Click underlined text for links
George E. Carvell, PhD, PT   University of Pittsburgh
 
SPINAL CORD: Ventromedial Descending Pathway
The Ventromedial Descending Pathway represents a number of tracts located in the Anterior (Ventral) funiculus. The tracts include: Reticulospinal Tracts originating from Reticular Formation Nuclei in the pons and medulla, Vestibulospinal Tracts originating in the Vestibular Nuclei, the Anterior Corticospinal Tract (crossed & uncrossed fibers) originating from Pyramidal Tract Neurons (PTNs) in the Cerebral Cortex, and the Tectospinal Tract (cervical cord only) originating in neurons in and around the Superior Colliculus of the midbrain. Together these tracts influence Segmental Motor Center Interneurons and Motoneurons in the Medial Motor Nucleus and some Segmental Motor Center neurons in the medial aspect of the Lateral Motor Nucleus where the limb girdle muscles are represented. These tracts influence Long Propriospinal Tract Neurons that intereconnect many segments across more than one level of the cord; and to a limited extent Short Propriospinal Tract Neurons. The Ventromedial Descending Pathway influences Commissural Interneurons located close
to the midline in the spinal gray and thus effect bilateral actions of the trunk/neck and limb girdle muscles. This pathway provides descending postural and balance control, eye/neck coordination for visuomotor tasks, and regulation of 'gross' motor activities requiring a high degree of synergistic muscle activity such as locomotion, lifting, and mobilization/stabilization of axial musculature for all types of 'fine' and 'gross' actions. These ‘steering’ actions provide the mobile yet stabile platform upon which we construct highly skilled distal limb actions.