Peripheral Nervous System Flashcards
What forms the peripheral nervous system?
- axons of sensory, motor, and autonomic neurons
- specialized sensory endings
- entire postganglionic autonomic neruorns
What do peripheral nerves consist of?
parallel bundles of axons surrounded by three connective tissue sheaths: endoneurium, perineurium, and epineurium
What connective tissue separates individual axons?
endoneurium
What connective tissue surrounds fascicles?
perineurium
What connective tissue encloses the entire nerve trunk?
epineurium
What do peripheral nerves supply?
both the viscera (autonomic) and somatic structures
Are somatic peripheral nerves usually sensory, motor, or mixed?
mixed
What do the cutaneuous branches of somatic peripheral nerves supply?
the skin and subcutaneous tissues
What do the muscular branches of somatic peripheral nerves supply?
the muscles, tendons, and joints
What are peripheral axons classified according to?
speed of conduction and diameter
What do the junctions of anterior rami form?
nerve plexuses
What are the 4 nerve plexuses?
- Cervical
- Brachial
- Lumbar
- Sacral
The cervical plexus arises from the anterior rami of C_ to C_
C1 - C4
What does the cervical plexus supply?
- sensory information from the posterior scalp to the clavicle
- motor innervation of the anterior neck muscles and diaphragm
The brachial plexus arises from the anterior rami of C_ to T_
C5 - T1
What does the brachial plexus supply?
The entire motor and sensory innervation of the upper limb
The lumbar plexus arises from the anterior rami of L_ to L_
L1 - L4
What does the lumbar plexus supply?
The skin and muscles of the anterior and medial thigh
The sacral plexus arises from the anterior rami of L_ to S_
L5 - S4
What does the sacral plexus supply?
the posterior thigh and most of the leg and foot
Why is movement essential for nerve health?
It optimizes the health of nerves by promoting blood flow throughout the nerves and the flow of axoplasm through the axons
What does movement cause the axoplasm to do?
thin and flow more easily, facilitating axoplasmic transportation
Where do motor axons synapse with muscle fibers?
at neuromuscular junctions
Is summation of action potentials is required to depolarize the postsynaptic membrane at the neuromuscular junction?
No