The thalamus is a paired, symmetrical structure located in the center of the brain near the brainstem. Each half is bulb-shaped and around the size of a walnut. The thalamus contains several nuclei that receive and relay sensory information to the cerebral cortex. It plays an important role in regulating states of consciousness and sleep/wake cycles. Damage to the thalamus can cause sensory deficits, involuntary movements, and even permanent coma. Common pathologies include lesions from blocked blood vessels and thalamic syndromes that cause loss of sensation.

1. Topic:
Thalamus
Zulcaif Ahmad

2. Thalamus
Etymology:
From New Latin, from Latin thalamus,
from Ancient Greek θάλαμος ~an inner chamber ~

3. Thalamus
Anatomy:
~
The thalamus is a paired and symmetrical structure
in the brain ,
The thalamus is perched on top of the brainstem,
near the center of the brain, with nerve fibers projecting out
to the cerebral cortex in all directions.
It surrounds the third ventricle.

4. Thalamus
Morphology:
Both parts of this structure of the brain in the human
are each about the size and shape of a walnut.
 About three centimeters in length,
 At the widest part 2.5 centimeters across
 About 2 centimeters in height.
The two halves of the thalamus are prominent
bulb-shaped masses
 About 5.7 cm in length,
located obliquely (about 30°) and symmetrically
on each side of the third ventricle.

5. Thalamus
Thalamic nuclei:
Each side contain five major groups.
• Midline nuclei
• Intralaminar nuclei
• Medial mass of nuclei
• Lateral mass of nuclei
• Posterior group of nuclei

6. Thalamus
• Midline nuclei:
It is a group of small nuclei, situated on the medial surface
of thalamus near the midline.
• Intralaminar nuclei:
Smaller nuclei which present in the medullary septum of
the thalamus.
• Medial mass of nuclei:
It is situated to the septum and it comprises two nuclei
1. anterior nuclei
2. dorsomedial nuclei

7. Thalamus
Lateral mass of neclei:
It is situated lateral in the septum,
Further divided into 3 subgroups.
1. Dorsal group
• Dorsolateral nuclei
• Posterolateral nuclei
2. Ventral group
• Anterior ventral nuclei
• lateral ventral nuclei
3. Posteroventral group
• Ventral posterolateral nuclei
• Ventral posteromedial nuclei

8. Thalamus
Posterior group of nuclei:
It is the continuation of lateral mass of nuclei,
Contains two subgroups.
1. Pulvinar
2. metathalamus
It also contains 2 structures.
• Medial geniculate body
• Lateral geniculare body

10. Thalamus
Thalamic radiation:
It is the collection of nerve fibers connecting thalamus
and cerebral cortex.
Thalamic radiation is divided into 4 groups called peduncle:
o Anterior (frontal) peduncle
o Superior (centroparietal) peduncle
o Posterior (occipital) peduncle
o Inferior (temporal) peduncle

11. Thalamus
o Anterior (frontal) peduncle
It connects the frontal lobe of cerebral cortex with medial leteral
Thalamic nuclei, it contain mostly motor nerve fibers.
o Superior (centroparietal) peduncle
The fiber of this peduncle connects parietal lobe at adjacent
area in frontal cortex with leteral mass of thalamic nuclei,
it contains mainly the sensory fibers

12. Thalamus
o Posterior (occipital) peduncle
It connects occipital lobe of cerebral cortex,
It contain the nerve fibers concerned with vision
o Inferior (temporal) peduncle
Fibers of this peduncle connects the temporal lobe,
It contains nerve fibers concerned with hearing.

13. Thalamus
Connections:
The spinothalamic tract is a sensory pathway originating
in the spinal cord. It transmits
information to the thalamus
about pain, temperature,
itch and crude touch.
There are two main parts:
the lateral spinothalamic tract,
which transmits pain and
temperature, and the anterior
(or ventral) spinothalamic tract,
which transmits crude touch and pressure.

14. Thalamus
Functions:
• In particular, every sensory system (with the exception
of the olfactory system) includes a thalamic nucleus that
receives sensory signals and sends them to the
associated primary cortical area.
• The thalamus also plays an important role in regulating
states of sleep and wakefulness. Thalamic nuclei have
strong reciprocal connections with the cerebral cortex,
forming thalamo-cortico-thalamic circuits that are believed
to be involved with consciousness. The thalamus plays a
major role in regulating arousal, the level of awareness,
and activity. Damage to the thalamus can lead to
Permanent coma.

15. Thalamus
Pathology
• Thalamic lesion:
Thalamic lesion occur mainly because of blockage
(due to thrombosis) in the thalamogeniculate branch
of posterior cerebral artery
• Thalamic syndrome:
It is the neurological disease caused by infarction of postero-ventral part of thalamus
Symptoms:
Loss of sensation.
Involuntary movement
Its also called by different names by different area.
o Thalamic hyperesthetic anesthesia
o Retro lenticular syndrome
o Central pain syndrome

16. Thalamus
Pathology:
Need to know
o Astereognosis
o Ataxia
o Thalamic phantom limb
o Amelognosia
o Thalamic hand

17. References:
 Harper - index & University of Washington Faculty Web Server & Search engine search page
+ Perseus Project tufts.edu Retrieved 2012-02-09
 Gray's Anatomy 39th Edition, Elsevier
 Sherman, S. (2006). "Thalamus". Scholarpedia 1 (9): 1583. DOI:10.4249/scholarpedia.1583.
 Carlesimo, GA; Lombardi, MG; Caltagirone, C (2011). "Vascular thalamic amnesia: A reappraisal".
Neuropsychologia 49 (5): 777–89. DOI:10.1016/j.neuropsychologia.2011.01.026. PMID 21255590.
 Steriade, Mircea; Llinás, Rodolfo R. (1988). "The Functional States of the Thalamus and the
Associated Neuronal Interplay". Physiological Reviews 68 (3): 649–742. PMID 2839857.
 Essentials of Medical physiology 5th Edition by K Sembulingam, Prema Sembulingam : Thalamic lesion #815
: Thalamic nuclei#812