Ventral horn

The ventral horn of the spinal cord is one of the grey longitudinal columns found within the spinal cord. It contains the cell bodies of the lower motor neurons which have axons leaving via the ventral spinal roots on their way to innervate muscle fibers.

Gross anatomy

On transverse section of the spinal cord the spinal grey matter is described as being 'butterfly-shaped' or in an arrangement of the letter 'H'. The ventral horns are bilateral structures which form the anterior projection of this shape.

Contained within are two types of lower motor neurons:

• alpha motor neurons: innervating extrafusal muscle fibers
• gamma motor neurons: innervating intrafusal muscle fibers

Neurons in the ventral horn are roughly arranged somatotopically with neurons innervated axial musculature of the neck and trunk (medial longitudinal motor column) tending to be localized more medially. Those innervating limbs and more peripheral muscle fibers are located more laterally (lateral longitudinal motor column).

The medial longitudinal motor column extends along the entire length of the spinal cord. In contrast, the lateral longitudinal motor column only exists in the cervical and lumbar enlargements of the spinal cord to correspond to innervation of the upper and lower limbs.

Related pathology

• Progressive muscular atrophy
  • subtype of motor neuron disease affecting lower motor neurons
  • degeneration can be seen histologically in the ventral horns causing lower motor neurology such as weakness, wasting, hypotonia and fasciulation