2.kuliah sensoris 2006

8/11/2019 2.Kuliah Sensoris 2006

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Sensation and perception of the internal /

external environment and the response of theorganism achieved through the integrated

operation of the sensory system



RECEPTORS

The end organs of afferent nerve fibers

Receptors Classification :

Receptors function (Sherrington’s) Receptors location

Head’s classification



According to receptors functions (Sherrington’s)

1. Exteroceptors : mediating superficial sensation

1.1. Mechanoreceptors ( touch, pressure )

Meissner’s corpuscles – touch

Merkel’s corpuscles – pressure

Hair cells corpuscles – touchPaccinian corpuscles – vibration, tickle

1.2. Thermoceptors ( cold, heat )Krau se’s end bulbs – coldRuffini’s cylinde r – warm / heat

1.3. Nociceptors ( pain )Free nerve endings



2. Proprioceptors

mediating deeper somatic structursinform of muscle, joint position

Golgi tendon

Muscle spindles

Paccinian corpuscles

Golgi – Mazzoni corpuscles

3.Interoceptors

within visceral tissue & blood vessels



According to receptors location :1. Superficial

touchpaintemperaturetwo – point discrimination

2. Profonda / deepmuscle & joint position ( propriception )deep muscle pain

vibration sense3. Combined

stereognosistopognosis



Head’s classification

1. Protopathic senses

pain

severe degree of temperature

2. Epicritic senses

light touch

two – point discrimination

lesser differences in temperature



The Sensory Pathways

Three sensory neuron.

Nerve fibers :

unmyelinated fibers : C fibers*

myelinated fibers : A-alfa fibers, A-beta fibers* (6-16um)

A-gamma fibers, A-delta fibers* (2-6um)



1st neuron Peripheral Nerves

spinal root ganglia ( cranial nerveganglia N.V )

2nd neuron Spinal Cord

tophografic

3rd

neuron ThalamicCerebral Cortex

somatothopic



Anterior and posterior spinocerebellar tracts



DERMATOME

a specific segmental territory of the skin

to make certain about location of the lesion

Vertebras Spinal nerves

Cervical 7 8

Thoracal 12 12

Lumbal 5 5

Sacral 5 5

Coccigeus 4 -



THE DERMATOMES



The spinal cord is shorter than the spinalcollumn

& terminates at the L I - L II vertebrae

Segment cervical vertebrae C : ( – ) 1

Segment thoracal vertebrae Th : ( – ) 2

Segment Th 12 – LS vertebrae Th IX XII,

L I



Head Innervations

A t Z



Autonomous Zones



DISORDERS OF THE SENSORY SYSTEM

• Negative symtoms : sensory losse.g hypesthesia

hypalgesia

• Positive symtoms : paine.g stabbing pain , burning pain

paraesthesia , dysesthesiahyperesthesia , allodynia




Types of (pathological) pain :

• Nociceptive pain, inflamation pain• Neuropathic pain• Idiopathic pain, psychogenic pain




1.Peripheral nerves lesion

Mononeuropathy, mononeuropathy multiplexe.g traumatic

compression

inflammation infection of M. Hansen

Diabetes Mellitus



Polyneuropathyimmunologytoxic ( e.g alcohol,Co, Pb )vit B1 deficiencyDiabetes Mellitus



Gullain – Barre Syndrome :

Cranial nerves

ventral / dorsal roots dorsal root gangliaperipheral nerves

Gloves & stocking –

negative/positive sensory disturbancesMotor disturbances :

flacid paralysis trunk & upper extremities

LCS : cyto-albuminic dissociation



The posterior root ganglia

e.g. Herpes zoster ( shingles ) Acute pain & vehicle formation –

segmental distribution

Post herpetic neuralgia

The dorsal roots of the spinal nerves

e.g. Tabes dorsalis

Ataxia ( dorsal roots + post columns )

Areflexia

Tabetic crises

Extradural, extramedularry tumor



HNP

Between L IV – V or L V – S I

Radicular pain.

pain increases with cough, snezzing,straining

Positif Laseque test / Nafziger test

Sometimes motor paralysis



Syndrome of Root Damage (Radiculopathy)



Syndromes of Epiconus, Conus and Cauda Equina



2. Spinal cord lesion

. Brown – Sequard syndrome

Caused by hemisection of the spinal cord( tumor, traumatic, compression fracture )

Dorsal funiculus

spinal thalamic tractspinocerebellar tract

corticospinal tract

Below the lesionIpsilateral loss proprioceptive & ataxia

Contralateral loss of exteroceptive

Ipsilateral motor paralysis



Transvers lesion of the spinal cord

motor, sensory, vegetatif, disturbancesbelow the lesion



Intramedullary lesion of the spinal cord

e.g. > Syringomyelialoss of exteroceptive, but retainsproprioceptive in the affected parts

( dissociated anesthesia )

Caused by gliosis around

The central canal of the spinal cord



Subacute combined degeneration

Degeneration of the posterior & lateral column

Loss of proprioceptive

Tetraparalysis

In the advanced cases of pernicious anemia

( vit. B 12 deficiency )



Friedreich’s ataxia

A familial & hereditary disease

Degeneration of the cerebellum, dorsal & ventralspinocerebellar tracts, lateral corticospinal tracts

Gliosis of the posterior column

Nystagmus

cerebellar disartri

ataxialoss of proprioceptive

3 B i l i



3. Brain stem lesion

Medulla oblongata

Wallenberg’s Syndrome ( lateral medulla syndrome )

Occlusion of the main trunk of the post. inf. cerebellar artery Alternans hemihypesthesia

( spinothalamic tracts & N.V )

Ipsilat weakness of the vocal cords & pharinx ( N.IX, X )

Nistagmus, vertigo, vomitus ( N.VIII vestibularis )

Ipsilat ataxia

( spinocerebellar tract )

Contralat hemiparalysis

Loss of sense of taste( solitarius tract )

Pons

Mesencephalon



4. Thalamic lesion

Thalamic pain : central pain paresthesiaallodynia

hyperesthesia

Weakness Ataxia

2.kuliah sensoris 2006

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