superficial receptors

Afferents: afferents enter the spinal cord through posterior horn.Center: AHCs of spinal segments ………..


Effector: Contraction of muscle.

Lost in: UMNL & LMNL affecting their pathways.

Abdominal reflexes: T7- T12.Cremasteric reflex: L1-2.

Corneal reflexStimulus: Touching cornea from its side by a piece of cotton.Receptors: irritant receptors

Afferent: opthalmic branch of 5th cranial nerve.

Center: superior colliculus of midbrain

Efferent: 7th cranial nerve.

Response: Bilateral blinking.

Importance: test the integrity of 2 cranial nerves at the same time.

Janderassik maneuver

Aim: - Reinforcement of deep tendon reflexes.- Increasing the excitatory level of spinal cord.- Decrease central inhibition.

Importance of deep reflex examination

- Give idea about state of spinal cord & higher centers.

- Give idea about muscle tone.- Localization of site of lesion in CNS.

Deep reflexesNormoreflexia: - Normal person. - parkinsonism.Hyperreflexia:- Chronic UMNL. - Hypoparathyroidism

(tetany).- Hyperthyroidism. - Anxiety (neurosis).Hyporeflexia:- Acute UMNL. - LMNL.- Area 4 lesion. - Dorsal root lesion.- Hypothyroidism. -

Hyperparathyroidism.Pendular jerks: - Neocerebellar lesion. - Chorea.

Muscle toneDefinition: continuous, rhythmic, alternating contraction of skeletal muscle during rest. - It is muscle to muscle reflex.Stimulus: Maintained muscle stretch during rest.Receptor: central part of nuclear chain intrafusal fibers. Afferent: primary (Ia) & 2ry (II). Center: AHCs of spinal cord. Efferent: alpha motor neuron (LMN)Effector: extrafusal contractile fibers.Response: maintained contraction.

Muscle toneFunctions: - Maintains upright posture.- Maintains postural background for voluntary

movements. - Maintains venous & lymphatic return.- Maintains body temperature constant.- Maintains viscera in position.

Clonus: Rhythmic oscillations occurs when a hypertonic muscle is subjected to sudden maintained stretch.- It is due to cycles of stretch-inverse stretch

reflexes.- It occurs in: patellla, ankle.

Facilitated Inhibited- Area 4.- Neocerebellum.

- Area 6.- Paleocerebellum.

- Vestibular nucleus. - Red nucleus.

- Facilitatory reticular formation.

- Inhibitory reticular formation.

- Caudate nucleus. - Putamen & globus pallidus.

Tendon jerks & Muscle tone

Hypertonia without hyperreflexia: parkinsonism.

UMNL LMNL

- Lesion from motor cortex till the spinal cord.

- Lesion from spinal cord till the muscle.

- Generalized, contralat. Paralysis.

- Localized, ipsilat. Paralysis.

- Hyperreflexia & clonus.

- Hypo or Areflexia.

- Loss of superficial reflexes below lesion level.

- Loss of superficial reflexes at lesion level.

- +Ve Babiniski - Only when S1-2 affected.

- Spasticity of antigravity muscles + clasp knife.

- Flaccidity of affected muscles.

- Minimal disuse atrophy.

- Marked atrophy.

Coordination

Examination

Finger to nose

Finger to doctor’s finger

Test for coordination of rapid alternating movements

Heel to knee test

Test for coordination of gait movements

Coordination testsTests: - Finger to finger test.- Finger to nose test. - Finger to doctor’s finger test.- Arm pulling test.- Wrist slapping test.- Heel to knee test.- Tests for rapid alternating movements.- Tests for gait, speech, nystagmus & tremors.

These tests should be done with open eyes & then with closed eyes.

- circumduction. - Unilateral UMNL.

- Shuffling gait. - Parkinsonism.

- Drunken gait. - Cerebellar syndrome.

- Stamping gait. - Sensory ataxia.

- Waddling gait. - Congenital dislocation of hip.

- Scissoring gait. - Bilateral UMNL.

Gaits

Physiological Pathological

- Rotatory. - Cerebellar ataxia.

- Optokinetic. - Searching nystagmus (visual defect).

- Menier’s disease.

- Static tremors. - Parkinsonism.

- Kinetic (intention) tremors.

- Cerebellar syndrome.

- Fine tremors. - Hyperthyroidism, anxiety, excess coffee, alcoholism.

- Flapping tremors. - Liver failure.

- Senile tremors. - Old age.

- Familial & hereditary tremors.

Cranial nerves

Examination

Olfactory nerve examination

Examination of III, IV & VI

Tests: - Test eye movements by extraocular muscles.- All extraocular muscles are innervated by

occulomotor except: - Lateral rectus by abducent nerve.- Superior oblique by trochlear nerve.

- Occulomotor lesion produces:- Paralytic divergent squint.- Dropping of upper eye lid.- Dilated fixed pupil.- Loss of accomodation to near object.

Effects of atropine eye drops

- Loss of parasympathetic actions of occulomotor:- Loss of accomodation.- Dilated pupil.- Intact somatic actions of occulomotor:- No paralysis of extraocular muscles supplied by oculomotor nerve.

Examination of V nerve- Sensory Tests: - Sensations of face.- Corneal reflex. - Motor Tests: - Temporalis & masseter muscles.- Pterygoid muscles.- Jaw jerk.

- Trigeminal lesion produces:- Loss of corneal reflex.- Loss of sensations from corresponding half of

face.- Weakness of muscles of mastication.- Exaggerated jaw jerk (in bilateral UMNL).

Examination of VII nerve- Sensory Tests: - Sensations of taste in anterior 2/3 of tongue.- Motor Tests: - Frontalis & orbicularis oculi muscles.- Orbicularis oris & buccinator muscles.

Upper part of facial nucleus:- Has bilateral pyramidal tracts innervation. So,

upper part of face is not affected in UMNL.lower part of facial nucleus:- Has contralateral pyramidal tracts innervation.

So, lower part of face is affected in UMNL.In LMNL of facial: upper & lower parts of face are affected.

UMNL LMNL

- No effect (sparing) of upper part of face.

- Paralysis of upper & lower parts of face.

- Effects are opposite to side of lesion.

- Effects are to the same side of lesion.

Examination of IX & X nerves

- Examination of uvula: - Normally, it is central in position and moves up

& down while being central.- If uvula is deviated: - Uvula deviates to the healthy side, then the

other side has unilateral lesion.

Examination of XI nerve

- Examination of: - Sternomastoid muscle.s- Trapezius muscles

Examination of XII nerve

Examination of TONGUE.

- In bilateral lesion of XII nerve: - Patient can not protrude his tongue out of

mouth.- In unilateral lesion of XII nerve: - Tongue is deviated to paralyzed side.

- Look at the paralysed side:- Atrophy & fasciculations = LMNL.- Small spastic tongue = UMNL.

Special Senses

Examination

Pupillary light reflex

Stimulus: exposure of one eye to light.Receptors: rods & cones.

Afferents: optic nerve of stimulated eye → crossing of nasal fibers in optic chiasma to opposite side & continuation of temporal fibers without crossing → optic tract → fibers leave optic tract from posterior part.Center: pretectal area which stimulates EWN of both sides.

Efferent: occulomotor nerve bilaterally.

Effector: constrictor pupillae muscles bilaterally.

Response: bilateral miosis.

Pupillary light reflexImportance: - Protection of retina from excess light.- Regulation of amount of light entering eyes.- Diagnosis & localization of lesions in visual

pathway.

Types of pupillary light reflex:- Direct LR: constriction of pupil of the

stimulated eye.- Indirect LR (consensual): constriction of pupil

of the unstimulated eye.

Causes of indirect light reflex: - Crossing of nasal fibers of the stimulated eye

in optic chiasma.- The stimulated pretectal area stimulates EWN

bilaterally.

Pupillary light reflexLesions: - Amauratic pupil: pupil of blind eye (optic nerve

lesion) that gives no response to direct light but constricts normally indirectly when the normal eye is exposed to light.

- Hemianopic pupil: pupil of hemianopic eye (lesion in optic chiasma centrally or peripherally, lesion in anterior part of optic tract) that gives no response to light when it comes from its blind half of field, but gives normal responses (bilaterally) when light comes from its normal half of field.

- Normal light reflex: in normal persons, lesions in posterior part of optic tract, in LGB, in optic radiations, in visual cortex.

- Argyll-Robertson pupil (light-near dissociation): no response in light reflex, but normal response in near response. Occurs in tabes dorsalis due to bilateral damage of pretectal areas of midbrain.

Pupillary light reflexMiosis Mydriasis

Increase parasympathetic activity:- sleep.- 3rd stage of anesthesia.

Decrease parasympathetic activity:- awakening.- Occulomotor nerve

lesion.

Decrease sympathetic activity:- Horner’s syndrome.- Pontine hemorrhage.

Increase sympathetic activity:- stress, excitement, fear,

..- 2nd & 4th stages of

anesthesia.

Afferents from:- Superior colliculus (near

response).- Pretectal areas (light

reflex).

Decrease impulses in afferents:- Far vision.- Dark conditions.

Drugs:- Parasympathomimetics

(pilocarpine).- Anticholine esterase

drugs.- Morphine (pin point

pupil)

Drugs:- Sympathomimetics

(adrenaline, active).- Parasympatholytics

(atropine, passive).

Near responseStimulus: blurred image of a near object.

Receptors: rods & cones.

Afferents: optic nerve → crossing of nasal fibers in optic chiasma to opposite side & continuation of temporal fibers without crossing → optic tract → LGB → optic radiations → visual cortex (17) → visual association cortex (18, 19) → frontal eye field area (8).Center: superior colliculus which stimulates EWN.

Efferent: occulomotor nerve bilaterally.

Effector: constrictor pupillae muscles, ciliary muscles & medial recti muscles.

Response: - bilateral miosis. - bilateral medial convergence. - bilateral accomodation.

Near response

Importance: to see near objects clearly.

Miosis (by constrictor pupillae muscles): - Prevents falling of light on peripheral parts of lens → prevents spherical & chromatic aberration.Medial convergence (by medial recti): - Allows falling of the image of the near object on corresponding parts of retinae of both eyes → prevents diplopia (double vision).Accomodation (by ciliary muscles): - To increase diopteric power of the lens → strong refraction and focusing of diverging light of near object on the retina.

Near response

Accomodation occurs by: - Contraction of ciliary muscles → - Relaxation of suspensory ligaments → - Decrease pull on lens capsule → - Increase convexity of anterior surface of lens.Prove: - Prkinje-Sanson image.

Power of the resting lens: 20 diopters.Power of maximally accomodating lens: 34 diopters.power of accomodation = Difference between maximal power & resting power.

Near responseFar point (punctum remotum): - Farest point from eyes at which an object is

seen clear without accomodation.- = 6 meters & more. Near point (punctum proximum): - Nearest point from eyes at which an object is

seen clear with maximal accomodation.- = 20 cm in young adults and more than that

with aging. Presbyopia: decrease power of accomodation by aging due to decrease lens elasticity.- Far point: no change.- Near point: receeds away from eyes (becomes

more).- Correction: convex lens for near vision.

Near responsemyopia hypermetropia

Focusing of parallel light infront of retina without accomodation.

Focusing of parallel light behind retina without accomodation.

- Axial: long eye.- Refractive: strong

cornea (keratoconus) or lens (spasm of ciliary muscle).

- Axial: short eye.- Refractive: weak

cornea (cornea plana) or lens (paralysis of ciliary muscle).

- Far point: less than normal.

- Near point: less than normal.

- Far point: uses accomodation to see it.

- Near point: more than normal.

Correction: concave lens.

Correction: convex lens.

Astigmatism: irregularity in corneal or lens surfaces → unequal refraction of light.

- lesion ‘A’ …………………………….

- lesion ‘B’ ………………………- lesion ‘C’ ………………………- lesion ‘D’ ………………………- lesion ‘E’ ………………………- lesion ‘F’ …………………………- lesion ‘G’ …………………………

Visual field examinationDefinition: - The maximal part of the external environment

seen by the fixed eyes. Normal boundaries: - Temporal: 90 Nasal: 60- Upper: 60 Lower: 70Projection: - Nasal field: projects on temporal half of retina.- Temporal field: projects on nasal half of retina.Tests: - Confrontation test.- Perimeter.

Visual field examinationUses of perimeter: - Examination of visual field.- Diagnosis of scotoma (localized area of

blindness within the normal visual field).- Diagnosis of optic atrophy (generalized

contractions in visual field).- Diagnosis & localization of lesions in visual

pathway.

Visual field examinationLesions that produce hemianopia: - Lesion in optic chiasma.- Lesion in optic tract.- Lesion in optic LGB.- Lesion in optic radiations.- Lesion in visual cortex. Lesions that produce homonymous hemianopia: - Lesion in optic tract.- Lesion in optic LGB.- Lesion in optic radiations.- Lesion in visual cortex.

Visual field examinationHow to differentiate between Lesion in optic tract & lesion in optic radiation (both produce homonymous hemianopia?By light reflex.- Lesion in anterior part of optic tract →

hemianopic pupil.- Lesion in optic radiations → normal light reflex.Why the lesion in visual cortex produces no effect on macular vision (macular sparing)?Because the macula has:- Bilateral representation.- Large cortical areas of representation.- Area of representation has double blood

supply.

Visual field examinationArea 17 Area 18,19

Perception of image without understanding.

Understand the meaning of visual impulses.

Perception of colors. Relate visual sensation to other sensations.

Localization of object in space.

If the image of the object is not clear → impulses to area 8 to produce accomodation reflex.

Fusion of images from both eyes to give one mental impression

Lesion: crossed homonymous hemianopia with macular sparing.

Lesion: agnosia (can not understand the meaning of visual information).

Fundus examinationInstrument: ophthalmoscope; the instrument used in fundus examination.

It consists of:- Source of light.- Mirror.- Set of lenses.

Uses of ophthamoscope:- Fundus examination.- Diagnosis of errors of refraction.- Diagnosis of intracranial tumors & high

intracranial tension.- Diagnosis of systemic disease (DM,

Hypertension).

Fundus examinationFundus: part of retina seen by ophthalmoscope .

Comment on:- Macular region. - Retinal

vessels.- Optic disc. - Retina proper.

1) Macular region:- Oval area, red-yellow in color and has a whitish

center.- Located at the center of retina (3 mm temporal

to optic disc).- Area of sharpest vision.- Its receptors are mainly cones.- Bilaterally represented in the visual cortex.

Fundus examination2) Optic disc:- Site of exit of optic nerve & entry of retinal

vessels.- Round, well defined borders, 1.5 mm in

diameter, 3 mm to the nasal side from the center of retina, pale pink in color, has physiological cup (depression) in its center.

- No photoreceptors in this area (physiological blind spot).

- Diagnosis of intracranial tumors & high intracranial tension.

Abnormalities:- Obliteration of its cup OR oedema of optic disc

= brain tumor & high intracranial tension.- Very pale & small contracted disc = optic

atrophy & glucoma.

Fundus examination3) Retinal vessels:- Retinal artery & vein in the center of optic disc.- Both give many upper & lower branches.- Arteries are narrow & brighter in color than

veins.Abnormalities:- Dilated & tortious vessels = hypertensive

retinopathy.

4) Retina proper:- It is transparent, but appears pink (color of

choroidal vessels).Abnormalities:- Capillary microaneurysms with hemorrhages &

exudates = diabetic retinopathy.

Visual acuity examination

Definition:- The ability of eyes to detect details &

boundaries of objects.- It is the function of cones.

The emmetropic eye:- Can differentiate between 2 points at a

distance of 6 meters.- Light rays coming from these 2 points make an

angle of 1 minutes (1/60 degree) in the nodal point AND

- Stimulate 2 cones in the retina separated by at least one unstimulated cone → 2 separate images in the visual cortex.


Maximal acuity occurs in fovea centralis because:- Receptors are only cones (high acuity).- 1:1 connection (no convergence).- Highly developed pigmented epithelium

(absorption of extralight).- Light falls on receptors directly.

Tests:- Landolt’s chart.- Snellen’s chart.


What is meant by 6/24:- It means that: while the patient is sitting at 6

meters distance from the char, the last raw he sees clearly is the raw of circle that can be seen clearly by a normal person at a distance of 24 meters.

What the next steps in visual acuity examination:- If he can not see clearly any raw at 6 meters

distance, move him closer to the chart to become at 5 meters distance, then 4 meters, 3 meters, 2 meters and finally 1 meter.

- If he can not see clearly at 1 meter distance, stand at 50 cm distance from the patient and ask him to count your fingers.

- If he can not, go closer and detect if he can perceive your hand movement in front of his eyes or not.

- If he can not, detect if he can perceive gross light or not.

Color vision examinationDefinition:- The ability of eyes to discriminate colors.Tests:- Ishihara test charts.- Colored wool test.Color vision:- Function of cones.- 3 different cones are present in retina (red,

green & blue cones), corresponding the 3 primary colors.

- Any other color can be perceived by simultaneous & differential stimulation of the 3 cone systems.

Color blindnessDefinition:- The inability of eyes to discriminate colors.Cause:- Genetic: x linked recessive, 8% in males & 0.4%

in females.- Acquired: 2ry to eye diseases, in one or both

eyes.Types:1) Trichromatic (anomaly): one cone system is weak, can see deep colors but pale colors can not be discriminated.2) Dichromatic (anopia): one cone system is absent, deep & pale colors are perceived as different colors.3) Monochromatic (anopia): 2 cone systems are absent.(Red= prot) (geen= deutr) (blue=trit)

Hearing examinationDeafness:- Partial or complete hearing loss.Types & causes:1) Conductive deafness:- Obstruction of external ear by wax or foreign

bodies.- Rupture of tympanic membrane.- Otitis media.- Otosclerosis. 1) Nerve (sensori-neural) deafness:- Injury of cochlear nerve.- Degeneration of hair cells by drug toxicity.- Tumor affecting inner ear.

Hearing examinationTests:- Rinne & Weber tests (qualitative)- Audiometry (quantitative & qualitative).

1) Rinne test:Compares air conduction to bone conduction in one ear.- Rinne +ve = Normal: air conduction is better

than bone conduction.- Rinne –ve = Conductive deafness: bone

conduction is better than air conduction- Reduced Rinne +ve (pseudo +ve) = nerve

deafness: air conduction is better than bone conduction, but both are not heard well.

Hearing examination2) Weber test:Compares bone conduction in both ears at the same time. - Normal: sound is heard with equal intensity in

both ears.- Conductive deafness: sound is heard louder in

the diseased ear (due to absence of the sound that comes through air that normally masks the sound comes through bones.

- Nerve deafness: sound is heard louder in the normal ear.

Other tests:- Watch test: sound is heard at a shorter

distance in the diseased ear.- Scwabach test: compares bone conduction of

the patient with that of the doctor.- Audiometer.

2nd year ospe ( sensory motor - special sense )

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