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Blood Supply of the Spinal Cord

- Discussion:
    - blood is supplied to vertebral column by way of segmental arteries that arise near it from the aorta, or from adjacent arteries in areas
           beyond the extent of the aorta;
    - costocervical & intercostal arteries in thorax; lumbar and iliolumbar arteries in lumbar region; and lateral sacral arteries in pelvis;
    - dependence on 3 vessels: anterior median logituninal arterial trunk & pair of posterolateral trunks near the posterior nerve rootlets;
    - relative demands of gray matter and white matter;
          - longitudinal arterial trunks are largest in cervical and lumbar regions near the ganglionic enlargements and are much smaller in thoracic 
          - metabolic demands of gray matter are > those of white matter, which contains fewer capillary networks;

- Anterior Spinal Artery:
     - single artery runs in the ventral midline from foramen magnum to the filum terminale;
     - artery is supplied by series of 5-10 unpaired radicular arteries that originate from vertebral arteries & aorta and its branches;
     - blood supply of anterior portion of cord is much more vulnerable than that of posterior portion and can be decompensated by occlusion 
           of large radicular branch or lesions of the aorta;
     - two longitudinal pathways include the anterior spinal artery (ASA) & posterolateral arteries;
           - 75% of the blood supply to spinal cord is derived from ASA;
           - ASA arises from the vertebral artery caudal to the basilar artery;
           - two arteries from either side, one from each vertebral artery, join each other between C1 & C6 & form single arterial channel;

- Posterior spinal arteries:
     - posteriorly, there are paired posterior spinal arteries, which are fed by smaller radicular arteries at nearly every spinal level;

- Segmental Arteries of the vertebral column supply radicular arteries;
    - in thoracic and lumbar regions segmental arteries are known as intercostal and lumbar arteries which arise from posterior aspect of aorta;
          - these segmental arteries proceed to intervertebral foramina appropriate to their level, where they divide into terminal branches;
          - one of the largest radicular arteries is the ARM (or Artery of Adamkiewicz);
    - Artery of Adamkiewicz;
          - largest of the segmental arteries w/ a characteristic hairpin bend is referred to as the arteria radicularis magna (ARM) and is also 
                 known as artery of Adamkiewicz;
          - although in early embryonic development every segment of spinal cord receives paired radicular arteries, these disappear, leaving one 
                 or two cervical, two or three throacic, and one or two lumbar arteries;
          - most commonly arises at T10 on left side, however, position may vary from T7 to L4, with it being on right side in 17% of pts;
                 - usually the artery enters a single intervetebral foramen between the levels of T9-T11

The blood supply of the spinal cord.