thalamus

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THALAMUS : 

THALAMUS

Intoduction : 

Intoduction It constitutes the main part of the Diencephalon. The thalamus (from GREEK = bedroom, chamber) is a pair and symmetric Large ovoid mass of grey matter above midbrain, seperated by subthalamus Two thalami on each side of slit like third ventricle Functionally considered as the great sensory gateway to the cerebral cortex

Introduction : 

Introduction Thalamus Subthalamus Hypothalamus Epithalamus

External Features : 

External Features End : Anterior & Posterir Surface : Superior Inferior Medial Lateral

Relation

Internal Structure : 

Internal Structure White Matter- External Medullary Lamina covering lateral surface Stratum Zonale covering Superior Surface Internal Medullary Lamina-“Y”shaped & dividing thalamus in to three parts Anterior, Medial and Lateral, with their groups of nuclei

Thalamic Nuclei : 

Thalamic Nuclei Anterior Lateral Dorsal Tier lateral dorsal lateral posterior pulvinar Ventral Tier ventral anterior ventral lateral ventral posterior (VLP & VPM) posterior nucleus

Thalamic Nuclei : 

Thalamic Nuclei Medial medial/dorso medial midline nuclei Pulvinar Geniculate bodies Reticular Intralaminar centromedian parafasciular

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connection

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Anterior VA VL VPL VPM LD LP Pulvinar LGN MGN DM Functional Connections Mammillary Body Cingulate Gyrus Amygdala Hypothalamus Olfactory Cortex Prefrontal Cortex Globus Pallidus Substantia Nigra Premotor Cortex Prefrontal Cortex GP SN Cerebellum (Dentate) Primary Motor Cortex (4) Supplementary Motor Cortex (5_ Cingulate Superior Parietal Cortex (5,7) Spinothalamic and LL/ML Sensory Cortex (3,1,2) , Solitary Nucleus Sensory Cortex Right Optic Tract Primary visual Cortex (17) (lingual gyrus, cuneus) Brachium of Inferior Colliculus Primary Auditory Cortex (41,42) LGN, Superior Colliculus Association areas of temporal, occipital, parietal lobes Lesion: memory loss (Wernicke-Korsakoff) Lesion: Sensory Aphasia Lesion: contralateral loss of pain/temp, discrim touch Lesion: contralateral loss of pain/temp, discrim touch in head; ipsilateral loss of taste Lesion: Left Homonymous Hemianopsia

Arterial supply : 

Arterial supply mainly by branch of - Posterior communicating artery - Posterior cerebral artery - Posterior choroidal artery - Lenticulo thalamic branch of middle cerebral artery

Venous Drainage : 

Venous Drainage - Thalamostriate Vein - Choroid vein of 3rd venticle both unite & form internal cerebral vein at interventricular foramen

Functions of Thalamus : 

Functions of Thalamus Sensory integration and relay station for all the sensory pathways except Olfactory Recognition of crude pain, temperature & touch Influences voluntary movements by receiving impulses from basal ganglia & cerebellum & relaying them to motor cortex , influence LMN Participates in maintenance of state of wakefulness & alertness through RAS Role in emotions & recent memory

Thalamic syndrome : 

Thalamic syndrome Due to vascular lesion (thrombosis of thalamogeniculate artery) Threshold for pain, touch & temperature decreased on opposite side of body When threshold reached then exaggerated Emotional instability, spontaneous laughing & crying

Thalamic hand : 

Thalamic hand Opposite hand shows abnormal posture Forearm is pronated, wrist flexed, metacarpophalangeal joints flexed & interphalangeal joints extended Fingers can move actively, but movements are slow Due to altered muscle tone in different muscle groups

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THANK YOU