PNS and neuropathy

what creates myelin?

schwann cells

what is endoneurium?

- connective tissue that encloses axons and their myelin sheaths

what is perineurium?

- connective tissue that bundles fibers into fascicles

what is epineurium?

- sheath around a nerve

what is a multipolar axon?

- most common type in CNS

- one axon + multiple dendrites

what is a unipolar axon?

- single process emerging from cell body

- found in invertebrates

what is a bipolar neuron?

- one axon + one dendrite

- found in retina, olfactory system, inner ear

what is pseudounipolar axon?

- single process splints into two branches

- found in dorsal root ganglia

what is the function of multipolar neuron?

- motor control

- integration of information

what is the function of unipolar neurons?

- simple reflexes

- basic conduction

what is the function of bipolar neuron?

- special sense transmission

what is the function of pseudounipolar neuron?

- sensory information from body to CNS

what is neuropraxia?

- only myelin is damaged

what is axonotmesis?

- axon and its myelin coating are disrupted

- integrity of outer connective tissue covers are maintained

what is neurotmesis?

- complete nerve and connective tissue are involved

what is PNS wallerian degeneration?

- process of anterograde degeneration of the axons and their accompanying myelin sheaths

- helps to create an environment for regeneration

what is the gold standard treatment if there is a large gap?

- autograft nerve grafting

what is a neuroma?

- disorganized fibrous mass that can develop and complicate restoration of nerve function after an injury

what is collateral branching of intact axons?

- starts within days of injury and lasts 3-6mo

- surviving axons in the region of the injury branch/sprout out towards the injured regions to try and reinnervate the muscle to restore function

what is presentation of peripheral nerve damage

- reduced or loss of function in associated structures

- gradual onset of numbness, pinprick sensation in feet or hands, which can spread to legs and arms

- sharp, burning, freezing pain

- extreme sensitivity to touch

- lack of coordination and falling

- pain

what are 3 LMN signs for peripheral nerve damage?

- fasciculations

- atrophy

- hyporeflexia