ddescription of hypothalamus, boundaries of hypothalamus, relation of hypothalamus, subdivision of hypothalamus, medial and lateral zone of hypothalamus, preoptic area, tuberal area and mamillary area of hypothalamus, nuclei of hypothalamus and their functions, afferent pathways of hypothalamus, efferent pathways of hypothalamus, function of hypothalamus, hormones released by hypothalamus, clinical features with hypothalamic disorders

1. HYPOTHALAMUS
DR SANA YASEEN
ANATOMY DEPARTMENT
KIMS

2. INTRODUCTION
 Is the part of diencephalon.
 Constitutes small part of brain approx; 0.3 ˚/˳
 It controls many essential functions of the body.
 It the chief center to maintain the internal melieu of the
body.
 It control autonomic & endocrine system and so involved
in controlling the homeostasis and emotional behaviour

3. RELATION/ EXTEND/ BOUNDARIES
 Hypothalamus lies below thalamus and forms the floor and lateral
wall of the third ventricle.
 It extends from region of optic chiasma to the caudal border of
mamillary bodies
 Anteriorly the area between hypothalamus and optic chiasma is
funtioonally included in hypothalamus and is known as pre optic area
i.e; optic chiasma, lemina terminalis, anterior commisure.

4. BOUNDARIES
 Anteriorly: it extends up to optic chiasma to lamina terminalis and
anterior commissure. This area is also known as pre optic area.
 Caudally: merges into tegmentum of midbrain
 Superiorly: thalamus
 Inferolaterally : subthalamus
 Laterally : internal capsule
 Inferiorly: anterior to posterior
 Optic chaisma, optic tract, tubercenereum, infundebulum, mamillary bodies`

5. OPTIC
CHIASMA
INFUNDIBULUM
WITH
TUBERCENAREUM
MAMMILLARY
BODIES

6. SUB DIVISION OF THE HYPOTHALAMUS
 Different ways:
1. Is divided into MEDIAL ZONE & LATERAL ZONE
2. Is divided into OPTIC, TUBERAL and MAMMILLARY PARTS

7. MEDIAL & LATERAL ZONE
 The nuclei of hypothalamus
are divided into medial and
lateral zone via an
imaginary parasagittal
plane.
 Within the plane lies the
columns of fornix and
mammillothalamic tract ,
which serves as markers

8. 3rd Ventricle Periventricular
zone
Medial Zone Lateral Zone
Fornix
Medial
Forebrain
Bundle
Anterior
chiasmatic
Middle
Tuberal
Caudal
Mammilary
Preoptic,
Supraoptic,
Suprachiasmatic,
Anterior,
Paraventricular
Dorsomedial
Ventromedial
Arcuate Nucleus
Posterior
Mamillary

9. NUCLEI INCLUDED IN THE MEDIAL AND LATERAL
ZONE
MEDIAL ZONE
From anterior to posteriorly
 Part of pre optic nucleus
 Anterior nucleus
 Suprachismatic nucleus
 Paraventricular nucleus
 Infundibular nucleus (arcuate)
 Posterior nucleus
LATERAL ZONE
From anterior to posteriorly
 Part of preoptic nucleus
 Suprachiasmatic nucleus
 Supraoptic nucleus
 Lateral nucleus
 Tuberomammillary nucleus
 Lateral tuberal nucleus

11.  Some of the nucleus such as
preoptic nucleus ,
suprachiasmatic nucleus and
mammillary nucleus overlaps
both zone.
 Most of the hypothalamus nuclei
have ill defined boundaries.

14. OPTIC, TUBERAL AND MAMMILLARY AREAS
PREOPTIC AREA
 Supra optic nucles
 Paraventricular
nucleus
TUBERAL AREA
 Ventromedial
nucleus
 Dorsomedial
nucleus
 Tuberal nucleus
MAMMILLARY AREA
 Posterior nucleus
 Lateral nucleus

17. ANTERIOR ( SUPRAOPTIC ) REGION
Preoptic Nucleus Control of parasympathetic function
Supraoptic Nucleus Synthesis and secretion of vasopressin. Damage
causes diabetes insipidus.
Suprachiasmatic
Nucleus
Fibers from the retina; fibers to the pineal body.
Controls circadian rhythms.
Anterior
Nucleus
Controls temperature and sexual behavior.
Paraventricular
Nucleus
Synthesis and secretion of oxytocin (milk secretion
& uterine contraction). Controls food intake

18. MIDDLE OR TUBERAL
Dorsomedial Nucleus
- center of satiety
- on stimulation rage, cruelty
Ventromedial Nucleus
- center of satiety
- on stimulation depression of appetite
Arcuate Nucleus
- periventricular in tuber cinereum
- secretes releasing-factors
- dopaminergic neurons inhibit release of prolactin

19. POSTERIOR OR MAMILLARY REGION
Mamillary Nucleus
- impulses from hippocampal formation via fornix
- impulses from tegmental nuclei, nuclei raphae via mamillary peduncle
- projections to anterior thalamic nucleus via mamillothalamic peduncle
Nucleus posterior
- controls thermoregulation (preserving temperature and producing heat)
- damage causes poikilothermia – inability of thermoregulation

20. LATERAL ZONE
Crossed by Medial forebrain bundle
Contains two nuclei:
1. lateral preoptic Nucleus
2. lateral hypothalamic Nucleus
Clinical Correlate
- when stimulated feeling of hunger
- when destroyed anorexia nervosa and fast

21. The Hypothalamus
Neural Influences Hormonal Influences
Endocrine
System
Autonomic
Nervous
System
Limbic
System

22. CONNECTIONS OF HYPOTHALAMUS
AFFERENT NERVOUS CONNECTION OF
HYPOTHALAMUS :
 SOMATIC AND VISCERAL AFFERENT:
enters hypothalamus via lamniscus fibers,
tractus solitarius and reticular formation.
 VISUAL AFFERENTS: leaves optic chiasma
and enters suprachiasmatic nucleus
 OLFACTION: travels through medial
forebrain bundle
 AUDITORY AFFERENTS: from inner ear

23. CORTICOHYPOTHALAMIC FIBERS: from frontal lobe of cerebral cortex
to hypothalamus
HIPPOCAMPOHYPOTHALAMIC FIBERS: pass through hippocampus
thorugh the fornix to mammillary body.
AMYGDALOHYPOTHLAMIC FIBERS: from amygdaloid complex
tohrough stria terminalis
THALAMOHYPOTHALAMIC FIBERS: from dorsomedial and midline
thalamic nuclei
TEGMENTAL FIBERS: from mid brain

24. EFFERENT NERVOUS CONNECTION OF HYPOTHALAMUS :
Many neurophysiologists ragards the hypothalamus as the
main output pathway of the LIMBIC SYSTEM.
Descending fibers in reticular formation to brainstem and
spinal cord
MAMMILLOTHALAMIC TRACT: from mammillary bodies to
anterior nucleus of thalamus
MAMMILLOTEGMENTAL TRACT: From mammillary bodies to
reticular formation in tegmentum of mid brain

25. HORMONES RELEASED BY HYPOPHYSIS
HYPOTHALAMIC REGULARITY
HORMONE
 GROWTH HORMONES RELEASING HORMONE
 GROWTH HORMONE INHIBITORY HORMONE /
SOMATOSTATIN
 PROLACTIN RELEASING HORMONE
 PROLACTIN INHIBITORY HORMONE
 CORTICOTROPIN RELEASING HORMONE
 THYROTROPIN- RELEASING HORMONE
 LUTEINIZING HORMONE RELEASING
NUCLEAR ORIGIN
 Infundibular / arcuate nuclei
 Suupra chiasmatic nucleus
 ?
 ?
 Paraventricular nucleus
 Paraventricular, dorsomedial
nucleus
 Preoptic an anterior nucleus

26. FUNCTIONS OF HYPOTHALAMUS
1. Autonomic control: producing sympathetic and parasympathetic responses
2. Endocrine control : by producing releasing factors or release inhibitory factors
and control the hormone production of anterior lobe of hypophysis. Examples
controls secretion of TSH (thyrotropin), corticotropin (ACTH), luteinizing
hormomes (LH), FSH.
3. NEUROSECRETIONS: secretions of vasopressin and oxytocin.
4. TEMPERATURE REGULATION: by maintaining the heat production and heat loss
from the body
5. REGULATION OF WATER AND FOOD INTAKE: as the result of presence of thirst
center and hunger centre.

27. 6. SEXUAL BEHAVIOUR AND REPRODUCTION: by controling gametogenesis,
reproductive cycle, maturation and maintainance of secondary sexual
charachter.
7. BIOLOGICAL CLOCKS: hypothalamus control many circardian rythyms.
Examples are sleep and wakefullness
8. Emotions, fear, rage, pleasure and reward.

28. CLINICAL ASPECT

29.  Hypothalamus may be the site of inflammation, neoplasm or vascular
disorder.
 Can easily be pressed upon by surrounding tissue tumours.

30. Lesion of hypothalamus may produce one of the following symptoms:
Obesity and wasting: wasting is less common than obesity
Diabetes insipidus:
Diencephalic autonomis epilepsy; characterised by flushing , sweating,
salivation, lacrimation, tachycardia, retardation of respiratory rate, etc
Sexual disturbance: impotence or amenorrhea
Disturbance of sleep. Somnolence or narcolepsy
Hyperglycemia and glycosuria
Acute ulceration in upper part of GIT.
Emotional disordders: unexplained weeping or laugher, uncontrollable
rage,depressive reaction, or maniacal outburst

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