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

Cerebellum Figure 7.15a

Cerebellum Figure 7.15a

Figure 7.15a

Figure 7.15a

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

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

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

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) http://www.youtube.com/watch?v=PYoTQ9HG_cE http://www.youtube.com/watch?v=ayzKqxzTa7U&feature=related

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

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 http://www.youtube.com/watch?v=JCf273U0ktc http://www.youtube.com/watch?v=PUb8iLgpY8E&NR=1 https://www.youtube.com/watch?v=2MKNsI5CWoU

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

Ventricles and Location of the Cerebrospinal Fluid Figure 7.17c

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

Traumatic Brain Injuries Concussion - Slight brain injury No permanent brain damage unless they are repeated … football, boxing, etc. http://www.youtube.com/watch?v=Tyv4du7BTOc http://www.youtube.com/watch?v=fY7J7bccNoU http://www.youtube.com/watch?v=wMlpP2dqfW0&feature=related 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

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 https://www.youtube.com/watch?v=bp1HRfpOUo0

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 http://www.youtube.com/watch?v=IcuDz7tOL7E&NR=1&feature=fvwp

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

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

Spinal Cord Anatomy Figure 7.19

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

Spinal Cord Anatomy Figure 7.19

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

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

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

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

Distribution of Cranial Nerves Figure 7.21

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

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

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