1. The Brain and Cranial Nerves

2. Cerebrum Largest part of brain Controls higher mental functions
Divided into left and right cerebral hemispheres
Surface layer of gray matter (neural cortex)
Also called cerebral cortex
Folded surface increases surface area
Elevated ridges (gyri)
Shallow depressions (sulci)
Deep grooves (fissures)

3. Three Functional Principles of the Cerebrum
Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of the body
The two hemispheres have different functions, although their structures are alike
Correspondence between a specific function and a specific region of cerebral cortex is not precise

4. White Matter of the Cerebrum
Association fibers connect within on hemisphere
Arcuate fibers
Short
Connect one gyrus to another
Longitudinal fasiculi
Longer bundles
Connect frontal lobe to other lobes in same hemisphere
Commissural fibers connect two hemispheres
Projection fibers link cerebral cortex with diencephalon, brain stem, cerebellum, and spinal cord

5. Motor and Sensory Areas of the Cortex
Central sulcus separates motor and sensory areas

6. The percentages of total cerebral cortex volume for the different lobes are:
frontal lobe = 41%
temporal lobe = 22%
parietal lobe = 19%
occipital lobe = 18%

7. Hemispheric Lateralization
Functional differences
between left and right
hemispheres
Each cerebral
hemisphere performs
certain functions that are not ordinarily performed by the opposite hemisphere

8. The Basal Nuclei of the Cerebrum
Also called cerebral nuclei
Are masses of gray matter embedded in white matter of cerebrum
Direct subconscious activities
control of skeletal muscle tone
coordination of learned movement patterns (walking, lifting)

9. Cerebellum Second largest part of brain Two hemispheres
Covered with cerebellar cortex
Coordinates repetitive body movements
Adjusts postural muscles
Fine-tunes conscious and subconscious movements

10. Diencephalon Located under cerebrum and cerebellum
Links cerebrum with brain stem
Made up of:
Thalamus
Relays and processes sensory information
Hypothalamus
Hormone production
Emotion
Autonomic function
Pituitary Gland
Major endocrine gland
Interfaces nervous and endocrine systems

11. The Brain Stem Processes information between Includes
Spinal cord and cerebrum or cerebellum
Includes
Mesencephalon
Pons
Medulla oblongata

12. Mesencephalon Pons Medulla oblongata Also called midbrain
Processes sight, sound, and
associated reflexes
Maintains consciousness
Pons
Connects cerebellum to brain stem
Is involved in somatic and visceral motor control
Medulla oblongata
Connects brain to spinal cord
Relays information
Regulates autonomic functions: heart rate, blood pressure, and digestion

13. Embryological Development
Determines organization of brain structures
Neural tube- origin of brain

14. Ventricles of Brain Origin
Neural tube encloses neurocoel
Neurocoel expands to form chambers (ventricles) lined with ependymal cells
Each cerebral hemisphere contains one large lateral ventricle

15. Third ventricle Fourth ventricle Ventricle of the diencephalon
Lateral ventricles communicate with third ventricle:
via interventricular foramen (foramen of Monro)
Fourth ventricle
Extends into medulla oblongata
Becomes continuous with central canal of the spinal cord
Connects with third ventricle: via narrow canal in mesencephalon (aqueduct of midbrain)

16. Brain Protection and Support
Physical protection
Bones of the cranium
Cranial meninges
Cerebrospinal fluid
Biochemical isolation
Blood–brain barrier

17. The Cranial Meninges Dura mater Arachnoid mater Pia mater
Inner fibrous layer (meningeal layer)
Outer fibrous layer (endosteal layer) fused to periosteum
Venous sinuses between two layers
Arachnoid mater
Covers brain
Contacts epithelial layer of dura mater
Subarachnoid space: between arachnoid mater and pia mater
Pia mater
Attached to brain surface by astrocytes

18. Cerebrospinal Fluid (CSF)
Surrounds all exposed surfaces of CNS
Interchanges with interstitial fluid of brain
Functions of CSF
Cushions delicate neural structures
Supports brain
Transports nutrients, chemical messengers, and waste products

19. CSF formation & circulation
CSF circulates
From choroid plexus through ventricles to central canal of spinal cord
Into subarachnoid space around the brain, spinal cord, and cauda equina
Reabsorbed by arachnoid granulations in subarachnoid space

20. Brain Protection and Support
Blood–Brain Barrier
Isolates CNS neural tissue from general circulation
Allows chemical composition of blood and CSF to differ
Astrocytes control blood–brain barrier by releasing chemicals that control permeability of endothelium
Four Breaks in the BBB
Portions of hypothalamus secrete hypothalamic hormones
Posterior lobe of pituitary gland secretes hormones ADH and oxytocin
Pineal glands for pineal secretions
Choroid plexus where special ependymal cells maintain blood–CSF barrier

21. The Limbic System Establishes emotional states
Links conscious functions of cerebral cortex with autonomic functions of brain stem
Facilitates memory storage and retrieval

22. Four Categories of Brain Waves
Alpha waves
Found in healthy, awake adults at rest with eyes closed
Beta waves
Higher frequency
Found in adults concentrating or mentally stressed
Theta waves
Found in children
Found in intensely frustrated adults
May indicate brain disorder in adults
Delta waves
During sleep
Found in awake adults with brain damage
Brain Waves are analyzed with the use of an EEG or electroencephalogram

23. Cranial Nerves 12 pairs connected to brain
Four Classifications of Cranial Nerves
Sensory nerves: carry somatic sensory information, including touch, pressure, vibration, temperature, and pain
Special sensory nerves: carry sensations such as smell, sight, hearing, balance
Motor nerves: axons of somatic motor neurons
Mixed nerves: mixture of motor and sensory fibers