16-Spinothalamic tract

What are the three modalities of this pathways

1. Pain

2. Temperature

3. Crude Touch

Pain Modality tract

Lateral Spinothalamic

Pain Modality

Receptors: Free nerve endings, Nociceptors

Polymodal

Thin myelinated fibers: A-delta

Unmyelinated: Type C

Temperature modality tract

Lateral spinothalamic

Temperature Modality

Receptor: Free nerve endings

Cold temperature

<35C→ >45C

Fibers A delta

Hot temperature

35°C – 45 °C

Fibers: type C

Crude Touch Tract

Anterior Spinothalamic tract

Crude Touch Modiality

Receptors: mechanoreceptors

No exact localization (approximate impression of the surrounding)

Viscerosensory fibers travel with this tract and end up in the same segments as the somatosensory fibers

Visceral pain is projected to a skin segment (pain radiation)

First order of spinothalamic tract

Dorsal Root Ganglion

Second Order of Spinothalamic Tract

Begins in the Dorsal horn of the spinal Chord

Laminae I,II,IV-VI

Where is the crossing?

In the anterior white commissure

Where does it ascend?

In the lateral or anterior funiculus depending on the tract

Where does the second order terminate?

In the contralateral thalamus

3rd order Nueron of the spinothalamic tract

Begin in the thalamus, (VPL nuclei)

terminate in the post central gyrus after coursing through the superior thalamic radiation and in the corona radiata