PHT2162 Unit 5 Exam Study Guide
Nerve Anatomy - Answer Neurons have axons & dendrites
Endoneurium
fascicle
perineurium
nerve
epineurium
endoneurium - Answer Covering the neuron
fascicle - Answer Bundles of neurons
perineurium - Answer Covering the individual fascicle is the
Nerve - Answer Bundles of fascicles and blood vessels make a
epineurium - Answer Covering the nerve
Peripheral Nerve Injury - "Seddon's Classifications" - Answer Neurapraxia:
Axontmesis:
Neurotmesis:
Neurapraxia: - Answer o Mild nerve stretch or contusion
o Focal conduction block of message
o No Wallerian degeneration
o No disruption in myelin sheath
o Epineurium, perineurium, endoneurium intact
o Prognosis excellent; full recovery
o EX: foot falls asleep, hitting funny bone
Axontmesis: - Answer * tmesis means cut
o Injury to neuron that destroys the axon but does not do damage to the other
supporting structures of the cell, making regeneration possible. Often caused by
prolonged or severe compression (crush trauma). Wallerian degeneration occurs.
Wallerian degeneration - Answer Injury to axon and the myelin sheath starts to
degenerate and unravel everything distal to the lesion
, Axons die and the schwann cells and the endoneurium stay in place
Wallerian Regeneration - Answer Axons in the proximal segment regrow into the distal,
denervated segment.
Growth occurs at a rate of about 1 inch a month
Once the axons regrow back into the denervated muscles, the muscles will begin to
function again
During the time it takes for the axons to regrow into the muscles the muscles will be
paralyzed and will atrophy ; but recovery is possible
It will start regenerating from the proximal end and follows the schwann cells; about 6
months to a year it will continue to regenerate.
Neurotmesis: - Answer o A complete anatomical disruption of both the axon and all of
the surrounding connective tissue (rupture of the nerve) Mechanism is laceration or
severe blunt trauma. Requires surgical intervention to save neurological function
o Prognosis will be different and things may not grow back normally
o Neuroma formation usually happens after this injury;
Neuroma - Answer clumps of nerve endings growing everywhere unable to find the path
back to the muscle because it's been split.
Nerve Plexuses - Answer o A plexus is a interconnected network of peripheral nerves
originating from multiple root levels; nerve roots co-mingling with each other
Four Plexuses: - Answer Cervical- C1-C5
Brachial- C5-T1
Lumbar- T12-L5
Sacral- L4-S5
Cervical Plexus (C1-C5) - Answer spinal accessory
phrenic
Spinal Accessory Nerve - Answer Coming from the brain stem, but it also comes from
the cervical plexus
Innervates: the trap and SCM
Phrenic Nerve 3,4,5 - Answer Coming off the cervical plexus
Innervates: the diaphragm
Brachial Plexus (C5-T1) - Answer Comes out between the scalenes;
Nerve Anatomy - Answer Neurons have axons & dendrites
Endoneurium
fascicle
perineurium
nerve
epineurium
endoneurium - Answer Covering the neuron
fascicle - Answer Bundles of neurons
perineurium - Answer Covering the individual fascicle is the
Nerve - Answer Bundles of fascicles and blood vessels make a
epineurium - Answer Covering the nerve
Peripheral Nerve Injury - "Seddon's Classifications" - Answer Neurapraxia:
Axontmesis:
Neurotmesis:
Neurapraxia: - Answer o Mild nerve stretch or contusion
o Focal conduction block of message
o No Wallerian degeneration
o No disruption in myelin sheath
o Epineurium, perineurium, endoneurium intact
o Prognosis excellent; full recovery
o EX: foot falls asleep, hitting funny bone
Axontmesis: - Answer * tmesis means cut
o Injury to neuron that destroys the axon but does not do damage to the other
supporting structures of the cell, making regeneration possible. Often caused by
prolonged or severe compression (crush trauma). Wallerian degeneration occurs.
Wallerian degeneration - Answer Injury to axon and the myelin sheath starts to
degenerate and unravel everything distal to the lesion
, Axons die and the schwann cells and the endoneurium stay in place
Wallerian Regeneration - Answer Axons in the proximal segment regrow into the distal,
denervated segment.
Growth occurs at a rate of about 1 inch a month
Once the axons regrow back into the denervated muscles, the muscles will begin to
function again
During the time it takes for the axons to regrow into the muscles the muscles will be
paralyzed and will atrophy ; but recovery is possible
It will start regenerating from the proximal end and follows the schwann cells; about 6
months to a year it will continue to regenerate.
Neurotmesis: - Answer o A complete anatomical disruption of both the axon and all of
the surrounding connective tissue (rupture of the nerve) Mechanism is laceration or
severe blunt trauma. Requires surgical intervention to save neurological function
o Prognosis will be different and things may not grow back normally
o Neuroma formation usually happens after this injury;
Neuroma - Answer clumps of nerve endings growing everywhere unable to find the path
back to the muscle because it's been split.
Nerve Plexuses - Answer o A plexus is a interconnected network of peripheral nerves
originating from multiple root levels; nerve roots co-mingling with each other
Four Plexuses: - Answer Cervical- C1-C5
Brachial- C5-T1
Lumbar- T12-L5
Sacral- L4-S5
Cervical Plexus (C1-C5) - Answer spinal accessory
phrenic
Spinal Accessory Nerve - Answer Coming from the brain stem, but it also comes from
the cervical plexus
Innervates: the trap and SCM
Phrenic Nerve 3,4,5 - Answer Coming off the cervical plexus
Innervates: the diaphragm
Brachial Plexus (C5-T1) - Answer Comes out between the scalenes;
