Spinal cord, tracts and pathways Flashcards
What types of somatosensation are carried by the spinothalamic tract and the dorsal column pathways?
The spinothalamic tract carries information for pain and temperature whereas the dorsal column pathways carry information for fine touch and proprioception
The cuneate fasciculus and the gracile fasciculus carry information for which parts of the body?
The cuneate fasciculus carries information for the upper body whereas the gracile fasciculus carries information for the lower body (think gracile= graceful= ballet legs)
Which is the only tract that crosses immediately in the spinal cord, and where does it cross?
Where does it synapse?
The spinothalamic somatosensory tract for pain and temperature perception, crosses at the ventral white commissure.
The synapse is in the dorsal horn before the decussation, so the axon that travels up to the thalamus is a 2nd order axon.
Where does the lateral corticospinal tract cross the midline?
What percentage of neurons in the corticospinal tract are present in the lateral corticospinal tract?
Where is the synapse?
The lateral corticospinal tract, 90% of the corticospinal tract neruons, crosses at the pyramidal decussation in the midbrain. It then targets the ventral horn ipsilaterally, where it synapses. Therefore the axon which travels down and decussates is a first order neuron.
Where does the anterior corticospinal tract cross the midline?
What percentage of neurons in the corticospinal tract are present in the anterior corticospinal tract?
Where is the synapse?
The anterior corticospinal tract, about 10% of the neurons present in the corticospinal tract, travel down the spinal cord and then decussate at the level of innervation, in the ventral white commissure.
The synapse is in the ventral horn. The axon travelling down the spinal cord and decussating is a first order neuron.
Where does the medial lemniscus pathway in the dorsal columns cross the midline?
Where is the synapse?
The dorsal column/ medial lemniscal pathway crosses the midline in the medulla, after synapsing. It’s a 2nd order neuron.
What is the destination of the 2nd order axons in both the dorsal column tracts and the spinothalamic tract?
The destination for the somatosensation tracts is the thalamus.
Are the pyramids visible at the ventral or dorsal view of the brainstem?
Which part of the brainstem are they visible, where the gracile and cuneate fasciculi are visible on the other side?
The pyramids are visible on the ventral surface of the brain stem, at the medulla.
What are the blobs at the top of the gracile and cuneate fasiculi on the medulla?
The gracile and cuneate tubercles
Damage to somatomotor pathways: Which levels would cause flaccid paralysis or spasticity?
Explain why.
Damage to these pathways at the level of the spinal cord ventral root would cause flaccid paralysis because this damages the innervation of the muscle, whereas damage to the first order neuron before decussation would cause spasticity, due to loss of correct information transmission from the cortex.
Where does the spinal cord finish? Name the segment.
Around L2/3
What change in the dorsal column at spinal segment T6?
The cuneate fasciculus is present from spinal segment T6 and above, carrying information for the upper body.
The gracile fasciculus is present for the entire length of the spinal cord, carrying information for the lower body
In which sections of the spinal cord is the lateral horn present?
What kind of information does it carry?
The lateral horn is present from T1-L2/3. It carries sympathetic motor information.
