CHAPTER 12 CENTRAL NERVOUS SYSTEM - Warner …classpages.warnerpacific.edu/bdupriest/BIO 221/Chapter...

Copyright © 2010 Pearson Education, Inc.

CHAPTER 12

CENTRAL NERVOUS SYSTEM



Embryonic Development


Figure 12.1 Development of the neural tube from embryonic ectoderm (1 of 4).

1 The neural plate forms from surface ectoderm.

Head

Tail

Surface ectoderm

Neural plate



2 The neural plate invaginates, forming the neural

groove, flanked by neural folds.

Neural folds

Neural groove



3 Neural fold cells migrate to form the neural crest,

which will form much of the PNS and many other

structures.

Neural crest



Surface ectoderm

Head

Tail

Neural tube

4 The neural groove becomes the neural tube, which

will form CNS structures.


Neural tube formation involves all of these

stages except…

1) Neural plate

2) Neural ring

3) Neural groove

4) Surface ectoderm

5) Neural tube


Figure 12.2 Embryonic development of the human brain.

(e) Adult

neural

canal

regions

(d) Adult brain

structures

(a)

Neural

tube

(c) Secondary brain

vesicles

(b) Primary brain

vesicles

Anterior

(rostral)

Posterior

(caudal) Spinal cord

Cerebellum

Brain stem: medulla oblongata

Brain stem: pons

Brain stem: midbrain

Diencephalon (thalamus, hypothalamus, epithalamus), retina

Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei)

Myelencephalon

Metencephalon

Mesencephalon

Diencephalon

Telencephalon

Rhombencephalon

(hindbrain)

Mesencephalon

(midbrain)

Prosencephalon

(forebrain)

Central canal

Fourth

ventricle

Cerebral

aqueduct

Third ventricle

Lateral

ventricles


Which of these adult brain structures is

derived from the prosencephalon?

1) Brain stem

2) Cerebellum

3) Cerebrum

4) All of the above



Regions and Organization


Figure 12.3d Effect of space restriction on brain development.

Cerebellum

Diencephalon

Cerebral hemisphere

(d) Birth

Brain stem

• Midbrain • Pons • Medulla

oblongata


Figure 12.4 Pattern of gray and white matter in the CNS (highly simplified).

Cerebrum

Cerebellum

Migratory

pattern of

neurons

Cortex of

gray matter

Inner gray

matter

Gray matter

Outer white

matter

Central cavity

Central cavity

Inner gray matter

Gray matter

Outer white matter

Central cavity

Inner gray matter

Outer white matter

Region of cerebellum

Brain stem

Spinal cord



Ventricles


Figure 12.5 Ventricles of the brain.

Anterior horn

Interventricular foramen

Inferior horn

Lateral aperture

(b) Left lateral view

Lateral ventricle

Septum pellucidum

Third ventricle

Cerebral aqueduct

(a) Anterior view

Fourth ventricle

Central canal

Inferior horn

Posterior horn

Median aperture

Lateral aperture


White matter represents…

1) High density areas of neuron cell bodies

2) Muscle

3) Blood vessels

4) High density areas of unmyelinated axons

5) High density areas of myelinated axons


True or false: The central canal of the spinal

Cord is continuous with the ventricles of the

Brain.

1) True

2) False



Cerebral Hemispheres:

Cerebral Cortex


Figure 12.6a Lobes and fissures of the cerebral hemispheres.

Postcentral

gyrus

Central

sulcus

Precentral

gyrus Frontal

lobe

(a)

Parietal lobe

Parieto-occipital sulcus

(on medial surface

of hemisphere) Lateral sulcus

Transverse cerebral fissure

Occipital lobe Temporal lobe

Cerebellum Pons

Medulla oblongata Spinal cord

Cortex (gray matter)

Fissure (a deep sulcus)

Gyrus

Sulcus

White matter


Figure 12.6b Lobes and fissures of the cerebral hemispheres.

Central

sulcus

(b)

Frontal lobe

Temporal lobe

(pulled down)

Gyri of insula


Figure 12.6c Lobes and fissures of the cerebral hemispheres.

Parietal

lobe

Frontal lobe

Right cerebral

hemisphere

Occipital

lobe

Left cerebral

hemisphere

Cerebral veins

and arteries

covered by

arachnoid

mater

Longitudinal

fissure

Posterior (c)

Anterior


Figure 12.7 Functional neuroimaging (fMRI) of the cerebral cortex.

Central sulcus

Longitudinal fissure

Left frontal lobe

Left temporal lobe

Areas active in speech and hearing (fMRI)


Figure 12.8a Functional and structural areas of the cerebral cortex.

Gustatory cortex (in insula)

Primary motor cortex

Premotor cortex

Frontal eye field

Working memory for spatial tasks

Executive area for task management

Working memory for object-recall tasks

Broca’s area (outlined by dashes)

Solving complex, multitask problems

(a) Lateral view, left cerebral hemisphere

Motor areas

Prefrontal cortex

Sensory areas and related

association areas Central sulcus

Primary somatosensory cortex Somatosensory association cortex

Somatic sensation

Taste

Wernicke’s area (outlined by dashes)

Primary visual cortex

Visual association area

Vision

Auditory association area

Primary auditory cortex

Hearing

Primary motor cortex Motor association cortex Primary sensory cortex

Sensory association cortex Multimodal association cortex


Figure 12.8b Functional and structural areas of the cerebral cortex.

Frontal eye field

Prefrontal cortex

Processes emotions related to personal and social interactions

(b) Parasagittal view, right hemisphere

Olfactory bulb

Orbitofrontal cortex

Olfactory tract

Fornix Temporal lobe

Corpus callosum

Premotor cortex Primary motor cortex

Cingulate gyrus Central sulcus

Primary somatosensory cortex

Parietal lobe

Parieto-occipital sulcus

Somatosensory association cortex

Occipital lobe

Visual association area

Calcarine sulcus

Parahippocampal gyrus

Uncus

Primary olfactory cortex

Primary visual cortex

Primary motor cortex Motor association cortex Primary sensory cortex

Sensory association cortex Multimodal association cortex


Figure 12.9 Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.

Genitals

Toes

Intra- abdominal

Swallowing

Tongue

Jaw

Primary motor

cortex

(precentral gyrus)

Primary somato-

sensory cortex

(postcentral gyrus)

Motor

Motor map in

precentral gyrus

Sensory

Sensory map in

postcentral gyrus

Posterior

Anterior


Quiz Q1: All of these are true of the primary

motor cortex except it…

1) Is located anterior to the central sulcus

2) Is located on the precentral gyrus

3) Controls voluntary muscle movement

4) Coordinates repeated/learned complex

muscle movements


Quiz Q2: The sensory homunculus has the

fingers mapped to a large area of the

brain because…

1) The fingers have a very large surface area

2) The fingers have lots of muscles required

to move them

3) The fingers contain many sensory

receptors

4) All of the above


Quiz Q3: True or false: The neural crest

develops into the central nervous system.

1) True

2) False


Quiz Q4: Information from the premotor cortex

mostly gets sent to…

1) muscles directly.

2) the primary somatosensory cortex

3) the somatosensory association cortex

4) the primary motor cortex


Quiz Q5: Gray matter includes…

1) myelinated axons

2) neuron cell bodies

3) Schwann cells

4) ganglia


Figure 12.10 Types of fiber tracts in white matter.

Corona radiata

Projection

fibers

Longitudinal fissure

Gray matter

White matter

Association fibers

Lateral ventricle

Fornix

Third ventricle

Thalamus

Pons

Medulla oblongata Decussation of pyramids

Commissural fibers

(corpus callosum)

Internal capsule

Superior

Basal nuclei • Caudate

• Putamen

• Globus

pallidus

(a) (b)


Figure 12.11a Basal nuclei.

Fibers of corona radiata

Corpus

striatum

(a)

Projection fibers

run deep to

lentiform nucleus

Caudate

nucleus Thalamus

Tail of

caudate

nucleus

Lentiform

nucleus

• Putamen • Globus pallidus (deep to putamen)


Figure 12.11b Basal nuclei (1 of 2).

Corpus callosum Anterior horn

of lateral ventricle Caudate nucleus

Putamen Lentiform

nucleus

(b)

Globus

pallidus

Thalamus

Tail of caudate nucleus Third ventricle

Cerebral cortex Cerebral white matter

Anterior

Posterior

Inferior horn

of lateral ventricle


Figure 12.11b Basal nuclei (2 of 2).

Corpus callosum Anterior horn

of lateral ventricle Caudate nucleus

Lentiform nucleus

(b)

Thalamus

Third ventricle

Cerebral cortex Cerebral white matter

Inferior horn

of lateral ventricle


Basal nuclei are…

1) Part of the cerebral cortex

2) Part of the cerebral hemispheres

3) Gray matter

4) 2 and 3 only

5) All of the above



Cerebral Hemispheres:

Lateralization and

Contralateralization



Diencephalon & Brainstem


Figure 12.12 Midsagittal section of the brain illustrating the diencephalon (purple) and brain stem (green).

Corpus callosum

Choroid plexus Thalamus

(encloses third ventricle)

Pineal gland

(part of epithalamus)

Posterior commissure

Corpora quadrigemina

Cerebral aqueduct

Arbor vitae (of cerebellum)

Fourth ventricle Choroid plexus Cerebellum

Septum pellucidum

Interthalamic adhesion (intermediate mass of thalamus)

Interven- tricular foramen

Anterior commissure

Hypothalamus

Optic chiasma

Pituitary gland

Cerebral hemisphere

Mammillary body Pons

Medulla oblongata

Spinal cord

Mid-

brain

Fornix


Figure 12.13 Selected structures of the diencephalon.

Dorsal nuclei

Medial

Anterior nuclear group

Reticular nucleus

Ventral anterior

Ventral lateral

Ventral postero- lateral

Lateral geniculate body

Medial geniculate body

Pulvinar

Lateral dorsal

Lateral posterior

Preoptic nucleus

Supraoptic

nucleus Supra-

chiasmatic nucleus

Anterior hypothalamic nucleus

Dorsomedial nucleus

Paraventricular

nucleus

Fornix Anterior commissure

Posterior hypothalamic nucleus

Lateral hypothalamic area

Ventromedial nucleus

Optic chiasma Infundibulum (stalk of the pituitary gland)

Pituitary gland

Mammillary

body

(a) The main thalamic nuclei. (The reticular

nuclei that “cap” the thalamus laterally are

depicted as curving translucent structures.)

(b) The main hypothalamic nuclei.

Arcuate nucleus

Ventral nuclei


The diencephalon is comprised of all of the

Following except…

1) Hypothalamus

2) Thalamus

3) Epithalamus

4) Midbrain


Figure 12.15a Three views of the brain stem (green) and the diencephalon (purple).

Optic chiasma View (a)

Optic nerve (II)

Mammillary body

Oculomotor nerve (III)

Crus cerebri of cerebral peduncles (midbrain)

Trigeminal nerve (V)

Abducens nerve (VI) Facial nerve (VII)

Vagus nerve (X)

Accessory nerve (XI)

Hypoglossal nerve (XII)

Ventral root of first cervical nerve

Trochlear nerve (IV)

Pons Middle cerebellar peduncle

Pyramid

Decussation of pyramids

(a) Ventral view

Spinal cord

Vestibulocochlear nerve (VIII)

Glossopharyngeal nerve (IX)

Diencephalon

• Thalamus • Hypothalamus

Diencephalon

Brainstem

Thalamus

Hypothalamus

Midbrain

Pons

Medulla oblongata


Figure 12.15b Three views of the brain stem (green) and the diencephalon (purple).

View (b)

Crus cerebri of cerebral peduncles (midbrain)

Infundibulum

Pituitary gland


Abducens nerve (VI)

Facial nerve (VII)

Vagus nerve (X)

Accessory nerve (XI)

Hypoglossal nerve (XII)

Pons

(b) Left lateral view

Glossopharyngeal nerve (IX)

Diencephalon

Brainstem

Thalamus

Hypothalamus

Midbrain

Pons

Medulla oblongata

Thalamus

Superior colliculus

Inferior colliculus

Trochlear nerve (IV)

Superior cerebellar peduncle

Middle cerebellar peduncle

Inferior cerebellar peduncle

Vestibulocochlear nerve (VIII)

Olive


Figure 12.15c Three views of the brain stem (green) and the diencephalon (purple).

View (c)

Diencephalon

Brainstem

Thalamus

Hypothalamus

Midbrain

Pons

Medulla oblongata

Pineal gland

Diencephalon

Anterior wall of fourth ventricle

(c) Dorsal view

Thalamus

Dorsal root of first cervical nerve

Midbrain • Superior

colliculus • Inferior

colliculus

• Trochlear nerve (IV) • Superior cerebellar peduncle

Corpora quadrigemina of tectum

Medulla oblongata

• Inferior cerebellar peduncle • Facial nerve (VII) • Vestibulocochlear nerve (VIII) • Glossopharyngeal nerve (IX) • Vagus nerve (X) • Accessory nerve (XI)

Pons

• Middle cerebellar peduncle

Dorsal median sulcus

Choroid plexus (fourth ventricle)


Figure 12.16a Cross sections through different regions of the brain stem.

Dorsal

Cerebral aqueduct

Superior

colliculus

Reticular formation

Crus cerebri of

cerebral peduncle

Ventral

Fibers of pyramidal tract

Substantia nigra

(a) Midbrain

Red nucleus

Medial lemniscus

Oculomotor nucleus (III)

Periaqueductal gray matter

Tectum


Figure 12.16b Cross sections through different regions of the brain stem.

Reticular formation


Pontine nuclei

Fibers of pyramidal tract

Middle cerebellar peduncle

Trigeminal main sensory nucleus

Trigeminal motor nucleus

Superior cerebellar peduncle

Medial lemniscus

Fourth ventricle

(b) Pons


Figure 12.16c Cross sections through different regions of the brain stem.

Choroid plexus

Fourth ventricle

Pyramid Medial lemniscus

Inferior olivary nucleus

Nucleus ambiguus

Inferior cerebellar peduncle

Cochlear nuclei (VIII)

Vestibular nuclear complex (VIII)

Solitary nucleus

Dorsal motor nucleus of vagus (X)

Hypoglossal nucleus (XII)

(c) Medulla oblongata

Lateral nuclear group

Medial nuclear group

Raphe nucleus Reti

cu

lar

form

ati

on


Mike the Headless Chicken

46

http://www.miketheheadlesschickenbook.com/


The brainstem is comprised of all of the

Following except…

1) Midbrain

2) Cerebellum

3) Pons

4) Medulla oblongata



Cerebellum


Figure 12.17b Cerebellum.

(b)

Medulla

oblongata Flocculonodular

lobe

Choroid

plexus of

fourth

ventricle

Posterior

lobe

Arbor

vitae

Cerebellar cortex

Anterior lobe

Cerebellar

peduncles • Superior • Middle • Inferior


Figure 12.17a Cerebellum.

(a)

Medulla

oblongata Flocculonodular lobe

Fourth

ventricle Posterior

lobe

Arbor vitae

Cerebellar

cortex

Anterior lobe

Choroid plexus

Pons


Figure 12.17c–d Cerebellum.

Anterior

lobe Primary

fissure Posterior

lobe

Anterior

lobe

Posterior

lobe

Vermis

Horizontal

fissure

Vermis

(c)

(d)


Which of the following is most directly

required for basic survival of the body?

1) Cerebrum

2) Cerebellum

3) Brainstem

4) Diencephalon


Which of the following is used in refining

movements of the body?

1) Cerebrum

2) Cerebellum

3) Brainstem

4) Diencephalon



Functional Brain Systems


Figure 12.18 The limbic system.

Corpus callosum

Septum pellucidum

Olfactory bulb

Diencephalic structures

of the limbic system

•Anterior thalamic nuclei (flanking 3rd ventricle)

•Hypothalamus •Mammillary

body

Fiber tracts

connecting limbic system structures

•Fornix •Anterior commissure

Cerebral struc-

tures of the limbic system

•Cingulate gyrus •Septal nuclei •Amygdala •Hippocampus •Dentate gyrus •Parahippocampal gyrus


Figure 12.19 The reticular formation.

Visual impulses

Reticular formation

Ascending general sensory tracts (touch, pain, temperature)

Descending motor projections to spinal cord

Auditory impulses

Radiations to cerebral cortex



Protection of the Brain: Meninges


Figure 12.24 Meninges: dura mater, arachnoid mater, and pia mater.

Skin of scalp Periosteum

Falx cerebri (in longitudinal fissure only)

Blood vessel Arachnoid villus Pia mater Arachnoid mater

Dura

mater Meningeal Periosteal

Bone of skull

Superior sagittal sinus

Subdural space

Subarachnoid space


Figure 12.25 Dural septa and dural venous sinuses.

Falx cerebri

Superior

sagittal sinus

Straight sinus

Crista galli of the ethmoid bone

Pituitary gland

Falx cerebelli

Occipital lobe

Dura mater

Transverse

sinus

Temporal bone

(b) Dural venous sinuses (a) Dural septa

Scalp

Skull

Tentorium

cerebelli

Cerebellum

Arachnoid mater over medulla oblongata


Which brain covering is the most closely

associated (in contact) with the brain?

1) Arachnoid mater

2) Dura mater

3) Pia mater



Protection of the Brain:

Cerebrospinal Fluid (CSF)


Figure 12.26a Formation, location, and circulation of CSF.

Superior sagittal sinus

Arachnoid villus

Subarachnoid space

Arachnoid mater

Meningeal dura mater

Periosteal dura mater

Right lateral ventricle (deep to cut)

Choroid plexus of fourth ventricle

Central canal of spinal cord

Choroid plexus

Interventricular foramen

Third ventricle

Cerebral aqueduct

Lateral aperture

Fourth ventricle

Median aperture

(a) CSF circulation

CSF is produced by the choroid plexus of each ventricle.

1

CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord.

2

CSF flows through the subarachnoid space.

3

CSF is absorbed into the dural venous sinuses via the arachnoid villi.

4

1

2

3

4


Figure 12.26b Formation, location, and circulation of CSF.

Ependymal

cells

Capillary

Connective tissue of pia mater

Wastes and unnecessary solutes absorbed

Section

of choroid

plexus

(b) CSF formation by choroid plexuses

Cavity of

ventricle

CSF forms as a filtrate containing glucose, oxygen, vitamins, and ions (Na+, Cl–, Mg2+, etc.)


Figure 12.27 Hydrocephalus in a newborn.



Blood-brain barrier (BBB)


True or false: the blood-brain barrier keeps

everything bad out of the brain.

1) True

2) False



Spinal Cord


Figure 12.29a Gross structure of the spinal cord, dorsal view.

Cervical

enlargement

Dura and

arachnoid

mater

Lumbar

enlargement Conus

medullaris

Cauda

equina

Filum

terminale

Cervical

spinal nerves

Lumbar

spinal nerves

Sacral

spinal nerves

Thoracic

spinal nerves

(a) The spinal cord and its nerve

roots, with the bony vertebral

arches removed. The dura mater

and arachnoid mater are cut

open and reflected laterally.


Figure 12.29c Gross structure of the spinal cord, dorsal view.

Vertebral

arch

Denticulate

ligament

Dorsal root

Spinal dura

mater

Dorsal

median

sulcus

Spinal cord

Denticulate

ligament

Arachnoid

mater

(c) Thoracic spinal cord, showing

denticulate ligaments.


Figure 12.30 Diagrammatic view of a lumbar tap.

Ligamentum flavum

Supra- spinous ligament

Lumbar puncture needle entering subarachnoid space

Filum terminale

Inter- vertebral disc

T12

L5

Cauda equina in subarachnoid space

Dura mater

L5

L4

S1

Arachnoid matter



Spinal Cord:

Cross-sectional anatomy


Figure 12.31a Anatomy of the spinal cord.

(a) Cross section of spinal cord and vertebra

Epidural space (contains fat)

Pia mater

Spinal meninges

Arachnoid mater

Dura mater

Bone of vertebra

Subdural space

Subarachnoid space (contains CSF)

Dorsal root ganglion

Body of vertebra


Figure 12.31b Anatomy of the spinal cord.

(b) The spinal cord and its meningeal coverings

Dorsal funiculus

Dorsal median sulcus

Central canal

Ventral median fissure

Pia mater

Arachnoid mater

Spinal dura mater

Gray commissure

Dorsal horn Gray matter

Lateral horn

Ventral horn Ventral funiculus

Lateral funiculus

White columns


Dorsal root (fans out into dorsal rootlets)

Ventral root (derived from several ventral rootlets)

Spinal nerve


Which nerve root has a ganglion?

1) Dorsal

2) Ventral

3) Anterior

4) Posterior


Figure 12.32 Organization of the gray matter of the spinal cord.

Somatic sensory neuron

Dorsal root (sensory)


Visceral sensory neuron

Somatic motor neuron

Spinal nerve

Ventral root (motor)

Ventral horn (motor neurons)

Dorsal horn (interneurons)

Visceral motor neuron

Interneurons receiving input from somatic sensory neurons

Interneurons receiving input from visceral sensory neurons

Visceral motor (autonomic) neurons

Somatic motor neurons


Figure 12.33 Major ascending (sensory) and descending (motor) tracts of the spinal cord, cross-sectional view.

Ascending tracts Descending tracts

Fasciculus gracilis Dorsal white column

Fasciculus cuneatus

Dorsal spinocerebellar tract

Lateral spinothalamic tract

Ventral spinothalamic tract

Ventral white commissure

Lateral corticospinal tract

Lateral reticulospinal tract

Ventral corticospinal tract

Medial reticulospinal tract

Rubrospinal tract

Vestibulospinal tract

Tectospinal tract

Ventral spinocerebellar tract


Figure 12.34a Pathways of selected ascending spinal cord tracts (2 of 2).

Medulla oblongata

Fasciculus cuneatus

(axon of first-order sensory neuron)

Fasciculus gracilis

(axon of first-order sensory neuron)

Axon of

first-order

neuron Muscle spindle (proprioceptor)

Joint stretch receptor (proprioceptor)

Cervical spinal cord

Touch

receptor

Medial lemniscus (tract)

(axons of second-order neurons) Dorsal

spinocerebellar tract (axons of second-order neurons)

Nucleus gracilis Nucleus cuneatus

Lumbar spinal cord

(a) Spinocerebellar

pathway

Dorsal column–medial

lemniscal pathway


Figure 12.34a Pathways of selected ascending spinal cord tracts (1 of 2).

Primary

somatosensory

cortex Axons of third-order

neurons

Thalamus

Cerebrum

Midbrain

Cerebellum

Pons

(a) Spinocerebellar

pathway

Dorsal column–medial

lemniscal pathway


Figure 12.35a Three descending pathways by which the brain influences movement (1 of 2).

Primary motor cortex

Internal capsule

Cerebral

peduncle

Midbrain

Cerebellum

Cerebrum

Pons

(a)

Pyramidal cells

(upper motor

neurons)

Pyramidal (lateral and ventral corticospinal) pathways


Figure 12.35a Three descending pathways by which the brain influences movement (2 of 2).

Medulla oblongata

Cervical spinal cord

Skeletal

muscle

Pyramids

Decussation

of pyramid Lateral

corticospinal

tract

Ventral

corticospinal

tract

Lumbar spinal cord

Somatic motor neurons (lower motor neurons)

(a) Pyramidal (lateral and ventral corticospinal) pathways

CHAPTER 12 CENTRAL NERVOUS SYSTEM - Warner …classpages.warnerpacific.edu/bdupriest/BIO 221/Chapter...

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