Transcript Bio211 Lecture 19

The Central Nervous System
Brain II
Cranial Nerves
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Lecture Overview
• Review/Questions from last lecture (Brain I)
• Brain II (pp. 84-87)
– Cerebrum
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Myelinated tracts
Basal ganglia
Sensory areas
Motor areas
Brain coverings (meninges)
Cerebrospinal fluid (CSF)
Ventricular System
Cranial nerves
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Review of Major Brain Areas
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1
2
3
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4
5
6
7
8
10 (White part)
9
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Summary from Last Lecture
Part of Brain
Major Function
Brainstem
Medulla Oblongata
(Embryology?)
(Ventricles nearby?)
1.
2.
3.
Contains cardiac, vasomotor, and respiratory control centers
Nucleus gracilis/cunneatus
Origin of CN 9, 10, 11, 12
Pons
(Embryology?)
(Ventricles nearby?)
1.
Bridge between medulla and midbrain via transverse tracts (to cerebellum) and
longitudinal tracts(to medulla/midbrain)
Helps regulate rate and depth of breathing
Origin of CN 5, 6, 7, 8
Midbrain
(Embryology?)
(Ventricles nearby?)
Cerebellum
(Embryology?)
(Ventricles nearby?)
2.
3.
1.
2.
3.
4.
5.
1.
2.
3.
Major connecting center between spinal cord and brain and parts of brainstem
Contains corpora quadrigemina (visual and auditory reflexes)
Origin of CN 3 and 4
Location of red nucleus (rubrospinal tract)
Origin of substantia nigra
Subconscious coordination of skeletal muscle activity, maintains posture
Hemispheres separated by falx cerebelli and vermis
Cerebellar peduncles (sup, middle, inf) attach to rest of brainstem
Diencephalon (Embryology?)
(Ventricles nearby?)
Thalamus
1.
2.
3.
4.
gateway (relay) for sensory impulses heading to cerebral cortex; hearing, vision, taste
Crude interpretation for pain, touch, pressure, and temperature
relay for motor information (voluntary)
Forms walls of third ventricle
Hypothalamus
1.
2.
Vital functions associated with homeostasis, ANS, psychosomatic illness, feeding/satiety
Connected to pituitary by infundibulum (pituitary stalk)
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Brain - Cerebrum
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
-Over 85% of brain mass, with about 14 billion multipolar neurons in cortex
- Lobes names for overlying bones. (See sulci above for divisions)
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Brain - Cerebrum
Upper figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
Lateral Sulcus
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
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Dural Folds
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
Falx Cerebri – within longitudinal fissure; separates
cerebral hemispheres
Tentorium Cerebelli – above cerebellum; separates
occipital lobe from cerebellum
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Myelinated Tracts of Cerebrum
Figure From: Marieb & Hoehn, Human
Anatomy & Physiology, 9th ed., Pearson, 2013
Three types of myelinated
tracts form cerebral white
matter:
1. Association – same
hemisphere
2. Commisural – between
corresponding gyri in opposite
hemispheres (corpus callosum)
3. Projection (Projector) –
Ascending and descending
tracts
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Basal Nuclei (formerly basal ganglia)
• nuclei are masses of
gray matter in CNS
• deep within cerebral
hemispheres
• three nuclei: caudate
nucleus and putamen,
(together called the
striatum), and the
globus pallidus
• subconscious control
certain muscular
activities, e.g., learned
movement patterns
1.
Receive input from entire cerebral cortex.
2.
Relay motor impulses originating in the substantia
nigra (where is this?), along with their own output,
through the thalamus to the motor cortex to
influence muscle movement.
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Basal Nuclei – Transparent View
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
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Brain – Sensory and Motor Areas
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6
1
5
8
7
2
9
3
40
(Gnostic)
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Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013
*Somatosensory (in figure) = Somesthetic (in your notes)
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Meninges of the Brain
- dura mater – outer, tough (anchoring dural folds)
- Subdural space – like interstitial fluid
- arachnoid mater – web-like
*Singular of
meninges is
meninx
- Subarachnoid space – CSF
- pia mater – inner, delicate
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
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Cerebrospinal Fluid
• ~500 ml/day secreted by
choroid plexus of ventricles;
only ~120 ml present in
subarachnoid space at one
time
• circulates in all ventricles,
cerebral aqueduct, central
canal of spinal cord, and
subarachnoid space
• completely surrounds brain
and spinal cord
• clear liquid (more Na+ and
Cl-, but less K+, Ca2+, glucose,
and protein than plasma)
• nutritive and protective
(shock absorber)
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Flow of CSF
(Monro)
(Luscka)
(Magendie)
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
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Ventricles of the Brain
• interconnected cavities
• within cerebral hemispheres
and brain stem
• continuous with central canal
of spinal cord
• filled with cerebrospinal fluid
(CSF)
• lateral ventricles (2)
• rt/lt cerebral hemispheres
• under corpus callosum
• third ventricle (1)
• between thalamus
• fourth ventricle (1)
• between cerebellum and pons
• cerebral aqueduct connect 3rd and 4th
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Divisions of the Nervous System
You are
here
CNS
PNS
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Peripheral Nervous System
• Cranial nerves arising from the brain
• Somatic fibers connecting to the skin and skeletal
muscles
• Autonomic fibers connecting to viscera
• Spinal nerves arising from the spinal cord
• Somatic fibers connecting to the skin and skeletal
muscles
• Autonomic fibers connecting to viscera
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Cranial Nerves
Paired. Numbered (roughly) in the order of their occurrence
from anterior to posterior. Abbreviated using N or CN.
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Figure from: Hole’s Human A&P,
12th
edition, 2010
The Cranial Nerves
Numeral
Name
Function
Sensory, Motor, or Both (Mixed Nerve)
I
OLFACTORY (OLD)
OLFACTION/SMELL
SENSORY (SOME) 
II
OPTIC (OPIE)
VISION
SENSORY (SAY) 
III
OCULOMOTOR (OCCASIONALLY)
MOVE EYE; ACCOMMODATION;
PUPIL SIZE
MOTOR (MARRY)
IV
TROCHLEAR (TRIES)
MOVE EYE (superior oblique)
MOTOR (MONEY)
V
TRIGEMINAL (TRIGONOMETRY)
MAJOR SENSORY NERVE FROM
FACE; MASTICATION
(chewing)
BOTH (BUT)
VI
ABDUCENS (AND)
MOVE EYE (lateral rectus)
MOTOR (MY)
VII
FACIAL (FEELS)
MAJOR MOTOR NERVE OF FACE
BOTH (BROTHER)
VIII
VESTIBULOCOCHLEAR (VERY)
(ACOUSTIC)
HEARING AND EQUILIBRIUM
SENSORY (SAYS) 
IX
GLOSSOPHARYNGEAL (GLOOMY)
MOVE MUSCLES OF TONGUE AND
PHARYNX; CIRCULATORY
AND ESPIRATORY REFLEXES
BOTH (BIG)
X
VAGUS (VAGUE)
INNERVATE VISCERAL SMOOTH
MUSCLE; MUSCLES OF
SPEECH; CVS REFLEXES
BOTH (BOOBS)
XI
ACCESSORY (AND)
MOVE NECK MUSCLES
MOTOR (MATTER)
XII
HYPOGLOSSAL (HYPOACTIVE)
MOVE TONGUE; SPEECH,
MASTICATION,
DELGLUTITION (swallowing)
MOTOR (MOST)
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Cranial Nerves I and II
Olfactory (I)
• sensory
• fibers transmit
impulses associated
with smell
Optic (II)
• sensory
• fibers transmit
impulses associated
with vision
Figures from:
Martini,
Anatomy &
Physiology,
Prentice Hall,
2001
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Cranial Nerves III, IV, and VI
Oculomotor (III)
• primarily motor
• origin in midbrain
• motor impulses to
muscles that
• raise eyelids
Abducens (VI)
• primarily motor
• origin in pons
• motor impulses to the
lateral rectus (LR) muscles
that move the eyes
• move the eyes
• focus lens
• adjust pupil size
Trochlear (IV)
• primarily motor
• origin in midbrain
• motor impulses to
the superior oblique
(SO) muscles that
move the eyes
What’s a ganglion?
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Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Cranial Nerve V
Trigeminal (V)
• both sensory and motor
• origin in pons
• opthalmic division
Figure from: Hole’s Human A&P, 12th edition, 2010
• sensory from surface of eyes
(cornea), tear glands, scalp,
forehead, and upper eyelids
• maxillary division
• sensory from upper teeth,
upper gum, upper lip, palate,
and skin of face
• mandibular division
• sensory from scalp, skin of jaw,
lower teeth, lower gum, and
lower lip
• motor to muscles of mastication
and muscles in floor of mouth
Major sensory nerve of face
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Cranial Nerve VII
Figures From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed.,
Pearson, 2013
Facial (VII)
• both sensory and motor
• sensory from taste
receptors (ant. 2/3 tongue)
• motor to muscles of facial
expression, orbicularis
oculi, tear glands, and
submandibular and
sublingual salivary glands
Major MOTOR nerve
of face
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Cranial Nerves VIII and IX
Vestibulocochlear (VIII)
• sensory
• origin in pons
• sensory from
equilibrium receptors of
ear
• sensory from hearing
receptors
Glossopharyngeal (IX)
• both sensory and motor
• origin in medulla
• sensory from pharynx,
tonsils, tongue (post. 1/3),
and carotid arteries
• motor to parotid salivary
gland and muscles of
pharynx
Figures from: Martini, Anatomy &
Physiology, Prentice Hall, 2001
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Cranial Nerve X
Vagus (X)
Figure from: Saladin,
Anatomy & Physiology,
McGraw Hill, 2007
• both sensory and motor
• origin in medulla
• somatic motor to muscles of
speech and swallowing
• autonomic motor
(parasympathetic) to viscera of
thorax and abdomen
• CVS and respiratory reflexes
• sensory from pharynx,
larynx, esophagus, and viscera
of thorax and abdomen
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Cranial Nerves XI and XII
Accessory (XI)
• primarily motor
• origin in
medulla/spinal cord
• motor to muscles of
soft palate, pharynx,
larynx, neck
(sternocleidomastoid),
and back (trapezius)
Hypoglossal (XII)
• primarily motor
• origin in medulla
•motor to muscles of
the tongue
• impt in speech,
mastication, and
deglutition
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004
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