2. Over view
• Anatomy and Connections
• Functions
• Vacular supply and thalamic Stroke
• Clinical correlates
3. Questions ?
1.Name the thalamic nuclei ?
• somatosensory input—
• somatosensory face input—
• visual input–
• auditory input—
• basal ganglia and cerebellar input—
• limbic input—
2.Parts of Diencephalon ?
4. Diencephalon
• Diencephalon – lies between the cerebrum
and brainstem.
• 3rd ventricle-cavity of diencephalon.
• 2 major divisions - hypothalamic sulcus
5.
6. Thalamus
• Thalamus derives from a Greek word
means “inner chamber” or “meeting place”.
• Largest part of diencephalon
• Other names-MASSA INTERMEDIA
GATE WAY FOR CORTEX
MINIATURE BRAIN
11. • Thalamic nuclei are classified into three main
functional groups:
Specific--receive input from certain ascending
tracts and project to specific cortical areas
Nonspecific--Do not receive afferents from
ascending tracts, but have abundant
connections with other diencephalic nuclei
Reticular-- Connected with reticular formation
21. Functions
• Sensory integration relay station for all
sensory pathway(Except olfaction)
• Unique features of olfactory pathway:
--consists of only two neurons (other conscious
sensory pathways - at least three neurons).
--Olfactory impulses are transmitted directly to
the cerebral cortex without relay in the
thalamus.
22.
23. • Influences voluntary movements through basal
ganglia & cerebellum – cerebral cortex – cortico-
nuclear / cortico-spinal pathways
• Ascending reticular activating system – state of
wakefulness and alertness
• Impulses received from hypothalamus projected
to prefrontal &cingulate gyrus – Determination of
mood Recent memory and emotions
• Influences electrical activity of cerebral cortex
(EEG)
24. Vascular supply
• The anterior territory : supplied by
the polar artery or thalamotuberal
arteries (PcomA)
• The inferolateral territory :
thalamogeniculate arteries, (P2
of PCA).
• The posterior territory : posterior
choroidal arteries (P2 of PCA)
• The paramedian territory :
perforating thalamic or
paramedian arteries. (P1 of PCA) .
28. Thalamic syndrome
• Also known as "Dejerine-Roussy disease",after Joseph
jules dejerine & Gustave Roussy
• usually occurs subsequent to a vascular lesion of the
thalamus (patient is recovering from a thalamic infarct)
• The threshold for pain, touch and temperature is
decreased on the opposite side of the body (thalamic
overreaction) but, when the threshold is reached, the
sensations are exaggerated, perverted and
disagreeable. Examples--
• There may be emotional instability, with spontaneous
(or forced) laughing and crying.
29. Thalamic hand
• The contrlateral hand is flexed and pronated
at the wrist and metacarpo-phalangeal joints
and extended at the interphalangeal joints,
fingers may be abducted, thumb is either
abducted or pushed against the palm
• sometimes seen in thalamic lesions , due to
altered muscle tone in the different muscle
groups.
• Also known as Athetoid Hand
30.
31. Thalamic pain syndromes
The four types are differentiated from each other
on the basis of
• the presence or absence of central (thalamic)
pain
• proprioceptive sensations (vibration, touch, joint)
• exteroceptive sensations (pain and temperature)
• abnormalities in somatosensory evoked
potentials
32.
33. Thalamic eye signs
• “Peering at the tip of the nose” sign,
reflecting acute downward and esodeviation
of the eyes, is highly suggestive of thalamic
haemorrhage.
• It is thought to reflect damage to the
mesodiencephalic junction, which contains
structures important for vertical gaze and
vergence.
34.
35. Thalamic Aphasia
• Sub cortical aphsia– thalamic, basal ganglia
• Wernicke like fluent aphasia,with better
comprehension,with hypophonia
• Fluctuating or dichotomous aphasia
-alert state with near normal language
-Drowsy state with mumbles paraphasically and
comprehend poorly
36. Applied aspects
DBS of Thalamus-- Used in the treatment of :
• Parkinsonism
• Essential tremor
• Dystonia
• Pain
• Epilepsy
• Tourette syndrome
Thalamotomy:
• PD
• Essential tremor
37. Questions
1.Name the thalamic nuclei ?
• somatosensory input—
• somatosensory face input—
• visual input–
• auditory input—
• basal ganglia and cerebellar input—
• limbic input—
2.Parts of Diencephalon ?
