Transcript Chapter 12 PowerPoint

Chapter 12 Part B
The Central
Nervous
System
© Annie Leibovitz/Contact Press Images
© 2016 Pearson Education, Inc.
PowerPoint® Lecture Slides
prepared by
Karen Dunbar Kareiva
Ivy Tech Community College
12.2 Cerebral Hemispheres (cont.)
Cerebral White Matter
• Second of the three basic regions of cerebral
hemispheres
• Responsible for communication between
cerebral areas, and between cortex and lower
CNS
• Consists of myelinated fibers bundled into large
tracts
• Classified according to direction they run:
– Association, commissural, and projection
fibers
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Cerebral White Matter (cont.)
– Association fibers: horizontal running fibers
that connect different parts of same hemisphere
– Commissural fibers: horizontal fibers that
connect gray matter of two hemispheres
– Projection fibers: vertical fibers that connect
hemispheres with lower brain or spinal cord
• Internal capsule: projection fibers on each side of
brain stem form compact band
– Passes between thalamus and some of basal nuclei
• Corona radiata: projection fibers that radiate through
cerebral white matter to cortex
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Figure 12.9a White fiber tracts of the cerebral hemispheres.
Superior
Longitudinal fissure
Lateral
ventricle
Basal nuclei
• Caudate
• Putamen
• Globus
pallidus
Thalamus
Association fibers
(within hemisphere)
Commissural fibers
(between hemispheres)
• Corpus callosum
Projection fibers
(cerebral cortex to
or from lower area)
• Corona
radiata
• Internal
capsule
Gray matter
Third
ventricle
Pons
Medulla oblongata
Frontal section
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White matter
Decussation
(cross-over)
of pyramids
Figure 12.9b White fiber tracts of the cerebral hemispheres.
Association fibers
Commissural fibers
• Corpus callosum
Projection fibers
• Corona radiata
• Internal capsule
Parasagittal section and dissection
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Gray
matter
Basal Nuclei (Ganglia)
• Third of the three basic regions of cerebrum
• Each hemisphere’s basal nuclei include a:
– Caudate nucleus
– Putamen
– Globus pallidus
• Caudate nucleus + putamen = striatum
• Closely associated with subthalamic nuclei
(diencephalon) and substantia nigra (midbrain)
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Figure 12.10a Basal nuclei.
Striatum
Caudate
nucleus
Putamen
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Thalamus
Tail of caudate
nucleus
Basal Nuclei (Ganglia) (cont.)
• Functions of basal nuclei are thought to:
– Influence muscle movements
– Play role in cognition and emotion
– Regulate intensity of slow or stereotyped
movements
– Filter out incorrect/inappropriate responses
– Inhibit antagonistic/unnecessary movements
• Parkinson’s disease and Huntington’s disease
are disorders of the basal nuclei
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Figure 12.10b Basal nuclei.
Anterior
Cerebral cortex
Cerebral white matter
Corpus callosum
Anterior horn of
lateral ventricle
Head of caudate nucleus
Putamen
Globus pallidus
Thalamus
Tail of caudate nucleus
Third ventricle
Inferior horn of
lateral ventricle
Posterior
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12.3 The Diencephalon
• Consists of three paired gray-matter structures:
– Thalamus
– Hypothalamus
– Epithalamus
• All three enclose third ventricle
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Figure 12.11a Midsagittal section of the brain.
Cerebral hemisphere
Septum pellucidum
Corpus callosum
Interthalamic
adhesion
(intermediate
mass of thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third ventricle)
Interventricular
foramen
Posterior
commissure
Pineal gland
Anterior
commissure
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
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Epithalamus
Arbor vitae (of cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Thalamus
• Bilateral egg-shaped nuclei that form
superolateral walls of third ventricle
• Makes up 80% of diencephalon
• Bilateral nuclei connected by interthalamic
adhesion (intermediate mass)
– Contains several nuclei, named for location
– Nuclei project and receive fibers from cerebral
cortex
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Figure 12.12a Selected structures of the diencephalon.
Medial Lateral Lateral
dorsal dorsal
posterior
nucleus nucleus nucleus
Pulvinar
Anterior
nuclei
Medial
geniculate
body
Reticular
nucleus
Lateral
geniculate
body
Ventral
Ventral Ventral posteroanterior lateral lateral
Ventral nuclei
The main thalamic nuclei. (The reticular nuclei that
“cap” the thalamus laterally are depicted as curving
translucent structures.)
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Thalamus (cont.)
• Main thalamic function is to act as relay station
for information coming into cortex
– Sorts, edits, and relays ascending input such as:
• Impulses from hypothalamus for regulating emotion
and visceral function
• Impulses from cerebellum and basal nuclei to help
direct motor cortices
• Impulses for memory or sensory integration
• Overall, it acts to mediate sensation, motor
activities, cortical arousal, learning, and memory
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Hypothalamus
• Located below thalamus
• Forms cap over brain stem and forms
inferolateral walls of third ventricle
• Contains many important nuclei such as:
– Mammillary bodies: paired anterior nuclei that
act as olfactory relay stations
• Infundibulum: stalk that connects to pituitary
gland
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Figure 12.12b Selected structures of the diencephalon.
Paraventricular
nucleus
Anterior
commissure
Preoptic
nucleus
Anterior
hypothalamic
nucleus
Supraoptic
nucleus
Suprachiasmatic
nucleus
Optic
chiasma
Infundibulum
(stalk of the
pituitary gland)
The main hypothalamic nuclei.
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Fornix
Dorsomedial
nucleus
Posterior
hypothalamic
nucleus
Lateral
hypothalamic
area
Ventromedial
nucleus
Arcuate
nucleus
Pituitary
gland
Mammillary
body
Hypothalamus (cont.)
• The hypothalamus is the main visceral control
and regulating center that is vital to homeostasis
• Chief homeostasis controls:
– Controls autonomic nervous system
• Examples: blood pressure, rate and force of
heartbeat, digestive tract motility, pupil size
– Initiates physical responses to emotions
• Part of limbic system: perceives pleasure, fear, rage,
biological rhythms, and drives (sex drive)
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Hypothalamus (cont.)
• The hypothalamus also:
– Regulates body temperature: sweating or
shivering
– Regulates hunger and satiety in response to
nutrient blood levels or hormones
– Regulates water balance and thirst
– Regulates sleep-wake cycles
• Suprachiasmatic nucleus of thalamus sets our
biological clock
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Hypothalamus (cont.)
– Controls endocrine system functions such as:
• Secretions of anterior pituitary gland
• Production of posterior pituitary hormones
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Clinical – Homeostatic Imbalance 12.4
• Hypothalamic disturbances cause a number of
disorders such as:
– Severe body wasting
– Obesity
– Sleep disturbances
– Dehydration
– Emotional imbalances
• Implicated in failure to thrive: delay in growth or
development
– Occurs when child is deprived of a warm,
nurturing relationship
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Epithalamus
• Most dorsal portion of diencephalon
• Forms roof of third ventricle
• Contains pineal gland (body)
– Extends from posterior border
– Secretes melatonin that helps regulate sleepwake cycle
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Figure 12.11a Midsagittal section of the brain.
Cerebral hemisphere
Septum pellucidum
Corpus callosum
Interthalamic
adhesion
(intermediate
mass of thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third ventricle)
Interventricular
foramen
Posterior
commissure
Pineal gland
Anterior
commissure
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
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Epithalamus
Arbor vitae (of cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Figure 12.11b Midsagittal section of the brain (continued).
Corpus callosum
Fornix
Lateral ventricle
Thalamus
Third ventricle
Posterior
commissure
Pineal gland
Epithalamus
Corpora
quadrigemina
Cerebral
aqueduct
Anterior
commissure
Hypothalamus
Arbor vitae
Optic chiasma
Fourth ventricle
Mammillary body
Pons
Medulla oblongata
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Cerebellum
Midbrain
Figure 12.13a Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Optic chiasma
Optic nerve (II)
Optic tract
Diencephalon
• Thalamus
• Hypothalamus
Mammillary body
Crus cerebri of cerebral
peduncles (midbrain)
Oculomotor nerve (III)
Trochlear nerve (IV)
Abducens nerve (VI)
Trigeminal nerve (V)
Pons
Facial nerve (VII)
Vestibulocochlear nerve (VIII)
Glossopharyngeal nerve (IX)
Pyramid
Ventral root of first cervical nerve
Decussation of pyramids
Hypoglossal nerve (XII)
Middle cerebellar peduncle
Ventral view
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Spinal cord
Vagus nerve (X)
Accessory nerve (XI)
Figure 12.13b Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Optic tract
Infundibulum
Pituitary gland
Crus cerebri of cerebral
peduncles (midbrain)
Trigeminal nerve (V)
Pons
Facial nerve (VII)
Abducens nerve (VI)
Glossopharyngeal nerve (IX)
Hypoglossal nerve (XII)
Vagus nerve (X)
Accessory nerve (XI)
Left lateral view
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Thalamus
Superior colliculus
Inferior colliculus
Trochlear nerve (IV)
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle
Vestibulocochlear nerve (VIII)
Olive
Figure 12.13c Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Thalamus
Pineal gland
Midbrain
Corpora
• Superior colliculus
quadrigemina
• Inferior colliculus
of tectum
• Trochlear nerve (IV)
• Superior cerebellar peduncle
Floor of
fourth ventricle
Pons
• Middle cerebellar peduncle
Diencephalon
Facial nerve (VII)
Choroid plexus
(fourth ventricle)
Dorsal median sulcus
Dorsal root of
first cervical nerve
Dorsal view
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Medulla oblongata
• Inferior cerebellar peduncle
• Vestibulocochlear nerve (VIII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
12.4 Brain Stem
• Consists of three regions: midbrain, pons,
medulla oblongata
• Similar in structure to spinal cord but contains
nuclei embedded in white matter
• Controls automatic behaviors necessary for
survival
• Contains fiber tracts connecting higher and
lower neural centers
• Nuclei are associated with 10 of the 12 pairs of
cranial nerves
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Figure 12.14 Inferior view of the brain, showing the three parts of the brain stem: midbrain, pons, and medulla oblongata.
Frontal lobe
Olfactory bulb
(synapse point of
cranial nerve I)
Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Midbrain
Pons
Temporal
lobe
Medulla
oblongata
Cerebellum
Spinal cord
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Midbrain
• Located between diencephalon and pons
• Cerebral peduncles: two ventral bulges that
contain pyramidal motor tracts
– Form pillars that hold up cerebrum
• Cerebral aqueduct: channel running through
midbrain that connects third and fourth
ventricles
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Midbrain (cont.)
• Periaqueductal gray matter: nuclei that play a
role in pain suppression and fight-or-flight
response
– Also include nuclei that control cranial nerve III
(oculomotor) and IV (trochlear)
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Figure 12.13c Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Thalamus
Pineal gland
Midbrain
Corpora
• Superior colliculus
quadrigemina
• Inferior colliculus
of tectum
• Trochlear nerve (IV)
• Superior cerebellar peduncle
Floor of
fourth ventricle
Pons
• Middle cerebellar peduncle
Diencephalon
Facial nerve (VII)
Choroid plexus
(fourth ventricle)
Dorsal median sulcus
Dorsal root of
first cervical nerve
Dorsal view
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Medulla oblongata
• Inferior cerebellar peduncle
• Vestibulocochlear nerve (VIII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
Midbrain (cont.)
• Midbrain nuclei scattered throughout white
matter include:
– Corpora quadrigemina: paired dorsal
protrusions
• Superior colliculi: visual reflex centers
• Inferior colliculi: auditory relay centers
– Substantia nigra: functionally linked to basal
nuclei
• Parkinson’s disease is degeneration of this area
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Midbrain (cont.)
– Red nucleus: relay nuclei for some descending
limb flexion motor pathways
• Part of reticular formation
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Figure 12.13c Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Thalamus
Pineal gland
Midbrain
Corpora
• Superior colliculus
quadrigemina
• Inferior colliculus
of tectum
• Trochlear nerve (IV)
• Superior cerebellar peduncle
Floor of
fourth ventricle
Pons
• Middle cerebellar peduncle
Diencephalon
Facial nerve (VII)
Choroid plexus
(fourth ventricle)
Dorsal median sulcus
Dorsal root of
first cervical nerve
Dorsal view
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Medulla oblongata
• Inferior cerebellar peduncle
• Vestibulocochlear nerve (VIII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
Figure 12.15a Cross sections through different regions of the brain stem.
Tectum
Superior
colliculus
Periaqueductal gray
matter
Oculomotor nucleus (III)
Medial lemniscus
Cerebral
aqueduct
Reticular
formation
Dorsal
Red nucleus
Substantia
nigra
Fibers of
pyramidal tract
Ventral
Midbrain
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Crus cerebri
of cerebral
peduncle
Pons
• Located between midbrain and medulla
oblongata
• Fourth ventricle separates pons from
cerebellum
• Composed of conduction tracts:
– Longitudinal fibers connect higher brain centers
and spinal cord
– Transversal/dorsal fibers relay impulses between
motor cortex and cerebellum
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Pons (cont.)
• Origin of cranial nerves V (trigeminal), VI
(abducens), and VII (facial)
• Some nuclei play role in reticular formation, and
some help maintain normal rhythm of breathing
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Figure 12.15b Cross sections through different regions of the brain stem.
Superior cerebellar
peduncle
Trigeminal
main sensory
nucleus
Fourth
ventricle
Reticular
formation
Trigeminal
motor
nucleus
Middle
cerebellar
peduncle
Trigeminal
nerve (V)
Medial lemniscus
Pons
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Pontine
nuclei
Fibers of
pyramidal tract
Medulla Oblongata
• Also known as medulla
• Blends into spinal cord at foramen magnum
• Contains fourth ventricle
– Continuation of central canal of spinal cord
– Medulla and pons form ventral wall
– Contains choroid plexus: capillary-rich
membrane that forms cerebral spinal fluid
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Medulla Oblongata (cont.)
• Structures of the medulla oblongata
– Pyramids: two ventral longitudinal ridges formed
by pyramidal tracts from motor cortex
– Decussation of the pyramids: point where
pyramidal tracts cross over to opposite side of
body
– Olives: swellings caused by underlying inferior
olivary nuclei that relay stretch information from
muscles and joints to cerebellum
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Medulla Oblongata (cont.)
– Cranial nerves VIII, IX, X, and XII
– Vestibular and cochlear nuclei: mediate
responses that maintain equilibrium
– Nucleus cuneatus and nucleus gracilis: relay
ascending sensory information from spinal cord
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Figure 12.11a Midsagittal section of the brain.
Cerebral hemisphere
Septum pellucidum
Corpus callosum
Interthalamic
adhesion
(intermediate
mass of thalamus)
Fornix
Choroid plexus
Thalamus
(encloses third ventricle)
Interventricular
foramen
Posterior
commissure
Pineal gland
Anterior
commissure
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
© 2016 Pearson Education, Inc.
Epithalamus
Arbor vitae (of cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Figure 12.13c Three views of the brain stem (green) and the diencephalon (purple).
Thalamus
Hypothalamus
Midbrain
Pons
Medulla
oblongata
Diencephalon
View (a)
View (c)
Brain stem
View (b)
Thalamus
Pineal gland
Midbrain
Corpora
• Superior colliculus
quadrigemina
• Inferior colliculus
of tectum
• Trochlear nerve (IV)
• Superior cerebellar peduncle
Floor of
fourth ventricle
Pons
• Middle cerebellar peduncle
Diencephalon
Facial nerve (VII)
Choroid plexus
(fourth ventricle)
Dorsal median sulcus
Dorsal root of
first cervical nerve
Dorsal view
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Medulla oblongata
• Inferior cerebellar peduncle
• Vestibulocochlear nerve (VIII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
Figure 12.15c Cross sections through different regions of the brain stem.
Hypoglossal
nucleus (XII)
Dorsal motor
nucleus of
vagus (X)
Reticular formation
Inferior
cerebellar
peduncle
Lateral
nuclear
group
Medial
nuclear
group
Raphe
nucleus
Fourth
ventricle
Choroid
plexus
Solitary
nucleus
Vestibular
nuclei
(VIII)
Cochlear
nuclei
(VIII)
Nucleus
ambiguus
Inferior
olivary
nucleus
Medial lemniscus
Pyramid
Medulla oblongata
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Medulla Oblongata (cont.)
• Functions of the medulla oblongata
– Medulla is an autonomic reflex center
• Many functions overlap with hypothalamus
– Hypothalamus relays instructions via medulla
– Functional groups of medulla include:
• Cardiovascular center
– Cardiac center adjusts force and rate of heart
contraction
– Vasomotor center adjusts blood vessel diameter for
blood pressure regulation
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Medulla Oblongata (cont.)
• Respiratory centers
– Generate respiratory rhythm
– Control rate and depth of breathing (with pontine
centers)
• Various other centers regulate:
– Vomiting
– Hiccupping
– Swallowing
– Coughing
– Sneezing
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12.5 Cerebellum
• 11% of brain mass
• Located dorsal to pons and medulla
• Processes input from cortex, brain stem, and
sensory receptors to provide precise,
coordinated movements of skeletal muscles
• Also plays a major role in balance
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Cerebellar Anatomy
• Cerebellar hemispheres connected by
wormlike vermis
• Folia: transversely oriented gyri
• Each hemisphere has three lobes
– Anterior, posterior, and flocculonodular
• Contains thin cortex of gray matter with
distinctive treelike pattern of white matter called
arbor vitae
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Cerebellar Anatomy (cont.)
• Purkinje fibers originate in cortex, synapse
with cerebellum
• Cerebellar homunculi show sensory maps of
entire body
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Figure 12.16a Cerebellum.
Anterior lobe
Arbor vitae
Cerebellar
cortex
Folia
Pons
Fourth ventricle
Choroid plexus
Medulla oblongata
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Posterior
lobe
Figure 12.16b Cerebellum.
Anterior lobe
Cerebellar cortex
Arbor vitae
Cerebellar
peduncles
• Superior
• Middle
• Inferior
Medulla oblongata
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Posterior
lobe
Flocculonodular
lobe
Choroid
plexus of
fourth
ventricle
Figure 12.16c Cerebellum.
Anterior lobe
Primary
fissure
Posterior
lobe
Horizontal
fissure
Vermis
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Cerebellar Peduncles
• All fibers in cerebellum are ipsilateral—from
and to the same side of body
• Three paired fiber tracts connect cerebellum to
brain stem
– Superior cerebellar peduncles connect
cerebellum to midbrain
– Middle cerebellar peduncles connect pons to
cerebellum
– Inferior cerebellar peduncles connect medulla
to cerebellum
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Figure 12.16b Cerebellum.
Anterior lobe
Cerebellar cortex
Arbor vitae
Cerebellar
peduncles
• Superior
• Middle
• Inferior
Medulla oblongata
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Posterior
lobe
Flocculonodular
lobe
Choroid
plexus of
fourth
ventricle
Cerebellar Processing
• Cerebellum fine-tunes motor activity as follows:
1. Receives impulses from cerebral cortex of
intent to initiate voluntary muscle contraction
2. Receives signals from proprioceptors
throughout body, as well as visual and
equilibrium pathways that:
• Pathways continuously “inform” cerebellum of body’s
position and momentum
3. Cerebellar cortex calculates the best way to
smoothly coordinate muscle contraction
4. Sends “blueprint” of coordinated movement to
cerebral motor cortex and brain stem nuclei
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Cognitive Functions of Cerebellum
• Neuroimaging suggests that cerebellum plays
role in thinking, language, and emotion
• As it does for motor processes, it may compare
actual output of higher functions with expected
output and adjust accordingly
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