The brain

1. The Brain
The brain is composed of the cerebrum, cerebellum,
and brainstem.

2. The cerebrum is the largest part of the brain and is
composed of right and left cerebral hemispheres. It
performs higher functions like interpreting touch,
vision and hearing, as well as speech, reasoning,
emotions, learning, and fine control of movement.
cerebrum

3. The outer 4 mm surface of the cerebrum is called the
cerebral cortex. The cortex contains about 70 - 75%
of the 100 billion neurons of the brain. The neuron cell
bodies, or gray matter, is at the surface and it has a
folded structure. Beneath the gray matter are long,
myelinated axons, which make up the white matter of
the cortex.

4. The folding of the cortex increases the brain’s
surface area allowing more neurons to fit inside the
skull and enabling higher functions. Each fold is
called a convolution or gyrus, and each groove
between folds is called a sulcus.

5. Lobes of the Cerebrum
The cerebral hemispheres
have distinct fissures,
which divide each
hemisphere has four
lobes: frontal, temporal,
parietal, and occipital.

6. Each lobe may be divided into areas that serve very
specific functions. It’s important to understand that
each lobe of the brain does not function alone. There
are very complex relationships between the lobes of
the brain and between the right and left hemispheres.

7. Frontal lobe
•Personality, behavior, emotions
•Judgment, planning, problem solving
•Speech: speaking and writing (Broca’s area)
•Body movement (motor strip)
•Intelligence, concentration, self awareness

8. Parietal lobe
•Interprets language, words
•Sense of touch, pain, temperature (sensory strip)
•Interprets signals from vision, hearing, motor,
sensory and memory
•Spatial and visual perception

9. Occipital lobe

•Interprets vision (color, light, movement)

10. Temporal lobe
•Understanding language (Wernicke’s area)
•Memory
•Hearing
•Sequencing and organization

11. The cerebellum is located under the cerebrum. Its
function is to coordinate voluntary muscle movements
and to maintain posture and balance.
cerebellum

12. The brainstem includes the midbrain, pons, and
medulla oblongata. Some texts include the
diencephalon as a brain stem structure, but others
include it in the forebrain. The brain stem acts as a
relay center connecting the cerebrum and cerebellum
to the spinal cord and performs many of the body’s
automatic functions.
diencephalon
midbrain
pons
medulla oblongata

13. The medulla oblongata lies between the pons and the
spinal cord. It contains centers which control key,
autonomic body functions and it relays nerve signals
between the brain and spinal cord. Important control
centers include:
•The respiratory center – controls
the rate, rhythm, and depth of
breathing
•The cardiac center – regulates
heartbeat
•The vasomotor center – controls
blood pressure
•Reflex centers – reflex arc centers
for vomiting, coughing, sneezing,
hiccupping and swallowing

14. The Pons is an enlarged structure located just below
midbrain and above the medulla oblongata. The
word “pons” is the Latin word for “bridge” and
indicates the function of the pons. It acts as a relay
station between the lower centers and the higher
centers of the brain. The 5
th
through the 8
th
cranial
nerves connect directly to the pons.

15. The midbrain (also called the mesencephalon) is
located between the diencephalon and the pons. It also
acts as a relay station between the lower centers and
the higher centers of the brain, but also contains
important visual and auditory reflex centers, as well
as motor pathways that connect the cerebrum to the
cerebellum.

16. The diencephalon lies at the top of the brain stem,
under and between the cerebral hemispheres and
includes the thalamus, hypothalamus, optic tracts,
optic chiasma, infundibulum, Ventricle III,
mammillary bodies, posterior pituitary gland and the
pineal gland.

17. Hypothalamus - is the master
control of the autonomic system.
It maintains homeostasis by
regulating such things as:
2.Hunger and body weight
3.Water and electrolytes through
controlling thirst
4.Sleep and wakefulness
5.body temperature
6.blood pressure and heart rate
7.sexual response
8.secretion of hormones from the
pituitary gland.

18. Thalamus - serves as a central relay station for all
sensory information (except smell) that goes into and
comes out of the cerebral cortex. It plays a key role in
pain, touch, and temperature sensation, as well as in
attention, alertness and memory.
Thalamus

19. The corpus callosum
connects the left and
right cerebral
hemispheres and
facilitates
communication
between the
hemispheres. It is the
largest white matter
structure in the
brain, consisting of
200–250 million
myelinated axons.

20. 3. The brain and spinal cord are covered and
protected by three layers of tough, connective tissue
called meninges. From the outermost layer inward
they are: the dura mater, arachnoid mater, and pia
mater.
2. The brain has hollow fluid-filled cavities called
ventricles. A clear, colorless fluid called
cerebrospinal fluid flows within the ventricles and
around the brain and spinal cord to help cushion them
from injury.
1. The brain and spinal cord are covered and
protected by the bones of the cranium and the
vertebral column.
Protection of the Central Nervous System

21. Cranial nerves
The brain communicates with
the body through the spinal cord
and twelve pairs of cranial
nerves. Ten of the twelve pairs
of cranial nerves that control
hearing, eye movement, facial
sensations, taste, swallowing
and movement of the face,
neck, shoulder and tongue
muscles originate in the
brainstem. The cranial nerves
for smell and vision originate in
the cerebrum.

22. Cranial nerves
Number Name Function
I olfactory smell
II optic Sight
III oculomotor moves eye, pupil
IV trochlear moves eye
V trigeminal face sensation
VI abducens moves eye
VII facial moves face, salivate
VIII vestibulocochlearhearing, balance
IX glossopharyngealtaste, swallow
X vagus heart rate, digestion
XI accessory moves head
XII hypoglossal moves tongue