Download Nervous System: Brain and Cranial Nerves (Chapter 14) Lecture

Nervous System:
Brain and Cranial Nerves
(Chapter 14)
The Brain and Cranial Nerves
Spinal cord ! reflex = immediate response
Brain ! thinking = adaptable but slower
Lecture Materials
for
Amy Warenda Czura, Ph.D.
Suffolk County Community College
Eastern Campus
Brain Structure
1. Cerebrum
-largest part of human brain
-2 cerebral hemispheres covered in cerebral
(neural) cortex
-surface convoluted to increase surface area
for neurons (~3ft2)
-gyri = elevated ridges
-sulci = depressions
-fissures = big sulci
Primary Sources for figures and content:
Marieb, E. N. Human Anatomy & Physiology 6th ed. San Francisco: Pearson Benjamin
Cummings, 2004.
Martini, F. H. Fundamentals of Anatomy & Physiology 6th ed. San Francisco: Pearson
Benjamin Cummings, 2004.
-central sulcus divides frontal lobes from
parietal lobes
-lateral sulcus divides frontal lobes from
temporal lobes
-parieto-occipital sulcus divides parietal lobes
from occipital lobes
-insula located at base of lateral sulcus beneath
frontal and temporal lobes
-longitudinal fissure separates left and right
hemispheres
-base of fissure has corpus callosum: axons to
connect neurons of hemispheres
-hemispheres divided into five lobes each
Amy Warenda Czura, Ph.D.
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SCCC BIO130 Chapter 14 Lecture Notes
2. Cerebellum
-second largest part
-consists of right and left hemispheres
connected by the vermis
-covered in cerebellar cortex
-folia instead of gyri
-each hemisphere divided into anterior and
posterior lobes by the primary fissure
3. Diencephalon
-links cerebral hemispheres to brain stem
-3 parts: epithalamus, thalamus,
hypothalamus
4. Brain stem
-connects to spinal cord
-consists of mesencephalon, pons, and
medulla oblongata
5. Ventricles
-holes in brain that circulate CSF
A. Lateral ventricles
-in each cerebral hemisphere
B. Third ventricle
-in diencephalon
C. Fourth ventricle
-in between pons and cerebellum
-connects to central canal of spinal cord
2. Cranial meninges
-hold brain in place
-prevent contact with skull
A. Dura mater
-two layers
-no epidural space: fused to periosteum
-forms dural folds deep into fissures:
1. falx cerebri: between cerebral
hemispheres in longitundinal fissure
2. tentorium cerebelli: between cerebrum
and cerebellum
3. falx cerebelli: between cerebellar
hemispheres
Protection of the brain
1. Cranial bones: form the skull
-occipital, frontal, sphenoid, ethmoid,
parietals, temporals
Amy Warenda Czura, Ph.D.
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SCCC BIO130 Chapter 14 Lecture Notes
-volume of CSF in brain and cord turned over
every 8hrs
-choroid plexus secretes ~500ml/day
B. Arachnoid
1. arachnoid membrane
2. arachnoid trabeculae: span subarachnoid
space which contains CSF
C. Pia mater
-adheres to brain via astrocytes
-follows topology of gyri and sulci
-CSF reabsorbed at arachnoid granulations
3. Cerebrospinal fluid
-functions: a. cushion brain
b. support brain
c. diffusion medium
-produced by choroid plexus (= ependymal
cells plus capillaries in brain ventricles)
Hydrocephalus = (infants) failure to reabsorb
CSF, fluid expands cranium and crushes
brain
4. Blood-brain barrier
-capillaries of CNS less permeable:
-endothelial cells linked by tight junctions
-astrocytes cover capillary surface
http://www.telegraph.co.uk/news/graphics/2005/04/28/wviet28a.jpg
http://tier.cs.berkeley.edu/gallery/ghana05/IMGP1551_001
http://www.diagnostico.com/Trejos/HydrocephalusIII.JPG
Amy Warenda Czura, Ph.D.
-only lipid soluble compounds diffuse into
CNS, all others actively transported by
astrocytes
-inflammation (infection, cancer) can break
down blood brain barrier
http://uuhsc.utah.edu/healthinfo/images/ei_0433.gif
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SCCC BIO130 Chapter 14 Lecture Notes
Brain Anatomy:
(on handout)
Brainstem
1. Medulla Oblongata (details on handout)
3. Midbrain / Mesencephalon
(details on handout)
Diencephalon
(details on handout)
2. Pons (details on handout)
Cerebellum
(details on handout)
-located between cerebrum and diencephalon:
parts of both
-functions:
-establishes emotional states and drives
-links conscious functions of cerebrum
to autonomic functions of brainstem
-facilitates memory storage and retrieval
Special regions
1. amygdala: fight or flight, initiates fear
response, links emotion with memory
2. hippocampus: memory and learning
3. cingulate gyrus: expressing emotions via
gestures, & resolves mental conflicts
Ataxia = loss of balance due to disruption in
cerebellum (e.g. alcohol)
Limbic System
-functional not anatomical separation
Amy Warenda Czura, Ph.D.
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SCCC BIO130 Chapter 14 Lecture Notes
Cerebrum
(details on handout)
Examples of integrative centers:
1. Wernicke’s area = general interpretive area
-center of left hemisphere
-gives meaning to auditory or visual cues
2. Broca’s area = speech center
-left hemisphere superior to lateral sulcus
-coordinates motor controls for speech
3. Prefrontal cortex
-anterior frontal lobes
-prediction, estimation, and related emotions
Association and integration areas all over
cortex carry out all levels of thought but
in general:
-Left hemisphere: language, math, logic
-Right hemisphere: interpret sensory info,
generate emotions, spatial visualization
-each hemispheres sends info to opposite side
of body but each also has unique functions
-hemispheres communicate for whole thought
-if corpus callosum cut, hemispheres work
independently e.g.
(used as treatment for seizures)
Epileptic seizures = abnormal electrical activity
in brain; causes loss of normal function
Anencephaly = brain fails to develop above
mesencephalon, fatal
Cerebrovascular Accident (CVA) = “stroke”,
loss of blood supply to brain, neuron death
occurs in minutes
*Individual cranial nerves and their
innervations will be examined in detail in lab!
Amy Warenda Czura, Ph.D.
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SCCC BIO130 Chapter 14 Lecture Notes