525L3

• ‘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”

Gyri (Gyrus): Ridges

Sulci (Sulcus): Shallow grooves

Fissures: Deep grooves

Cerebrum:

• • 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

• toward
• forehead

• toward
• cord

Cerebrum, cerebellum

& brainstem

• surface
• layer of gray matter

= neuron cell bodies, dendrites, and synapses

• –forms
• cortex over cerebrum and cerebellum

• –forms
• nuclei deep within brain

• bundles
• of axons that form tracts that connect parts of the brain & gray matter

• Parieto-occipital sulcus only seen on this
• type of section

•Prosencephalon (forebrain)


•Mesencephalon (Midbrain)


•Rhombencephalon(hindbrain)

• Telencephalon:
• Becomes cerebrum

• Metencephalon:
• Forms cerebellum and pons

• Myelencephalon:
• Becomes medulla oblongata

• Note: Diencephalon
• and Mesencephalon persist

Physical protection

• 1) Bones of the
• cranium

2) Cranial Meninges (Dura/Arachnoid/Pia)

• 3) Cerebrospinal
• fluid (CSF)

Biochemical isolation

• 4) Blood–brain
• barrier

–Boneabsorbs most of impact

- Shell of car absorbs most of impact

–Membranes anchor brain in place

–Seat belt keeps body from slamming into car

–Fluid absorbs and disperses shock

–Airbag further cushions shock

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

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)

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

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

• 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)

• 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

• –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

• “The stalk of the brain” relays messages between the spinal cord and brain; composed of Midbrain and Hindbrain.
• Medulla Oblongata/ Pons /Midbrain

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)

• 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

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).

• 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

• •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

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

• •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

• •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

• 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

• 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.

• Amygdala
• Parts of thalamus & hypothalamus

• •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

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

• 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

• •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