Overview of Ascending and Descending Tracts Flashcards
Between what spinal levels is there spinal cord?
foramen magnum –> L1/L2
What runs in the subarachnoid space?
CSF and large named blood vessels
What is the subdural space associated with?
venous bleeds
between dura and arachnoid
Where is there the most white matter in the spinal cord ? What does this reflect?
more is rostral cord, little in caudal cord - reflects ascending and descending tracts joining / leaving cord
What are the alternative names of the sensory and motor tracts?
Sensory = spinothalamic Motor = corticospinal
Describe the somatotopic organisation of the ventral horn (somatic motor)
North = flexor South = extensor East = proximal West = distal
Briefly describe the blood supply of the spinal cord
x1 anterior and x2 posterior spinal arteries
+ anastomoses
What is the pre central and postcentral gyri?
pre central gyrus = primary motor cortex
post central gyrus = primary sensory cortex
Where is the association motor cortex?
3 gyri in front of the pre central gyrus
- planning
Describe the sensory homunculus from lateral to medial
intraabodminal pharynx tongue teeth, gums, and jaw lower lip lips upper lip face nose eye fingers (thumb --> little) hand, wrist, forearm, elbow, arm, shoulder head, neck, trunk hip, leg, foot, toes genitals
What are the 4 fibres in white matter tracts?
short association fibres - between gyri
long association fibres - between lobes
commissure fibres - corpus callosum - between hemispheres
projection fibres - internal capsule –> midbrain, cross over –> SC
What is the 3 neurone pathway of the ascending tracts/
primary - receptor to spinal cord (cell body in DRG)
secondary - decussates in grey matter, synapses in thalamus
tertiary - arises in thalamus, terminates in primary sensory cortex
What sensory information is carried by the spinothalamic tract?
pain, temperature, crude touch
Describe the pathway of the spinothalamic tract.
primary - receptor in spinal cord (cell body in DRG, synapses in dorsal horn
secondary - decussates in cord, synapses in thalamus
tertiary - terminates in primary sensory cortex
What sensory information is carried by the trigeminothalamic tract?
pain, temperature, crude touch
Describe the pathway of the trigeminothalamic tract
primary - receptor to spinal cord (cell body in CN V ganglion), synapses in brainstem
secondary - decussates in brainstem, synapses in thalamus
tertiary - terminates in primary sensory cortex
What sensory information is carried by the dorsal column/medial lemniscus pathway?
fine touch and proprioception
Describe the pathway of the dorsal column/medial lemniscus pathway
primary - receptor to spinal cord (cell body in DRG), synapses in brainstem
secondary - decussates in brainstem, synapses in thalamus
tertiary - terminates in primary sensory cortex
cuneate/gracilis = upper/lower limb
What sensory information is carried by the spinocerebellar pathway?
unconscious proprioception
Describe the pathway of the spinocerebellar tract
primary - receptor to spinal cord (cell body in DRG), synapses in SC
secondary - ipsilateral synapse in cerebellum
Describe the 2 neurone descending motor pathway
UMN - primary motor cortex to SC, decussates, synapses on interneurone or LMN
LMN - SC to muscle/MEP, arises in vental horn, may be involved in plexi
- decussate at spinal level or pyramid
Give examples of ischaemai, trauma and disease that can assault the CNS and PNS
CNS - ischaemia = stroke/haemorrhage - trauma = direct or indirect due to compression e.g. tumour or haematoma - disease = parkinson's/ alzheimers PNS - ischaemia = little effect - trauma = direct e.g. knife, indirect e.g. compression - disease = MND, myasthenia gravis
