Blood supply

Spinal Cord Blood Supply

I. Arterial Blood Supply

Main Sources

• Blood supply comes mainly from:

  • Vertebral arteries

  • Ascending cervical arteries

  • Posterior intercostal arteries

  • Lumbar arteries

Spinal Branches

• These arteries give spinal branches:

  • Directly from:

    • Vertebral arteries

    • Ascending cervical arteries

  • Indirectly from:

    • Dorsal branches of posterior intercostal and lumbar arteries

Entry into Vertebral Canal

• Spinal branches:

  • Enter through intervertebral foramina

  • Divide into:

    • Anterior radicular branches

    • Posterior radicular branches

1. Anterior Radicular Branches

General Features

• Number: 4–10

Constant Branches

• Cervical region: 1 artery

• Inferior thoracic region: 2 arteries

• Superior lumbar region: 1 artery

Course & Branching

• Larger (voluminous) branches:

  • Reach the anterior surface of the spinal cord

  • Divide into:

    • Ascending branch (thinner)

    • Descending branch (thicker)

Anastomosis

• These branches anastomose with opposite ones

• This forms the anterior spinal artery at the level of linea splendens

Special Artery

• Adamkiewicz artery:

  • Most voluminous anterior radicular artery

  • Origin: T8 – L3

2. Posterior Radicular Arteries

Course & Function

• Give:

  • Ascending branches

  • Descending branches

• These:

  • Unite with branches above and below

  • Participate in forming the posterior spinal arteries

1. Vertebral Arteries

Origin

• Arise from the subclavian artery

Course

• Ascend upward and medially

• Pass through the foramen transversarium of C6

• Enter the transverse canal

• Located anterior to cervical spinal nerves

• Accompanied by the vertebral nerve

Between Axis (C2) and Atlas (C1)

• Form a curvature in the sagittal plane

• Concavity directed posteriorly

At the Atlas

• After passing the foramen transversarium:

  • Move laterally to the lateral mass

  • Form a second curvature in the horizontal plane

  • Concavity directed anteriorly

Entry into Skull

• Cross the posterior atlanto-occipital membrane

• Enter through the foramen magnum

Intracranial Course

• Cross:

  • Dura mater

  • Arachnoid

• Located in the subarachnoid space

Termination

• Reach the anterior aspect of the medulla oblongata

• Unite with the opposite vertebral artery

• Form the basilar artery

Branches to Spinal Cord

• From the lateral aspect of the medulla oblongata arise:

  • 2 anterior spinal arteries

  • 2 posterior spinal arteries

2. Anterior Spinal Artery

Origin

• Arises from the superior aspect of the vertebral artery

• Forms before the basilar artery

Formation

• Two branches:

  • Have a short descending course

  • Unite on the anterior aspect of the medulla

• Form a single anterior spinal artery

Course & Position

• Runs along:

  • Anterior surface of the spinal cord

  • Median fissure

Branches

• Gives few branches to the medulla

Anastomoses

• From the inferior cervical region:

  • Anastomoses with ascending and descending branches of anterior radicular arteries

Blood Source

• In the cervical region:

  • Contains mainly blood from the vertebral arteries

At Filum Terminale

• Forms an anastomotic loop with posterior spinal arteries

Segmental Branches

• At each spinal segment:

  • Branches penetrate the median fissure

  • More numerous in intumescences

  • Are terminal branches

Supply

• Supplies:

  • Anterior horn

  • Base of posterior horn

  • Surrounding white matter (anterior 2/3)

3. Posterior Spinal Arteries

Course

• Begin with a short descending course on the posterior medulla

• Descend along:

  • Posterior surface of the spinal cord

  • Medial to posterior roots of spinal nerves

Anastomoses & Arrangement

• Anastomose with posterior radicular arteries

• Extend inferiorly as:

  • Two plexiform arterial channels

• These:

  • Run along posterior cord

  • Sometimes unite at the midline

Supply

• Supply:

  • Head of posterior horn

  • Surrounding white matter

4. General Arterial Supply of Spinal Cord

Main Sources

• Vertebral arteries

• Ascending cervical arteries

• Posterior intercostal arteries

• Lumbar arteries

Spinal Branches

• Arise:

  • Directly from vertebral and ascending cervical arteries

  • Indirectly from dorsal branches of posterior intercostal and lumbar arteries

Entry

• Enter vertebral canal through:

  • Intervertebral foramina

Division

• Divide into:

  • Anterior radicular branches

  • Posterior radicular branches

5. Anterior Radicular Branches

Number

• 4–10

Constant Branches

• Cervical region → 1 artery

• Inferior thoracic region → 2 arteries

• Superior lumbar region → 1 artery

Course

• Larger branches:

  • Reach anterior surface of spinal cord

  • Divide into:

    • Ascending (thin) branch

    • Descending (thick) branch

Anastomosis

• Unite with opposite branches

• Form the anterior spinal artery at the level of linea splendens

Special Artery

• Adamkiewicz artery:

  • Most voluminous anterior radicular artery

  • Origin: T8–L3

6. Posterior Radicular Arteries

Course & Function

• Give:

  • Ascending branches

  • Descending branches

• These:

  • Unite with branches above and below

  • Contribute to formation of posterior spinal arteries

7. Perimedullary Network

• Anterior and posterior spinal arteries:

  • Give branches that anastomose

  • Form a perimedullary network

Radial Branches

• From this network:

  • Radial branches arise

  • Pierce the white matter

8. Final Note

• Blood supply of:

  • Gray matter > White matter