1. Anatomy of the Hypothalamus 2013 %5b1%5d

8/12/2019 1. Anatomy of the Hypothalamus 2013 %5b1%5d

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THE ANATOMY OFTHE HYPOTHALAMUS

M.T. GARDNER

NOV 2013


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Lamina terminalis

Rostral extent of theaqueduct of Sylvius

HYPOTHALAMIC SULCUS


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ThalamusHypothalamic

Sulcus

LaminaTerminalis

Optic Chiasma

Fornix

Mamillary BodyInfundibulum

Pineal

Aqueduct

of Sylvius

Hypothalamus


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MEDIAN EMINENCE

Tuber cinereum


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Surface Anatomy of the

Hypothalamus

Is visible only from the ventral aspect of

the undissected brain

Lies between the optic chiasma and the

posterior perforated substance

Includes the following ventral surface

structuresinfundibulum, tuber cinereum

(includes the median eminence which

contains the arcuate nucleus)

Mamillary bodies


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Forrnix connects

Hippocampus to

mamillary body of

Hypothalamus


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Topographical Relations of the

Hypothalamus

Superiorly: Thalamus (sup. to the

hypothalamic sulcus)

Laterally: Internal capsule

Medially: Lateral wall of third ventricle

covered by ependyma


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?

?

?

?


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Hypothalamus

Anteriorly: extends up to the lamina

terminalis and merges with the

olfactory area at the ant.

perforated substance


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Hypothalamus

Posteriorly: continuous with the

Subthalamus and tegmentum

of the midbrainalso to the

sup. extent of the aqueduct of

Sylvius

The floor of the third ventricle can also beconsidered as a part of the Hypothalamus


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REVIEW LATERL / MEDIAL RELATIONS - HOT SLIDE !!!!!

INTERNAL CAPSULE

Hypothalamic sulcus

Hypothalamus

THALAMUS

MAMILLARY BODY

FRONTAL SECTION

III VENTRICLE


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THALAMUSinferior to thisHYPOTHALAMUSInt Capsule lateral to

the Hypothalamus

POSTERIOR LIMB OF THE INTERNAL CAPSULE

Horizon tal Sect ion through the Brain

FORNIX

III VENTRIC


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Divisions of the Hypothalamus

1. Various ways to subdividegenerally

into a MEDIAL and LATERAL ZONES,

the column of the fornix occurring (in

part) in between these two zones.

2. Further subdivided into 4 zones or

regions in a rostro-caudal direction each

having specific nuclei.


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FORNIX


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Optic Chiasma

Hypothalamic Sulcus

Thalamus

Mamillary Body

Lamina Terminalis

Fornix

Ant. Commissure


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Hypothalamus

What exactly is a NUCLEUS?????

this term will be used repeatedly in this

lecture.

It is an accumulation (group) of neuronal

cell bodies within the CNS (in this case in

the brain itself)

An accumulation (group) of neuronal cell

bodies in the PNS is referred to as a

ganglion.


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A. Preoptic Region:

- Preoptic nucleus

B. Supraoptic Region:

- Suprachiasmatic nucleus

- Supraoptic

- Paraventricular

- Ant nucleus

- Periventricular cell groups


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C. Tuberal Region:

- Dorsomedial

- Ventromedial

- Arcuate (infundibular)

- Premamillary- Lateral Tuberal


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D. Mamillary Region:

- Posterior- Mamillary nucleus


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Optic Chiasma

Hypothalamic Sulcus

Thalamus

Mamillary Body

Lamina Terminalis

Fornix

Ant. Commissure


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Important Points on the

Hypothalmic Nuclei

1.Paraventricular and Supraoptic Nuclei:

- Regulate water balance

- Produce ADH and oxytocin

- Destruction causes diabetes insipidus

2. Anterior Nucleus:

- Stimulates parasympathetic NS

- Thermal regulation (heat dissipation)

- Destruction results in hyperthermia


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Hypothalmic Nuclei

Corticotropin-releasing hormone issecreted by the paraventricular

nucleus (PVN) of the surraoptic

region of the hypothalamus inresponse to stress


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Hypothalmic Nuclei

3. Preoptic Area:

- (a lot of research done on this nucleus

esp in relation to sexual orientation)

- Contains sexual dimorphic nucleus- Regulates release of gonadotropic

hormones

4. Suprachiasmatic Nucleus:

- Receives input from retina

- Controls circadian rhythms

I t t P i t th


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Hypothalmic Nuclei5. Dorsomedial Nucleus:

- Stimulation results in obesity andsavage behaviour

6. Posterior Nucleus:

- Stimulates the Sympathetic NS- Thermal regulation (heat conservation)

- Destruction results in inability to

thermoregulate

7. Lateral Nucleus

- Stimulation induces eating

- Destruction results in starvation

I t t P i t th


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Hypothalmic Nuclei

8.Mamillary Body:

- Receives input from hippocampal formation

- contains hemorrhagic lesions in Wernickes

encephalopathy

9. Ventromedial Nucleus:

- Satiety center

- Destruction results in obesity and savage behaviour

10. Arcuate Nucleus:

- Produces hypothalmic releasing factors

- Contains DOPA-ergic neurons that inhibit prolactin release


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Supraoptic

Paraventricular

Pars distalis

Pars intermedius

Adenohypophysis

Pars nervosaCleft

Pars tuberalis

Neurohypophysis


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y

Sulcus

LaminaTerminalis Optic Chiasma

Fornix


Pineal

Aqueduct

of Sylvius

Hypothalamus


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Eating Disorders


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https://reader010.{domain}/reader010/html5/0619/5b2838eac489

Anorexia nervosa

Feeling great !!!!


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https://reader010.{domain}/reader010/html5/0619/5b2838eac4897/5b283902b3e0

Feeling great !!!!


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Major Afferents

1. Fornix: A projection fibre system from theHippocampus

2. Stria Terminalis: From the Amygdaloid nuc

3. Medial Forebrain Bundle: From the Septal

area

4. Ventral Amygdalofugal Fibres: Also from the

Amygdala


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Major Afferents

5. Periventricular Fibres: From the Medial

nucleus of the thalamus (this nucleus

has rich interconnections with the

prefrontal cortex of the brain)

6. Pallido-Hypothalamic Fibres

7. Autonomic Ascending Input


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Major Afferents

Of great importance is the circulating

blood through the capillary bed of the

various hypothalamic nuclei resulting

in stimulation/ inhibition. Theimportance of no blood brain barrier

e.g. in the median eminence is of great

physiological significance.


S lFornix


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Sulcus

LaminaTerminalis Optic Chiasma

Fornix


Pineal

Aqueduct

of Sylvius

Hypothalamus


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Ri Ri GETTING ON BAD !


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Major Efferents

1. Mamillothalamic tract: to the anteriornucleus of the thalamus (part Circle ofPapez)

2. Mamillotegmental Pathway: to reticularformation and autonomic centers in thebrain stem and spinal cord (polysynaptic)e.g. reticulospinal to parasympatheticS234


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Major Efferents

3. Supraoptico / paraventicular / hypophyseal

tracts: release of oxytocin and vasopressin

from the pars nervosa

4. Fornix efferents back to hippocampus

5. To Subthalamic nuclei

6. Projection to neocotex (cortico arousal role)


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Major Efferents

7. Periventricular fibres descend in the

dorsal longitudinal fasciculus to

reticular formation (overlap with

Mamillotegmental fibres?)

8. Stria terminalis: reciprocal connection

with the Amygdala


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Arterial Blood Supply

The supraclinoid or cerebral part of the

internal carotid artery gives off the superior

hypophyseal arteries. These break up in the

region of the median eminence in to acapillary plexus which lacks a blood brain

barrier (BBB). From here porto hypophyseal

vessels descend along the infundibular stalk

to break up into a second capillary plexus inthe adenohypophysis (portohypophyseal

system).


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The Fornix a

major projectionpathway from the

hippocampus to

the mamillary

body

Question


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The hypothalamus:

a. Receives afferent fibres from the amygdaloidbody through the fornix

b. Sends efferent fibres to the anterior lobe of thepituitary in the supraopticohypophyseal tract

c. Sends efferent fibres to the cerebral cortex in

the median forenrain bundle

d. Is related posteroinferiorly to the posterior

perforated substance

Answers


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Answers

a. FThe fibres from the amygdaloid body pass in the

stria terminalis. The fornix carries fibres from thehippocampus to the hypothalamus

b. F - The tract passes to the posterior lobe

c. F - The bundle and the dorsal longitudinal fasciculus

pass from the hypothalamus to the midbrain reticular

nuclei

d. FThis perforated substance is further back in the

interpenducluar fossa and underlies the adjacent

subthalamus and midbrain


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I WISH TO ACKNOWLEDGE THE

GOOGLE IMAGES AND PICTURES FROM

NETTERS ANATOMY ATLAS USED HERE.

1. Anatomy of the Hypothalamus 2013 %5b1%5d

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