CH 7 part 2

The Spinoreticular and Spinomesencephalic Tract ascends w what? And terminates where?

The Spinoreticular and Spinomesencephalic Tract ascends w what? And terminates where?

Spinothalamic Tract until terminating in the Brainstem

Spinoreticular Tract: Where does the Spinoreticular Tract synapse w?

Dorsal Horn (Intermediate Zone)

Spinoreticular Tract: Where does the Spinoreticular Tract decussate and ascends in which pathway?

• Decussates: Anterior commissure

• Ascends: In Anterolateral Pathways

Spinoreticular Tract: Where does the Spinoreticular Tract terminate?

Medullary-Pontine Reticular Formation

Where does the Medullary-Pontine Reticular Formation turn and project to?

• Intralaminal Thalamic Nuclei

  • w/ project diffusely to entire cerebral cortex

Spinoreticular Tract: What is the Spinoreticular Tract involved in? And what types?

• Responses to Pn

  • Behavioral

  • Arousal

  • Emotional

  • Autonomic

Spinomesencephalic Tract: Where does the Spinomesencephalic Tract synapse?

In Dorsal Horn (Lamina 1 and 5)

Spinomesencephalic Tract: Where does the Spinomesencephalic Tract Decussate and Ascend?

• Decussate: Anterior Commissure

• Ascend: In Anterolateral Pathway

Spinomesencephalic Tract: Where does the Spinomesencephalic Tract Terminate?

Periaqueductal Gray Matter and Superior Colliculi

Spinomesencephalic Tract: What is the Spinomesencephalic Tract involved in?

Modulation of pain

How does the Spinomesencephalic Tract modulate pain?

Activated descending systems that inhibit pain transmission

Visceral Pain Pathway: Where do Pain Fibers of the Visceral Pain Pathway enter the SC?

Via dorsal roots

Visceral Pain Pathway: What does the Visceral Pain Pathway ascend w?

Spinothalamic Tract and Spinoreticular Tract (Bilateral)

Visceral Pain Pathway: Where does Visceral Pain Pathway relays signals to?

Reticular Formation and Thalamus (Intralaminar Nuclei)

Visceral Pain Pathway: Where does Visceral Pain Pathway terminate?

Post Central Gyrus

What does visceral pain feel like?

Vague and Poorly Localized

Why does visceral pain feel vague and poorly localized?

Small representation of viscera in cortex and relatively few visceral fibers

What does the Thalamus consist of? And where is it located

Multiple nuclei located above brainstem

Purpose of Thalamus: (2)

• Major Relay Center (Mostly Sensory)

• Conveys nearly all inputs to the cortex

Thalamus: All Sensory modalities (except one) has specific relays where?

Lateral Thalamus en route to their primary cortical areas

Thalamus: Which sensory modality DOES NOT have specific relay at Lateral Thalamus?

Olfaction

Thalamus: What does Ventral Posterior Lateral Nucleus (VPL) relay?

• SS spinal inputs to cortex

  • L for Limbs <<

Thalamus: What does Ventral Posteromedial Nucleus (VPM) relay?

• SS CN inputs and taste to cortex

  • M for Mouth <<

Thalamus: What does Lateral Geniculate Nucleus (LGN) relay?

• Visual Inputs to cortex

  • L for Light <<

Thalamus: What does Medial Geniculate Nucleus (MGN) relay?

• Auditory inputs to cortex

  • M for Music <<

Thalamus: What does Ventral Lateral Nucleus (VL) relay?

• BG and Cerebellar inputs to cortex

  • 2 L's fo LL <<

Lesions to the Sensory Pathways can cause what?

Abnormal Sensations (Parethesias)

Sensory Abnormalities: Dorsal Column pn

Tingling, numb sensation, a feeling of a tight, band-like sensation around the trunk or limbs, or a sensation similar to gauze on the fingers when trying to palpate objects

Sensory Abnormalities: Anterolateral pn

Sharp, Burning, or Shearing pn

Sensory Abnormalities: Parietal Lobe or Primary Sensory Cortex pn

Contralateral numbness and tingling pn

Sensory Abnormalities: Thalamus pn

Severe contralateral pn

What is Algesia?

Capacity to feel pain

What is Analgesia?

Inability to feel pain or absence of pain (Analgesics = Painkillers)

What is Hyperalgesia?

Enhanced pn to normally painful stimuli (Increased sensitivity to pn)

What is Allodynia?

Painful sensation provoked by normally non painful stimuli (Like light touch)

What is Neuropathy?

Generalized term for nerve disorder/dysfunction

What is Dysthesia?

Unpleasant, abnormal sensation, usually painful (vague term, not used often anymore)

What is a Dermatome?

Sensory region of skin innervated by a single nerve root