Neuroanatomy - Spinal cord Flashcards
_____, _____, ____ and _____ account for >75% of the entire CNS
sensorimotor, reflex, and autonomic function pathways and nuclei
Ascending pathways discriminate what 5 things?
1 touch
- vibration
- pain and temperature
- conscious and non-conscious proprioception
descending pathways control what 2 things
voluntary and non-voluntary reactions
- what is the primary neuron in ascending tracts?
- secondary neuron?
- tertiary neuron?
- termination?
- dorsal root ganglion
- brain stem or spinal cord
- thalamus (ventrobasal nuclear complex)
- cerebral or cerebellar cortex, or brain stem
three types of receptors for ascending pathways
- Exteroceptor
- interoceptor
- proprioceptor
Posterior (dorsal) column - medial lemniscus pathway:
modalities (4)
receptors?
- discriminative touch sensation
- vibration
- conscious proprioception
Most receptors except free nerve endings
Medial Lemniscus
1st, 2nd, 3rd neurons and termination
1st Dorsal root ganglion - posteriorcolumn
2nd dorsal column nuclei (gracilis/cuneatus) - in caudal medula
[deccusates as internal arcuate fibers to medial lemniscus]
3rd Thalamus (VPL) - [posterior limb of internal capsule via central thalamic radiations]
Termination: primary somatosensory cortical area (post-central gyrus)
What comprises the dorsal column?
Fasiculus Gracilis:
Cuneatus:
lumbosacral to T6
T6 and above
lesion to medial lemniscus pathway would show:
ipsalateral loss of discriminative touch, sensation/vibration and conscious proprioception below the level of the lesion.
Spinothalamic tract - anterolateral system
Modality (3):
Receptors
M: pain, temperature, light touch (non-disc)
R: free nerve ending
Spinothalamic tract - anterolateral system: 1st neuron 2nd neuron 3rd neuron Termination
1st: Dorsal Root Ganglion
2nd: Dorsal horn (substantia gelatinosa)
anterior white commissure
—-spinothalamic tract—
3rd: Thalamus (VPL)
—- Internal capsule, corona radiata —
Term: primary somatosensory area (SI) & diffuse widespread cortical region
decussation for spinothalamic tract
anterior white commissure
What is unique about the substantia gelatinosa?
tract it is assosiciated with?
Some dorsal root ganglion axon branches ascend or descend 1-2 levels.
spinothalamic tract
describe a lesion to spinothalamic tract
contralateral loss of pain and temperature sensation below the level of the lesion.
Spinoreticular tract:
Modalities:
positioned closely to the lateral spinothalamic tract; relays automatic responses to pain such as in the case of injry
Spinoreticular tract: 1st neuron 2nd neuron 3rd neuron Termination
1st: Dorsal Root Ganglion
2nd: Dorsal horn (substantia gelatinosa)
anterior white commissure
3rd: brainstem (medullary-pontine reticular formation)
4: intramedian nucleus of thalamus
5. Diffuse widespread cortical region
Spinocerebellar tract:
Modalities:
Receptor:
M: non-conscious proprioception
R: Muscle spindle, golgi tendon apparatus
Three forms of spinocerebellar tract
(a) dorsal horn (nucleus proprius) - anterior spinocerebellar tract.
(b) Clarkes column - posterior spinocerebellar tract.
(c) Accessory Cuneate Nucleus - cuneocerebellar tract
Term: Cerebellar vermis and cortex
- all end up ipsilateral
Anterior spinocerebellar tract encompasses what receptor region of the body
sacral and lower lumbar trunk, lower extremity
Anterior spinocerebellar tract pathway: 1st neuron 2nd neuron 3rd neuron Termination
1st dorsal root - nucleus proprious
anterior white commissure
anterior spino cerebellar tract
superior cerebellar peduncle
Posterior spinocerebellar tract encompasses which receptor region of the body
upper lumbar and thoracic
Posterior spinocerebellar tract pathway: 1st neuron 2nd neuron 3rd neuron Termination
1st dorsal root - clarke’s nucleus
posterior spinocerebellar tract
inferior cerebellar peduncle
Lesions of the spinocerebellar tracts?
rough uncoordinated movements ipsilateral to the lesion.
(isolated lesion of spinocerebellar tract rarely occurs and may be masked by weakness or hemiplegia due ot loss of descending motor influences)
Cuneocerebellar tract encompasses what body region?
Cervical C1-7