residency neuro Flashcards
What steps does the nervous system take in response to type IV mechanorecptor depolarization?
- mechanical or alpha motor neuron
- cognitive or perceptual response
- local Sympathetic response
- Gamma motor or tonic guarding
What is perikaryon?
cytoplasm of the nerve cells nucleus
What are the small swellings at the end of the axon know as?
terminal buttons
What structures surround the axon of the nerve>
Schwan cells
what is the endonural fluid pressure
- the interstial fluid pressure inside the neural fascicle
2. slightly greater than the pressure in the surround tissues
What is the normal endoneurol fluid pressure for the median nerve?
2.5 mmHg
What are nerve roots more prone to entrapment than peripheral nerves?
- they lack perineurium and have poorly developed epineurium
- the perineurium helps to resist compression forces
What layer of connective tissue surrounding nerves helps to resist compression?
perineurium
What is the difference between simple and complex receptors?
- simple-branched or unbranched free nerve endings responsible for cutaneous, temperature and pain
- complex-associated with non neural tissues to complete their function such as a barorecptor or corpuscle
What is the cytoplasm of the nerve cell nucleus call?
Perikaryon
What is the function of the muscle spindle receptor?
responsible for the regulation of muscle tone via the muscle stretch reflex
How is the sensitivity of the muscle spindle regulated?
- intrafusal muscle tone regulates the tension or sensitivity of the receptor
- the gamma motor neuron projectes the efferent signal from the spinal cord to regulate the tone of the muscle spine
What is the purpose of the muscle spindle?
to regulate the tone of the muscle
What are the type II afferents of the muscle spindle?
- flower spray
- mylinated
- smallest of the spindle afferents
- attach directly to the striated portion of the fusiform muscle
- sense static activity
What happens when the muscle spindle is stretched?
- stretch causes tension on the nuclear bag or chain intrafusal muscle
- triggers the annulo spiral or flower spray afferents
- reflexive alpha motor or extrafuscle muscle contraction
What is the dual nociceptive system
- intrinsic- plexus of unmylinated nerve endings through out the tissues
- perivascular- nociceptive receptor system within blood vessels
What is the perivascular nociceptive system?
- all blood vessels, except skull capillaries, contain nociceptive free nerve endings
- activated by by extreme changes in vessel wall diameter
What is the pathway of the recurrent nerve?
- branches off or into the ventral rami since it is afferent only at this point
- picks up sympathetic efferents
- travels into/out the foramen
- afferents innervate the disc, anterior dura and PLL
What are the apical and basilar nuclei of the spinal cord?
- apical is lamina I and II of the dorsal horn
2. basilar is lamina V and VI of the dorsal horn
What nuclei in the dorsal horn play a role in the pain response?
- apical or lamina I and II
2. basilar or lamina V and VI
How do you stop peripherally regulated pain?
remove the primary cause of the type IV depolarization
At what point will a type IV mechanoreceptor stop firing
- they are non adapting so you must remove the stimulus
- deformity less than 3%
- thermal level below 44.8 C or 112 F
- normalize chemical levels
What subjective report or pain perception will clue you into referred pain versus nerve root compression
if the pain report skips from one spot to another it must be referred
Nerve root pain will travel the length of the nerve
What does the medial branch of the posterior rami innervate?
- afferent stimulus
- facets
- iliolumbar
- interspinal ligaments
- mulitifidus
- travels several segments
What is the segmental reference pattern for the MBPPR
- lumbar spine tends to innervate its segment plus one
2. upper cervical spine its level plus as many as five below
Why is the recurrent nerve referred to as a mixed nerve?
it contain afferents senory and efferent vasomotor fibers
What are the synaptic relay point so peripheral afferent nerves?
Dorsal root ganglion -> lamina I and II -> lamina V and VI
What is the pathway for sympathetic response to type IV depolarization?
Type IV -> lamina I and II -> lamina V adn VI -> medial and lateral column -> white rami -> sympathetic chain -> increased HR, BP, reparation, emotional reponse, loccal vascular response
What is the pathway for alpha motor response following type IV depolarization?
type IV -> apical nec -> basilar nuc -> ventral horn -> alpha motor neuron -> reflexive withdrawl
What is the pathway for perception of pain?
type IV -> apical nuclei -> basiclar nuclei -> cross spinal cord to lateral spinothalamic tract -> thalamus -> cortical projections to frontal lobe for emotion, pariatal lobe for logic ,temporal lobe for memory -> cascade of centrally regulated responses to pain
What type of subjective descriptors might someone use for vascular types of pain
throbbing, burning, pulsing, beating
What type of subjective descriptors might someone use for mechanical types of pain
stabbing, crushing, pinching, hot, searing, itchy, stinging, pulling, jumping, shooting, pricking, gnawing
What type of subjective descriptors might someone use for musculoskeletal types of pain
aching, sore, heavy, hurting, dull
What type of subjective descriptors might someone use for emotional types of pain
tiring, miserable, viscious, agonizing, nauseating, frightful, piercing, dreadful, punishing, torturing, killing, unbearable, annoying
What is the pathway for type I and II mechanoreceptor inhibition of pain?
type I and II -> apical nuclei of dorsal horn-> inhibition of dorsal horn basilar nuclei projections
How can immobilization influence the use of DH inhibition?
loss of elasticity reduces tissue response to loading
How can you recruit type I and II mechanorecptors for pain inhibition?
- high reps and low resistance exercises in pain free ranges
- massage with particular emphasis on skin stretching
- joint articulation or mobilization from loose pack position at 2 per second
- work above and below the segment in lesion
- distraction manipulation
What is the segmental referral pattern for the MBPPR and recurrent nerve?
- MBPPR one above and below up to as many as five below in the upper cervical spine
- RN 2-3 segments above and below
How do cutaneous receptors influence exercise response?
- effect gamma motor loop and muscle tone
2. minor influence directly on the alpha motor neurons
How can you use the muscle spindle to protect a pathological range of movement or position
- increasing spindle sensitivity will increase muscle recruitment for protecting to pathological position or movement
- you can increase spindle activity with repetitive motion up to but not into pathology
What role does the muscle spindle play in human performance?
- regulates ROM by facilitating alpha motor neurons in response to muscular tension
- weight lifters and their loss of ROM due to muscle tone
- swimmers and gymnast and their ability to perform through hypermobile ranges of motion
How does bilateral performance of motion increase torque capacity and why is this important to rehab?
- motion on one side will trigger and gamma motor response on both sides
- to improve recruitment on an inhibited muscle you can perform the same motion on the other side to improve recruitment
What are the layers of connective tissue around a nerve?
- ENDOneurium surrounds individual fibers
- PERIneurium surrounds fascicles or nerve fiber bundles
- EPIneurium surrounds bundles of fascicles
What much pressure will impair nerve function?
30 mmHg
What is normal nerve pressure?
2.5 mmHG
How much pressure is needed to inhibit blood flow?
- 30 mmHg impairs flow
- 50 mmHg occludes venules
- 60 mmHg complete ischemia
What are interoceptors?
- specialized nerve endings that convert visceral function into afferent nerve signals
- examples include chemoreceptors in blood vessels, baroreceptors detecting distension of hollow viscera
What are the different types of muscle spindle motor fibers?
- bag- the central nonelastic portion is a bag like collection of nuclei sensitive to both static and dynamic stimuli
- chain- the nuclei are lined up in series and are sensitive to dynamic stimuli
What are the anatomical parts of the muscle spindle?
- imbedded within and parallel to the muscle fiber
- they are encapsulated and contain 2-10 intrafusal muscle fibers of bag and chain type
- afferent signals are transmitted by 1a annulospiral and II flower spray nerve
What are the afferent nerves of the muscle spindle?
- Type Ia annulospiral to all lintrafusal muscles
2. II flow spray to static intrafusals only
What are type Ia annulospiral nerves?
- afferent nerves of the muscle spindle
- branched and nonmylinated
- very fast
- longest sensory fiber in the body
- wrap around nonstriated portions of intrafusal muscle
- sense dynamic and static activity
What is the pathway for tonic muscle guarding in response to type IV depolarization?
type IV -> DH apical nuc -> DH basilar nuc -> 2x
- ventral horn -> gamma motor neuron -> increased intrafusal muscle tone -> annulospiral and flower spray afferent -> alpha motor -> tonic guarding
- lateral spinothalamic trac -> thalamus and hypthalamus -> corticalspinal and reticulospinal trac -> DH apical nuc -> gamma motor …
What does the recurrent nerve innervate?
- 40-50% of annulus fibrosis
- blood vessels of the ventral canal
- ventral dura
- ascends one segment and descends two segments
- crosses to the contralateral side
- ALL and PLL
A balance of which neurologic systems is important for good connective tissue health?
1.afferent nociceptors
2.effernet sympathetics
they work together to balance autonomic function
What unique characteristics do type IV afferents nerves have?
- they are the smallest and slowest nerve of the nervous system
- extremely resistent to ischemia
- metabolic rate is proportional to their diameter
- extremely sensitive to local anesthetics
What are the charateristics of the somatosympathetic nerve fibers?
- small diameter afferents
- primarily white rami
- branches from the sympathetic chain
