Diencephalon. Epithalamus Hypothalamus Thalamus clacifications Epithalamus: 1-Pineal gland...
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Transcript of Diencephalon. Epithalamus Hypothalamus Thalamus clacifications Epithalamus: 1-Pineal gland...
Diencephalon
Epithalamus
Hypothalamus
Thalamus clacifications
Epithalamus:
1-Pineal gland
2-Habenular nuc.(trigon)
3-Post.comissure
4-Stria medularis thalami
Pars ventralis
Hypothalamus:
1-Anterior nuc. Group
2- Medial nuc. Group
3-Lateral nuc. group
1- Reticular nuc.
2- Zona incerta
3- Nucleus of the fields of Forel
4- Subthalamic nuc.
Subthalamus
(Ventral thalamus):
Thalamus proper (thalamus):
Pars dorsalis
Metathalamus: Ventral & lateral geniculate nuc
1 Medial nuc. Group
2-Lateral nuc. group
Epithalamus
Pineal bodyHabenular trigonesStria medullaresPosterior commissure
Habenular nuclei
Pineal gland or Epiphysis
HYPOTHALAMUS HYPOTHALAMUS
Boundaries : Superior : The hypothalamic sulcus
separating it from the thalamus
Inferior : Optic chiasma , tuber
cinereum and mamillary bodies . Anterior : Prepotic area ( from optic
chiasma to the lamina terminalis and anterior commissure )
Poster : The tegmentum of the mid brain
Medial : The third ventricle
Lateral : The internal capsule & optic
tract
Hypothalamus
Cytoarchitectural organization (Nuclei) :
Medially
1- Anterior hypothalamic region Suprachiasmatic Supraoptic Preoptic Anterior Paraventricular
2- Middle hypothalamic region• Arcuate or infundibolar• Ventromedial• dorsomedial
3- Posterior hypothalamic region• Mamillary body• posterior
•LaterallyLateral Lateral tuberal
Afferent connections :
1- Medial forebrain bundle
2- Hippocampo-hypothalamic fibers
3- Amygdalo-hypothalamic fibers
4- Brainstem afferents
5- Retino-hypothalamic fibers
6- Cortico-hypothalamic fibers
7- Forebrain afferents
Efferent connections :
1- Medial forebrain bundle2- Dorsal longitudinal fasciculus3- Mammillary efferent fibers4- Descending hypothalamic projections5- Hypothalamocortical fibers6- Supraoptic decussations7- Supraopticohypophysial tract8- Tuberohypophysial tract
Functional considerations :
1- Coordination of the autonomic nervous system
2- Regulation of body temprature
3- Maintenancce of water balance
4- Control of anterior pituitary
5- Control of reproductive functions
6- Control of growth
7- Control of food intake
8- Control of emotional behavior
9- Hypothalamus and sleep
Three Methods of Hypothalamic Control over the Endocrine System
Control of anterior pituitary
Coordination of the autonomic nervous system
Autonomic functions : - Water balance - internal secretion - sugar and fat metabolism - temprature regulation
Chief subcortical center for the regulation of both sympathetic & parasympathetic activities
- ventricular portion of the tuber cinerum
- Ant & med hyp. R. (supraoptic & preoptic)
control of sympathetic activities - lat & post hyp. R.
control of control of parasympatheticparasympathetic activitiesactivities
Coordination of the autonomic nervous system
Mamillary body
Hypothalamus Mesencephal Mesencephal tegmentaltegmental
Mamilotegmental tract
Mamilotegmental tract
Medial forbrain bundleMedial forbrain bundle
Periventricular fibersPeriventricular fibers
Polysynaptic con
nections
Polysynaptic con
nections
Parasympathetic nucleus Parasympathetic nucleus of brain stemof brain stem
autonomic nucleus of autonomic nucleus of spinal cordspinal cord
Dorsal longitudina
l fasciculus D
orsal longitudinal fasciculus
LacrimalLacrimalSalivatorySalivatoryGI tractGI tract
Regulation of body temprature hyperthermia Ant hypothalamus : sensitive to hyperthermia (hyperpyrexia) Mechanism for Dissipation of excess heat : 1) sweating 2) vasodilation of the cotaneous blood vessels 3) Thirst
hypothermia Post hypothalamus: sensitive to hypothermia Mechanisms for heat conservation & heat production : 1) vasoconstriction of the cotaneous blood vessels 2) ceastion of sweat secretion 3)Augmentation of visceral activities oxidation 4)Shivering of somatic muscles
Thus :Coordination of sympathetic & parasympathetic response
regulation of body temprature
Maintenance of water balance A:
Supraoptic n. (ADH) Kidney:1) reabsorption of renal water,Nacl & bicarbonate2) alter the osmotic permiability of water in the distal and
collecting tubules
B:Ant region on the hyp thirst consumption of water
C:Lat hypo at the level of ventromedial n. Reduction in water intake
Control of growth :
GH releasing factor
Ant lobe of hypophysis
Growth of bone & soft tissue
Ventromedial n. :Satiety
Control of food intake
Lat hypothalamic n. : feeding center
Control of emotional behavior
1) Lat region of the ant hyp : flight responses
2) Ventromedial n. : aggressive responses
Coordination of sympathetic & parasympathetic response
Hypothalamus and sleep
Tuberomammillary n.
Raphe n “sleep centers” Pontine reticular
formation
Intralaminar & reticular thalamic nuclei