Neuro L5 Flashcards
Nucleus gracilus and nucleus cuneatus are collectively known as
Posterior column nuclei
Somatosensory receptors detect these types of changes
mechanical
chemical
thermal
All somatosensory receptors are this type of neuron
pseudounipolar
All somatosensory receptors have
1: Cell body in DRG or CN ganglion
2: A central CNS process
3: Peripheral process ending in skin, muscle, or joint
Cutaneous nerve endings are broadly divided into
Encapsulated
Nonencapsulated
Temperature sensitivity is due to
channels that open within a specific range of temperatures
Delta pain
Description
Myelination
Sharp, well localized, short duration
Carried by rapidly conducting myelinated fibers
Slow pain
Description
Myelination
Poorly localized, aching
carried by unmyelinated fibers
Three general types of ascending and descending pathways
1: Long ascending going to thalamus, cerebellum or various BS nuclei
2: Long descending going from cerebral cortex or BS nuclei to spinal cord gray
3: Short propriospinal fibers interconnecting spinal cord levels (coordinate flexor reflexes)
Descending tracts are primarily located in
Anterior funiculi
Lateral funiculi
Ascending tracts are primarily located in
Anterior funiculi
Lateral funiculi
Posterior funiculi
Propriospinal tract
Description/location
propriospinal fibers surround spinal cord gray matter
Discriminative touch is part of the _____ pathway located in ________
medial lemniscal pathway in the posterior column
Discriminative touch pathway synapses in ______then ____ to form _______ then to ____ then terminates in _____
synapses in medulla then decussates to form medial lemniscus then to Ventral posterolater nucleus of lateral thalamus
Terminates in postcentral gyrus
Posterior column is mostly
ascending large myelinated primary afferents from mechanoreceptors
Spinal afferents have their cell bodies where
ipsilateral DRGs
DRG rootlets enter cord fibers, divide into
Medial
Lateral
Medial division
Myelination
diameter
path
Heavily myelinated
large diameter
enter posterior column and ascend to brainstem
Lateral division
Myelination
diamter
finely myelinated and unmyelinated
small diameter
Rostral to this vertebral level, few fibers are added to fasiculus _____ and fasiculus ____ starts to form
Rostral to T6
fasiculus gracilis
fasiculus cuneatus starts to form
Fibers entering the posterior column are added ______ so sacral is most _____ and cervical is most______
added laterally
sacral is most medial
cervical is most lateral
Second order fibers of Medial lemniscus pathway
path
cross midline in caudal medulla and form medial lemniscus
Third order fibers path
Originate in
Go thru
Go to
Originate in thalamus (VPL)
asend thru internal capsule
synapse in primary somatosensory cortex in post central gyrus
Posterior column-medial lemniscus system info is important for
conscious appreciation of touch pressure vibration joint position/movement
Injury of posterior column medial lemniscus system leads to
Ataxia (from proprioception)
impaired complex tactile discrimination
Ability to discriminate complex shape of an object
sterognosis
Spinothalamic tract/anterolateral pathway conveys ______ info
pain and temperature
Spinothalamic tract/anterolateral pathway ends in
VPL of thalamus
or Reticular formation or limbic system to mediate pain responses (spinomesencephalic fibers go to PAG)
Pain, temperature, and some mechanoreceptor fibers enter cord via
project to
Many synapse in
lateral division of dorsal root
project to posterior horn
many synapse in substantia gelatinosa
In the anterolateral pathway, new fibers join at
anteromedial edge
Somatotopic organization of anterolateral pathway
Caudal body parts: posterolateral
Rostral body parts: anteromedial
Cortical areas involved in anterolateral pathway
widespread (postcentral gyrus, insula, others) reflects complex conscious awareness of pain
Types of fibers in anterolateral pathway
Spinothalamic
Spinoreticular
Spinomesencephalic (spine, midbrain)
Spinohypothalamic
Spinoreticular fibers important for
changes in level of attention of pain response
Spinomesencephalic fibers important for
pain control mechanisms
Spinohypothalamic fibers important for
mediate autonomic response to pain
damage to anterolateral pathway causes
Loss of pain and temperature sensations
Loss of itch and tickle sensations
Bowel, bladder pressure, sex sensations are saved because bilateral
Tactile deficit is NOT noted because most are in posterior columns
Primary somatosensory
postcentral gyrus
Cordotomy
destroy spinothalamic tract to produce contralateral analgesia
Cut lateral funiculus from dentiate ligament to ventral root
Cut rostral to highest level of pain
Three well characterized spinocerebellar tracts
Posterior spinocerebellar tract
Anterior spinocerebellar tract
Cuneocerebellar tract
Posterior spinocerebellar tract conveys this info
ipsilateral proprioceptive leg
Posterior spinocerebellar tract ascends this way thru ____
ipsilaterally through lateral funiculus
Posterior spinocerebellar tract synapses in
clarkes nucleus
Axons in the cuneocerebellar tract come from____, enter ______, synapse in____
cuneate nucleus
enter inferior cerebellar peduncle
synapse in vermis and cerebellar hemispheres
Anterior spinocerebellar tract origin
Lateral surface of anterior horn at lumbar levels
Anterior spinocerebellar tract is primarily concerned with _____
attempted movement of the leg (more complex than PSCT)
Anterior spinocerebellar tract path
crosses midline twice so ultimately ipsilateral
