Chapter 13 Study Guide – Brain & Cranial Nerves
1. Identify the relative locations of white and gray matter in the brain. Identify which
neuron components compose each and the function that takes place within each.
Gray matter made of neuron cell bodies, dendrites, and unmyelinated axons
Cortex is superficial layer of gray matter
Nucleus are regions of grey matter (clusters of cell bodies)
White matter consists of myelinated axons
Organized in bundles called tracts
2. Describe the meninges. Identify the 3 layers, spaces and where CerebroSpinal Fluid (CSF)
is located.
Separate and support soft tissue of brain.
Enclose and protect blood vessels supplying the brain
Help contain and circulate cerebrospinal fluid
From deep to superficial
Pia mater
Arachnoid mater
Dura mater
CSF circulates in ventricles and subarachnoid space
3. Describe the origination and circulation of CSF (include the 4 ventricles). Describe some
of its functions.
Two lateral ventricles, Large cavities in cerebrum, Separated by medial partition, septum
pellucidum
Third ventricle- Narrow space in middle of diencephalon, Connected to each lateral
ventricle by an interventricular foramen
Fourth ventricle- Sickle-shaped space between pons and cerebellum, Connected to third
ventricle by cerebral aqueduct, Opens to subarachnoid space medially and laterally,
Narrows before merging with central canal of spinal cord
Cerebrospinal fluid (CSF)
Clear, colorless liquid surrounding CNS
Circulates in ventricles and subarachnoid space
Functions:
Buoyancy – reduces brain’s apparent weight by 95%
Protection – provides a liquid cushion
Environmental stability – transport of nutrients / wastes and protects against
fluctuations
4. Describe structure and function of the Blood-Brain Barrier (BBB).
Functions of blood-brain barrier (BBB)- Regulates which substances enter brain’s
interstitial fluid, Helps prevent neuron exposure to harmful substances, Drugs, wastes,
abnormal solute concentrations, Note: some drugs can pass and affect the brain (for
example, alcohol). BBB composed of specialized capillaries Endothelial cells are
connected by many tight junctions. Walls have a thick basement membrane. Wrapped
by perivascular feet of astrocytes. BBB reduced in certain locations for functional
reasons. Choroid plexus needs to produce CSF. Hypothalamus and pineal gland need to
secrete hormones
5. Be able to identify how the brain is protected: bone, meninges, CSF, BBB.
CFS- provides a liquid cushion
BBB- Helps prevent neuron exposure to harmful substances
Bone- skull protects the brain
Meninges- Separate and support soft tissue of brain, Enclose and protect blood vessels
supplying the brain, Help contain and circulate cerebrospinal fluid
6. Identify the following structures and anatomical features of the brain: Cerebrum:,
occipital lobes, , gyri, sulci, central sulcus, precentral and postcentral gyri, corpus
callosum, cerebral cortex. Diencephalon, optic chiasma. Cerebellum: cerebellar
hemispheres, arbor vitae. Brain Stem: midbrain, pons, medulla oblongata.
Frontal lobe: anterior part of cerebrum
Posterior border is deep central sulcus
Precentral gyrus controls voluntary movement
Parietal lobe (superoposterior part of cerebrum)
Anterior border is central sulcus
Postcentral gyrus is ridge just posterior to central sulcus
Posterior border is parieto-occipital sulcus
Lateral border is lateral sulcus
Serves general sensory functions
For example, evaluating shape and texture of objects
Temporal lobe (internal to temporal bone)
Located inferior to lateral sulcus
Occipital lobe (posterior part of cerebrum)
Insula (deep to lateral sulcus)
• Small lobe that can be observed by pulling away temporal lobe
• Hypothalamus
• The Master Control Center
• Infundibulum: stalk of pituitary that extends from hypothalamus
• Neurons in preoptic area detect altered temperature
• Signal other hypothalamic nuclei to heat or cool the body
Thalamus
• Oval masses of gray matter on lateral sides of third ventricle
• Composed of about a dozen thalamic nuclei
• Axons from a given nucleus project to a particular region of cortex
Pons- Bulging region on anterior brainstem Includes sensory and motor tracts
connecting brain to spinal cord
Midbrain- Cerebral peduncles, Superior cerebellar peduncles
7. Describe the functions of the following brain regions and structures: Cerebrum, frontal
lobe, parietal lobe, corpus callosum, brain stem, hippocampus.
Temporal lobe- hearing smell
Occipital lobe- Functions in vision and visual memories
Insula- memory and taste
Hypothalamus- Control of autonomic nervous system
a. Influences heart rate, blood pressure, digestive activities, respiration
b. Control of endocrine system
c. Secretes hormones that control activities in anterior pituitary gland
d. Produces antidiuretic hormone and oxytocin
e. Regulation of body temperature
f. Food intake
g. Water intake
h. Emotional behavior
i. Sleep-wake rhythms
Thalamus- Receives signals from all conscious senses except olfaction Relays some
signals to appropriate part of cortex and filters out other signals distracting from subject
of attention
Cerebrum
Primary visual cortex- receives, processes, stores visual information
Visual association area- integrates and interprets color, form, to allow
identification/recognition of things (for example, faces)
Primary auditory cortex- receives, processes, stores auditory information
Auditory association area- integrates and interprets sounds
Primary olfactory cortex- Receives, processes, stores odor information
Primary gustatory cortex- Receives, processes, stores taste information
Prefrontal cortex- Complex thought, judgment, personality, planning, deciding
Wernicke area- Involved in language comprehension
8. Locate and describe the following functional areas of the cerebrum: primary
somatosensory cortex and somatosensory association area, primary visual cortex and
visual association area, primary auditory cortex, primary motor (somatomotor) cortex,
premotor area, motor speech area.
Cerebrum
Primary visual cortex- receives, processes, stores visual information
Visual association area- integrates and interprets color, form, to allow
identification/recognition of things (for example, faces)
Primary auditory cortex- receives, processes, stores auditory information
Auditory association area- integrates and interprets sounds
Primary olfactory cortex- Receives, processes, stores odor information
Primary gustatory cortex- Receives, processes, stores taste information
Prefrontal cortex- Complex thought, judgment, personality, planning, deciding
Wernicke area- Involved in language comprehension
9. Differentiate the functions of the primary sensory areas and the association areas.
Primary somatosensory cortex
i. Located in postcentral gyrus of parietal lobes
ii. Receives somatic sensory information from
1. Proprioceptors, touch, pressure, pain,
temperature receptors
iii. Areas of the body sending input can be mapped as a sensory
homunculus
1. Distorted proportions reflect the amount of
sensory information collected from that region
2. Large regions for lips, fingers, genital regions
b. Somatosensory association area
i. Immediately posterior to postcentral gyrus (in parietal lobe)
Integrates touch information allowing us to identify objects by feel
10. Describe the organization of the primary somatosensory cortex and primary
somatomotor cortex as a homunculus. What causes the fingers to have greater
representation in the primary somatomotor cortex? primary somatosensory cortex?
somatic motor area
•
i. Controls skeletal muscle activity on opposite side of body
ii. The controlled body regions map as a motor homunculus
1. Distorted proportions of the body reflect
amount of cortex dedicated to each part
For example, hands are large on homunculus because large area of brain
controls their precise movements
Primary somatosensory cortex
• Located in postcentral gyrus of parietal lobes
• Receives somatic sensory information from
• Proprioceptors, touch, pressure, pain,
temperature receptors
• Areas of the body sending input can be mapped as a sensory
homunculus
• Distorted proportions reflect the amount of
sensory information collected from that region
• Large regions for lips, fingers, genital regions
11. Define decussation and apply that to sensory and motor information projecting to the
hemispheres of the brain.
Decussation- any crossing over or intersections of parts. Motor- The two pyramids
contain the motor fibers that pass from the brain to the medulla oblongata and medulla
spinalis, corticobulbar and corticospinal fibers. Sensory- The sensory decussation or
decussation of the lemnisci is a decussation or crossover of axons from the gracile
nucleus and cuneate nucleus, which are responsible for fine touch, vibration,
proprioception and two-point discrimination of the body.
12. Differentiate between nerves and tracts.
A tract is a collection of nerve fibers (axons) in the central nervous system. A nerve is a
collection of nerve fibers (axons) in the peripheral nervous system.
13. Describe the role of the limbic system.
Hippocampus- Superior to parahippocampal gyrus (temporal lobe), Helps form longterm memories, Neurogenesis (formation of new neurons)
Amygdaloid body (Amygdala)- Involved in many aspects of emotion and emotional
memory, especially fear
14. Describe the role of the reticular activating system.
Sensory component = reticular activating system (RAS)
Processes sensory information, sends signals to cortex to bring about alertness (for
example, response to sound of alarm clock)
Alertness helps bring about awareness (of sensations, movements, thoughts), which is
necessary for highest states of consciousness
15. Identify the 3 types of memory, how long information can remain in each and how
information can be moved from one type to the next.
Sensory memory- Associations based on sensory input (for example, smell of café) that
last for seconds
Short-term memory (STM)- Limited capacity (about seven bits of information) Brief
duration (seconds to hours)
Long-term memory (LTM)- Can be encoded from short-term memory if information
repeated, May exist indefinitely, but can be lost if not retrieved occasionally
16. Name, in proper sequence, the 12 pairs of cranial nerves. Give major sensory and/or
motor functions of each nerve.
CN I Olfactory Nerve- Sensory smell
CN II Optic Nerve- Sensory vision
CN III Oculomotor Nerve- Motor, move eye, lift eyelid, change pupil diameter, change
lens shape
CN IV Trochlear Nerve- Motor controls superior oblique eye muscle
CN V Trigeminal Nerve- Mixed, receives somatic sensation from face; controls muscles
involved in chewing
CN VI Abducens Nerve- Motor controls lateral rectus muscle that abducts eye
CN VII Facial Nerve- Mixed, controls muscles of facial expression and conducts taste
sensations from tongue
CN VIII Vestibulocochlear Nerve- Sensory, involved in hearing and equilibrium
CN IX Glossopharyngeal Nerve- Mixed, receives taste and touch from tongue; motor
control of a pharynx muscle
CN X Vagus Nerve- Mixed, controls muscles in pharynx and larynx; conducts sensation
from many viscera; major source of parasympathetic output
CN XI Accessory Nerve- Motor, controls muscles of neck, pharynx
CN XII Hypoglossal Nerve- Motor, controls tongue muscles