1. Cerebellum Cerebellum - Two hemispheres with convoluted surfaces
Provides involuntary coordination of body movements
Input from inner ear, eye, and receptors from skeletal muscles
Makes body movements smooth and coordinated
Like “auto pilot” comparing brains intentions with what is happening in the body

2. Cerebellum
Figure 7.15a

3. Cerebellum
Figure 7.15a

4. Figure 7.15a

5. Figure 7.15a

6. Protection of the Central Nervous System
1) Scalp and skin 2) Skull and vertebral column 3) Meninges
Figure 7.16a

7. Protection of the Central Nervous System
4) Cerebrospinal fluid 5) Blood brain barrier
Figure 7.16a

8. Meninges Dura mater – means “tough mother”
p. 241 if you don’t believe me!
Double-layered external covering that folds inward in several areas
Periosteum – attached to surface of the skull
Meningeal layer – outer covering of the brain

9. Meninges 2) Arachnoid layer - Middle layer and is Web-like
The threadlike extensions connect to the pia mater
Subarachnoid Space – the space between the arachnoid layer and pia mater and contains cerebrospinal fluid.
3) Pia mater – means “gentle mother”. Internal layer and clings to the surface of the brain
Meningitis – inflammation of the meninges usually caused by a bacteria or virus.
In the brain the swelling is called encephalitis.
Diagnosed by a taking a Lumbar “spinal tap” from subarachnoid space.
Normal pressure is reduced and person must lay for 6 – 12 hours or suffer a spinal headache. (normal amount of CSF is 150 ml or about ½ cup)

10. Cerebrospinal Fluid
Cerebrospinal Fluid - Similar to blood plasma composition
choroid plexus - Clusters of capillaries hanging from the roof of the ALL brain ventricles.
Made of Ependymal Cells and produce the cerebrospinal fluid in the brain
Capillaries carry blood … so CSF is made from blood.
Forms a watery cushion to protect the brain
Circulated in arachnoid space, ventricles, and central canal of the spinal cord

11. Cerebrospinal Fluid Circulation
Inside the brain, CSFluid is continually moving
The CSF is produced in the ventricles at the same rate that it is returned into the bloodstream.
1) Circulation pattern begins in the TWO Lateral Ventricles
(one in each cerebral hemisphere)
2) … to the Third Ventricle (in diencephalon)
3) … through the cerebral aqueduct (midbrain)
4) … into the Fourth ventricle (dorsal to Brain Stem! Brain Stem!)
5) … some CSF moves down the Central Canal of the spinal cord but most of it goes into the Subarachnoid space through 3 openings in the fourth ventricle
6) … the CSF returns to the blood through openings called
Arachnoid Villus

12. Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17a–b

13. Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17c

14. Blood Brain Barrier
No other organ is so absolutely dependent on a constant internal environment (… duh, control center!)
Includes the least permeable capillaries of the body for protection
Excludes many potentially harmful substances
Useless against some substances
Fats and fat soluble molecules, Respiratory gases, Alcohol, Nicotine, Anesthesia

15. Traumatic Brain Injuries
Concussion - Slight brain injury
No permanent brain damage unless they are repeated … football, boxing, etc.
Contusion - Nervous tissue destruction occurs
Nervous tissue does not regenerate
Cerebral edema - Swelling from the inflammatory response
May compress and kill brain tissue. No room for fluids to go with the skull

16. Cerebrovascular Accident (CVA)
Cerebrovascular Accident (CVA) - Commonly called a stroke
The result of a ruptured or blocked blood vessel supplying a region of the brain
Brain tissue supplied with oxygen from that blood source dies
Loss of some functions or death may result

17. Alzheimer’s Disease Progressive degenerative brain disease
Mostly seen in the elderly, but may begin in middle age
Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons
Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

18. Spinal Cord
Extends from the medulla oblongata to the region of T12 vertebrae
Below T12 is the cauda equina (a collection of spinal nerves) means horse tail
Enlargements occur in the cervical and lumbar regions
In humans there are 31 pairs of spinal nerves that come from the spinal cord.
Figure 7.18

19. Spinal Cord Anatomy
Exterior white mater – myelinated conduction tracts
Sensory or Afferent Tracts - take impulses to the brain
 Motor or Efferent Tracts - carry impulses from brain to skeletal muscles
Figure 7.19

20. Spinal Cord Anatomy
Figure 7.19

21. Spinal Cord Anatomy
Internal gray matter - mostly cell bodies; looks like a butterfly
Dorsal (posterior) horns – contain association or interneurons
Anterior (ventral) horns – contains motor or efferent neurons
Dorsal Root Ganglia – contains sensory or afferent neurons
Spinal Nerves – created by fusion of dorsal and ventral roots
Figure 7.19

22. Spinal Cord Anatomy
Figure 7.19

23. Spinal Cord Anatomy Central canal - filled with cerebrospinal fluid
Meninges cover the spinal cord in the same way they cover the brain.
Figure 7.19

24. Peripheral Nervous System
Nerves and ganglia outside the central nervous system
Nerve = bundle of neuron fibers
Neuron fibers are bundled by connective tissue

25. Structure of a Nerve
Endoneurium – delicate connective tissue sheath that surrounds each individual nerve fiber
Perineurium – coarser connective tissue that binds groups of fibers into fascicles
Epineurium – Tough, fibrous sheath that binds together many fascicles to form a cordlike nerve
Figure 7.20

26. Cranial Nerves
12 pairs of nerves that are connected directly to the brain
Mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only

27. Distribution of Cranial Nerves
Figure 7.21

28. Cranial Nerves I Olfactory nerve – sensory for smell
II Optic nerve – sensory for vision
III Oculomotor nerve – motor fibers to eye muscles
IV Trochlear – motor fibers to eye muscles

29. Cranial Nerves
V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles
VI Abducens nerve – motor fibers to eye muscles
VII Facial nerve – sensory for taste; motor fibers to the face
VIII Vestibulocochlear nerve – sensory for balance and hearing

30. Cranial Nerves
IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx
X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera
XI Accessory nerve – motor fibers to neck and upper back
XII Hypoglossal nerve – motor fibers to tongue