Brain

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Brain

• Meninges, ventricles, cerebrospinal fluid
  blood supply
• Hindbrain and midbrain
• Forebrain
• Limbic system

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Brain Description

• Brain weighs 3 to 3.5 pounds
• Major portions -- brainstem, cerebrum, and
  cerebellum
• cerebrum is 83 of brain volume
• ___________________ contains 50 of the neurons

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Brain

• Longitudinal fissure separates 2 cerebral
  hemispheres.

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Meninges

• Dura mater
• outer periosteal layer
• inner meningeal layer
• dural venous sinuses
• dural septa
• falx cerebri, falx cerebelli and tentorium
  cerebelli
• dural hemorrhages
• Arachnoid mater
• Pia mater

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Cranial Meninges
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Ventricles and Cerebrospinal Fluid

• Internal chambers within the CNS
• lateral ventricles
• third ventricle
• cerebral aqueduct
• fourth ventricle
• central canal of spinal cord
• Lined with ependymal cells and contains ______

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Brain Ventricles
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Cerebrospinal Fluid

• Clear liquid fills ventricles and canals bathes
  its external surface ________________________
• Brain produces absorbs about 500 ml/day
• filtration of blood through choroid plexus
• has more Na Cl- but less K,Ca2, and proteins
  than plasma
• Functions (3)
• Buoyancy, protection, and chemical stability
• Escapes from 4th ventricle to subarachnoid space
• Drains from _________________________ into venous
  sinus

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Flow of Cerebrospinal Fluid
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Blood-Brain and Blood-CSF Barriers

• BBB - endothelium perivascular astrocyte feet
• permeable to lipid-soluble materials (alcohol,
  O2, CO2, caffeine, nicotine and anesthetics)
• administer drugs through nasal sprays
• Circumventricular organs breeches in the system
• Hypothalamus, Post. pituitary, Pineal, Choroid
  plexus
• monitoring of glucose, pH, osmolarity others
• may allow route for HIV virus to invade the brain
• Blood-CSF barrier - choroid plexus is ependymal
  cells joined by _________________________

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Choroid Plexus
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Medulla Oblongata

• 3 cm long
• Ascending descending tracts
• CN nuclei (VIII, IX, X, XI, XII)
• Nuclei for somatic and visceral
  sensory somatic cerebellar relay
• Cardiac, vasomotor, respiratory centers
• Reflex centers for coughing, sneezing, gagging,
  swallowing, vomiting, salivation, sweating, and
  movements of the tongue and head

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Medulla and Pons
Olive
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Pons

• Bulge in the brainstem, rostral to the medulla
• Ascending sensory tracts
• Descending motor tracts
• Pathways in out of cerebellum - peduncles
• Nuclei concerned with sleep, hearing, balance,
  taste, eye movements, facial expression, facial
  sensation, respiration, swallowing, bladder
  control posture
• cranial nerves V, VI, VII, and VIII

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Cerebellum

• Connected to brainstem by cerebellar peduncles
• White matter _____________________
• Folia?
• Sits atop the 4th ventricle

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Input to Cerebellum
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Output from Cerebellum

• Smoothes muscle contractions, maintains muscle
  tone posture, coordinates motions of different
  joints, aids in learning motor skills
  coordinates eye movements

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Midbrain

• ____________________
• Mes. aqueduct
• CN III and IV
• eye movement
• Cerebral peduncles hold corticospinal tract
• Tegmentum connects to cerebellum helps control
  fine movements through red nucleus
• Substantia nigra sends inhibitory signals to
  basal nuclei thalamus

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Superior Inferior Colliculus

• Tectum (4 nuclei) called corpora quadrigemina
• superior colliculus
• inferior colliculus

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Reticular Formation

• Clusters of gray matter scattered throughout
  pons, midbrain medulla
• Regulate balance posture
• relaying information from eyes ears to
  cerebellum
• gaze centers allow you to track moving object
• Includes cardiac vasomotor centers
• Analgesic pathways
• Regulates sleep, conscious attention, fatigue

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Thalamus

• Oval mass of gray matter in center of
  ________________
• Receives nearly all sensory information on its
  way to cerebral cortex
• integrate directs information to appropriate
  areas
• Interconnected to limbic system so involved in
  emotional memory functions

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Hypothalamus

• Walls floor of 3rd ventricle
• Functions
• hormone secretion pituitary
• autonomic NS control
• thermoregulation
• food water intake
• sleep circadian rhythms
• memory (mammillary bodies)
• emotional behavior

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Epithalamus (Pineal Gland)
No output In fish, amphibians, and reptiles
monitors day and season length Endocrine
function in mammals, secreting melatonin Seasonal
sexual cycles Humans - circadian
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Cerebrum -- Gross Anatomy

• Cerebral cortex is 3mm layer of gray matter with
  extensive folds to increase surface area ----
  divided into lobes

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Functions of Cerebrum Lobes

• Frontal contains voluntary motor functions and
  areas for planning, mood, smell and social
  judgement
• Parietal contains areas for sensory reception
  integration of sensory information
• Occipital is visual center of brain
• Temporal contains areas for hearing, smell,
  learning, memory, emotional behavior

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Association Areas
Association areas interpret information

• Somesthetic association area
• limb position, location of touch or pain, and
  shape, weight texture of an object
• Visual association area
• identify the things we see
• Auditory association area
• remember the name of music or identify a person
  by voice
• Motor association area

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Tracts of Cerebral White Matter
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Basal Nuclei

• Masses of gray matter deep to cerebral cortex
• Receive input from substantia nigra motor
  cortex send signals back to these regions
• Involved in motor control inhibition of tremors

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LimbicSystem

• Loop of cortical structures surrounding deep
  brain
• amygdala, hippocampus, fornix cingulate gyrus
• Amydala important in ________________ and
  ____________________________ in memory

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Somesthetic Sensation

• Somatosensory area is postcentral gyrus

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Sensory Homunculus

• Demonstrates that the area of the cortex
  dedicated to the sensations of various body parts
  is proportional to how sensitive that part of the
  body is.

Ditto for Motor Homunculus
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Motor Control

• Intention to contract a muscle begins in motor
  association (premotor) area of frontal lobes
• Precentral gyrus (primary motor area) processes
  that order by sending signals to the spinal cord
• upper motor neurons
• to contralateral muscles
• Motor homunculus is proportional to number of
  muscle motor units in a region

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LEFT BRAIN FUNCTIONS uses logicdetail orientedfacts rulewords and languagepresent and pastmath and sciencecan comprehendknowingacknowledgesorder/pattern perceptionknows object namereality basedforms strategiespracticalsafe RIGHT BRAIN FUNCTIONS uses feeling"big picture" orientedimagination rulessymbols and imagespresent and futurephilosophy religioncan "get it" (i.e. meaning)believesappreciatesspatial perceptionknows object functionfantasy basedpresents possibilitiesimpetuousrisk taking