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CHAPTER 16

Brain & Cranial Nerves
LECTURE - Learning Objectives
1
...
Compare and contrast the structures that protect and support the brain
Scalp= skin and connective tissue, have spongy and compact bone in brain
Cranial meninges:
Dura mater: 2 fibrous layers, on outside
arachnoid mater:membrane covering brane, between dura and pia
pia mater: membrane highly vascularized, follows the surface contours of brain and lining of
sulci
Cerebrospinal fluid-colorless bodily fluid produced in choroid plexus of brain acts as cushion
or buffer, provides a basic mechanical and immunological protection to the brain inside the
skull, provides buoyancy, protection, chemical stability, and prevention of brain iscemia
Blood-brain barrier: makes sure things in brain do not get exposed to things of outside of the
brain

3
...


4
...
Identify the major features of the mesencephalon and describe its function
Composed of
Gray matter
which includes
Tectum(roof)
which includes
• superior colliculi- Integrate visual information with other sensory input; initiate reflex
responses to visual stimuli
• inferior colliculi- integrate auditory information with medial geniculate nuclei; initiate
reflex responses to auditory stimuli
Walls and floor
which includes
• Substantia nigra- regulates activity in the basal nuclei
• Red nuclei-involuntary control of background muscle tone and limb position
• Reticular formation-automatic processing of incoming sensations and outgoing motor
commands; can initiate motor responses to stimuli; helps maintain consciousness
other nuclei/centers: Nuclei associated with two cranial nerves
White matter
which includes
cerebral peduncles: connect primary motor cortex with motor neurons in brain and spinal
cord; carry ascending sensory information to thalamus
6
...
Identify the components of the cerebellum and describe the function
Gray matter:
Cerebral cortex: Subconscious coordination and control of ongoing movements and
body parts
Cerebellar nuclei: As above
White matter
Arbor vitae: Connects cerebellar cortex and nuclei with cerebellar peduncles
Cerebellar peduncles
Superior: Link the cerebellum with mesencephalon, diencephalon, and
cerebellum
Middle: Contain transverse fibers and carry communications between the
cerebellum and pons
Inferior: Link the cerebellum with the medulla oblongata and spinal cord

8
...
Compare and contrast the motor, sensory, and association areas of the cerebral cortex
Primary motor cortex
Primary sensory cortex
Visual cortex
Auditory cortex
Olfactory cortex
Gustatory cortex
Somatic sensory association area
Somatic motor association area (premotor cortex)
Visual association area
10
...
Compare and contrast the 12 cranial nerves (names, type of nerve, function)

Brain & Cranial Nerves, 5

TERMINOLOGY

Divisions of the Nervous System
1) Central

2) Peripheral

Functions of the Nervous System

Brain & Cranial Nerves, 6

Major Regions of Adult Brain
1)
2)
3)
4)

5)
6)

‘Higher centers of the brain’

Ventricles of the brain

Brain & Cranial Nerves, 7

FOREBRAIN
Cerebrum

Layers: outer = gray, inner = white (read pages 408, 430-431)

LOBES: (know location & primary lobe functions)
1
...
Parietal

3
...
Occipital

5
...
17b
Primary motor cortex
Primary sensory cortex
Visual cortex
Auditory cortex
Olfactory cortex
Gustatory cortex

Association Areas of the Cerebral Cortex
Somatic sensory association area
Somatic motor association area (premotor cortex)
Visual association area

Integrative Center(s) of the Cerebral Cortex
Prefrontal cortex

Brain & Cranial Nerves, 11

Supplemental Notes, Chapter 16 – Brain & Cranial Nerves
The brain develops from the anterior end of the neural tube
...

These ventricles contain cerebrospinal fluid
...
cerebrum, 2
...
mesencephalon, 4
...
medulla oblongata) each of which contains certain adult brain structures
...
Each hemisphere has within
it the cortex, the white matter, and the basal nuclei
• The diencephalon contains the thalamus, hypothalamus, and epithalamus
• The mesencephalon contains the midbrain
• The metencephalon includes the pons and cerebellum
• The myelencephalon is the medulla oblongata
The midbrain, pons, and medulla are collectively called the brainstem
...
1
Arrangement of gray and white matter:
In the spinal cord the gray matter is found only as an H-shaped area in the center of the cord
...

The cerebellum has its own gray and white matter distribution, which is like that of the
cortex
...

Gray matter in the brain functions much like that in the cord: it is the site of
connections between neurons and contains the cell bodies of motor and interneurons
...

White matter in the brain, like that in the spinal cord, is composed of myelinated
fibers in tracts which carry information from one place to another
...
2)
Ventricles are cavities within the brain derived from the original lumen of the neural tube
...

Canals connect these ventricles together
...
The
fourth ventricle connects to the central canal of the spinal cord, and other canals, called
apertures, lead to the subarachnoid space of the meninges
...
Filtration forces water, electrolytes,
and nutrients out of the blood
...
At the same time waste products are
removed from the CSF and released into the blood
...
It also enters the subarachnoid and subdural
spaces through apertures near the fourth ventricle
...
Eventually it must be reabsorbed into the bloodstream and
this occurs at pockets of arachnoid tissue that invaginate into a large vein called the superior
sagittal sinus
...
The absorption must occur at the same rate as production of CSF in
order to prevent an imbalance
...
This condition usually shows up in early childhood and can
damage the brain and lead to abnormal development
...

THE CEREBRAL HEMISPHERES:
The cerebrum is divided into two hemispheres separated by the longitudinal fissure, the
largest fissure of the cerebrum
...
Most of
the time fissure refers to a larger groove than a sulcus, although they are somewhat
interchangeable
...

Certain of these structures are consistent landmarks for the brain
...

The cerebral cortex is the area of conscious thought and perception
...

The cortex can be described as made up of regions called lobes
...

The central sulcus separates the parietal from the frontal lobe
...
A short parieto-occipital fissure
indicates the upper delineation of the parietal from occipital lobe
...
These tracts permit the hemispheres to
communicate with one another
...
The hemispheres normally divide up the tasks with one hemisphere,
usually the left, being dominant
...
In
most people (90 to 95%) the left hemisphere is dominant and responsible for logic,
mathematics, and language
...
However, when one hemisphere is damaged the other may be capable of
performing the lost functions
...

The pre-central gyrus (the raised area in front of the central sulcus) is the primary motor
area
...

Each area of the body, for that matter each muscle, is controlled by a specific part of
the pre-central gyrus
...
e
...
The area
represented reflects the level of activity and control over the muscles, not their size
...

The pre-central gyrus is the origin of the corticospinal tracts
...
It receives the conscious sensations from the musculocutaneous regions
of the body: pain, temperature, touch, and pressure (these sensations terminate in specific
positions on the gyrus which are inversely related to body position and directly related to the
degree of sensation and its importance, not the size of the area)
...

• Broca's area - the motor speech area for control of the muscles of speech
...
This area normally exerts control over other areas such as
those responsible for emotions and stress response, and is thus thought to be the
center for self-control, reasoning, and such
...

• Wernicke's area - Language comprehension and elaboration; a general interpretive
area
...

• Auditory association areas - areas involved with association of hearing with other
functions such as speech and memory, necessary to speak and to understand speech
...

• Visual association area - this area interprets the image and relates it to images in
memory for recognition
...

Its structures include the caudate nucleus, putamen, and globus pallidus, and it connects to
the substantia nigra and amygdaloid nucleus
...
The basal nuclei function in association with the corticospinal system to control
complex patterns of motor activity
...
Included
are: writing letters of the alphabet, using scissors, hammering nails, shooting a basketball,
passing a football, shoveling dirt, controlled eye movements and many others
...

[Additional info (not on test): The basal nuclei utilize a wide range of
neurotransmitters: GABA (gamma amino butyric acid) and dopamine are inhibitory
neurotransmitters
...

PARTS OF THE BRAIN BELOW THE CEREBRUM: 
Corpus callosum - connects the hemispheres
...

Septum pellucidum - a membrane which covers the opening into the lateral ventricles
The Dienchephalon
The thalamus - its halves connected by the intermediate mass, the thalamus receives all
conscious sensations and acts as a relay center
...
The thalamus also
lies at the top of the reticular formation and is part of the alert mechanism of the reticular
activating system
...

The hypothalamus is a small yet very important part of the brain below the thalamus
(hypo=below)
...
Through
its connection with the pituitary gland through the infundibulum the hypothalamus directs the
pituitary's secretions, which in turn direct many other endocrine glands
...

The pineal gland is considered part of the epithalamus (epi=upon the thalamus) and receives
stimuli from the hypothalamus
...

This establishes our biological clock and regulates our circadian rhythm (day-night cycle)
which affects many behaviors such as sleeping, eating, sexual desire, etc
...
This disorder affects their mood and mental state as
well as their physiology
...


Brain & Cranial Nerves, 15




The cerebellum - this part coordinates the skeletal muscles
...
From this input the
cerebellum monitors muscle contractions and planned muscle contractions and maintains a
constantly adapting system to coordinate them
...
The corpora quadrigemina (four bodies, twins) are the superior colliculi, which are
the center for visual reflexes (blinking, accommodation of the lens), and the inferior colliculi
where auditory reflexes are centered
...

However its main functions are as part of the regulation of the rate and depth of respiration
...

The medulla - center for the vital functions of heart rate, respiration, and blood pressure
...
The pyramids are
also part of the medulla
...
It regulates the heart rate and volume and controls blood pressure and
overall blood distribution
...

The Limbic System: There is wide disagreement about the actual validity of this system, with
some scientists believing it is composed of unrelated parts which should not be considered as
a system
...

The hypothalamus - contains the pleasure, reward, or satiety center
...

Mamillary body - contains memory pathways, especially for olfaction
...

Amygdaloid nucleus - the center for many emotional response pathways
...


Functions of the Limbic System - this system is sometimes called the "emotional brain"
...
emotional states and behavior
...
the bridge between the conscious and subconscious brain
...

3
...


The Reticular Formation and Reticular Activating System:

Brain & Cranial Nerves, 16

The Reticular Formation is a brainstem pathway which receives sensory input of many types
including vision, auditory, and somatic senses
...

This allows unwanted and unimportant stimuli to be filtered out, while making us aware of
important and critical stimuli
...
The result is that without
these inhibitory impulses, tremor and rigidity occur
...
 
Treatments: 1) use of L-dopa which is converted into dopamine in the brain (eventually the
brain resists this); 2) transplanted fetal dopamine cells and genetically engineered dopamine
cells; 3) the use of the MAO inhibitor Deprenyl
...
The activation of existing stem cells in the new frontier
of research for possibly curing Parkinson's and other neurological disorders
...
It is caused
by a genetic mutation of an enzyme-producing gene
...

Alzheimer's Disease - caused by the development of neurofibrillar tangles and beta-amyloid
plaques in the brain
...
Without transport proteins
neurons cannot function or survive
...
In response to these the immune
cells produce chemicals called cytokines which attack the plaques
...

Treatments focus on various aspects of the problem
...
On another front
antibodies against the beta amyloid plaque have been developed which show promise in
eliminating it in mice
...
These questions will simply encourage you to study and
learn important concepts from the chapter
...

1
...
What is the Reticular Activating System (RAS) and how is it important in sleep? Where it
the Reticular Formation (RF) found in the brain? Give some other examples that involve RF
activation
...
In the figure below, use an arrow to identify the following brain regions:

a) Primary visual cortex

b) Somatosensory input from the lips

c) Somatomotor output controlling the lips

d) Primary auditory cortex

e) Motor association cortex

f) Visual association cortex

g) Broca's area and Wernicke's area

h) Cortex associated with personality traits

i) Inhibition of an inappropriate behavior

j) Regulation of blood pressure

k) Brainstem

l) Cortex associated with reasoning

m) Motor
cortex

association

Brain & Cranial Nerves, 18

4
...
What neural processing is associated with each?
5
...

6
...
What is the role of the basal ganglia (=basal nuclei) in motor output? --in training (learned
behavior)? Briefly explain how the basal ganglia operate
...
Compare the actions of the basal ganglia and the cerebellum in influencing motor output?
How are they alike? How are they different? Do they initiate or modify motor commands?

9
...
To what region of the brain does the thalamus belong? Describe the importance/function
of the thalamus in the nervous system
...
Which region(s) play a role in regulating respiration?
12
...
What three factors offer this protection?
13
...

14
...
List the specific brain and spinal
cord areas involved in the execution of this simple behavior
...


Brain & Cranial Nerves, 19

MULTIPLE-CHOICE PRACTICE
Includes chapters: 13, 14, 16

PLEASE READ: The following multiple-choice questions are designed to give students a sample of question content
and difficulty that is similar to the content and difficulty of actual lecture exams for this course
...
There is only ONE best answer per question
...


The marking that separates the temporal lobe from the frontal and parietal lobes called the
a
...
Longitudinal fissure
c
...
Transverse fissure
e
...


The basal nuclei do not include which of the following structures
a
...
Globus pallidus
c
...
Putamen

3
...
Ventricles of the brain
b
...
Spinal nerves
d
...
Both a and b

4
...
Is involved in processing visual input
b
...
Maintaining consciousness
d
...


Components of the metencephalon include the
a
...
Cerebellum and pons
c
...
Thalamus and cerebellum
e
...


The white fibers that connect the cerebrum with the spinal cord and visa-a-versa are known as
a
...
Commussural fibers
c
...
Association fibers
e
...


Which structure is responsible for initiating reflexive actions of the head and neck in response to visual
stimuli

Brain & Cranial Nerves, 20

a
...

c
...

e
...


The fornix
a
...
Is present in only one cerebral hemisphere, typically the left
c
...
Links the hippocampus with the hypothalamus
e
...


Which brain structure is found in the brainstem and regulates level of wakefulness and alertness?
a
...
Mamillary bodies
c
...
Reticular formation
e
...
Which of the following structures is considered the “gate” or “relay” to the cerebrum through which most
sensory input passes?
a
...
Pons
c
...
Reticular formation
e
...
The cerebrum and cerebellum are separated by the
a
...
Longitudinal fissure
c
...
Lateral sulcus
e
...
In the mesencephalon, integrating visual information with other sensory inputs and initiating involuntary
motor responses are function of the
a
...
Substantia nigra
c
...
Cerebral peduncles
e
...
Which of the following is the correct pairing of cranial nerve #, cranial nerve name, and type (mixed or
sensory)
a
...
III – occulomotor nerve– mixed
c
...
IX – glossopharyngeal nerve – sensory
e
...
Which neuronal tissue cell type is likely to be malfunctioning if the blood-brain barrier is no longer
adequately protection the brain?
a
...

c
...

e
...
The myelin sheath covering the axons in the PNS is produced by
a
...
Microglia
c
...
Schwann cells
e
...
Which of the following is the most correct sequence of parts along which a nerve impulse normally travels
(reception to stimulation)?
a
...
Dendrite – cell body – axon
c
...
Dendrite – receptor – effector
17
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Pseudounipolar
b
...
Multipolar
d
...
A collection of cell bodies in the PNS is known as a (an)
a
...
Nuclei
c
...
Tract
e
...
Which type of cell is responsible for regulating O2, nutrients and neurotransmitters around neurons in the
PNS?
a
...
Microglia
c
...
Schwann cells
e
...
The order of the meningeal layers, from inside out
a
...
Pia, arachnoid, dura
c
...
Dura, pia, arachnoid
21
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Cushioning delicate neural structures
b
...
Supporting the brain
d
...
Transporting waste products away from the brain tissues

Brain & Cranial Nerves, 22

22
...
It lacks myelin
b
...
Both a and b
d
...
Bundles of axons in the CNS are known as a
a
...
Nuclei
c
...
Tract
e
...
Extending from the conus medullaris of the spinal cord as a slender, fibrous strand that helps provide
support for the spinal cord is the
a
...
Dorsal root ganglion
c
...
Cauda equina
25
...
Are known as efferent neurons
b
...
Carry information to the central nervous system
d
...
Only b and c
26
...
Transverse fissure
b
...
Parieto-occipital sulcus
d
...
Lateral sulcus
27
...
Ventral columns of white matter
b
...
Ventral horns of gray matter
d
...
The central nervous system includes which of the following?
a
...
The neural tissue in the brain and spinal cord
c
...
Only the neural tissue in the brain
29
...
Providing sensory information to the CNS
b
...
Carrying motor commands from the spinal cord to the peripheral tissues and systems
d
...
Both a and c are correct

Brain & Cranial Nerves, 23

30
...
Form myelin around axons
b
...
Support the neurons
d
...
a, b, c, are correct
MULTIPLE-CHOICE PRACTICE ANSWERS
1
...
c
3
...
b
5
...
a
7
...
d
9
...
c
11
...
c
13
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a
15
...
b
17
...
e
19
...
b
21
...
c
23
...
c
25
...
d
27
...
d
29
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a

Brain & Cranial Nerves, 24



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