Sensory and Motor Systems 2 Flashcards
Where does the gracile fasiculus receive axons from?
The lumbar and saccral vertebrae- lower body and it is more medial in the dorsal column of the spinal cord
Where does the cuneate fasiculus receive axons from?
More lateral in the dorsal horn-Cervical and thoracic axons for upper body
Which pathways follow conscious sensation?
Dorsal column pathway and the spinothalamic pathway
Which pathways follow unconscious sensation?
Spinocerebellar, spinotectal, spinoreticular and spino-olivary tract
How does sensation travel from the peripheries to the somatosensory cortex?
What is the signficance of level T6?
Above T6, cunneate fasiculus in the dorsal column transmits the first order neurons. Below T6, gracile fasiculus in the dorsal column transmits the first order neurons.
What is the dorsal column pathway?
Sensation of fine touch, vibration, pressure and propioception
What is the dorsal column pathway?
Sensation of fine touch, vibration, pressure and propioception
What is an overview of the dorsal column pathway?
Sensory receptors -> cunneate/gracile fasiculus of spinal cord and ascends ipsilaterally-> cunneate/gracile nucleus of the medulla -> decussates and ascends the medial leminsicus of the medulla as second order neuron and ascends contralaterally -> synapses at the thalamus -> somatosensory cortex
What is the first oder neuron of the dorsal column pathway?
In the gracile/cunneate fasiculus of spinal cord
What is the 2nd order neuron of the dorsal column pathway?
Gracile/cunneate nucleus of the medulla and ascends the medial leminiscus after decussation contralaterally
What is the 3rd oder neuron of the dorsal column pathway?
Thalamus
What is the spinothalamic tract?
Sensation of crude touch, pain and temperature
What is the role of the anterior spinothalamic tract?
Crude touch
What is the role of the lateral spinothalamic tract?
Pain and temperature
What is Lissauer’s tract?
Bundle of fibres which transmit first order neuron impulses of the spinothalamic tract to ascend 1-2 segments before decussating at the ventral white commisure contralaterally
Where does decussation occur in the dorsal column?
In the medial leminiscus of the medulla
What is the internal arcuate fibres?
The crossing of the axons from the cuneate and gracile nucleus of the medulla which make up the medial leminiscus
Where does decussation occur in the spinothalamic tract?
In the ventral medial commisure of the spinal cord contralaterally to the ventral horn
What are the consequences of brainstem lesions?
Loss of sensation in both pathways on the contralateral side below the lesion