Sjldllds ;l;sf’;’;s بسم الله الرحمن الرحیم 1389 1 IUMS, Depart of Anatomical...

sjldllds

• ;l;sf’;’;s

بسم الله الرحمن الرحیم

1389 1IUMS, Depart of Anatomical Sciences & Molecular Biology

1389 IUMS, Depart of Anatomical Sciences & Molecular Biology

2Figure 12.2b

Diencephalon

ThalamusHypothalamusEpithalamusSubthalamusMethathalamusRetinaClinical points Anatomy

Function


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Diencephalon


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Cerebrum

• It is derived from prosencephalon and is the largest part of brain

• It consists of two parts :– Diencephalon, which is a symmetrical

central core of the brain– Telencephalon, which forms cerebral

hemispheres


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Diencephalon, or 3rd ventricle & its walls

• Located between midbrain and cerebral hemisphere

• Consists of a thin & slit like cavity called; 3rd ventricle, and thick walls

• In an intact brain, the only surface of diencephalon which can be seen is its inferior surface


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Derivatives from diencephalon :

• Thalamus

• Hypothalamus

• Epithalamus

• Subthalamus

• Methathamus

• Retina

• Neural hypophysis


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Diencephalon


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Boundries of Diencephalon

• Inferior surface :– made by hypothalamus and the other

structures include:– Optic chiasm– Infundibulum– Tuber cinereum– Mammillary bodies


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• Superior surface:– Fornix

• Lateral surface:– Internal capsule

• Medial surface:– 3rd ventricle


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3rd ventricle

• Anterior wall, lamina terminalis, a thin sheet of gray matter across which passes anterior commissure

• Posterior wall:– Opening of cerebral aqueduct– Posterior commissure – Pineal recess– Habenular commissure


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•*•*


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Diencephalon

Figure 9-10: The diencephalon


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3rd ventricle ....

• Lateral wall:– Thalamus– Hypothalamus– Hypothalamus sulcus– Stria medullaris thalami – Interthalamic connection


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Thalamus

• Dorsomedial part : 1 section

• Lateral part : 2 section

• Ventral part : 3 section *


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•Slide 40*•Slide 40*


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Hypothalamus boundaries

• Inferior surface• Optic chiasm• Tuber cinereum, a convex mass of grey

matter as seen from inferior surface:– Infundibulum– Median eminence, a raised part of tuber cinereum

to which is attached the infundibulum

• Infundibulum + median eminence + posterior lobe of hypophysis = neurohypophysis

• Mammillary bodies + &


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Hypothalamic nuclei 12

Medial

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Lateral

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Medial & lateral, 3

Anterior zone

Paraventricular

L Supra-

A Optic

Preoptic

Intermediat-e zone

Dorso medial, ventro medial & Infundibular

T Lateral

E Tuberal

R

suprachiasmatic

Posterior zone

posterior A Tubero

L Mammi.

Mammillary

•*•*


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Hypothalamic function

• Survival of individual & species


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Survival of individuals & species

• Body homeostasis:– Regulation of body

fluids, electrolytes & circulation.

– Regulation of body temperature

• Survival strategies:• Regulation of eating• Regulation of

drinking• Defense • Sexual activity • Regulation of sleep

and awareness

• Memory +*


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Epithalamus

• Habenular nuclei and their connections & pineal glands– Pineal glands, pinealocytes and glial cells– Brain sands (concretions of calcified

material in pineal glands)


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Subthalamus

– Cranial ends of red nucleus & substantia nigra

– Cranial ends of lemnisci tracts

• *


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Function of hypothalamus

• Survival of individuals & species


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Function of hypothalamus …

• I. Hypothalamus is an executive arm of limbic system

• II. Integrates somatic and visceral responses to maintain homeostasis

• III. All hypothalamic function is done through :– A - Endocrine system (via hypophysis)– B - Autonomic system


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A - Hypothalamus is connected to hypophysis through 2 pathways:

• 1. Hypothalamohypophyseal portal system: releasing or inhibiting hormones that act on the anterior pituitary (anterior hypophysis or adenohypophysis)

• 2. Hypothalamohypophyseal tract: oxytocin (pitocin) and antidiuretic hormone (vasopressin) that are released by the posterior pituitary ( posterior hypophysis or neurohypophysis) +


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B - Hypothalamus controls autonomic nervous system through:

• 1. Sympathetic system: fight or flight (intruder in your apartment)

• 2. Parasympathetic system: rest and digest (after Thanks giving dinner) +


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THE ENDTHE END


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Diencephalon

Figure 9-10: The diencephalon


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• Superior surface:– Fornix

• Lateral surface:– Internal capsule

• Medial surface:– 3rd ventricle


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•Slide 40*•Slide 40*


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Hypothalamus boundaries

• Inferior surface• Optic chiasm• Tuber cinereum, a convex mass of grey

matter as seen from inferior surface:– Infundibulum– Median eminence, a raised part of tuber cinereum

to which is attached the infundibulum

• Infundibulum + median eminence + posterior lobe of hypophysis = neurohypophysis

• Mammillary bodies + &


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Hypothalamic nuclei 12

Medial

5

Lateral

4

Medial & lateral, 3

Anterior zone

Paraventricular

L Supra-

A Optic

Preoptic

Intermediat-e zone

Dorso medial, ventro medial & Infundibular

T Lateral

E Tuberal

R

suprachiasmatic

Posterior zone

posterior A Tubero

L Mammi.

Mammillary

•*•*


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Epithalamus

• Habenular nuclei and their connections & pineal glands– Pineal glands, pinealocytes and glial cells– Brain sands (concretions of calcified

material in pineal glands)


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•*•*

Sjldllds ;l;sf’;’;s بسم الله الرحمن الرحیم 1389 1 IUMS, Depart of Anatomical...

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