medial lemniscus (Reil band)

Introduction

A band of fibers ascending from the nucleus gracilis & nucleus cuneatus in the brainstem to the ventral posterior nucleus of the thalamus.

Function

the medial lemniscus carries somatic sensory information, including:

• tactile discrimination
• proprioception
• vibration

Structure

• fibers retain their somatotopic organization, such that those from the nucleus gracilis representing the lower extremity lie lateral to those originating in the nucleus cuneatus representing the arm

Course

• in the medulla
  • decussates in the lower medulla
  • ascends through the center of the medulla, close to the median raphe
• in the pons, it spreads out laterally to form a band over the dorsal border of the pontine nuclei
• in the mesencephalon
  • passes dorsally to the substantia nigra
  • displaced laterally by the red nucleus
  • passes medially to the medial geniculate body

More general terms

• CNS white matter tract

Component of

• mesencephalon (midbrain)
• pons