FUNCTIONS OF THE DESCENDING TRACTS

1. Corticospinal tracts
• Voluntary, discrete, skilled movements, especially those of the distal parts of the limbs
2. Reticulospinal tracts
• Facilitate or inhibit the activity of the alpha and gamma motor neurons
• Facilitate or inhibit voluntary movement or reflex activity
3. Tectospinal tract
• Reflex postural movements in response to visual stimuli
4. Rubrospinal tract
• Acts on both the alpha and gamma motor neurons in the anterior gray columns
• Facilitates the activity of flexor muscles and inhibits the activity of extensor or antigravity muscles
5. Vestibulospinal tract
• Acting on the motor neurons in the anterior gray columns
• Facilitates the activity of the extensor muscles, inhibits the activity of the flexor muscles
• Postural activity associated with balance
6. Olivospinal tract
• May play a role in muscular activity, but there is doubt that it exists
7. Descending autonomic fibers
• Control of visceral activity