Ascending and descending pathways Flashcards
Ascending pathways are sensory / motor ?
Sensory
Sensory information travels to which part of the brain?
Primary somatosensory cortex
Where in the brain is sensory information interpreted?
Post central gyrus
How is the primary somatosensory cortex arranged?
By mapping out the body onto the cortex via the somatosensory strip.
- this gives rise to the homunculus
At what location do sensory fibres cross the midline?
In the medulla
- i.e. the left side of the boy is represented on the right side
Name 2 ascending pathways
Dorsal column medial lemniscus (DCML)
Spinothalamic tract
Which sensory pathway conveys fine touch, pressure, vibration and conscious proprioception?
DCML tract
Sensory information travels up the grey matter of the spinal cord. True or false?
False
- white matter
Which sensory pathway conveys pain, temperature, deep pressure signals?
Spinothalamic tract
DCML tract - where does decusation occur?
Medulla
DCML tract - first order neurones
Carry sensory info from the peripheral nerves to the medulla
DCML tract - signals from the upper limb (above T6) travel in the fasciculus GRACILIS / CUNEATUS ?
Fasciculus cuneatus
DCML tract - signals from the lower limb (T6 and below) travel in the fasciculus GRACILIS / CUNEATUS ?
Fasciculus gracilis
DCML tract - second order neurones
Begin in nucleus cuneatus/gracilis in the medulla.
They deliver information to the third order neurones by crossing over to the other side of the CNS.
DCML tract - where are third order neurones located?
In the thalamus
DCML tract -third order neurones transmit sensory signals from the thalamus to the IPSILATERAL/CONTRALATERAL primary somatosensory cortex
Ipsilateral
Spinothalamic tract - where does decusation occur?
Spinal cord level
Spinothalamic tract - first order neurones
Arise from the peripheral sensory receptors and synapse occurs at spinal cord
Spinothalamic tract - second order neurones carry information from spinal cord level to _____
thalamus
Spinothalamic tract - fibres ascend the spinal cord within the IPSILATERAL/CONTRALATERAL tract?
Contralateral
Spinothalamic tract - third order neurones carry signals from the thalamus to the IPSILATERAL/CONTRALATERAL primary somatosensory cortex
Ipsilateral
A spinal cord lesion is likely to be associated with ipsilateral/contralateral signs and symptoms?
Contralateral
Descending pathways are sensory/motor ?
Motor
LMNs directly innervate muscles to produce movement. True or false?
True
Where is the primary motor cortex located?
In the dorsal portion of the frontal lobe
The right motor cortex controls muscles on the right/left side of the body?
Left
Name 4 descending pathways
Corticospinal tract (pyrimidal)
Tectospinal tract
Reticulospinal tract
Vestibulospinal tract
Which pathway is responsible for fine control - fine, precise movements, particular in the distal limb muscles
Corticospinal tract
Corticospinal tract controls voluntary body movements. True or false?
True
Corticospinal tract - decussation of most motor fibres occurs where?
Medullary pyramids
Corticospinal tract - what structures do fibres cross through to get to the spinal cord?
Internal capsule -> midbrain -> spinal cord
Internal capsule occlusion can block the corticospinal tract and cause which movement in the upper limbs?
Spastic paralysis with hyeprflexion