Diencephalon

DiencephalonDiencephalon

Slide 7.34a

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Sits on top of the brain stem Enclosed by the cerebral heispheres Made of three parts

Thalamus Hypothalamus Epithalamus

DiencephalonDiencephalon

Slide 7.34b

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 7.15

Figure 4.8  The human brain stemThis composite structure extends from the top of the spinal cord into the

center of the forebrain. The pons, pineal gland, and colliculi are ordinarily surrounded by the cerebral cortex.

The Brainstem: Medulla oblongata Most inferior portion, functions as a conduction pathway (descending motor neuron pathways decussate here)

Reflex centers for:

regulating heart rate

blood vessel diameter

coughing, sneezing

breathing

swallowing

The Brainstem: Pons

Superior to Medulla oblongata.

Contains more ascending and descending pathways.

Relays information from cerebrum to cerebellum.

Also includes sleep and respiratory centers.

The Brainstem: Midbrain

Small section superior to the pons.

Part of the auditory pathways and visual reflexes

Also involved in regulating muscle tone/activity and coordination

The Brain: Reticular formation 2 types of nuclei:Cranial nerves III-XIIandReticular Formation nuclei which are scattered throughout brainstem

Many pathways from RF project directly to cerebrum to modulate activity

Habituation (repetitive stimuli)

Reticular Activating System

The Diencephalon: Thalamus

“Gateway to cerebral cortex”

Most sensory stimuli project to the thalamus, which in turn projects to the cerebrum.

Thalamus also influences moods and activities associated with strong emotion.

(Two concepts: Sensory integration and Mood)

The Diencephalon: Hypothalamus Major control center of autonomic nervous system and endocrine system.

Centers associated with:

* Food/H2O intake* Thermoregulation* Cardiovascular regulation* Hormone secretion* Sleep/waking* Emotional behavior

ThalamusThalamus

Slide 7.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Surrounds the third ventricle The relay station for sensory impulses Transfers impulses to the correct part of

the cortex for localization and interpretation

HypothalamusHypothalamus

Slide 7.36a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Under the thalamus Important autonomic nervous system

center Helps regulate body temperature Controls water balance Regulates metabolism

HypothalamusHypothalamus

Slide 7.36b

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

An important part of the limbic system (emotions)

The pituitary gland is attached to the hypothalamus

EpithalamusEpithalamus

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Forms the roof of the third ventricle Houses the pineal body (an endocrine

gland) Includes the choroid plexus – forms

cerebrospinal fluid

Brain StemBrain Stem

Slide 7.38a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Attaches to the spinal cord Parts of the brain stem

Midbrain Pons Medulla oblongata

Brain StemBrain Stem

Slide 7.38b

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 7.15a

MidbrainMidbrain

Slide 7.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Mostly composed of tracts of nerve fibers Reflex centers for vision and hearing Cerebral aquaduct – 3rd-4th ventricles

PonsPons

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The bulging center part of the brain stem

Mostly composed of fiber tracts Includes nuclei involved in the control of

breathing

Medulla OblongataMedulla Oblongata

Slide 7.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers

Heart rate control Blood pressure regulation Breathing Swallowing Vomiting