Nerves II

Question 1

describe the choroid plexus

Answer 1

• invaginated folds of pia mater containing tufts of fenestrated capillaries covered by simple cuboidal ependymal cells
• lateral, 3rd and 4th ventricles
• ependymal cells modified to produce CSF by transporting and secreting material from the fenestrated capillaries

Question 2

describe the cerebrum

Answer 2

• cerebral cortex and white matter
• 6 layers
• pyramidal cells are found in layers 3 and 5

Question 3

describe the cerebellar cortex

Answer 3

• 3 layers of gray matter
• molecular layer (outer)
  
  • stellate cells
  • basket cells
• Purkinje cell layer (middle layer)
  
  • single layer of motor neurons
• granular layer (inner layer)
  
  • granule cells
  • type II Golgi cells

Question 5

describe Purkinje cells

Answer 5

• located between outer molecular layer and inner granular layer
• apical dendrites
  
  • that arborize in molecular layer
• have a single axon
  
  • extends into granular layer
  • represents beginning of outflow from cerebellum

Question 6

describe the meninges

Answer 6

• dura mater:
  
  • outer covering
  • dense CT
  • vascular
  • innervated
• arachnoid mater
  
  • loose CT
  • lined back to back by simple squamous epi.
  • avascular
• Pia mater
  
  • loose CT
  • lies directly on brain + spinal cord
  • vascular

Question 7

describe the epineurium

Answer 7

• outermost tissue of peripheral nerve
• typical dense CT
  
  • binds fascicles together
• adipose tissue often seen in larger nerve sheaths
• carry blood vessels supplying nerves
  
  • vessels branch and penetrate perineurium

Question 8

describe the perineurium

Answer 8

• surrounds bundles of nerve fibers
• sheath of unique connective tissue cells
  
  • epithelioid myofibroblasts
• cells joined by tight junctions
• restrict passage of most macromolecules - blood-nerve barrier
• has contractile property
  
  • numerous actin microfilaments

Question 9

describe endoneurium

Answer 9

• associated with individual nerve fibers
• consists of thin layer of reticular fibers produced by the Schwann cells

Question 10

describe the enteric nervous system

Answer 10

• confined within wall of gut
• 2 sets of plexus:
  
  • myenteric (Auerback)
  • submucosal (Meissner)
• composed of unmyelinated nerve fibers intermingled with neuronal cell bodies
• maintain peristaltic movements and secretory function of gut

Question 11

Answer 11

• neuronal cell bodies (post ganglionic parasympathetic) making up the Auerbach’s plexus

Question 12

describe the BBB

Answer 12

• continuous capillaries
  
  • complex tight junctions between endothelial cells
  • continuous basal lamina
  • no fenestration in cytoplasmic membrane
• surrounded by foot processes of astrocytes