Q 1.25. Spinal Cord: Anatomy, Physiology, and Blood Supply

Anatomy and Structure of the Spinal Cord

  • The spinal cord is a vital part of the central nervous system (CNS). It resides within the vertebral canal of the vertebral column.
  • During development, there’s a discrepancy between spinal cord growth and vertebral column growth. The spinal cord completes its growth by age 4, while the vertebral column continues growing until around ages 14-18.
  • The spinal cord extends from the foramen magnum at the base of the skull down to the L1/L2 vertebra, where it terminates as the conus medullaris (medullary cone).
  • A delicate thread called the filum terminale extends from the tip of the conus medullaris to the first coccygeal vertebra (Co1), anchoring the spinal cord in place.
  • Remember this extent with the mnemonic “SCULL”Spinal Cord Until L2 (LL).

Spinal Cord Segments

  • Along its length, the spinal cord consists of several segments:
    • Cervical: Located in the neck region. Contains eight cervical segments.
    • Thoracic: Found in the upper back. Consists of 12 segments.
    • Lumbar: Situated in the lower back. Contains five lumbar segments.
    • Sacral: Occupying the pelvic region. Contains five sacral segments.
    • Coccygeal: The final segment near the tailbone. Contains one coccygeal segment.

Blood Supply of the Spinal Cord

  • The vertebral arteries are the primary source of blood supply to the spinal cord.
  • Additionally, specific arteries branch directly from the vertebral arteries to supply the spinal cord:
    • One anterior spinal artery
    • Two posterior spinal arteries
    • Anterior and posterior radicular arteries

Function of the Spinal Cord

  • The spinal cord serves as a conduit for information between the brain and the periphery.
  • It conducts impulses from the brain to the body and plays a crucial role in generating reflexes that facilitate our daily functioning.


Let’s summarize the main motorsensory, and other pathways within the spinal cord cross section:

1. Motor Pathways:

    • Corticospinal Tract (Pyramidal Tract):
      • Location: Located in the lateral white matter.
      • Function: Carries voluntary motor commands from the cortex to skeletal muscles.
      • Decussation: Most fibers decussate (cross) in the medulla oblongata.
      • Lesion Effects: Damage leads to contralateral weakness.

2. Sensory Pathways:

    • Dorsal Column-Medial Lemniscus Pathway:

      • Location: Found in the posterior white matter.
      • Function: Transmits fine touchvibration, and proprioception information.
      • Decussation: Fibers decussate in the medulla.
      • Lesion Effects: Damage results in ipsilateral loss of fine touch and proprioception.
    • Spinothalamic Tract (Anterolateral Pathway):

      • Location: Located in the anterolateral white matter.
      • Function: Carries pain and temperature information.
      • Decussation: Fibers decussate at the spinal cord level.
      • Lesion Effects: Damage leads to contralateral loss of pain and temperature sensation.

3. Other Pathways:

    • Spinocerebellar Tracts: Transmit proprioceptive information to the cerebellum for coordination.
    • Reticulospinal and Vestibulospinal Tracts: Influence muscle tone and posture.
    • Autonomic Pathways: Control involuntary functions (e.g., heart rate, digestion).



1 kenhub.com

2 geekymedics.com

3 med.libretexts.org

4 open.oregonstate.education

5 openstax.org



Verified by Dr. Petya Stefanova