Thalamus and Hypothalamus
occlusion of the arteries that supply the thalamus results in _________
thalamic syndrome
occlusion of what branch causes thalamus sydrome?
thalamogeniculate
what is the gateway to the cerebral cortex? It is the relay station and it processes information
thalamus
what is diabetes insipidus
-lack of ADH release -water not reabsorbed by the kidney -excessive urine production and urination (polyuria) -excessive thirst and drinking (polydipsia)`
what is a thalamus
-large, bilateral symmetrical, egg shaped structure -relay and association nuclei
what is thalamic syndrome?
-lesion in the posterior thalamus -contralateral side
hypothalamus input
-mainly from structures of the limbic system (emotions, memory, and learning) -also from spinal cord and brainstem -vascular route: blood glucose, hormones, osmolality, and temp
functions of the hypothalamus
-major control center of the ANS -influence viscera via ANS and regulates endocrine function -chief effector of the limbic system -regulates temp, thirst, feeding behavior -central regulator of homeostasis
what are sagittal subdivisions of the hypothalamus?
-medial -perventricular -lateral zones
where does the VPL relay information?
-medial leminiscus -spinothalamic tract
what is sensory ataxia?
-motor discoordination, difficulty with planning, coordinating and executing movement
thalamic pain might present with _______
dysesthesia
where does the VL nuclei relay information?
-Globus pallidus internal, deep cerebellar nuclei, substantia nigra pars reticula (BG and cerebellar input)
function of the anterior portion of the pituitary gland
(endocrine) -manufactures and releases hormones
function of the posterior portion of the pituitary gland
(neural) -only releases the hormones manufactured in hypothalamus
what are the major functions of the thalamus
-1) sensory integration -2) motor integration 3)- participates in controlling level of consciousness, altertness, and attention
what are the limbic thalamic nuclei
-A -LD
what are some examples of hormones
-ACTH: (adrenocorticotropic h.) -ADH -FSH: follicle-stimulating H. -GH -ISHS: interstitial cell stimulating -LH: luteinizing -MSH: melanocyte stimulating -TSH: thyroid-stimulating h.
what are limbic association nuclei
-DM
what are sensory association nuclei?
-P -LP
what are the motor thalamic nuclei
-VA -VL
what are the sensory thalamic nuclei
-VPL -VPM -MGB -LGB
what is dysesthesia?
-abnormal perceive of somatic stimuli
emotional and behavior changes with hypothalamus syndromes (venteromedial)
-anger and aggressive
what are the longitudinal subdivisions of the hypothalamus?
-anterior -tuberal -posterior (mammillary regions)
what is the primary blood supply to the thalamus?
-branches of the PCA and posterior communicating arteries
what are hypothalamus functions?
-endocrine functions -body temps regulation -sleep wakefulness cycles -emotional and behavioral functions
dystrophia adiposogenitalis-hyperphasia (venteromedial)
-excessive eating (obesity) -adiposity--> may be associated to underdeveloped genitalia (froeliche's syndrome) -may be combined with antisocial behavior and unprovoked anger
what is thalamic pain
-excrutiating, may be triggered by non-painful somatic stim -non responsive to analgesics due to deficient pain modulation rather than overactivity of pain afferent system
what are 3 components of thalamus syndrome?
-hemianesthesia -sensory ataxia -thalamic pain
disordered sleep wakefulness cycles
-hypersomnia (posterior) -waking up -insomnia (anterior)-go to sleep
disordered body temperatures regulation (hypothalamus syndromes)
-hyperthermia (anterior)=bring down temp via vasodilation -hypothermia (posterior) =bring temp up via shivering/vasoconstriction
deficits in endocrine function (hypothalamus syndromes)
-hypothyroidism and menstrual irregularities
what is the blood supply to the subthalamus? what does an occlusion of this artery cause
-penetrating branches of the posterior cerebral artery -hemiballismus (whole movement in the arm and leg on one side)
what three things are considered the functional organization of the thalamus
-projection neurons -specific subcortical inputs -regulatory inputs
what supplies the anterior and medial portions of the thalamus?
-proximal portions of the PCA (thalamoperforating arteries)
what do association thalamic nuclei do?
-receive multimodal inputs and project to association areas of the cortex
what are midline and intralaminar nuclei?
-receive specific inputs from basal ganglia or limbic system project to the cerebral cortex and back to the basal ganglia and limbic system
describe the thalamic relay nuclei. What are three functions of the thalamic relay nuclei
-receive specific inputs from the subcortical structures (cerebellum) or pathways (ML) and project to a well defined area of the cerebral cortex -motor, sensory, limbic system
what is the sensory integration function of the thalamus
-receives, processes and forwards sensory information to the cerebral cortex (except olfaction)
describe the projections neurons in the thalamus
-reciprocal projections between the cortex and thalamus -exceptions: reticular n. and olfactory inputs
where does the LGN relay information?
-retina (vision)
What is the epithalamus?
-single midline structure -pineal gland -no known neural output, secretes melatonin, circardian rhythms
what is the hypothalamus and what does it do?
-small, mediates complex functions
where does the VA nucleus relay information?
-substantia nigra pars reticula, Gpi, deep cerebellar nuclei, (BG and cerebellar input)
what supplies the caudal (posterior) half of the thalamus (LGB, pulvinar and lateral nuclear group and most of ventral tier)
-supplied by distal portions of the PCA (thalamogeniculate arteries)
where does the posterior hypothalamus project pathways?
-sympathetic nervous system
what is the specific subcortical inputs?
-takes information from one primary major source to specific parts of the cortex. -outnumbers specific inputs
what are the thalamic nuclei categories?
-thalamic relay nuclei -association thalamic nuclei -midline and intralaminar nuclei
what is the motor integration function in the thalamus
-the major outputs of the BG and cerebellum are processed in the thalamus prior to projecting to the cortex
where does VPM relay information?
-trigeminal lemniscus -trigeminothalamic tract
what arteries supply the hypothalamus?
-two groups of penetrating branches -Anterior: anterior cerebral arters (ACA) and anterior communicating artery (anterormedial regions) -posterior cerebra artery (PCA) and posterior communicating arteries (posteromedial regions)
what are the major thalamus nuclei we need to know?
-ventral lateral (VL) -ventral posterior (VP) -ventral posterolateral (VPL) -ventral posteromedial (VPM) -medial geniculate body (MGB) -lateral geniculate body (LGB)
what is the subthalamus
-wedge-shaped transition between thalamus and midbrain
what is the subthalamus?
-wedgeshaped transition between thalamus and midbrain -contains the subthalamic nucleus which is also a nucleus of the basal ganglia
what are outputs from the hypothalamus
-widespread to cerebral cortex, hippocampus, amygdala, septal nuclei, pituitary gland, thalamus, brainstem, and spinal cord, thalamus, RF
______ percent of projection neurons go to the cerebral cortex
75%
what are examples of the specific subcortical inputs?
auditory inputs--> MGB visual inputs -->LGB
where does the anterior hypothalamus project pathways?
parasympathetic nervous system
what is hemianesthesia?
partial or complete paralysis on one side of head and body
what does the regulatory inputs do?
whether information will be forwarded to the cortex
