Diencephalon Thalamus dorsal thalamus Hypothalamus pituitary gland Epithalamus habenular nucleus and commissure pineal gland Subthalamus ventral thalamus subthalamic nucleus (STN) field of Forel
Classification of Thalamic Nuclei I. Lateral Nuclear Group II. Medial Nuclear Group III. Anterior Nuclear Group IV. Posterior Nuclear Group V. Metathalamic Nuclear Group VI. Intralaminar Nuclear Group VII. Thalamic Reticular Nucleus
Summary of Thalamic Connectivity I. Sensory Input general sensation special sensation taste, equilibrium, hearing, vision II. Motor Input cerebellum, basal ganglia III. Reticular Formation IV. Limbic System mammillary nucleus hippocampal formation
Thalamus Functions of the thalamus I. Relay functions from the spinal cord, brainstem, cerebellum basal ggl. to the cortex II. Modulatory functions Influences the excitability of the cx, synchronised vs. desynchronised states (repetitive and burst firing) III. Integrative functions 1. Sensory connections (sensory relay station) 2. Motor coordination 3. Psychological functions (instinct, affection, limbic functions etc) 4. Autonom function control 5. Cortical activation
Clinical Syndromes of the Thalamus Posterolateral thalamic syndromes sensory disorders Thalamic (Dejerine-Roussy) syndrome ----- VP nucleus - pain Medial thalamic syndromes disorders of consciousness thalamic neglect, thalamic amnesia, akinetic mutism Anterolateral thalamic syndromes motor disorders paresis, ataxia, motor incoordination, dysphagia
Visual (Optic) Pathway Modality: Vision Receptor: Photoreceptor Cell of Retina Cranial Nerve: II (Optic nerve) 1st Neuron: Bipolar Cell 2nd Neuron: Ganglion Cell optic nerve optic chiasm optic tract 3rd Neuron: Lateral Geniculate Nucleus optic radiation Termination: Visual Areas (V I, V II) Brodmann area 17 (V I), 18, 19 (V II)
Visual Pathway 1. Optic nerve 2. Optic chiasm 3. Optic tract 4. Lateral geniculate body 5. Optic radiation 6. Visual cortex
Visual (Optic) Pathway
Clinical Features of Visual Pathway Lesion 1. optic nerve 2. optic chiasm 3. optic tract 4. 5. optic radiation A. unilateral blindness B. bitemporal hemianopsia C. left homonymous hemianopsia D. left inferior homony- mous quadranopsia E. left superior homony-
Signs of Visual Pathway Lesion Optic nerve - ipsilateral blindness Optic chiasm - bitemporal hemianopsia Optic tract - contralateral homonymous hemianopsia Optic radiation - contralateral homonymous quadranopsia - intact light reflex Visual Cortex - macular sparing
left inferior optic radiation lesion right superior quadranopsia Visual Field Defect left inferior optic radiation lesion right superior quadranopsia
Hypothalamus Limbic System
Diencephalon 3rd ventricle Surrounded by cerebrum Thalamus Intermediate mass Pineal body Hypothalamus Epithalamus Mammillary body Pituitary gland
epithalamus Located at dorsal part of the diencephalons, it includes the pinieal body. It secretes melatonin which signals the nighttime stage of the sleep-wake cycle. pineal body — internal secretion gland habenular triangle— habenular nucleus habenular commissure thalamic medullary stria posterior commissure
subthalamus subthalamic nucleus participate in the function of extracorticospinal tract