Ventral Horn

cornu anterius medullae spinalis

The ventral (anterior) horn is the front part of the spinal grey matter and contains the lower motor neurons that directly drive skeletal muscle. Alpha motor neurons cause muscle contraction and gamma motor neurons set the sensitivity of muscle spindles. The ventral horn is largest in the cervical and lumbosacral enlargements.

Anatomical Data

Structure & Connections

Location	Anterior part of the spinal grey matter at every cord level
Parts	Alpha motor neurons Gamma motor neurons Medial motor column (trunk and neck muscles) Lateral motor column (limb muscles) Renshaw cells and other interneurons Phrenic nucleus (C3-C5) Accessory nucleus (C1-C5)
Connections	Ventral roots and spinal nerves Lateral and anterior corticospinal tracts Rubrospinal, vestibulospinal and reticulospinal tracts Dorsal root afferents (stretch reflex)
Blood Supply	Anterior spinal artery (via sulcal arteries)

Biomechanics

Function & Actions

Contains the final common pathway for all voluntary and reflex movement, sending motor commands to skeletal muscles.

Clinical Relevance

Clinical Notes

Loss of ventral horn cells causes lower motor neuron signs: weakness, wasting, fasciculations, low tone and reduced reflexes. Poliomyelitis and spinal muscular atrophy specifically destroy these cells, and motor neuron disease affects both these and upper motor neurons. Anterior spinal artery infarction damages the ventral horns at the affected level.

Pathology

Common Injuries & Conditions

Spinal Muscular Atrophy

A genetic loss of ventral horn motor neurons causing progressive weakness and wasting, now treatable with gene-targeted therapies.

Poliomyelitis

A viral infection that destroys ventral horn cells, causing asymmetric flaccid paralysis.

Amyotrophic Lateral Sclerosis

Progressive degeneration of upper and lower motor neurons, including those of the ventral horn, causing weakness, wasting and fasciculations.

Explore

More in Spine

Browse all of Spine →