Download Figure 13.13a - El Camino College

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prepared by Leslie Hendon,
University of Alabama,
Birmingham
13
HUMAN
ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
PART 2
The Central
Nervous
System
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publishing as Benjamin Cummings
The Brain

Performs the most complex neural functions
 Intelligence
 Consciousness
 Memory
 Sensory-motor integration
 Involved in innervation of the head
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Embryonic Development of the Brain


Brain arises from rostral part of the neural tube
Three primary brain vesicles in four-week old
embryo
 Prosencephalon – the forebrain
 Mesencephalon – the midbrain
 Rhombencephalon – the hindbrain
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Embryonic Development of the Brain

Secondary brain vesicles
 Prosencephalon
 Divides into telencephalon and diencephalon
 Mesencephalon – remains undivided
 Rhombencephalon
 Divides into metencephalon and myelencephalon
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Embryonic Development of the Brain

Structures of the adult brain
 Develop from secondary brain vesicles
 Telencephalon the cerebral hemispheres
 Diencephalon thalamus, hypothalamus, and
epithalamus
 Metencephalon pons and cerebellum
 Myelencephalon medulla oblongata
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Embryonic Development of the Brain

Brain stem includes
 The midbrain, pons, and medulla oblongata

Ventricles
 Central cavity of the neural tube enlarges
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Embryonic Development of the Brain
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Figure 13.7a–e
Embryonic Development of the Brain

Brain grows rapidly, and changes occur in the
relative position of its parts
 Cerebral hemispheres envelop the diencephalon
and midbrain
 Wrinkling of the cerebral hemispheres
 More neurons fit within limited space
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Brain Development from Week 5 to Birth
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Figure 13.8a–d
Basic Parts and Organization of the Brain

Divided into four regions
 Cerebral hemispheres
 Diencephalon
 Brain stem
 Midbrain, pons, and medulla
 Cerebellum
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basic Parts and Organization of the Brain
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Figure 13.9
Basic Parts and Organization of the Brain

Organization
 Centrally located gray matter
 Externally located white matter
 Additional layer of gray matter external to white
matter
 Due to groups of neurons migrating externally
 Cortex – outer layer of gray matter
 Formed from neuronal cell bodies
 Located in cerebrum and cerebellum
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basic Parts and Organization of the Brain
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.10
Ventricles of the Brain





Expansions of the brain’s central cavity
Filled with cerebrospinal fluid
Lined with ependymal cells
Continuous with each other
Continuous with the central canal of the spinal
cord
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Ventricles of the Brain

Lateral ventricles – located in cerebral
hemispheres
 Horseshoe-shaped from bending of the cerebral
hemispheres

Third ventricle – lies in diencephalon
 Connected with lateral ventricles by
interventricular foramen
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Ventricles of the Brain


Cerebral aqueduct – connects 3rd and 4th
ventricles
Fourth ventricle – lies in hindbrain
 Connects to the central canal of the spinal cord
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Ventricles of the Brain
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Figure 13.11a, b
The Brain Stem

Includes the
 Midbrain
 Pons
 Medulla oblongata
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The Brain Stem

Several general functions
 Produces automatic behaviors necessary for
survival
 Passageway for all fiber tracts running between the
cerebrum and spinal cord
 Heavily involved with the innervation of the face
and head
 10 of the 12 pairs of cranial nerves attach to it
 Which CN do NOT attach to brain stem?
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Ventral View of the Brain
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Figure 13.12
The Brain Stem – The Medulla Oblongata

Most caudal level of the brain stem
 Is continuous with the spinal cord
 Choroid plexus lies in the roof of the fourth
ventricle
 External landmarks of medulla
 Pyramids of the medulla
 Lie on its ventral surface
 Decussation of the pyramids
 Crossing over of motor tracts
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The Brain Stem – The Medulla Oblongata

External landmarks of medulla (continued)
 Inferior cerebellar peduncles
 Fiber tracts connecting medulla and cerebellum
 Olive (olive of the medulla)
 Contains inferior olivary nucleus
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The Brain Stem – The Medulla Oblongata

Cranial nerves VIII–XII attach to the medulla
 VIII – Vestibulocochlear
 IX – Glossopharyngeal nerve
 X – Vagus nerve
 XI – Accessory
 (Spinal Accessory – a branch of the vagus nerve)
 XII – Hypoglossal nerve
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The Brain Stem – Medulla Oblongata
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Figure 13.13a
The Brain Stem – Medulla Oblongata
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Figure 13.13b
The Brain Stem – The Medulla Oblongata

The core of the medulla contains
 Much of the reticular formation
 Nuclei influence autonomic functions
 Visceral centers of the reticular formation include
 Cardiac center
 Vasomotor center
 The medullary respiratory center
 Centers for hiccupping, sneezing, swallowing, and
coughing
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The Brain Stem – The Medulla Oblongata
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Table 13.1 (1 of 3)
The Brain Stem – The Medulla Oblongata
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Figure 13.13c
The Brain Stem – The Pons


A “bridge” between the midbrain and medulla
oblongata
Pons contains the nuclei of cranial nerves
 V – Trigeminal nerve
 VI – Abducens nerve
 VII – Facial nerve
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The Brain Stem – The Pons

The pons contains
 Motor tracts coming from the cerebral cortex
 Pontine nuclei
 Connect portions of the cerebral cortex and
cerebellum
 Send axons to cerebellum through the middle
cerebellar peduncles
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The Brain Stem – The Pons
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Figure 13.14b
The Brain Stem – The Pons
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Table 13.1 (2 of 3)
The Brain Stem – The Midbrain


Lies between the diencephalon and the pons
Cerebral aqueduct
 The central cavity of the midbrain

Cerebral peduncles located on the ventral surface
of the brain
 Contain pyramidal (corticospinal) tracts

Superior cerebellar peduncles
 Connect midbrain to the cerebellum
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The Brain Stem and Diencephalon
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Figure 13.13a
The Brain Stem and Diencephalon
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.13b
The Brain Stem – The Midbrain

Periaqueductal gray
matter surrounds the
cerebral aqueduct

Involved in two
related functions
 Fright-and-flight

reaction
Mediates response
to visceral pain
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Figure 13.21
The Brain Stem – The Midbrain

Corpora quadrigemina (quad-ri-gemina)
 The largest nuclei
 Divided into the superior and inferior colliculi
 Superior colliculi – nuclei that act in visual
reflexes
 Inferior colliculi – nuclei that act in reflexive
response to sound
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The Brain Stem – Dorsal View
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Figure 13.13c
The Brain Stem – The Midbrain

Imbedded in the white matter of the midbrain
 Two pigmented nuclei
 Substantia nigra – neuronal cell bodies contain
melanin
 Functionally linked to the basal nuclei
 Red nucleus – lies deep to the substantia nigra
 Largest nucleus of the reticular formation
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The Cerebellum

Located dorsal to the pons and medulla
 Smoothes and coordinates body movements
 Helps maintain equilibrium
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The Cerebellum


Consists of two cerebellar hemispheres
Surface folded into ridges called folia
 Separated by fissures

Hemispheres each subdivided into
 Anterior lobe
 Posterior lobe
 Flocculonodular lobe (tiny)
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The Cerebellum
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Figure 13.15a
The Cerebellum

Composed of three regions
 Cortex – gray matter
 Arbor vitae
 Internal white matter
 Deep cerebellar nuclei – deeply situated gray
matter
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The Cerebellum

Cerebellum receives information from the cerebral
cortex
 On equilibrium
 On current movements of
 Limbs, neck, and trunk
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The Cerebellum – Cerebellar Peduncles

Thick tracts connecting the cerebellum to the brain
stem are
 Superior cerebellar peduncles
 Middle cerebellar peduncles
 Inferior cerebellar peduncles

Fibers to and from the cerebellum are ipsilateral
 Run to and from the same side of the body
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