Brain
and
Cranial Nerves
Parts of the Brain
Parts of the Brain
CEREBRUM
(b) Sagittal section, medial view
CEREBELLUM
Spinal cord
DIENCEPHALON:
Thalamus
Hypothalamus
BRAIN STEM:
Midbrain
Pons
Medulla oblongata
Parts of the Brain
Meninges
Meninges
Ventricles
Ventricles
Origin and Flow of CSF
Cerebrum
perception - sensory
initiate voluntary movements
memory
learning
understanding
conscious behavior
• The lobes of the cerebrum correspond to the bones of the
braincase which bear the same names.
frontalparietal
temporaloccipital
Cerebrum
parietal
temporal
frontal
occipital
Cerebrum
Cerebrum
Cerebral Gray and White Matter
Cerebrum Functional Areas
1. Sensory areas
2. Motor areas
3. Association area
Cerebrum Functional AreasPrimary somatosensory area (1, 2, 3)
Primary visual area (17)
Primary auditory area (41, 42)
Primary gustatory area (43)
Primary olfactory area (28 - not visible)
Primary motor area (4)
Broca’s area (44, 45 left hemisphere)
Somatosensory association area (5, 7)
Prefrontal cortex (9, 10, 11, 12 -medial view only)
Visual association area (18, 19)
Auditory association Area (22)
Wernicke’s area (22, 39, 40 - left hemisphere)
Common integrative area (5, 7, 39, 40)
Premotor area (6)
Frontal eye field (8)
Cerebrum Functional Areas
Cerebrum Functional Areas
Cerebrum Motor/Sensory
Lateralization
Basal Nuclei• The basal nuclei also control subconscious contractions of
skeletal muscles. Examples include automatic arm swings while
walking and true laughter in response to a joke.
Limbic System• Encircling the upper part of the brain stem and the corpus callosum is
a ring of structures on the inner border of the cerebrum and floor of the
diencephalon that constitutes the limbic system.
• The limbic system is sometimes called the
“emotional brain” because it plays a
primary role in promoting a range of
emotions, including pleasure, pain,
docility, affection, fear, and anger.
• Together with parts of the cerebrum,
the limbic system also functions in
memory.
Brain Waves• Summing waves of different frequency
produces some characteristic, and diagnostic
patterns.– Alpha (10–12 Hz (cycles/sec) waves are
present when awake but disappear
during sleep. – Beta (14–30 Hz) waves are present with
sensory input and mental activity when
the nervous system is active.– Theta (4–7 Hz) waves indicate emotional
stress or a brain disorder.– Delta (1–5 Hz) waves appear only during
sleep in adults but indicate brain damage
in an awake adult.
The medulla begins at the inferior border of the pons and extends to the foramen magnum. It contains all ascending and descending tracts extending between the spinal cord and cerebrum.
Brain Stem - Medulla Oblongata
The medulla contains nuclei which are regulators for vital body functions.
Medulla Oblongata
Axons from the left pyramid cross over to the right and axons on the right cross over to the left (decussation of pyramids) – so that the left hemisphere of the brain controls the right side muscles, while the right hemisphere controls the left side.
Brain Stem -Pons• The pons lies directly above the medulla and anterior to the
cerebellum (2.5 cm). It acts as a bridge connecting the spinal cord
with the brain and
parts of the brain with
each other.
Brain Stem- Midbrain• The midbrain extends from the pons to the
diencephalon. – The cerebral aqueduct passes through the midbrain
connecting the 3rd ventricleabove with the 4th
ventricles below
(both locations
of CSF formation
and circulation.)
Reticular Formation
Cerebellum
Cerebellum
Cerebellum
1. Cerebrum initiates voluntary muscle contractions and notifies cerebellum.
2. Cerebellum gets information from proprioceptors.
3. Assesses information.
4. Dispatches “blueprint” for coordination to cerebrum
Compares intention with actual performance
Diencephalon
Diencephalon - Thalamus
Major relay station for sensory ascending
to sensory cortex, and inputs of subcortical
motor nuclei and the cerebellum
All sensory input
Sort out information
Diencephalon - Hypothalamus
1. Autonomic control center
2. Center for emotional response
3. Body temperature regulation
4. Regulation of food intake
5. Regulation of water balance and thirst
6. Regulation of sleep-wake cycles
7. Control of endocrine system
Diencephalon- Epithalamus
• Pineal gland– secretes melatonin
during darkness– promotes sleepiness &
sets biological clock• Habenular nuclei
– emotional responses to odors
Cranial Nerves vs. Spinal NervesSpinal Cranial
Designation C1-8, T1-12, L1-5, S1-5,
Co1
Roman Numerals
I – XII
Number 31 pairs 12 pairs
Origin Spinal cord Brain
Number of roots
2 - a dorsal and a ventral
rootSingle root
Contents MixedMost mixed; some
sensory only
Target Limbs/TrunkAll in the Head/Neck
(vagus n leaves)
Cranial Nerves
I. Olfactory nerve
II. Optic Nerve
III. Oculomotor nerve
VI. Abducens nerveIV. Trochlear nerve
V. Trigeminal nerve
VII. Facial nerve
VIII. Vestibulocochlear nerve
IX. Glossopharyngeal nerve
X. Vagus nerve
XI. Accessory nerve
XII. Hypoglossal nerve