Exam 4 Review:  Chapter 13:  Peripheral Nerve Histology

fascicles - The organizational subunits of peripheral nerves, the bundles of myelinated and unmyelinated processes being routed to and from similar destinations/locations which are bound by a dense fibrous connective tissue liner called the perineurium.

 

epineurium - The outermost dense irregular fibrous connective tissue protective sheath surrounding each peripheral nerve, composed of various nerve fascicles/bundles; this outer layer contains some adipocytes and small blood vessels.

 

perineurium - The intermediate layer of dense irregular fibrous connective tissue protective sheath surrounding each nerve fascicle/bundle within a peripheral nerve, composed of various nerve fascicles/bundles.

 

endoneurium - The innermost loose irregular fibrous connective tissue protective sheath surrounding each nerve fiber (axon or dendrite) within each fascicle/bundle of a peripheral nerve; this layer will be external to the myelin sheath of a myelinated axon; this inner layer contains some mast cells and small blood capillaries.

 

List:

1. the protective coverings of a peripheral nerve from deep to superficial.

          myelin sheath (certain myelinated axons only) -- endoneurium -- perineurium -- epineurium

Sketch and Label :

 

3. a cross-section of a nerve illustrating the connective tissue coverings, fascicles, myelin sheaths, and axons.