Spinal Tracts Simplified

Organization of Ascending and Descending Tracts in Spinal Cord

A. 2 Posterior Tracts:

The fibers of these tracts cross to the opposite side at the level of medulla:

1. Dorsal column (Cross at medulla)
   • Fasciculus gracilis
   • Fasciculus cuneatus
2. Lateral corticospinal tract (Cross at medulla)

B. 2 Lateral Tracts:

The fibers of these tracts remain on ipsilateral side:

1. Dorsal spinocerebellar tract (Do not cross)
2. Ventral spinocerebellar tract (Crosses 2 times to lie on ipsilateral side)
   • 1st crossing in the spinal cord
   • 2nd crossing in the cerebellum

C. 2 Anterior Tracts:

The fibers of these tracts cross at the level of spinal cord:

1. Anterior corticospinal tract
2. Anterior and Lateral spinothalamic tract

D. Extrapyramidal tracts:

1. Rubrospinal tract (Cross at midbrain)
2. Vestibulospinal tract: Uncrossed
3. Reticulospinal tract: Uncrossed
4. Olivospinal tract: Uncrossed

Now, look at the somatotropic arrangement of the various tracts:

• Fasciculus gracilis: lower limbs
• Fasciculus cuneatus: upper limbs
• Corticospinal tract: upper limbs medially and lower limbs laterally
• Spinothalamic tract: upper limbs medially and lower limbs laterally