The Brain

Four Major Regions
 Cerebral hemispheres
 Diencephalon
 Brian stem
 Cerebellum
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 tissue
 Sulci – shallow grooves
 Fissures – deeper grooves that separate
large areas of the brain
 Lobes – 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 Sensory
Homunculus

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
