Lecture4: Histology Of Peripheral Nerve And Injury Flashcards
What does the Epineurium cover?
Covers the nerve trunk from outside
What does the Perineurium cover?
Surrounds each bundle of nerve fibres
What does the Endineurium cover?
Each nerve fibre separately
What connective tissue sheath is a dense CT and formed of collagen fibres?
Epineurium
Which connective tissue sheath is joined by tight junctions and forms the blood-nerve barrier?
The Perineurium
Which connective tissue sheath has fine reticular fibres in between axons to allow distribution of blood supply?
Endoneurium
What is the difference between both sheathed peripheral and central nerve fibres?
Central has only myelin, not neurilemma
What is the Internodal segment?
The segment between 2 nodes, occupied by a single Schwann Cell
What is the function of the internodal segment?
Insulation, fast conduction of nerve impulse, and protection of the nerve fibre
Where are nerve fibres that are myelinated with neurilemma?
In nerve trunks
Where are unmyelinated with neurilemma only?
In autonomic nervous system
Where are nerve fibres that are naked with no sheath?
In the terminal part of the axons
What is Chromatolysis?
Dispersion of nissl granules, decreased basophilia
What are the changes that happen to Schwann cells in Wallerian Degeneration?
They proliferate to fill area of synapse, and lose their ability to synthesize myelin
What is the fate of the degenerated cells?
Phagocytosis by macrophages and Schwann cells
