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)