What is the Spinal Cord and Its Tracts?
The spinal cord is the cylindrical bundle of nervous tissue that extends from the brainstem down through the vertebral column, relaying signals between the brain and the rest of the body. Inside it, organized bundles of axons called tracts carry sensory information up and motor commands down.
The spinal cord runs from the foramen magnum to about the L1-L2 vertebra, with inner gray matter (neuron cell bodies) surrounded by white matter tracts — ascending tracts carry sensory signals to the brain, descending tracts carry motor commands to the body.
- •Dorsal columns – touch, vibration, proprioception
- •Spinothalamic tract – pain & temperature
- •Spinocerebellar tract – unconscious proprioception
- •Carry signals body → brain
- •Corticospinal tract – voluntary movement
- •Rubrospinal tract – muscle tone & posture
- •Vestibulospinal tract – balance & posture
- •Carry signals brain → body
Step-by-step worked examples
A patient loses fine touch and vibration sense in both legs, but pain and temperature sensation stay normal. Which tract is likely damaged?
Fine touch, vibration and proprioception travel in the dorsal columns Pain and temperature travel separately in the spinothalamic tract Since pain sensation is preserved, the lesion is isolated to the dorsal columns (a classic sign of vitamin B12 deficiency)
Where does the adult spinal cord end, and what structure lies below that point?
The spinal cord tapers into the conus medullaris around vertebral level L1-L2
Below this, spinal nerve roots continue down inside the vertebral canal
This bundle of nerve roots is called the cauda equina ('horse's tail')Trace a voluntary motor signal from the brain to a leg muscle.
Signal starts in the primary motor cortex Descends via the corticospinal tract Crosses to the opposite side at the medullary pyramids (decussation) Synapses onto a motor neuron in the spinal cord's anterior horn Travels via a peripheral nerve to contract the target muscle
Flashcards
Quick quiz
Q1.In an adult, the spinal cord typically ends at which vertebral level?
Q2.Ascending tracts in the spinal cord mainly carry:
Q3.Which tract carries pain and temperature sensation?
Q4.How many pairs of spinal nerves does the human spinal cord give rise to?
The full card deck, worked steps and AI-tutor support for “What is the Spinal Cord and Its Tracts?” are in Notek — study by hand before your exam.
Common mistakes
Thinking the spinal cord runs the full length of the vertebral column. — Correct: It actually ends around L1-L2; below that, only nerve roots (cauda equina) continue inside the canal.
Mixing up which tracts are ascending vs descending. — Correct: Ascending = sensory, going up to the brain. Descending = motor, going down to the body.
Assuming gray matter is on the outside, like in the brain. — Correct: In the spinal cord, gray matter is central/inner and white matter (the tracts) is on the outside — the reverse of the brain's organization.
Believing the dorsal columns and spinothalamic tract carry the same information. — Correct: They're separate: dorsal columns = fine touch/vibration/proprioception; spinothalamic = pain/temperature.
FAQ
What is the spinal cord?
The spinal cord is a cylindrical bundle of nervous tissue running from the brainstem to about the L1-L2 vertebra, carrying signals between the brain and body.
What are ascending and descending tracts?
Ascending tracts carry sensory signals up to the brain (e.g., dorsal columns, spinothalamic tract); descending tracts carry motor commands down to the body (e.g., corticospinal tract).
Where does the spinal cord end?
In an adult, it tapers into the conus medullaris around vertebral level L1-L2; below that, the cauda equina (a bundle of nerve roots) continues.
How many spinal nerves are there?
There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.