Nociceptors, Thermoreceptors and the Spinothalamic Tract

50 question-and-answer flashcards covering nociceptors, thermoreceptors, and the spinothalamic tract based on the lecture notes.

What sensations does the spinothalamic tract transmit?

Pain and temperature.

Which receptors detect nociception and temperature changes?

Nociceptors and thermoreceptors.

How many neurons are in the spinothalamic tract pathway?

Three neurons.

Where are the cell bodies of the 1st order neurons located?

Dorsal root ganglia (DRGs).

Where do 1st order neurons synapse onto 2nd order neurons?

In the ventral horn of the spinal cord.

What happens to the axons of 2nd order neurons?

They decussate and ascend in the contralateral anterior funiculus.

Where are the cell bodies of the 3rd order neurons located?

In the ventral posterior lateral (VPL) nucleus of the thalamus.

Where does the spinothalamic tract terminate?

In the SI cortex (postcentral gyrus, primary somatosensory cortex).

After decussation, which side do the signals ascend on?

The contralateral side.

What is the cortical destination for spinothalamic sensory information?

Primary somatosensory cortex (SI).

What is the role of the DRG in the pathway?

Houses the cell bodies of the 1st order neurons.

Which receptors detect tissue-damaging stimuli?

Nociceptors.

Which receptors detect temperature changes?

Thermoreceptors.

Which neurons decussate in the spinothalamic tract?

The axons of 2nd order neurons.

What is the exact order of the spinothalamic tract neurons from receptor to cortex?

1st order in DRG -> 2nd order in ventral horn (decussates) -> 3rd order in VPL thalamus -> SI cortex.

In which spinal cord region do 2nd order neuron axons ascend after crossing?

Contralateral anterior (ventral) funiculus.

Which nucleus in the thalamus houses the 3rd order cell bodies?

Ventral posterior lateral (VPL) nucleus.

The 3rd order neurons project from the thalamus to which cortex?

Primary somatosensory cortex (SI).

What type of pathway is the spinothalamic tract?

An ascending somatosensory pathway.

What is the function of nociceptors and thermoreceptors as a pair in this pathway?

They detect painful stimuli and temperature changes, respectively.

True or False: The spinothalamic tract carries information to the brain about pain and temperature.

True.

Which structure houses the first-order neuron cell bodies?

Dorsal root ganglia (DRGs).

Where do first-order neurons synapse onto second-order neurons?

In the ventral horn of the spinal cord.

What decussates in this pathway?

The axons of 2nd order neurons decussate.

Which tract carries pain and temperature signals from the body to the thalamus and cortex?

Spinothalamic tract.

Which part of the brain receives pain and temperature signals after the thalamus?

The cortex, specifically SI.

What is the significance of decussation in this pathway?

It creates contralateral representation of sensory inputs.

Where are the 3rd order neuron cell bodies located?

In the VPL nucleus of the thalamus.

What is the primary sensory cortex location for perceiving touch and pain?

Postcentral gyrus.

Where is the ventral horn located in the spinal cord?

The ventral (anterior) horn.

How many orders of neurons are required to reach the cortex?

Three orders.

List the sequence DRG -> ventral horn -> VPL -> SI.

DRG (1st order) -> 2nd order in ventral horn (decussation) -> VPL thalamus (3rd order) -> SI cortex.

Which neuron serves as the 2nd order neuron?

The neuron whose cell bodies are in the ventral horn and decussates.

What is the role of the VPL in this pathway?

Relays 3rd order sensory information to the cortex.

In which gyrus is the primary somatosensory cortex located?

Postcentral gyrus.

Do 1st order neurons cross the midline?

No; crossing occurs by 2nd order neurons.

After decussation, in which white matter tract do the 2nd order fibers ascend?

Contralateral anterior (ventral) funiculus.

What is the thalamic relay for this pathway?

The VPL nucleus of the thalamus.

Which cortex is the final cortical target for this pathway?

The primary somatosensory cortex (SI).

What two senses are carried by the spinothalamic tract according to the notes?

Pain and temperature.

Is the spinothalamic tract an ascending or descending pathway?

Ascending.

Where do 2nd order neurons synapse?

In the ventral horn (of the spinal cord).

What is the overall route to the thalamus for pain and temperature signals?

DRG -> ventral horn -> decussate -> contralateral anterior funiculus -> VPL -> cortex.

Which nucleus houses the 3rd order neurons in this pathway?

The ventral posterior lateral (VPL) nucleus of the thalamus.

Which cortical area processes the somatosensory input from the body?

The primary somatosensory cortex (SI) in the postcentral gyrus.

What is the overall function of the spinothalamic tract?

To transmit pain and temperature sensations to the brain.

Which neurons decussate in the spinothalamic tract?

The axons of the 2nd order neurons.

What is the starting point of the spinothalamic tract?

Dorsal root ganglia (DRGs) housing 1st order cell bodies.

True or False: The spinothalamic tract terminates in the SI cortex.

True.

Which thalamic nucleus relays somatosensory information to the cortex in this pathway?

The VPL nucleus of the thalamus.