BRAIN

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BRAIN CRANIAL NERVES

• The brain and spinal cord develop from ectoderm

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The brain and spinal cord develop from the neural
tube

• Prosencephalon (Forebrain)
• Mesencephalon ( Midbrain)
• Rhombencephalon (Hindbrain)
• Primary brain vesicles are present around the 3rd
  week of development

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Prosencephalon (forebrain)

• Differentiates in 5th week into
• Telencephalon
• cerebral hemispheres
• Diencephalon
• thalamus hypothalamus
• pineal gland

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Midbrain

• Mesencephalon remains the same
• Brainstem midbrain

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Rhombencephalon

• Metencephalon
• cerebellum, pons
• Myelencephalon
• medulla oblongata

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Meninges

• Dura mater
• dural septa (extensions) falx cerebri, falx
  cerebelli, tentorium cerebelli
• Arachnoid
• Pia mater
• Cavities
• subarachnoid space, subdural space

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4 Ventricles filled with CSF

• Lateral ventricles (paired)
• Interventricular foramen connects to 3rd
  ventricle
• Third ventricle
• Cerebral aqueduct connects 3rd and 4th
  ventricles
• Fourth ventricle
• Connects with central canal of spinal cord

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Cerebrospinal Fluid

• Clear, colorless fluid that protects brain
• Formed by the choroid plexus
• Absorbed by arachnoid villi

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Parts of the Brain
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Medulla oblongata

• Major reflex center for the cardiovascular and
  respiratory system
• vasomotor, vasoconstriction
• Pyramids - decussation (crossing) center for
  motor tracts
• Non-vital center for coughing, hiccuping,
  swallowing, vomiting
• Ascending/descending fibers pass through
• Cranial nerves VIII-XII arise here

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PONS

• Acts as a bridge connecting the spinal cord to
  the brain
• Major relay center for voluntary skeletal
  movements from the cerebral cortex to the
  cerebellum
• Coordinates with the medulla to regulate
  respiration
• Cranial nerves V-VIII emerge here

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Midbrain

• Corpora quadrigemina
• Visual and auditory reflex centers
• Cerebral peduncles - containing large fiber
  tracts going to and from the brain
• Houses the cerebral aqueduct
• Cranial Nerves III-IV emerge here

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Thalamus

• Two halves connected by the intermediate mass
• Relay center for ALL sensory cranial and spinal
  nerves
• Interpretation center for crude awareness of
  pain, temperature and pressure
• Location of 3rd ventricle

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Hypothalamus

• Links the nervous system and endocrine system
• Major regulator of homeostasis
• Regulates many ANS functions
• Regulates appetite, water balance, thirst, body
  temperature
• Emotional part of brain - pleasure, fear, rage

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Cranial Nerves

• 12 Pairs
• 1 Olfactory - smell
• 2. Optic - sight
• 3. Oculomotor - eye movements
• 4. Trochlear - eye movements
• 5. Trigeminal - eyes face, chewing
• 6. Abducens - eyes

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Cranial Nerves (continued)

• 7. Facial - facial expression, taste
• 8. Vestibulocochlear - equilibrium, hearing
• 9. Glossopharyngeal - tonge swallowing
• 10. Vagus - heart, visceral organs
• 11. Accessory - neck back
• 12. Hypoglossal - tongue

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Cerebellum

• Second largest area of the brain
• 2 cerebellar hemispheres
• Arbor vitae - branchlike pattern
• Vermis - wormlike structure that connects left
  right side
• Major coordination of skeletal muscle contraction
• Assists with posture and balance

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Cerebrum

• Cerebral cortex - outer layer of gray matter
• Two hemispheres separated by longitudinal fissure
• Gyri - ridges on surface
• Sulci - grooves on surface
• Fissures
• Septum pellucidum - thin wall between ventricles

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Lobes of the Brain

• Frontal
• Parietal
• Occipital
• Temporal
• Central sulcus
• Lateral sulcus

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Cerebral Dominance

• Left hemisphere
• Language
• Logic
• Math

• Right Hemisphere
• Artistic
• Musical
• Creative

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Cerebral Cortex Specialization

• Motor Areas
• Control opposite side of body
• Control voluntary motor functions
• Sensory Areas
• Detect sensations from opposite side of body
• Association Areas
• Integrate diverse information into purposeful
  action

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Association Areas

• Prefrontal Cortex intellect, learning,
  personality
• Language Areas
• Wernickes area sounding out new words
• Brocass area speech
• General Interpretation
• Visceral Interpretation

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Basal Ganglia

• Cerebral nuclei
• Islands of gray matter located deep within the
  white matter
• Function controls large automatic skeletal
  muscle movements and produce dopamine

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White Matter

• Commissural fibers (corpus callosum) - connect
  corresponding parts of two hemispheres
• Association fibers - connect within the same
  hemisphere
• Projection fibers (higher centers to lower ones)

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Limbic System

• Includes part of thalamus, hypothalamus, and
  cerebrum
• Emotional brain
• Associated with memory
• Involuntary behavior for survival
• Pleasure and pain centers - fear, sorrow,
  affection

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Reticular Formation

• RAS System - reticular activating system
• Network of gray matter extending from the
  medulla, pons, midbrain into the cortex
• Maintains consciousness
• Awaken from sleep
• Alerts brain of incoming sensory signals