1.25 Tracts Lecture Flashcards
sensation/s associated with Meissner corpuscles
touch: flutter and movement
sensation/s associated with Pacinian corpuscles
touch: vibration
sensation/s associated with Ruffini corpuscles
touch: skin stretch
sensation/s associated with hair follicles
touch: movement
sensation/s associated with Merkel complex
- touch
- pressure
- form
sensation/s associated with free nerve endings
- pain
- touch
- temperature
primary neuron for anterolateral spinothalamic tract
Aδ, large myelinated
another name for anterolateral spinothalamic tract
neospinothalamic tract
What does the anterolateral spinothalamic tract transmit?
easily localized, fast pain
neurotransmitter for anterolateral spinothalamic tract
glutamate
What does glutamate do?
- excitatory
- depolarizes the membrane
anterolateral spinothalamic tract: pathway
1˚ nerve endings to DRG to dorsal horn
2˚ dorsal horn, decussates, synapses at thalamus
3˚ thalamus to somatosensory cortex
Where is the somatosensory cortex?
postcentral gyrus
How does the 2˚ neuron of the anterolateral spinothalamic tract decussate in the spinal cord?
via the anterior white commisure
Where does the 2˚ neuron of the anterolateral spinothalamic tract travel in the spinal cord?
along the lateral aspect
What is a lamina?
- histologically, somatotopically arranged
- inside out: cervical, thoracic, lumbar, sacral
What additional info travels through cervical cord?
upper limb
What additional info travels through lumbar cord?
lower limb
Which is the paleospinothalamic tract?
anterior spinothalamic tract
What are the tracts in the anterolateral system?
- (antero)lateral spinothalamic tract
- anterior spinothalamic tract
primary neuron of the anterior spinothalamic tract
- unmyelinated
- free nerve endings
neurotransmitter of the anterior spinothalamic tract
Substance P
What does the anterior spinothalamic tract transmit?
slow, hard to localize pain
What is a major characteristic of the neurons of the anterior spinothalamic tract?
- easily sensitized
- hitting someone repeatedly: might not hurt initially, but enough times and it will start to
Where do the 2˚ neurons of the anterior spinothalamic tract decussate?
- anterior white commissure
- more medial than the anterolateral spinothalamic tract
What are the 3 options for a 2˚ neuron in the anterior spinothalamic tract?
- spinoreticular
- spinomesencephalic
- spinolimbic
Which two pathways stop in the midbrain?
- spinoreticular
- spinomesencephalic
What is the midbrain a part of?
brainstem
Where does the spinoreticular tract end?
reticular formation in the midbrain
What is the reticular formation involved with?
- regulating sleep/wake cycles
- if you’re in bad pain, it will wake you up
Where does the spinomesencephalic tract stop?
midbrain
What does the spinomesencephalic tract do?
sends motor signals to ocular muscles to look at the source of pain
Where does the spinolimbic tract end up?
- can go through the thalamus, but doesn’t have to
LIMBIC SYSTEM
- striatum
- amygdala
- hippocampus
- somatosensory cortex
What is the limbic system involved with?
- emotion
- memory
fancy word for discriminate touch
stereognosis
DCML
dorsal column/medial lemniscus
What is the DCML involved in?
- discriminate touch (stereognosis)
- conscious proprioception
fasciculus
bundle of myelinated axons
How are the columns of the DCML arranged?
somatotopically within their fasciculi
funiculis
bundle of fasciculi
What is the fasciculus for the lower limbs?
fasciculus gracilis
Where is the fasciculus gracilis located?
medial
What is the fasciculus for the upper limbs?
fasciculus cuneatus
Where is the fasciculus cuneatus?
lateral
Where does the DCML 1˚ neuron synapse?
synapses at the medulla at either:
- nucleus cuneatus
- nucleus gracilis
What does the DCML 2˚ neuron do?
- crosses at the medial lemniscus
- synapses at the thalamus
What does the DCML 3˚ neuron do?
travels to the somatosensory cortex in the postcentral gyrus
medial lemniscus travels in the
internal capsule
Which tract has a 2˚ neuron that doesn’t synapse in the dorsal horns?
DCML
What are the spinocerebellar tracts for?
unconscious proprioception (unconscious adjustments to posture)
Which patients often have problems with their spinocerebellar tracts?
diabetics
Neurons of the spinocerebellar tracts
only have primary and secondary
overall pathway of spinocerebellar tracts
from muscles, tendons, and joints to the cerebellum
What are the spinocerebellar tracts?
- posterior spinocerebellar tract
- cuneocerebellar tracts
path of posterior spinocerebellar tract
primary: from lower body, synapses at nucleus dorsalis
secondary: nucleus dorsalis to dorsal cerebellar cortex
What is the nucleus dorsalis?
dorsal gray matter in the spinal cord
posterior spinocerebellar tract: What does the 2˚ neuron pass through on the way to the cerebellar cortex?
inferior cerebellar peduncle
path of the cuneocerebellar tract
primary: from upper body, synapses at lateral cuneate nucleus
secondary: lateral cuneate nucleus to ventral cerebellar cortex
Where is the lateral cuneate nucleus?
in the medulla
unconscious proprioception: lower body
posterior spinocerebellar tract
unconscious proprioception: upper body
cuneocerebellar tract
