Neurology (01/23) Ascending Sensory Systems Flashcards
cerebral blood flow is constant with regional changes due to what three things?
- autoregulation
- collaboration of brain and vessels
- cerebral vascular autonomics
one mechanism used to maintain constant cerebral blood flow that includes vessels being stretch sensitive and constricting under low pressure and dilating under high pressure
autoregulation
somatosensory receptors detect what three types of changes?
- mechanical
- chemical
- thermal
somatosensory receptors are ______ neurons
pseudounipolar
where are the cell bodies located for somatosensory receptors (pseudounipolar neurons)?
dorsal root ganglion or cranial nerve ganglion
somatosensory receptors have both a ____ process and a _____ process with an ending in the skin, muscle, or a joint
- CNS
- PNS
what are the two types of encapsulated receptors in the skin?
- pacinian corpuscles
- meissner corpuscles
for hairy skin, the receptor endings ____ ____ hairs
wrap around
hairless skin
glabrous
type of receptor in the skin that uses discriminative touch and is concentrated in finger tips. it uses A-beta (fast conducting) fibers
meisser corpuscle
type of receptor in the skin that uses discriminative touch and is used for fine detail (edges of objects, texture). it uses A-beta (fast conducting fibers)
merkel nerve ending
pathway of touch sensation in the posterior column
medial lemniscal pathway
the medial lemniscal pathway uses two point discrimination and is involved with _____ proprioception. it decussates in the _____ and relays info in the _____ thalamus. it ultimately terminates in the _____ _____
- conscious
- medulla
- lateral
- postcentral gyrus
spatial resolution correlates with number of _____ receptors
cutaneous
there are more meissner corpuscles and merkel endings in the finger tip than in the hand so two-point discrimination is more sensitive in the _____ ____
finger tip
type of receptor in the skin that is used to detect vibration (pressure). it is concentrated in the fingers and palm and uses A-beta (fast conducting) fibers
pacinian corpuscle
what three things do free nerve endings give the sensation of?
- pain
- crude touch
- temperature
for nocireceptors, thermoreceptors, and some mechanoreceptors, temperature sensitivity is due to _____ that open with a specific range of temperatures
channels
sharp prick or well-localized pain that has a short duration and is carried by rapidly conducting myelinated fibers
fast (delta) pain
slow, poorly localized, aching pain that may follow delta pain and is carried by unmyelinated fibers
slow pain
both the ascending and descending pathways in the spinal cord are located in well defined locations in the _____ matter
white
what are the three types of ascending/descending pathways?
- LONG ASCENDING fibers going to thalamus/cerebellum/brainstem
- LONG DESCENDING fibers going from cerebral cortex/brainstem to spinal cord gray matter
- SHORT PROPRIOSPINAL fibers interconnecting different spinal cord levels (used for reflexes)(will not be taught about)
fibers with similar connections (destinations) tend to travel together and form ____ in the spinal cord
tracts
descending tracts are primarily located in the _____ and _____ funiculi
- anterior (AF)
- lateral (LF)
ascending tracts are found in all three ______
funiculi
anterior, lateral, posterior
propriospinal fibers surround the spinal cord ____ matter
gray
the medial lemniscus system is located in the ____ column and conveys ____ and _____ _____ info
- posterior
- touch
- limb position
column that is comprised mostly of ascending large myelinated primary afferents from various mechanoreceptors
posterior column
what system is the main way that info from cutaneous, joint, and muscle receptors reaches the cortex
medial lemniscus system
in the medial lemniscus system, the spinal afferents have their cell bodies in _____ dorsal root ganglion
ipsilateral
what are the two divisions in which the dorsal root ganglion rootlets enter the cord fibers?
- medial (heavy myelinated, large diameter)
- lateral (finely myelinated and unmyelinated, small diameters)
division of the medial lemniscus system that is composed of heavily myelinated, large diameter fibers that enter posterior column and ascend to brainstem
medial
division of the medial lemniscus system that is composed of finely myelinated and unmyelinated, small diameter fibers
lateral
in the medial lemniscus system, fibers interring posterior columns are added _____ to those already present, so a pattern of _____ develops
- laterally
- lamination
in the medial lemniscus system, the sacral levels are the most _____ and the cervical levels are the most ____
- medial
- lateral
_____ organization is typical of sensory and motor pathways
somatotopic
in the medial lemniscus system, the fibers ultimately reach the brainstem and synapse in ____ ____ and _____
- nucleus gracilis
- cuneatus
in the medial lemniscus system, SECOND ORDER fibers cross the midline in the ____ ____ and form the _____ _____
- caudal medulla
- medial lemniscus
in the medial lemniscus system, THIRD ORDER fibers originate in the _____ (ventral posterolateral nucleus) and ascend through the internal _____ and synapse in primary ______ cortex located in the _____ _____
- thalamus
- capsule
- somatosensory
- postcentral gyrus
in the medial lemniscus system, _____ _____ is preserved as fibers end in posterior column nuclei and in medial lemniscus
somatic organization
injury of the medial lemniscus system leads to impaired ____ and discriminative _____ functions, especially complete _____ ______
- proprioception
- tactile
- tactile discrimination
injury to the what system is tested by placing a vibrating tuning fork on the body surface or have the patient identify a pattern drawn on their skin
medial lemniscus system
proprioception can be lost completely after a posterior column injury resulting in _____ which causes uncoordinated movements as brain is unable to direct motor activity without feedback from the body
ataxia
in the medial lemniscus pathway, sensory info reaches the brain in ____ pathways, so damage to a single pathway _____ leads to total loss of funciton
- multiple
- rarely
in the medial lemniscus system, if posterior columns are injured there is a large deficit at first but in time some ____ is possible
recovery
in the medial lemniscus system, if the posterior column is injured, what two things with most likely be unable to be repaired
- discriminiate complex shapes (stereognosis)
- direction/speed of stimulus moving across skin
one of multiple pathways that convey pain and temperature info and is involved in awareness and localization of painful stimuli ultimately ending in VPL of thalamus and some nearby thalamic nuclei
spinothalamic tract
pain pathways that end in reticular formation or limbic system to mediate other pain responses along with the spinothalamic tract together are known as?
anterolateral pathway
in the spinothalamic tract/anterolateral pathway, pain, temp, and some mechanoreceptor fibers enter cord via ____ division of dorsal root, project ____ to posterior horn, and many synapse in the _____ _____
- lateral
- branches
- substantia gelatinosa
in the spinothalamic tract/anterolateral pathway, neurons in other laminae form _____ order neurons that cross midline with _____ inclination, they collect and form the anterolateral pathway
- second
- rostral
in the spinothalamic tract/anterolateral pathway, after the second order fiber cross the midline, new fibers join at the ______ ____
anteromedial edge
in the spinothalamic tract/anterolateral pathway, the caudal body parts are in the ______ portion and the rostral body parts are in the _____ portion
- posterolateral
- anteromedial
in the spinothalamic tract/anterolateral pathway, there are multiple origins, destinations, and functions related to ___ and ____
- pain
- temp
in the spinothalamic tract/anterolateral pathway, ______ fibers start in laminae I and V and project to VPL, similar to lateral lemniscus
spinothalamic
in the spinothalamic tract/anterolateral pathway, _____ areas involve are widespread (post central gyrus, insula, others) and reflects our complex conscious awareness of ____
- cortical
- pain
in the spinothalamic tract/anterolateral pathway, _______ fibers (also from laminae I and V) are important in pain control mechanisms
spinomesencephalic
in the spinothalamic tract/anterolateral pathway, _______ fibers mediate autonomic response to pain
-spinohypothalamic
damage to the anterolateral pathway causes loss of what 4 sensations
- pain
- temp
- itch
- tickle
area also known as 312
brodman’s area
in a cordotomy, you destroy the ______ tract to produce contralateral analgesia in patients with severe and non curable pain (last several months)(use on terminal pts)
spinothalamic
ipsilateral tract that just deals with the leg, conveys NONCONSCIOUS PROPRIOCEPTIVE info
posterior spinocerebellar tract
in the posterior spinocerebellar tract, collaterals from posterior columns convey tactile pressure and proprioceptive info that synapse in ____ ____
clarke’s nucleus
in the posterior spinocerebellar tract, fibers enter cerebellum (vermis and adjacent hemispheres) via _____ ____ _____
inferior cerebellar peduncle
_____ _____ does not exist caudal to about L2 so neither does the posterior spinocerebellar tract
clarke’s nucleus
in the posterior spinocerebellar tract, afferents from levels caudal to L2 ascend to L2 via _____ ____ and synapse on _____ ____
- fasciculus gracilis
- clarke’s nuclues
tract that deals only with the arm, fibers DO NOT project to clarke’s nucleus but instead ascend in fasciculus cuneatus to lateral cuneate nucleus in medulla
cuneocerebellar tract
the cuneocerebellar tract enters the ____ ____ ____ to synapse in ____ and nearby cerebellar hemispheres
- inferior cerebellar peduncle
- vermis
tract that crosses twice so remains ipsilateral and conveys more complex info to cerebellum
anterior spinocerebellar tract
the origin of the anterior spinocerebellar tract is at the lateral surface of the anterior horn at ____ levels
lumbar
the anterior spinocerebellar tract is primarily concerned with leg but differs form posterior spinocerebellar tract in the fact that inputs are more _____ and related to ____ ____ than simple sensory signals
- complex
- attempted movement
