Veterinary Gross Anatomy-II

WHITE MATER

• The white mater is divided into three pairs of columns.
• The dorsal column lies on either side of the dorsal median septum to the dorsolateral groove.
• The ventral column is situated between the ventral median fissure and the ventral root. These are connected by the white commissure.
• The lateral columns are included between the dorsal and ventral root fibres. The amount of gray and white mater differs in different regions.
• The gray mater increases from the cervical to the sacral region.
• The white mater consists chiefly of medullated nerve fibres arranged in three columns or funiculi. Some of the fibres cross in the median plane to the opposite side through the white commissure but the majority directed to the same side.
• The latter are chiefly of three classes
  • Those which carry impulses from the periphery to the centre called ascending sensory or afferent tracts
  • Those which carry impulses from the centre to the periphery - descending motor or efferent tracts 
  • Those which connect the different segments of the cord - the intersegmental tract.
• The nerve tracts or fasciculi are not recognizable in the natural state but their identity has been established by special methods.
• The spinal cord of a medium sized ox is about 1.6 to 1.7 m long and weighs 2-2.5kg.