The Brain Four Major Regions

Cerebral hemispheresDiencephalonBrian stemCerebellum

Cerebral hemispheres Collectively know as the cerebrum Most superior part of the brain and covers the

other parts Gray matter of the cerebrum is known as the

cerebral cortex and makes up the surface of the brain

The deeper cerebral white matter is made of tracts that carry impulses to and from the cortex. The tract that connects the two hemispheres is called the corpus callosum

Basal nuclei (or basal ganglia) refers to gray matter that is buried deep within the white matter

Cerebral hemispheres Also Contains

Gyri – elevated ridges of tissueSulci – shallow groovesFissures – deeper grooves that separate

large areas of the brainLobes – areas of the brain that are named

for the bone that covers them

Areas of the cerebrum Somatic sensory area – area

responsible for sensory receptor interpretation

The map of the areas of the somatic sensory area responsible for body areas is known as the sensory homunculus

It is upside down and crossed

The SensoryHomunculus

From Page 238

Primary motor area Area that allows

us to control our skeletal muscles is located in the frontal lobe right in front of the central sulcus.

The body can also represented in a diagram called the motor homunculus

Other Areas of the Cerebrum Visual area – in the Occipital Lobe

Auditory and olfactory areas - Temporal Lobe Broca’s area –involved in our ability to speak is

found at the base of the precentral gyrus (raised area anterior to the central sulcus

Speech area – allows us to sound out words is found at the junction of the temporal, parietal, and occipital lobes

Higher intellectual reasoning and socially acceptable behavior are also believe to be part of the frontal lobe

Complex memories appear to be stored in the temporal and frontal lobes

Let’s label and color Figure 7.13 from Page 237

The Diencephalon Also called the interbrain Located just above the brain stem and is

enclosed in the cerebral hemispheres Made up of the thalamus,

hypothalamus, and epithalamus

Thalamus Encloses the 3rd ventricle (chamber) of

the brain Relay station for sensory impulses

passing upward to the sensory cortexes Allows for crude recognition of whether

the sensation will be pleasant or unpleasant

Hypothalamus Bottom part of diencephalon Body’s homeostasis control center –

controls temperature, metabolism, water balance

Center for many drives and emotions, which makes it the major part of the limbic system (emotional-visceral brain)

Regulates the pituitary gland and has mammillary bodies (reflex smell centers) bulge from the bottom of the hypothalamus

Epithalamus Roof of the 3rd ventricle Contains the pineal body (part of

endocrine system) and the choroid plexus (knots of capillaries) of the third ventricle

Brain Stem Small area (diameter of a thumb and 3

inches long, but contains the midbrain, pons, and medulla oblongata

Is responsible for vital activities like breathing and blood pressure

Cerebellum Found under the occipital lobe of the

cerebrum Has two hemispheres and a complex

surface with gray matter on the outside and white matter on the inside.

Provides the precise timing for skeletal muscle activity and controls our balance and equilibrium