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2010-11-05 21:21:32

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  1. Frontal Lobotomy
    • ‘cure’ mental illness in 20th century

    • •(1936 Egas Moniz): prefrontal “leukotomy”
    • aka lobotomy— incisions that destoyed connections between

    prefrontal region and rest of brain

    •Egas Moniz receives Nobel Prize 1949

    •before pharmacotherapy it was only “cure”

    • •Early on used for depression, obsessive compulsive
    • disorder, anxiety. ~40,000 done
    • before Rx

    •Walter Freeman (“The lobotomist”) and James Watts (USA)

    • “lobotomy gets them
    • home”
  2. Some Preliminary
    Brain Info
    Gyri (Gyrus): Ridges

    Sulci (Sulcus): Shallow grooves

    Fissures: Deep grooves


    • • largest
    • part of the brain

    • • controls
    • higher mental functions

    • • divided in
    • L & R cerebral hemispheres

    cortex = surface layer of gray matter

    nuclei = deeper masses of gray matter

    tracts = bundles of axons/white matter
  3. Rostral:
    • toward
    • forehead
  4. Caudal:
    • toward
    • cord
  5. Major
    parts of brain
    Cerebrum, cerebellum

    & brainstem
  6. Neural
    • surface
    • layer of gray matter
  7. Gray
    = neuron cell bodies, dendrites, and synapses

    • –forms
    • cortex over cerebrum and cerebellum

    • –forms
    • nuclei deep within brain
  8. White matter
    • bundles
    • of axons that form tracts that connect parts of the brain & gray matter
  9. Midsaggital (median) section of the brain
    • Parieto-occipital sulcus only seen on this
    • type of section
  10. Neural tube is the
    origin of brain
    Enlarges into 3
    primary brain vesicles
    •Prosencephalon (forebrain)

    •Mesencephalon (Midbrain)


    • Telencephalon:
    • Becomes cerebrum

    • Metencephalon:
    • Forms cerebellum and pons

    • Myelencephalon:
    • Becomes medulla oblongata

    • Note: Diencephalon
    • and Mesencephalon persist
  11. Brain protection
    & Support
    Physical protection

    • 1) Bones of the
    • cranium

    2) Cranial Meninges (Dura/Arachnoid/Pia)

    • 3) Cerebrospinal
    • fluid (CSF)

    Biochemical isolation

    • 4) Blood–brain
    • barrier
  12. Skull
    –Boneabsorbs most of impact

    - Shell of car absorbs most of impact
  13. cranial meninges
    –Membranes anchor brain in place

    –Seat belt keeps body from slamming into car
  14. Cerebrospinal
    Fluid (CSF)
    –Fluid absorbs and disperses shock

    –Airbag further cushions shock
  15. Cranial
    3 layers: Dura, Arachnoid, Pia

    Protect Brain from cranial trauma & continuous w/spinal meninges

    • • Outer membrane
    • Dura mater (endosteal layer)
    • Dura mater (meningeal layer)
    • Dural sinus: large collecting veins Between the layers

    • •Middle membrane
    • Arachnoid Mater (covers Pia)
    • Subarachnoid space: CSF

    • •Inner membrane
    • Pia mater: fits like a glove entirely covers all brain surface goes into all fissures and sulci
  16. Dural
    regions where dura mater dips down in between the brain regions.

    3 folded inner layers of dura mater that extend into cranial cavity & stabilize and support brain contain collecting veins (dural sinuses)
  17. dural sinuses
    large venous sinuses that drain CSF and CNS blood into jugular vein

    • 1)Falx Cerebri: contains Superior and
    • Inferior sagittal sinus (Projects between cerebral hemispheres)
    • 2) Tentorium Cerebelli (Separates cerebellum & cerebrum contains transverse Sinus)
    • 3) Falx Cerebelli divides cerebellar hemispheres
  18. Cerebrospinal
    Fluid made by choroid plexus of ventricles

    Made by specialized ependymal cells

    Approximately 500 ml/day

    • CSF is clear and colorless (150mL
    • circulate)

    • §Cushions and supports brain
    • Brain weighs less suspended

    §Transports nutrients, chemicals and wastes

    CSF is absorbed into venous blood via arachnoid villi (granulations) drains to dural sinuses
  19. Ventricles
    • Lateral ventricles: Each cerebral hemisphere contains one large lateral ventricle;separated by
    • a thin partition septa pellucidum

    • Third ventricle: within diencephalon
    • (thalamus on either side)

    Interventricular foramina aka Foramen of Monroe) joins lateral vents. w/3rd

    • Fourth ventricle: associated with pons and medulla oblongata; connected to 3rd ventricle by the cerebral aqueduct (of Sylvius) continuous
    • with the spinal cord, and connected to the subarachnoid space by the lateral and medial aperture (foramen of Luschka and Magendie)
  20. Blood
    Brain Barrier:
    • Isolates CNS neural tissue from general
    • circulation. BBB is formed by network of tight
    • junctions between
    • 1) Endothelial cells lining the CNS capillaries that have tight junctions between them (in contrast to periphery capillaries)
    • 2) Astrocytes have foot processes that influence capillary permeability. Guardians of the BBB permeability

    • Exceptions to BBB:
    • Not fully formed at birth
    • •Parts of the hypothalamus
    • •Capillaries of posterior pituitary and pineal glands
    • •Breaks in BBB where blood has direct
    • access: can monitor glucose, pH, and osmolarity
  21. Hydrocephalus
    • –Too much CSF production or too little drainage decreased removal can result in extra fluid
    • - Extra fluid compresses & distorts brain Causes ventricles to expand and put pressure on surrounding neural tissues
    • - Can result from blockage of aqueduct or subarachnoid
    • spaces
    • - In infants cranial sutures have not fused so the skull enlarges to accommodate fluid
    • •May cause retardation
    • –In adults, ventricles expand
    • •May damage neural tissue
    • –Surgical treatmentà shunts
    • –Drugs to decrease production of CSF e.g.Acetazolamide
  22. Brainstem
    • “The stalk of the brain” relays messages between the spinal cord and brain; composed of Midbrain and Hindbrain.
    • Medulla Oblongata/ Pons /Midbrain
  23. General Anatomy
    Medulla Oblongata
    Most inferior part of Brainstem: 3cm extension of spinal cord Pyramids and olives are visible on the surface

    Ascending and descending nerve tracts

    Nuclei of sensory and motor CNS (IX, X, Xl, Xll)
  24. Functions of Medulla
    • 1)Allows brain and spinal cord to communicate
    • 2)Coordinates complex autonomic reflexes
    • 3)Controls visceral functions: heart, vasoconstriction vasodilation and breathing
    • 4)non-vital reflexes i.e. coughing/sneezing swallwing/vomiting

    • 3 groups of Nuclei in the Medulla
    • 1.Autonomic nuclei that control visceral activities
    • 2.Sensory and Motor Nuclei of Cranial Nerves
    • 3.Relay stations along sensory and motor pathways
    Autonomic nuclei:
    1.Gray matter. ‘Vital’ centers monitor CO2 levels and make appropriate adjustments

    • Cardiovascular center: Cardiac (heart)
    • and vasomotor (vessels)
    • Respiratory rhythmicity center: Set “pace” as per input from pons.

    • Receive input (ascending/sensory) from cranial nerves, cerebrum and brain stem = output (descending/motor) to regulate activity of
    • peripheral systems (via tracts of white matter).

  26. M O/
    • 2. Sensory and motor nuclei: of 5 cranial
    • nerves, V, IX-XII

    4.Relay stations for sensory and motor:

    • Nucleus Gracilis and Nucleus cuneatus pass somatosensory information to thalamus. Tracts
    • leaving this area cross-over (decussate) to opposite side of spinal cord.
    • Pyramids (Nucleus cuteatus & gracilis)

    • Solitary nucleus: receives visceral
    • sensory information,Sneezing, coughing,
    • swallowing centers

    • Olivary nucleus: information from
    • somatic motor commands to cerebellar cortex
  27. Pons/
    • •Apneustic and pneumotaxic centers//respiratory centers
    • The pons regulates rate and depth of breathing By adjusting respiratory rhythmicity centers of medulla

    •Sensory and motor nuclei of 4 cranial nerves

    •Relay stations: pons links cerebellum w/brain stem, cerebrum & spinal cord: i.e. sensory & motor to cerebellum
  28. Brainstem:
    Midbrain /
    Connects pons and cerebellum with cerebrum

    • •Superior colliculus: visual reflex (turning from bright light)
    • •Inferior collicullus: auditory reflex (turning toward sound)
    • •Sensory and motor nuclei of 2 cranial nerves
    • •Substantia nigra: Helps fine-tune
    • voluntary motor activity “talks to the basal ganglia” (contain dopaminergic n.àParkinson’s d.)
    • •Reticular Activating System
    • –Helps maintain consciousness
    • •Nucleus ruber: (red nucleus)
    • - Involved in background muscle tone e.g. helps maintain posture
  29. Cerebellum “Little Brain”
    • •Input & Output
    • –Approximately 50 % of neurons in brain
    • –Purkinje cell: dendrites receive up to 200,000 synapses
    • –Folia = folds

    –Vermis =“worm” separates halves

    • 1) Adjusting Postural Muscles of Body:
    • Coordinates rapid, automatic adjustments to maintain balance and equilibrium
    • 2) Learning & Fine Tuning (conscious & subconscious movements): Compares motor commands with propriceptive information (position sense). Performs any adjustment to make the move smoother. Refines learned movement
    • patterns
    • Info.from proprioceptor/eyes/ears
    • via brainstem.
    • Fine tunes movement and makes it smoother with repetition
  30. Inner Brain Structures
    • •Major relay station for all sensory stimuli except olfaction
    • –Projects to primary somatic, gustatory, auditory and visual cortices in cerebrum

    • –Filters many signals out
    • Passes on only small portion of
    • Arriving sensory information
    • –Conscious awareness occurs in cortex
    • Coordinates activities of basal nuclei, limbic system and cerebral cortex by relaying info between them
  31. Thalamus cont'
    • Surrounds 3rd ventricle
    • oval Mass of gray matter (like 2 eggs side by side)
    • connected by intermediate mass (or interthalamic adhesion)

    Sensory information from spinal cord synapses in thalamus and the thalamus edits and synchronizes information

    • 23 nuclei in the thalamus:
    • Major players on the path to the cerebrum:
    • Medial geniculate nucleus: auditory information
    • Lateral geniculate nucleus: visual information

    • Other nuclei:
    • Coordinates activities of basal nuclei (motor &
    • learning), limbic system (emotion & motivation) and cerebral cortex (thinking, memory, language) by relaying info between them
  32. Diencephalon: Hypothalamus
    • Coordinates activities of nervous & endocrine systems
    • •Posterior & anterior pituitary
    • Control of autonomic function
    • Adjusts autonomic centers in pons and M.O. that
    • regulate heart rate, blood pressure, digestion respiration.

    •Subconscious control of skeletal muscle e.g. changes in facial expression that accompany rage

    • •Regulates body temperature (via M.O.)
    • •Circadian rhythms (day/night cycles)
    • •Drives: Controls hunger and thirst centers
    • •Feeding reflexes via mammaliary bodies
    • –ie) chewing, swallowing, licking
    • •Coordination between voluntary and
    • involuntary functions
    • –Thinking about a dangerous situation or stressful situation
    • Will make hr & respir rate increase e.g. Just thinking of IBHS exams = ­ b.p.
  33. Limbic System
  34. Hippocampus
    • Amygdala
    • Parts of thalamus & hypothalamus
  35. FCT
    limbic system
    • •Processing of memories
    • i.e. memory storage and retrieval
    • The hippocampus is important for transfer of immediate thoughts to long term memory stores

    •Important for emotional states, motivational drives and associated behaviors.

    • Input from many regions including olfactory

    • Limbic System: links conscious intellectual functions of cerebral cortex with unconscious and
    • autonomic brain stem functions.

    • e.g. Fornix tract of
    • white matter connects hippocampus with hypothalumus
  36. lymbic system associated diseases
    Famous” Lesions:

    1) Capgras (emotion)

    2) Clive Wearing*

    3) H.M. *

    • •Damage hippocampus
    • Can recall events from long ago but not hrs or
    • Minutes ago
  37. Reticular
    Activating System
    • Group of nuclei scattered throughout
    • brainstem. Nerve fibers connect hypothalamus, basal nuclei, cerebellum and cerebrum

    • •Controls cyclic activities such as sleep-wake
    • cycle

    •Clusters of gray matter scattered throughout pons, midbrain and medulla

    • •Regulate balance and posture
    • –relays information from eyes and ears to cerebellum
    • –gaze centers and central pattern generators

    •Includes cardiac and vasomotor centers

    • •Regulates sleep and conscious attention
    • –injury leads to irreversible coma
  38. Learning Objectives
    • •Review
    • what brain structures the forebrain, midbrain and hindbrain develop into.

    • •Review
    • what brain structures the telencephalon, diencephalon, mesencephalon, metancephalon and myelencephalon develop into.

    • •Understand
    • and describe how the skull, meninges, CSF and BBB protect.

    • •Describe
    • structure and function of Blood/brain and blood/CSF-barrier.

    • •Describe
    • the structure, function & importance of the brainstem regions

    • •Describe
    • the structure, function and importance of the cerebellum.

    • •Review
    • the structure, function and importance of the diencephalon & limbic system

    • •Review
    • clinical topics

    • •Review
    • the terms gyrus, sulcus and fissures.

    • •Where
    • does CSF get made? Absorbed?

    • •Flow
    • of CSF