The Brain (Components)

The brain is composed of:

• Brainstem

• Cerebellum

• Diancephalon

• Cerebrum

What are the components of the brainstem?

• Midbrain

• Medulla oblangata

• Pons

Midbrain

• superior to pons, extends to diancephalon

• Contains incoming sensory & outgoing motor information

Pons

• superior to medulla

• Links parts of the brain with one another via nerve tracts; bridge

• Contains both incoming sensory & outgoing motor information

• Contains control centre for breathing

  • Inhibits medullary respiration center to trigger exhalation

Medulla Oblangata

• Inferior to pons

• Contains both incoming sensory & outgoing motor information

• Contains control centres for many critical functions:

  • Breathing (inspiration)

  • Blood pressure

  • Heart rate

Cerebellum

• “little brain”

• Located inferior and posterior of brain, behind brainstem

• Important role in movement

  • Evaluates efficiency of intended movement compared to output action

  • Compares intended movement with actual movement

    • Communicates with cerebral motor cortex if movement is inaccurate to fix movement

What are the two subdivisions of the cerebellar hemispheres?

• Anterior lobe

• Posterior lobe

Vermis

Part of the cerebellum that separates the two hemispheres of the cerebellum, also includes the Falx cerebelli

What are the components of the diancephalon?

• Thalamus

• Hypothalamus

• Epithalamus

Thalamus

• superior to midbrain

• Relay station for:

  • all incoming sensory impulses EXCEPT SMELL

  • Information from the cerebellum to motor cortex

  • Communication between areas of the cerebrum

Hypothalamus

• inferior to thalamus

• Has 4 major regions

• Controls many body activities

• Regulator of homeostasis

Epithalamus

• superior & posterior to thalamus

• Contains pineal gland

  • Secretes melatonin & control centers for olfaction (smell)

Pineal gland

• Located in Epithalamus

• Responsible for secretion of melatonin and control centers for olfaction

Cerebrum

• largest portion of the brain

• Has two divisions:

  • Left hemisphere

  • Right hemisphere

Left hemisphere

Controls right side of body

• Math, analytics, speech

Right hemisphere

• controls left side of body

• Music, art, abstract ideas

Corpus callosum

• bundle of white matter tracts forming internal connection between hemispheres of cerebrum

• Allow communication between gyri in one hemisphere to corresponding gyri in other hemisphere

• Deeply connects the two hemispheres

What divides the cerebrum into left and right hemispheres?

Longitudinal fissure

Cerebral cortex

• located on surface of cerebrum

• Gray matter, billions of neurons

• Controls thinking, communicating, memory, understanding, and initiates involuntary movement

Gyri

• folds on cerebral cortex that increase surface area

  • Pre central gyrus - motor cortex

  • post central gyrus - sensory cortex

Sulci

• shallow indentations between gyri

Fissures

• Deep indentations between gyri

  • Longitudinal fissure - divides hemispheres

  • Central sulcus - divides frontal and parietal lobes

What divides the frontal & parietal lobes?

Central sulcus; fissure

Deep White Matter

• located deep to cortex

• Composed of white matter; myelinated tracts

• Connects parts of the brain to each other & the spinal cord

• Allows cross-communication between different brain areas