The Brain- Chpt. 7 Notes
I.
Brain’s 3 Major Regions
A. Brain Stem- includes the cerebellum, medulla
oblongata and pons
1. Cerebellum – old brain found in all organisms.
“little brain”
a. Provides precise timing for skeletal muscle
activity, controls balance and equilibrium.
b. Information from the ear, eye and skin of the
skeletal muscles meet here.
2. Medulla oblongata- lowest region on brain stem
a. The fourth ventricle lies posterior to the pons
and medulla
b. Center for heart rate, breathing, blood
pressure, swallowing, and other reflex reactions
(gag, salivate)
3. Pons- Connects the cerebellum to the brainstem
through a complex bridge of nerve fibers
a. Control of breathing
b. Sleep and arousal
4. Reticular formation- extends the length of the brain
stem
a. Control motor functions of visceral organs
b. Reticular activating system (RAS)- plays a role in
consciousness and awake/sleep cycles
c. Damage to this region can cause a coma
B. Midbrain- Diencephalon or Interbrain – located on top
of the brain stem includes the thalamus, hypothalamus,
epithalamus and third ventricle
1. Hypothalamus- the floor of the diencephalon- plays
a role in regulating body temperature, water
balance, and metabolism
a. Center of many emotions and drives (Limbic
system) or emotional brain for sex, thirst,
appetite, pain, and pleasure
b. Regulates the pituitary gland
2. Mammilary bodies- center for olfaction located on
floor of hypothalmus
3. Epithalamus- forms roof of third ventricle made up
of the pineal body and the choroid plexus which
forms cerebrospinal fluid
C. Cerebrum- largest and most superior part of the brain.
Composed of left and right hemisphere and divided by a
longitudinal fissure.
Connected by Corpus Callosum – bridge between two
hemispheres
Cerebral Cortex is the covering which conducts higher
order thoughts
1. Gyri- raised ridges of cerebral cortex; sulci- shallow
grooves that separate the ridges
2. Lobes- named for cranial bones; 4 major regions of
the brain
a. Occipital lobe- visual cortex
b. Temporal lobe- auditory area
c. Frontal lobe- primary motor cortex which
controls skeletal muscle movement
Motor homunculus- a body map showing
relative number of fine motor control
d. Parietal lobe- posterior to the central sulcus it
contains the sensory or somatosensory area
which allows us to recognize pain, coldness or
touch.
Sensory homunculus- a body map with relative
numbers of sensory receptors
3. Broca’s Area- center in frontal lobe for speech and
vocalization
4. Speech Area- located at the junction of the
temporal, parietal and occipital lobes
5. Basal nuclei or basal ganglia – islands of gray matter
in the white matter - regulate voluntary muscle
activity