DR NILESH KATE

MBBS,MDASSOCIATE PROF

ESIC MEDICAL COLLEGE, GULBARGA. DEPT. OF PHYSIOLOGY

THALAMUS.

OBJECTIVES Physiological

Anatomy. Functions of thalamus. Applied aspects.

Friday, February 27, 2015

Physiological Anatomy. Thalamus proper. Diencephalon.----

dorsal thalamus, ventral thalamus, epithalamus & hypothalamus.

Friday, February 27, 2015

External features. Large ovoid structure. Lateral to 3rd ventricle.

Ends Anterior Posterior.

Surfaces Superior Inferior. Medial Lateral.

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Internal structure.White matter

Stratum zonules. – Thin layer covering superior surface of thalamus.

External medullary lamina. -- Thin layer covering lateral surface of thalamus

Internal medullary lamina. – “Y’ shaped sheet of white matter

--- consists of internuclear thalamic connections.

Grey matter.

3 masses of nuclei Anterior Lateral. Medial.

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Classification of Thalamic nuclei. Anatomical

classification. Anterior. Lateral.

Ventral Dorsal

Medial.

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Functional classification. Non- specific

From RAS to Neocortex. 2 types

Midline nuclei. Centromedian nucleus.

Specific From specific sensation

to Neocortex or limbic system

Types. Specific sensory Motor Visceral efferent. Integrative & perceptual

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Connections of Thalamus.Non –specific projection nuclei.

Causes diffuse thalamic projection to entire Neocortex.

Produces electrical activity of cortex. Afferents – from RAS, & Basal Ganglia Efferents –stratum & entire Neocortex.

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Connections of Thalamus. Specific.

Sensory Motor Visceral Integrative.

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Sensory Medial geniculate

body. Destruction of small

part --- deafness for particular band of sound frequency.

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Sensory Lateral geniculate

body. Orderly organized

representation of retina.

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Sensory Ventral posterior

nucleus. VPL -- from N. gracilis,

cuneatus, Spinothalamic tract

i.e. somatosensory impulses from trunk & limbs except face.

VPM – trigeminal laminiscus & taste.

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Motor. Ventral lateral

nucleus. From cerebellum Dentothalamic fibres

from opp side. Proprioceptive

information & voluntary motor functions.

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Motor. Ventral anterior

nucleus. Programming of

movements.

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Visceral. Anterior nucleus. From hippocampus

through mammilary body.

Concerned with recent memory & emotions.

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Visceral. Concerned with

thinking, memory, judgment & emotional behaviour.

Dorsal medial nucleus.

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Integrative & perceptual function control.

Pulvinar nucleus. Integration of visual,

auditory & other sensation.

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Integrative & perceptual function control.

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Lateral posterior nucleus.

Lateral dorsal nucleus.

Functions of thalamus. Sensory relay centre. Crude centre for perception

of sensation. Arousal & alertness

reaction. Language. Emotional aspect of

behaviour. Sexual sensation. EEG Synchronization. Reflex activity centre

Integration of Sensory impulses. Motor functions. Visceral & somatic

function.

SCALE –SERINTEGRATION --3

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Sensory relay centre. All except olfactory. Head ganglion of all

sensory system. Thalamic radiations.

—projection fibres.

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Crude centre for perception of sensation.

2 Qualities of sensation Discriminative nature. Type, location --- by

cerebral cortex. Affective nature.

Pleasant, unpleasant, agreeable, disagreeable– by thalamus.

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Arousal & alertness reaction. Control level of

consciousness. Maintain state of

alertness & wakefullness.

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Language.

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Emotional aspect of behaviour. Acts as a part of limbic

system & papez circuits.

Concerned with recent memory & emotions.

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Sexual sensation. Centre for perception

of sexual sensation.

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EEG Synchronization. Genesis of

synchronization of EEG.

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Reflex activity centre As relay of sensory

fibres in Thalamus.

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Integration of Sensory impulses.

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Integration of Motor functions.

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Integration of Visceral & somatic function.

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Applied Aspects. Thalamic syndrome. Korsakoff’s syndrome Frontal lobotomy.

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Thalamic syndrome. Disturbance of emotional response to

sensory experience. Cause .

Thrombotic blockage of Thalamogeniculate branch of Posterior Cerebral Artery.

Damage to Posteroventral & Posterolateral nuclei.

Friday, February 27, 2015

Signs & symptomsSensory symptoms

Thalamic Phantom limb.- unable to locate position of limb with closed eye. Due to loss of kinaesthetic sensation.

Asteriognosis. Thalamic over-reaction.–

sensation to touch, pain , temp exaggerated.

Amelognosis. – illusion of absent limb.

Motor symptoms

Thalamic hand or Athetoid hand – Moderate flexion of the wrist with hyper extended fingers.

Ataxia.-- muscle tone & profound muscle weakness.

Involuntary movements.– chorea, athetosis & intension tremors.

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Korsakoff’s syndrome Difficulty in remembering new information. Due to – lesions of mediodorsal nucleus of

thalamus.

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Frontal lobotomy.

To relieve intractable pain.

Dividing dorsal nuclei of thalamus from the frontal lobe.

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Thank You