The Hypothalamus

Anatomy and Function

The Hypothalamus

• General Anatomy– Gross Anatomy– Nuclei – Fiber Connections

• Functional Considerations– Autonomic– The "Four F's"– Other Functions

What are the five regions of the hypothalamus? What are some

key nuclei in each region.

Gross anatomy of the Hypothalamus

• Gross Anatomy– Median Eminence

• Infundibulum– Pituitary Stalk

• Tuber Cinereum

– Mammilary Bodies

• Five Regions of Nuclei

OpticChiasm

Pons

Regions of the Hypothalamus

• Anterior Region

• Medial Region

• Lateral Region

• Infundibular Region– Tuberal

• Posterior Region

Nuclei of the Hypothalamus• Anterior Hypothalamus

– Preoptic

– Suprachiasmatic

• Medial Hypothalamus– Ventromedial Nucleus

– Supraoptic

– Paraventricular

• Lateral Hypothalamus– Lateral Nuclei– Medial Forebrain

Bundle (fibers)http://www.hms.harvard.edu/research/brain/atlas.html

Nuclei of the Hypothalamus

• Infundibular Hypothalamus– Tuberal Nuclei

• Posterior Hypothalamus– Posterior Nuclei– Mammilary Body Nuclei

How do these nuclei connect?

http://www-medlib.med.utah.edu/kw/sol/sss/mml/sol02273.jpg

What are the main inputs to the hypothalamus? Which are descending and which are

ascending inputs?

Inputs to the Hypothalamus• Ascending

– Spinal Cord Direct– Via Reticular Formation– Sensory Cranial Nerves

• Descending– Hippocampus (via Fornix)– Amygdala (via Stria terminalis and

Amygdalo-hypothalamic tract)

– Septal Nuclei (via MFB)– Accumbens (via MFB)

Hypothalamus

Spinal CordCranial Nerves

Reticular Nuclei

Hippocampus

Septal

Amygdala

NAcs

What are the main output of the hypothalamus (neuronal or

other)? Which are ascending and which are descending?

Descending Outputs of the Hypothalamus

• Spinal Cord– Hypothalamospinal tract

– Sympathetic - Lateral Horn

– Somatic - Ventral Horn

• Cranial Nerve Nuclei – Parasympathetic

– Somatic

• Reticular Formation• Pituitary Gland

– Endocrine System

Hypothalamus

Spinal Cord

Reticular Nuclei

Cranial MotorNuclei

Brainstem

Ascending Outputs of the Hypothalamus

• Mammilothalamic Tract• Anterior Thalamus

• Medial Forebrain Bundle– Septal Nuclei– Nucleus Accumbens– Cerebral Cortex

(Orbitofrontal)

Cerebral Cortex

Ant Thal

Hypothalamus

Septal

NAcs

MFB

MTT

What is the function of the different regions of the

hypothalamus?

Functions of the Hypothalamus

• The Classic Autonomic Control

• The Four Fs

• A Laundry List of Functions

Functions of the Hypothalamus I

• Controls Autonomic Nervous System– Anterior Stimulation elicits parasympathetic

responses– Posterior Stimulation elicits sympathetic responses– Lesion Effects

• Damage to Hypothalamospinal Tract in Lateral Medulla– Horner’s Syndrome

Functions of the Hypothalamus II --The Four Fs

• Feeding

• Fighting

• Fleeing

• Reproduction

Feeding Disorders

• Hyperphagia – Ventromedial Nucleus

• Aphagia – Lateral Hypothalamus

• Water Consumption Regulation – Adipsia and Polydipsia

Fighting and Fleeing

• Sham Rage - Undirected Agression– Damage to Descending Hypothalamic Inputs

produces Sham Rage– Hypothalamus produces rage, Cortex Controls it

• Affective Disorders– Fear and Phobia

Reproductive Behaviors

• Anterior Hypothalamus "Sex Center"– Lesions Reduce Drive– Stimulation - Hypersexuality– Control of Sex Hormones

• Sexual Dimorphism

Functions of Hypothalamus III• Motivation

– Self-Stimulation

• Memory– Korsakov’s Syndrome

• Temperature Regulation

• Circadian (etc.) Rhythms– Suprachiasmatic Nucleus

• Pituitary Control

Pituitary Control• Endocrine Hormone Regulation

– Made in Hypothalamus • Vasopressin(ADH), Oxytocin

– Made in Pituitary• Somatotropin, Somatostatin, ACTH, FSH, etc.

• Pituitary Gland– Posterior Lobe

• Hypothalamic Axons Only

– Anterior Lobes• True Gland Cells

Pituitary Posterior Lobe

• Nuclei– Supraoptic – Paraventricular Nuclei

• Hormones– Oxytocin– Vasopressin/Antidiuretic

Hormone (ADH)

• Direct Release into Blood System

Pituitary Anterior Lobe• Tuberal Nuclei (et. al.)

– Releasing Factor Peptides• GH-RF

• TSH - RF

• Etc

• Portal Capillary System• Anterior Lobe Gland Cells

– Hormone Proteins• GH

• TSH

• Etc

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