REGIONS OF THE BRAIN

PART I

Regions of the Brain

• cerebrum (cerebral hemisphere)

• diencephalon • brain stem • cerebellum

Cerebrum (cerebral hemisphere)• largest, obscures most of brain stem • looks like mushroom cap • made up of 2 deeply grooved

hemispheres - left and right • Surface is covered by: • - grooves - fissures or sulci • - ridges - gyri or convolutions which

serve as landmarks

Cerebrum (con’t)• concerned with higher brain functions • Contains centers for:

- interpreting sensory impulses - initiating voluntary muscular movements

• stores information of memory • utilizes information in reasoning processes • functions in determining a person’s

intelligence and personality

Left Hemisphere

• More important for: • - right-hand control • - spoken and written language • - numerical and scientific skills • - reasoning

Right Hemisphere• More important for:

- left-hand control - musical and artistic awareness - space and pattern perception - insight and imagination

• *Corpus Collosum (fibrous tract that connects left and right hemispheres)

Lobes• each hemisphere is subdivided

into 4 lobes • named for cranial bone that

covers them • more precisely defined by surface

landmarks, i.e., sulci and fissures

Lobes (cont.)

• parietal lobe • occipital lobe • temporal lobe • frontal lobe

DIENCEPHALON• Above brainstem• Major structures:

–Thalamus–Hypothalamus–Epithalamus

Thalamus• Crude

recognition whether a sensation will be pleasant or unpleasant

Hypothalamus• Floor of diencephalon• Regulates

– Body temperature, Water balance– Metabolism– Emotions (Limbic System: thirst,

appetite, sex, pain, pleasure)– Pituitary Gland (growth, sex

hormones)

Epithalamus• Pineal Body: gland that

secretes melatonin (regulates body’s day/night cycle)–Peak levels at night make us

drowsy

• Choroid Plexus: knots of capillaries that form CEREBROSPINAL FLUID

BRAIN STEM• Major

Structures:–Midbrain–Pons–Medulla

Oblongata

Midbrain• Cerebral peduncles (little feet of

cerebrum): convey ascending and descending impulses

• Corpora quadrigemina (four gemini (twins)) -reflex centers involved with vision and hearing

Pons• “bridge”• Mostly fiber

tracts• Involved in

the control of breathing

Medulla Oblongata• Most inferior part of brain stem• Merges into spinal cord• Contains centers that control:

– Heart rate– Blood pressure– Breathing– Swallowing– vomiting

CEREBELLUM• Dorsal from

occipital lobe• Two hemispheres• Outer cortex: gray

matter• Inner region: white

matter

CEREBELLUM• Provides precise timing for skeletal

muscle activity• Controls balance and equilibrium

(fibers connected to inner ear, eye, proprioceptors)

• If damaged, movements become clumsy (ATAXIA)