Long Motor & Sensory Pathways Flashcards
corticospinal tract: primary motor pathway for voluntary willed ____ control
motor
how many neurons in the corticospinal tract?
two neurons
coericospinal pathway from cerebral cortex to arm
pyramids are part of the ____
medulla oblongata
where is the synapse of upper and lower motor neuron? (corticospinal)
ventral horn of gray matter
order these from top to bottom: pons, pyramids, cerebral cortex, medulla, midbrain
cerebral cortex
midbrain
pons
medulla
pyramids
upper motor neurons arises from the
cerebral cortex
the pre-central gyrus is the _____ ______ cortex
primary motor
what is the yellow? what is the green dotted line?
pre-central gyrus
central sulcus
homunculus means “ “
little man
motor homunculus has a ______ distribution of neuroplasticity
uneven distribution
the ratio of the amount of upper neuron cell bodies
path that upper motor neurons take
pre-central gyrus (primary motor cortex)
midbrain - cerebral peduncle
pons - pons proper
medulla
pyramid
spinal cord
UMN’s descending in the brainstem influence muscles on the ______ side of the body
contralateral
upper motor neurons run through what part of the spinal cord?
later part of white matter (funiculus “cable”)
where is the corticospinal tract found in the spinal cord?
lateral part of white matter
funiculus
where is the UMN to LMN synapse?
ventral horn
neuromuscular junction has what neurotransmitter?
Acetylcholine
the LMN synapses with a _____ ______ receptor
Nm
nicotinic cholinergic receptor
Corticospinal tract summary:
UMN arise from
Axon descends _______
Axon descends in the spinal cord and synapses in the _______
LMN exits the _____ ____ to the _____ root, then _____ ____
Lastly to skeletal muscle
decussation of long motor pathways
occurs at pyramids
Where would a UMN lesion happen?
from cerebral cortex to length of spinal cord
symptoms of UMN lesion
muscle weakness
hypertonia/tight muscles
no muscle atrophy
hyper-reflexia
babinski sign
where would a LMN lesion happen?
from ventral horn to neuromuscular junction
symptoms of LMN lesion
Hypotonia/flaccid muscles
Prominent muscle atrophy
Hypo-reflexia (DTRs)
Fasciculations
what motor loss would be expected if the right corticospinal tract @ the L4 spinal cord region were damaged?
L4 and everything below L4
what motor loss would be expected if the right cerebral peduncle was injured?
left side
- from the right midbrain to the pyramids (medulla)
- from the left pyramids all the way down
cerebral peduncle (midbrain) is before the decussation (crossing)
facial motor nucleus to the forehead is stimulated by UMNs from the:
- contralateral cerebral cortex
- ipsilateral cerebral cortex
pathways of facial motor neurons
how many facial motor neurons stem from R/L side and where do they go?
Right:
- three MNs
- two crosses to the left (forehead and cheek)
- one is ipsilateral (forehead)
Left:
- three MN
- two crosses to the right (forehead and cheek)
- one is ipsilateral (forehead)
if right facial motor neurons are damaged what areas would droop?
left cheek droops
the right side is normal because left MNs innervate
the left forehead is normal because left MNs innervate
what location has a nerve injury
right facial canal
LMN problem because the forehead is also drooping
what location has a nerve injury?
left primary motor cortex
The forehead is not droopy so it is a UMN problem
how to determine if the facial motor neuron injury is at UMN or LMN?
order of long sensory pathways in words (basic)
Receptor is stimulated→sensation relayed by neurons→spinal cord→thalamus→cerebral cortex→ consciousness is perceived
if the nerve damage is at the dorsal root ganglion,
identify the effects this patient
would most likely present with?
no sensory info
*at that level
sensations
vibration
proprioception
fine touch (discriminative)
pain
temperature
crude touch (non-discriminative)
each sensation is transmitted by ______ neurons through dorsal root
sensory
what part of spinal cord transports somatic sensory input to the cerebral cortex?
white matter
spinal cord white matter contains 2 major ascending pathways for somatic sensation which are:
DCML: dorsal column medial lemniscus
ALS: anterior lateral system
what sensations use the DCML of white matter?
vibration
proprioception
what sensations use the ALS of white matter?
pain
temperature
crude touch (discriminative)
sensory dissociation
pain/temp pathways ascend the spinal cord separately from vibration/proprioception
how many neurons do the DMCL and ALS systems use to get from the skin to the cerebral cortex?
three
what sensory neuron of DMCL/ALS systems does the decussation occur?
2nd order neuron
anterior lateral system ALS is also known as…
spinothalamic tract
where is ALS located in the spinal cord?
where is the synapse of the 1st-order and 2nd-order neuron?
dorsal horn
where is the synapse of the 2nd-order and 3rd-order neuron?
thalamus
what order neuron is the longest? ALS
2nd-order neuron
overview of ALS
if the right ALS on L4 is damaged… what will be lost and where?
pain/temp on the left side at/below L4
vibration would be ok
if the left ALS at level T4 is damaged… what will be lost and where?
pain/temp on the right side at/below T4
vibration would be ok
A
DCML stands for
dorsal column medial lemniscus
what sensations are associated with DCML?
vibration
proprioception
DCML pathway from foot to cerebral cortex
D
orient: thoracic level spinal cord injury bc less gray matter
ALS (pain/temp) crosses at the level
DCML (vib/pro) crosses at spinomedullary junction
Right spinal cord injury
Left ALS impaired (loss of pain/temp)
Right DCML impaired (loss of vib/pro)
how many cranial nerves?
12
how many parts of the brainstem?
3
midbrain
pons
medulla
trigeminal is what nerve?
cranial nerve 5
CN V
distribution of trigeminal nerve (CN V)
CN V-1: ophthalmic
CN V-2: maxillary branch
CN V-3: mandibular branch
How many neurons are involved in somatic sensation to get from a facial dermatome to
the cerebral cortex (post-central gyrus)?
3 neurons
3 neurons, 3 synapses, 1 decussation (crossing)
trigeminal cell bodies of 1st order neurons is in the…
trigeminal ganglion
nucleus vs ganglion (NS)
nucleus (in central)
ganglion (in peripheral)
trigeminal 2nd order neurons ____
cross
corticospinal tract is the primary motor pathway for _______ willed motor control with ___ neurons
voluntary
2 motor neurons (upper and lower)
where does the upper motor neuron arise from?
cerebral cortex
where do the upper and lower motor neurons synapse?
spinal cord
trace upper motor neurons from the left cerebral cortex to the leg
what is the motor homunculus?
topographic representation of the body parts and its correspondents along the precentral gyrus of the frontal lobe
what neurotransmitter is used in neuromuscular junctions?
ACh
acetylcholine
what receptors on skeletal muscles bind with ACh at the neuromuscular junction of lower motor neurons?
nicotinic cholinergic
cerebellum provides ____, ______ movements like _______
smooth, coordinated movements
posture
balance
coordination
where does decussation occur in long motor pathway?
pyramids
lesions above the decussation produce ______ deficits
contralateral
lesions below the decussation produce _____ deficits
ipsilateral
effects of lesions on Upper motor neurons
many muscles affected
muscle weakness (mild-severe)
hypertonia/tight muscles
no muscle atrophy
hyperreflexia
Babinki sign (toes curve back)
effects of lesions on lower motor neurons
limited # of muscles affected
muscle weakness… paralysis
hypotonia/flaccid muscles
muscle atrophy
hyporeflexia
fasciculations (quivering)
what motor loss would be expected if the RIGHT corticospinal tract @ L4 spinal cord region were damaged?
at the level and below L4 (right)
what motor loss would be expected if the right cerebral peduncle was injured?
all of the left side of the body
sensation is the
awareness of a stimulus as a result of its perception by sensory receptors
sensations include:
vibration
proprioception
fine touch (discriminative)
pain
temperature
crude touch (non-discriminative)
what are the 5 different receptors?
Long sensory pathways:
1. mechanoreceptors
2. nociceptors
3. thermoreceptors
- chemoreceptors
- photoreceptors
spinal cord white matter transports ____ _____ input to the ___ ____
spinal cord white matter transports SOMATIC SENSORY input to the CEREBRAL CORTEX
what are the two major ascending pathways for somatic sensory sensation?
DCML:
dorsal column medial lemniscus
vibration, proprioception
ascend ipsilateral
ALS:
anterior later system
pain, temperature
ascend contralateral
how many neurons do the DCML and ALS systems use to get from skin to the cerebral cortex?
three
1st, 2nd, 3rd Order neurons
where are the cell bodies for the 1st, 2nd, 3rd order neurons found?
1: dorsal root ganglion
2: spinal cord/spinomed jnx
3. thalamus
pain and temperature pathways is…
ALS: anterior lateral system
trace a “pain/temp” pathway from the right foot (where are synapses?)
ALS
trace ALS (pain/temp) pathway from the right foot
where would pain/temp sensory loss occur if the left anterior lateral system L4 spinal cord region were damaged?
right side at and below L4 (contralateral)
will not get sensory to the brain
the left side of the body (neck down) does not feel pain, but the vibration sensation is unaffected. what part of CNS is most likely damaged?
right medulla
vibration and proprioception pathway is…
DCML
dorsal column medial lemniscus
trace vibration sensation from the right foot to the brain
trace DCML from right foot
where do DCML neurons synapse? (3)
??????
1: dorsal root ganglion
2: gracile/cuneate nucleus (spinomed junction)
3: thalamus
where is decussation of DCML?
spinomed junction
where would vibratory sensory loss occur if the right DCML L4 spinal cord region is damaged?
vibration/proprioception loss at right side of the body from L4 level and down
if the right side of the thoracic spinal cord is damaged, what part of the body will not process vibratory sensation?
right body from the thoracic region affected and down
If the right side of the thoracic spinal cord is injured, what sensations are affected, and where are they?
pain/temp on contralateral (right)
vibration/prop on ipsilateral (left)
trace differences between the two long sensory pathways
