Download Structured Overview

Unit 9 CNS Structured Overview—use in conjunction with lecture notes!
BRAIN DEVELOPMENT (WITH CRANIAL NERVES, CN)
Ectoderm
Prosencephalon
Telencephalon
Cerebrum
(stimulated (forebrain)
Diencephalon
Epithalamus
by
Thalamus
notochord)
Hypothalamus
Mesencephalon
Mesencephalon
Midbrain
neural tube Rhombencephalon
Metencephalon
Cerebellum
(hindbrain)
Pons
Myelencephalon Medulla oblongata
BRAIN STRUCTURE & FUNCTION
Medulla
Relay center
Brain stem—
Basic life support
Autonomic centers
Lateral ventricles
CN 1
3rd ventricle
CN 2
aquaduct of Sylvius
CN 3-4
4th ventricle
CN 5-8
CN 8-12
Sensory tracts
Motor tracts
Cardiovascular center
Respiratory center
Other centers
Pons
Midbrain
Relay center
Control functions:
Relay center
Corpora
quadragemina
Substantia nigra
Red nuclei
Cerebellum
Reticular
formations
Mixed axons & cell
bodies
Peduncles
To brain stem
Vermis connects
R/L cerebellar
hemispheres
Cortex
Medulla
Ant/Post Lobes
Flocculonodular lobe
Processing:
Olives—proprioception
Pyramids—decussation:
contralateral connections
Heart rate & force
Breathing depth & rate
Rhythmicity (with pons)
Coughing, sneezing, hiccuping,
swallowing, vomitting
Connects medulla with midbrain
Breathing rhythmicity (with medulla)
Connects pons with diencephalon (thalamus)
Superior colliculi
Head/eye movement in
scanning/following objects
Inferior colliculi
Startle reflex; auditory signal
relay to thalamus
Muscle tone/coordination—dopamine. Parkinson’s =
degeneration of dopamine-secreting nuclei.
Unconscious motor activities.
Relay center
Spinal cord to thalamus
Arousal from sleep
Control functions
Consciousness
Filters sensory input
Relay: ipselateral connections
Grey matter
Folia
White matter
Arbor vitae
Coordination of skeletal muscle movement initiated by cerebrum
Regulates posture, equilibrium & balance
Input from inner ear (semicircular canals, utricle & saccule)
Evaluation
Recommendation to cerebrum on
Cerebrum
how to proceed
of
Proprioceptors
signals
Inner ear
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Diencephalon
Hypothalamus
Relay function
Joins midbrain to thalamus
Infundibulum of pituitary attaches inferiorly
Visceral Mammillary bodies: Olfactory reflex
control
ANS control: Sympathetic & parasympathetic
Endocrine system control
Control function
(12 nuclei)
Emotion perception/response through medulla
Cerebrum
Thalamus
Large; lateral lobes
joined by
interthalmic
adhesion
Epithalamus
Pineal gland
Anatomy
Lateral
hemispheres
Medulla:
White matter
Circadian rhythms
Temperature homeostasis
Osmoregulation of blood
Nutrient levels in blood
Relay function—
Hypothalamus & cerebrum
connects
Cerebral hemispheres
Control functions: Evaluates sensory input into
cerebrum
Regulates mood & emotion (with
limbic system)
Melatonin—triggers sleep (with hypothalamus)
Split by longitudinal fissure
Joined by corpus callosum
Tracts
Association: Gyri in same hemisphere
Commissural: Gyri between hemispheres
(corpus callosum)
Projection: Gyri to/from lower parts of
brain/spinal cord—corona radiata
Basal
Include
Lentiform Putamen
nuclei
nucleus
Globus pallidus
Caudate nucleus
Amygdaloid nucleus
Connections Nuclei connect to one another
Input: Cerebral cortex
Output: Thalamus to motor
control centers of cerebrum
Functions
Begin/end motor & cognitive
functions
Regulates rhythmic movement
Inhibits unnecessary movement
Integrates with limbic system to
control emotions
Limbic
Includes thamic & hypothalmic nuclei
system
(mammillary bodies)
Connections Input: Lower & higher brain
regions
Output through hypothalamus
Functions
Emotions: Recognition/
generation (amygdala)
Memory
Smell memory
Hippocampus
accesses
Amygdala associates
with emotions
Psychosomatic illnesses
Emotion vs logic
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Cortex: Grey
matter, 2-3
mm thick
General
functions
Functional
divisions
Structural
divisions w/
functions
Consciousness & self awareness
Cognition, thought, memory
Reception & interpretation of sensory
signals
Voluntary movement
Sensory areas
Receive stimuli
Homunculus map
Association areas—evaluate sensory
signals, memory, upper cognition &
personality
Motor areas
Send motor signals
Homunculus map
Frontal lobe
Somatic motor function
(primary motor cortex)
incl. Broca’s area
Advanced problem solving
Cognition & personality
General sensory
processing (primary
sensory cortex)
Reading & speech
interpretation, incl.
Wernicke’s area
Temporal lobe Hearing (primary
auditory cortex)
Smell (primary
olfactory cortex)—
cranial nerve I
Memory
Occipital lobe Sight (primary visual
cortex)
R hemisphere: Somatic sensory input from L side
“The arts &
Somatic motor output to L side
senses”
Music/art abilities & perceptions
Emotion recognition, language assn.
Facial discrimination & recognition
Mental imaging
Odor discrimination & identification
L hemisphere: Somatic sensory input from R side
“Analysis &
Somatic motor output to R side
language”
Reasoning & logic
Analytical skills; mathematics
Language
Spoken
Written
Sign
Parietal lobe
Hemisphere Lateralization: R/L
hemispheres not functionally
symmetrical!
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MENINGES
Dura mater
Epidural space
Toughest meningeal layer
Dural sinuses
Extensions of dura mater
Arachnoid mater
Pia mater
Spinal cord
Well-developed; CT including adipose
Brain
Poorly-developed
Dense-irregular CT
Drain blood from skull—internal jugular vein
Arachnoid villi—CSF absorption
Falx cerebri—separates R/L cerebral hemispheres
Falx cerebelli—separates cerebellar hemispheres
Tentorium cerebelli—separates cerebrum from cerebellum
Subdural space—interstitial fluid
Delicate tissue—collagen & elastin
Subarachnoid space—CSF
Arachnoid villi—extend into dural sinuses; site of CSF absorption
Delicate tissue—collagen & elastin
Denticulate ligaments—spinal cord only
CEREBROSPINAL FLUID (CSF)
Formation
Circulation:
systolic
pressure waves;
2 by
ependymal cilia
Reabsorption
Ependymal cells
Line ventricles & central canal
Choroid plexi
Lateral ventricles/roof of third ventricle
(choroid papilli)
Fourth ventricle
1. Lateral ventricles (separated by septum pellucidum) (Produces CSF)
2. Interventricular foramina
3. Third ventricle
4. Aquaduct of Sylvius
5. Fourth ventricle (adds
Into subarachnoid
Lateral apertures
CSF), CSF exits:
space via
Medial aperture
Into central canal
6. Down central canal to end, into subarachnoid space
7. Posteriorly down subarachnoid space of spinal cord
8. Anteriorly up subarachnoid space of spinal cord into brain
Arachnoid villi; CSF reabsorbed into venous circulation in dural sinus.
Hydrocephalus
BLOOD BRAIN BARRIER
Structure/
physiology
Permeability
CNS capillaries highly impermeable
Astrocyte foot processes regulate permeability
Can’t pass through:
Large molecules:
basement membrane stops
Nitrogenous wastes &
waste-forming molecules:
Proteins
Antibiotics
Antibodies
Ammonia, urea, uric acid, creatine
Nonessential amino acids
Proteins
Pass through via
passive transport:
Glucose
Essential amino acids
Most ions (not K+)
Pass through via simple diffusion
Water
Can pass through:
Respiratory gases (O2, CO2)
lipid solubles
Vitamins
Fats & fatty acids
Alcohol
Nicotine
Anaesthetics
Actively transported
K+
out:
Nonessential amino acids
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CNS ENERGY ISSUES: ENERGY SOURCE
Not amino acids
Toxic nitrogenous wastes
Glucose
Aerobic respiration: needs O2
High vascularization required
Anaerobic respiration avoided Lactate buildup = brain swelling
Blockage = brain goes anaerobic
SPINAL CORD ANATOMY
Spinal nerves, paired
Cervical 8
Thoracic 12
Lumbar 5
Sacral 5
Coccygeal 1
Enlargements
Cervical
Lumbar
Lumbar region
Conus medullaris—L1
Cauda equina; L3 lumbar punctures
Functional anatomy
White matter
External
Myelinated
Divided by
Grey matter:
external
Posterior median sulcus
Anterior median fissure
Joined by anterior white commissure
Tracts of myelinated axons:
Sensory tracts
Motor tracts
Internal
Nonmyelinated
R & L horns
Posterior
Associative neurons
(dorsal) grey Input:
Lateral: Somatic sensory
horns
Dorsal roots Medial: Visceral sensory
Lateral grey Thoracic & lumbar areas only
horns
Cell bodies
Output:
Visceral motor neurons
Ventral roots
Anterior
Cell bodies
(ventral)
Output:
Somatic motor neurons
gray horns
Ventral roots
Grey
Connects R & L horns
commissure Central canal
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