Ascending tract Flashcards
Where is white matter largest in the spinal cord?
Superiorly- gets smaller as cord descends
Which matter of the sc does the nuclei reside?
Gray matter
Areas where white matter enlarges?
Cervical enlargement: Brachial plexus, upper limb C5-T1
Lumbar enlargement: L2-S2, lumbar plexus, lower limb
Lateral motor neurons innervate
Limbs
Medial motor neurons innervate
Trunk
What segment level does the spinal cord get smaller due to no innervation
T1-L2
Cell Types:
In ventral horn
Major motor neuron and is a lower motor neuron that goes to muscle
Alpha
Cell Types:
In ventral horn
Part of stretch receptor
Gamma
Cell Types:
In ventral horn
Communicates with cells in the spinal cord on different sides
Propriospinal
Cell Types:
In Ventral Horn
Carry message from one part of CNS to another
Relay Neurons
Cell Types:
In Ventral horn
Separation of gray matter
Lamina of Rexed
Psuedounipolar neurons that have centrifugal and centripetal branches
50,000 from T1-L2
100,000 from C5-T1 & L2-S2
Sensory
Dorsal root ganglia
Dorsal root ganglia branch that goes away from CNS to receptor
Centrifugal
Dorsal root ganglia branch that goes towards the CNS
Centripetal
Sensation that is only perceived when it is perceived by cerebral cortex
Conscious sensation
Classification of stimuli
Exteroception
Proprioception
Conscious Exteroception stimuli
Vision Hearing Touch Pressure Heat Cold Pain
Conscious Proprioeption function
Position sense
Kinesthetic sense
Sensation that is not perceived because it doesn’t reach the cerebral cortex
Unconscious sensation
Unconscious propriocetion
Motor coordination-mostly reflexive
Unconscious enteroception
Visceral Reflexes-acidity, pH, etc
Somatosensory pathways are primarily__________
exteroceptive
Somatic sensory pathway rules
- First order neuron is in DRG
- Second order neuron’s cell body is
ipsilateral but fibers cross into contralateral thalamus - Third order neurons projects into the postcentral gyrus (sensory cortex)
Somatic sensory pathways are Somatotopic.
What does that mean
Ability to map body part function on pathway
Somatic sensory pathways are modulated by interneurons, especially _________
Reticular formation
Dorsal Column-Medial Lemniscus-Function
Proprioception
Discrimminative touch/ Epicratic touch
Vibration
Dorsal column medial-Lemniscus refers to
Gracile and Cuneate fascicle that run up sc in end in medulla
What path do the gracile and cuneate fascicle of the dorsal column medial lemnicus pathway take
1st order- from DRG
2nd order- synapse in cuneate nucleus and gracile and ascend up brainstem to thalamus
3rd order- ends in ventral posteriolateral nucleus in the thalamus
The fibers of the the dorsal column -medial lemniscus cross into the medulla. What are the crossing fibers called?
Internal arcuate fibers
What are the tracts involved with the dorsal column -medial lemniscus pathway?
Gracile fascicle
Cuneate fascicle
Corona Radiatia
Once the fibers of the DCML cross, what do they do?
Ascend up brain stem
When are the fibers of the DCML called medial lemniscus ?
As they ascend up brainstem
Where do the fiber go after the leave the thalamus?
Travel post central gyrus (somatosensory)
Fibers are called internal capsule and then corona radiata
What are the fibers of the DCML leaving the thalamus called?
Internal capsule
After internal capsule fibers pass the basal ganglia what are they called?
Corona radiata
How many pathway are in the anterolateral system?
Spinothalamic
Spinoreticular
Spinotectal
Spinoolivary
What is the function of the anterolateral system?
Pain
Temperature
Crude touch
ALS:
Spinothalamic region responsible for noxious(pain) and temperature
Lateral
ALS:
Portion of spinothalamic tract responsible to light touch?
Anterior
ALS: Spinothalamic pathway
1st order- DRG
2nd order- synapse in lamina I️, IV, V (sometimes III)
3rd order- into ventral posterolateral of the thalamus
Tracts of the spinothalamic
Anterolateral system
Also called spinal lemniscus only as it goes through brainstem
Fibers of the spinothalamic pathway decussate over where?
Anterior white commissure
- Lateral- 1 segment (spinal nerve segment)
- Anterior- over several segments (2-3) (spinal nerve segment)
Spinoreticular (Paleospinothalamic) Pathway
DRG —> Lamina V, VI, VII —> some fibers decussate and some don’t, there is no somatotopography—> ascend bilaterally into reticular formation
Spinoreticular function
Awareness
Emotion of sensation such as pain
Cerebellar Tracts:
Unconscious proprioception From Lower body
DRG—>Dorsal Nucleus of Clarke/Dorsal thoracic (VII) T1-L2—> Posterior spinocerebellar tract—> inferior cerebellar peduncle into cerebellum
Posterior spinocerebellar
Cerebellar tracts:
unconscious proprioception Upper body
- Dorsal Root ganglion
-Ascend through cuneate fascicle
– second order - accessory cuneate nucleus
– inferior cerebellar peduncle in cerebellum
Cuneocerebellar
Cerebellar tract:
The reflex arcs
Anterior spinocerebellar
Rostral spinocerebellar
Cerebellar tracts:
Reflex arc for lower body
Fibers are crossed unlike other cerebellar tracts
Exit in superior cerebellar tract
Anterior cerebellar
Cerebellar tract:
Reflex arc of upper body
Fibers are uncrossed
Exit in superior and inferior peduncle to cerebellum
Rostral Spinocerebellar
Tract that is responsible for turning the head towards a stimulus
Spinotectal
