Lecture Notes: Ponto Reticulospinal Tract

Overview

• Series Context: Part of a four-part series on descending tracks.
• Focus: This lecture focuses on the Ponto Reticulospinal Tract.

Key Objectives

• Understand the pathway and function of the Ponto Reticulospinal Tract.
• Remember the tract's role in muscle activation, particularly extensor muscles.

Ponto Reticulospinal Tract

Function

• Primary Role: Activates extensor muscles.
• Assists: Works in conjunction with the lateral and medial vestibular spinal tracts.

Structure and Pathway

• Origin: Reticular formation in the pons.
• Pathway:
  • Descends from the pons through the ventral white column.
  • Gives off collaterals to cell bodies in the anterior or ventral gray horn.
• Neural Targets:
  • Supplies gamma and alpha motor neurons.
  • Stimulates extensor muscles via motor neurons:
    • Alpha motor neurons: Cause contraction of extrafusal muscle fibers.
    • Gamma motor neurons: Cause contraction of intrafusal muscle fibers to keep muscle spindles taut.

Integration with Other Tracts

• Vestibular Spinal Tract: Both tracts supply extensor muscles.
• Ascendant Influence: Receives input via ascending tracts:
  • Dorsal column medial lemniscus pathway.
  • Spinothalamic tract.
  • Spinal reticular tract.
• Anterior White Column Pathway: Both Ponto Reticulospinal and Vestibular Spinal tracts travel through this pathway.

Important Points to Remember

• The Ponto Reticulospinal Tract is crucial for extensor muscle function.
• Its pathway and integration with other neural tracts ensure proper muscle activation.
• Understanding of both descending and ascending influences is essential.

Next Steps

• Upcoming Lecture: Part three will cover the Rubrospinal Tract.