Anatomy & Physiology 34A
Chapter 12 - The Central Nervous System: Brain
I.
Overview
A. Basic Parts & Organization of the Brain
1. Cerebrum
2. Diencephalon
3. Brain Stem
4. Cerebellum
B. Functional Brain Systems
C. Higher Brain Functions
D. Brain Disorders
II. Basic Parts & Organization of the Brain
A. The brain may be divided into four major parts:
1. ____________ – largest, superior part of the brain
2. _______________ – thalamus, hypothalamus, epithalamus, and pituitary gland
3. _______________ – midbrain, pons, & medulla oblongata
4. ________________ – most posterior, inferior part of brain
B. The brain is enclosed by the cranium and meninges, and bathed in cerebrospinal fluid
(____). The ___________ include:
1. ______ mater – outermost tough fibrous CT layer with 2 layers
a. Periosteal layer (___________) lines the inner cranium (not found on the SC)
b. _____________ layer – deep to the periosteal layer
c. In some areas, these two layers are separated by _____ sinuses, which collect blood
from the brain and empty into the internal jugular veins in the neck. Two major
dural _________ are
1) Superior sagittal sinus – along inner _________ suture
2) ____________ sinus – runs horizontally from back of skull toward ear; forms a
“T” shape with the sagittal sinus
2. _______________ mater – CT layer deep to the dura mater;
a. Subdural space is between the ______ and arachnoid mater
b. Subarachnoid space, containing CSF & blood vessels is deep to the
_____________ mater
c. Arachnoid ________ are extensions of the arachnoid through the dura mater into the
superior sagittal sinus that allow CSF to mix with blood in the sinus
3. _____ mater – layer of highly vascular, delicate CT that adheres to the brain and SC
surface, deep to the subarachnoid space
C. ____ circulates in the hollow ventricles of the brain, the central canal of the SC, and in the
______________ space of the whole CNS
1. About ____ ml of CSF is produced a day by ___________ cells, but only ____ ml
(about ½ cup) is present at one time
2. Composition is similar to blood _______, from which it is made, except it has more
Na+ and Cl-, and less K+, Ca 2+, glucose, and protein
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3. CSF serves 3 purposes
a. ____________ – CSF has similar density to the brain, allowing the 1,500 gram brain
to weigh about 50 grams as it “floats” inside the cranium
b. _____________ – provides a fluid cushion for the brain if the head is jolted
c. Chemical stability – is a means of rinsing metabolic wastes from the CNS and
maintenance of ________________ in the chemical environment
D. Blood supply and the ______ ________ __________
1. The brain comprises 2% of body mass, but receives ___% of the blood supply and
___% of the body’s oxygen and glucose
2. The blood-brain barrier consists of tightly joined endothelial cells, ________, and the
basement membrane in brain capillaries; these ________ junctions restrict what is
allowed into the brain
a. Materials that cross the BBB include water, some electrolytes, __________, and
lipid-soluble molecules, such as O2, CO2, alcohol, caffeine, nicotine, and anesthetics
b. Larger materials such as __________, some toxins (e.g., bacteria), and most drugs
cannot cross the BBB
c. The BBB _________ the brain from harmful substances, but also interferes with
theraputic drugs administered to the brain
III. . _____________
A. Consist of 5 paired _______ within left & right _____________.
The cerebrum is
involved in higher brain functions, including:
1.
2.
Perception of _________ impulses and instigation of voluntary _______ responses
3.
4.
5.
____________, thought, sleep, and reasoning abilities
Neural ___________ takes place in the gray matter found in the cerebral cortex, basal
nuclei, and limbic system
Instinctual and limbic (____________) functions
The two hemispheres control __________ sides of the body and different brain
functions
a.
b.
________ controls analytical reasoning and language
________ controls spatial and artistic intelligence
B. Each cerebral hemisphere has 3 main regions
1. A superficial __________ of gray matter
2. ________ __________ nerve tracts deep to the cortex
3. _______ __________ gray matter deep within the white matter
C. Structure of the Cerebrum
1.
Cerebral ________ - 2-4 mm thick surface layer composed of ______ matter;
contains billions of neurons.
2.
Paired ______ of the cerebrum are mostly named for the cranial bones they are under:
a.
________ lobe – anterior cerebrum that sits in the anterior cranial fossa;
posterior border is the central sulcus
b.
__________ lobes – bordered by frontal, temporal, and occipital lobes
c.
___________ lobes – sits in the middle cranial fossa
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___________ lobes – posterior cerebrum located superior to the cerebellum,
which sits in the posterior cranial fossa
e.
_____________ - deep within the lateral sulcus
3. The cortex contains ______ (ridges), deep grooves called _________, and shallower
grooves called _______. These structures triple the surface area of the brain
4. Major fissures and ________ of the cerebrum include:
d.
a.
The ___________ fissure separates the cerebrum into right and left hemispheres.
Dura mater called the ____________ extends into this fissure
b.
c.
d.
e.
The ________ sulcus separates the frontal and parietal lobes
The _______ sulcus separates the frontal and temporal lobes
The parieto-occipital sulcus separates the ___________ and occipital lobes.
The ____________ fissure separates the cerebrum from the cerebellum.
5. Two prominent ______ are the ___________ (anterior to central sulcus) gyrus and
___________ gyrus (posterior to central sulcus)
6. Beneath the cortex lies the cerebral white matter, ________ that connect parts of the
brain with itself and other parts of the nervous system.
7. ________________ fibers (nerve tracts) transmit impulses from one cerebral
hemisphere to the other. Three of these are the:
a.
b.
Corpus ____________
Anterior & posterior _____________
8. Spaces called __________, which contain CSF, are found within and inferior to the
cerebrum
a.
b.
____________ ventricles (1 & 2) extend into left and right cerebral hemispheres
c.
The third ventricle connects with the cerebral ___________ (of Sylvius) in the
midbrain
d.
The ______ ventricle in the hind brain connects with the cerebral aqueduct and is
continuous with the SC central canal
e.
The _______ ventricle is deep within the diencephalon and connects with the
lateral ventricles via the _______________ foramina (of Monroe)
________________, small capillary knots & ependymal cells lining the roof of
the ventricles, create the CSF that circulates through the ventricles and central
canal.
9. CSF circulates at about ____ ml/24 hr. in and around the brain and SC as follows
a. Secreted by the _________ plexus in lateral ventricles
b. Flows through interventricular foramina into the ___ ventricle
c. 3rd ventricle choroid plexus adds more ____
d. Flows down cerebral aqueduct to ___ ventricle
e. 4th ventricle choroid plexus adds more _____
f. Flows out two _______ apertures and one ________ aperture
g. Fills the ______________ space and bathes external surfaces of brain and SC
h. At arachnoid ________, CSF is reabsorbed into dural venous sinus blood
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10. ________________ (water on the brain) is an accumulation of CSF in the brain
caused by a blockage in one or more of the above structures, causing expansion of
the ventricles and compression of brain tissue; can cause death if untreated
D. The cerebral cortex contains 3 main types of ___________ areas:
1. Motor areas that control voluntary ________ functions
2. _________- areas that provide for awareness of sensations. Motor and sensory
_______________ diagrams illustrate which areas of the cortex control various
areas of the body (contralateral)
3. _____________ areas integrate information from different areas for appropriate
actions (e.g., allow us to smell a rose, name it, and picture it)
E. _______ of the Cerebrum and their functions (Broadmann areas)
1.
2.
3.
4.
_________ lobes - form the anterior portion of each cerebral hemisphere. Major
functional areas include:
a.
_______________ cortex is involved in intellect, complex reasoning, personality,
and memories of plans & social roles
b.
_______________ gyrus - contains ______ areas (primary motor cortex & motor
association areas) involved in the control of voluntary muscles
c.
_________ area - a motor speech area at the base of the precentral gyrus just
above the lateral sulcus in the _____ hemisphere
_______ lobes - posterior to the frontal lobes. Functional areas:
a.
____________ gyrus - contains ________ areas that respond to incoming stimuli
from cutaneous and muscular receptors (primary somatosensory & somatosensory
association areas)
b.
________ area, at the junction of parietal and temporal lobes in the left
hemisphere, is where unfamiliar words are sounded out
c.
d.
Primary _____________ cortex – receives taste impulses
___________ is a language difficulty resulting from lesions in the Wernicke’s
and/or Brocas areas.
___________ lobes - inferior to parietal lobes; contains the
a. ___________ areas (primary auditory cortex and auditory association area) in the
superior temporal gyrus; receives auditory fibers (of CN ____) from the ear cochlea
for hearing
b. ___________ (smell) cortex in the medial temporal lobes and the inferior frontal
lobes, receives and processes sensory information from the olfactory tracts of CN __
c. _________ of vocabulary, faces, and familiar objects is found in the superior
temporal lobe
___________ lobes - posterior cerebrum
a.
Superior to the cerebellum and separated from it by a meningeal layer called the
___________ __________
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b.
________ areas (primary visual cortex and visual association area) here integrate
eye movements and correlate visual images (from CN ___) with other sensory
stimuli
5.
The _______ is a medial structure deep within the lateral sulcus. It is thought to
integrate other cerebral activities and be involved in language, taste, and the sense of
balance, as well as integrating sensory information from visceral receptors
F. _____ matter of the cerebrum - three types of nerve _____ named according to location
and direction they conduct impulses
1.
___________ fibers - conduct impulses between neurons within a hemisphere (e.g.:
fibers between ______ & Wernicke’s areas)
2.
_________________ fibers - connect the neurons & gyri of one hemisphere with
those of the other (e.g.: corpus ____________)
3.
_________ fibers - form the ascending and descending tracts of the brain & spinal
cord. At the top of the brain stem, these form
a. __________________ passes between the thalamus and basal nuclei, then the nerve
fibers fan out to form the
b. _______________ radiates through the white matter to cortex
G. __________________ - specialized paired masses of _____ matter located deep within
the cerebral white matter; involved in voluntary ________ movements; consists of the
following
1.
Corpus ________ - several masses of nuclei that appear striped; includes:
a. _________ nucleus - the “tail-like” mass above the thalamus
b. ________ nucleus - deep to the caudate nucleus; divided into
1) ___________ ___________ – medial part
2) _____________ – lateral part
2.
3.
______________ nucleus - at the tip of the caudate nucleus
4.
Damage to the basal nuclei causes motor movement dysfunction (_________), such
as that found in Parkinson’s & Huntington’s diseases
These nuclei receive input from the __________________ and motor areas of the
cerebral cortex and send signals back to both
IV. _______________ - area of brain above the brain stem; contains the thalamus,
hypothalamus, epithalamus, and pituitary gland
A. __________ – gateway to the cerebral cortex; paired organ that constitutes nearly 4/5 of
the diencephalon; positioned medially, just below the lateral ventricles
1.
Contains nuclei that serve as ________ stations for nearly all __________ impulses
to appropriate regions of cerebral cortex
2.
Nuclei include the medial & lateral ____________, which relay auditory & visual
information, respectively
3.
Receives input from regions of the cerebrum involved in ______ control
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4.
Is interconnected with the _________ system, thus is involved in emotional and
memory functions
5.
Also involved in _______, eye movements, taste, smell, hearing, equilibrium, and
somatosensory input
6.
The _________ mass of the thalamus is a cylindrical stalk that connects the two
lateral halves of the thalamus
B. _________________ - found inferior to the thalamus, has 4 major regions (mammillary,
tuberal, supraoptic, and preoptic); is one of the major regulators of homeostasis
1.
Mammillary region - most posterior portion of hypothalamus; contains __________
bodies, which relay info. from the limbic system to the thalamus
2.
Tuberal region - contains the __________________ (stalk that connects
hypothalamus to pituitary gland) and _____________, which secretes hypothalamic
regulating hormones.
3.
_____________ region - contains many nuclei (paraventricular, supraoptic, anterior
hypothalamic, & suprachisamatic). Axons extend through the infundibulum to
posterior pituitary.
4.
___________ region - contains the preoptic, periventricular, medial preoptic, and
lateral preoptic nuclei.
5.
_________________ of hypothalamus include:
a.
Control of _____ - Axons extend from hypothalamus to sympathetic and
parasympathetic nuclei in brain stem and spinal cord; so hypothalamus can control
and integrate the ANS, which regulates contraction of smooth muscle, cardiac
muscle, and glandular secretions.
b.
Control of __________ Gland via hypothalamic hormones:
1) Regulating neurohormones control hormones released by the
______________ pituitary.
2) Oxytocin & Antiduretic hormones (____) produced by the
paraventricular and supraoptic nuclei are transported via axons through the
infundibulum to the ___________ pitutary.
c.
d.
e.
Regulation of ________ & behavior - rage, aggression, pain, pleasure, sexual
arousal, copulation, & orgasm
Regulation of hunger, thirst, & _________
1) Neurons of hunger and satiety centers monitor _______ and amino acid levels
for hunger and satiety
2) ____________ neurons in hypothalamus monitor osmotic pressures and
stimulate the thirst center when thirsty; dehydration stimulates release of ____
Thermoregulation - control of body _______________ via nuclei in heatlosing center and heat-producing center, which control vasodilation,
vasoconstriction, sweating, etc.
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f.
_______ control - the superchiasmatic nucleus above the optic chiasm
establishes 24 hr. (circadian) sleep patterns.
g.
____________ – mamillary bodies are part of a signaling pathway from the
hippocampus (a memory center) to the thalamus
C. _____________ - posterior portion of diencephalon, forms a roof over the 3rd ventricle
1. Contains the ________ gland, which secretes ____________, a hormone that
influences diurnal cycles.
2.
V.
Posterior _____________, inferior to the pineal gland, connects the right & left
superior colliculi of the midbrain
___________ – includes the midbrain, pons, and medulla oblongata.
A. _____________ connects the forebrain and hindbrain; gives rise to CN III-IV; structures
between the diencephalon and pons are:
1. Cerebral _____________ - interconnects the 3rd & 4th ventricles
2. __________ _______________ - four rounded elevations on the posterior midbrain
a. The __________ __________ are the two upper eminences, involved in
_________ reflexes
b. The __________ __________ are the two lower eminences, responsible for
____________ reflexes
3. Cerebral _________ - pair of structures composed of ascending and descending
___________ fiber tracts that and connect the cerebrum to other parts of the brain
4. _____ nucleus - between the cerebral peduncle and cerebral aqueduct; connects
cerebrum & cerebellum; concerned with fine ______ control
5. ________________ - inferior to the red nucleus; a motor center that relays inhibitory
signals (__________) to the thalamus and basal nuclei; inhibits forced involuntary
movements (affected in Parkinson’s disease)
B. ______ - rounded bulge between the midbrain and medulla oblongata.
1.
Consists of white fiber tracts that connect it with the ________, cerebellum and
medulla oblongata (MO)
2.
3.
Nuclei of the pons function with those of the MO to regulate ____________
Cranial nerves that have nuclei in the pons include CN ______
C. Medulla oblongata (____) – between the pons and spinal cord
1. The medulla resembles the spinal cord, except for two triangular elevations called
__________, which contain nerve fibers of the corticospinal (_____________) tracts,
on the anterior side
2. Lateral to each pyramid is an oval enlargement called the _____, which contains a
nucleus that receives input from the brain and SC and relays the information to the
cerebellum
3. The MO contains ascending and descending nerve ______, which ____________,
allowing one side of the brain to receive info. from and send info. to opposite sides of
the body.
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4. The ____ ventricle within the MO is continuous with the cerebral aqueduct
superiorly and the central canal inferiorly
5. Cranial nerves _____ arise from the MO
6. Important nuclei in the MO include the nucleus gracilis & cuneatus, which relay
__________ info. to the thalamus, then to the cerebral cortex via thalamic nuclei
7. Three other nuclei function as _____________ motor centers of the MO for
controlling visceral functions:
a. _______ center – adjusts the force and rate of the heartbeat
b. ___________ center - sends impulses via the SC and spinal nerves to arteriole
walls, causing them to constrict and elevate BP
c. Respiratory center - controls the rate & depth of ________
8. Other MO nuclei are involved in sneezing, coughing, salivation, swallowing,
sweating, and _____________
VI. ___________ - second largest brain structure, found in the inferior, posterior cranial cavity
A. A ___________ fissure and associated _____________ cerebelli dura mater separates
the cerebellum from the cerebrum
B. The cerebellum consists of two hemispheres, between which the ________ cerebelli dura
mater extends
C. Between the hemispheres is a worm-like area called the ______
D. ______ are the convoluted folds of the cerebellum
E. The cerebellum has a thin outer layer of gray matter, the cerebellar ________
F. A thick deeper layer of white matter forms branches called the ________ __________
G. The cerebellar ____________ are 3 paired nerve tracts that allow the cerebellum to
communicate with the rest of the brain
1. __________ convey info. to the _________, then to motor areas of the cerebral cortex
2. ___________ convey impulses of voluntary movement from the cerebrum through the
_____ to the cerebellum
3. ____________ connect the cerebellum with the ____ and SC
H. The main ____________ of the cerebellum are to
1. ___________________ skeletal muscle contractions
2. Control ______________ and equilibrium
3. Maintain _____________
VII. Functional Brain Systems
A. _____________ Formation network of nuclei & ascending and descending nerve fibers
within the brain _____ that functions as the reticular activating system (_____) in
arousing the cerebrum. Functions include
1.
Somatic motor control- helps the _____________ to maintain muscle tone and
produce coordinated contractions of skeletal muscles
2.
Cardiovascular control – includes the cardiac center and vasomotor center of the
_____
3.
Pain modulation – origin of descending analgesic pathways of the __________spinal
tracts
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4.
Sleep & consciousness – has projection tracts to the thalamus and cerebral cortex;
acts as a “___________” that decides what sensory information comes to our
conscious attention
B. _________ System – a loop of cortical structures surrounding the corpus callosum and
thalamus, including the amygdala and hippocampus on the medial side of the temporal lobe,
the fornix, and the cingulate gyrus that arches over the corpus callosum. Functions
1. The __________, is part of the emotional brain, with a role in emotional memories, as
well as feelings of pleasure, love, anger, fear, and pain.
2. The _____________ acts in memory consolidation, organizing sensory and cognitive
experiences into a unified long-term memories, which are then stored in the temporal
and frontal lobes
VIII. Higher Brain Functions involve complex activities, such as sleep, memories, cognition,
emotion, sensation, motor control, and language
A. Brain waves & sleep
1. Brain waves are rhythmic changes in voltage that can be recorded on an
electroencephalogram (____).
2. Four types of brain waves are
a. ________ waves occur in the parieto-occipital area when a person is awake and
resting with the eyes closed
b. ________ waves occur in the frontal to parietal regions during mental activity and
sensory stimulation
c. _________ waves are found in normal children and sleeping adults; in awake adults
they suggest brain abnormalities
d. ____ waves are seen in infants when awake and adults during deep sleep; in awake
adults, they indicate brain damage
B. _________ – includes awareness, perception, thinking, knowledge, and memory.
1. Brain ________, or local brain injuries, caused by infection, trauma, cancer, and
stroke, lead to damage in association areas of the brain, such as
a. _________ lobe lesions can cause people to become unaware of body parts on one
side of the body
b. __________ lobe lesions may cause agnosia, the inability to recognize, identify,
and name familiar objects
c. ___________ lobe lesions can alter a person’s personality
2. In general, __________ areas of the above lobes are responsible for different areas of
cognition
a. ___________ – perceives sensory stimuli
b. ___________ – identifies the stimuli (via memories)
c. ___________ – plans and initiates the response to the stimuli
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IX.
CNS Disorders
A. Cerebral _________ – muscular incoordination due to damage to the motor areas of the
brain during fetal development; caused by measles exposure, drugs, radiation, oxygen
deficiency, hydrocephalus
B. ____________ – symptoms include massive discharge of neurons (seizures), resulting in
convulsions, sensory and psychic disturbances, and often impaired consciousness
C. ______________ – brain damage due to a blow, often with loss of consciousness, blurred
vision, and sometimes short-term amnesia
D. __________ or Subarachnoid Hemorrhage is bleeding into those spaces as a result of
head trauma; coma or death often result
E. Stroke (____) – occurs when blood circulation to a brain area is blocked and the brain
tissue dies
F. __________ disease – mental dementia caused by the development of beta amyloid
plaques (degenerated nerve fibers) and neurofibrillary tangles within neuron cell bodies