Brain and Cranial Nerves

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