Blood Supply of the Spinal Cord

Blood Supply of the Spinal Cord

• The spinal cord is supplied by three main arteries:
  • Anterior spinal artery
  • Two posterior spinal arteries
  • Segmental spinal arteries (radicular arteries)
• Anterior Spinal Artery:
  • Single artery that arises from the union of the two anterior spinal branches of the vertebral arteries.
  • Runs along the anterior median fissure, supplying the anterior two-thirds of the spinal cord.
• Posterior Spinal Arteries:
  • Two arteries branching from the vertebral artery (sometimes arising from the posterior inferior cerebellar artery - PICA).
  • Runs in the posterolateral sulcus of the spinal cord, supplying the posterior one-third of the spinal cord.
• Radicular Arteries:
  • Radicular arteries are branches of major arteries that enter the vertebral canal through the intervertebral foramina.
  • Major source of blood supply for the lower two-thirds of the spinal cord.
  • They join the anterior and posterior spinal arteries.
  • Radicular arteries originate from:
    • Neck: vertebral and ascending cervical arteries.
    • Thorax: intercostal arteries.
    • Abdomen: lumbar arteries.
    • Pelvis: lateral sacral arteries.

Venous Drainage of the Spinal Cord

• The six longitudinal channels correspond to the arteries:
  • Anterior spinal veins
  • Posterior spinal veins
  • Anterolateral spinal veins (two)
  • Posterolateral spinal veins (two)
• These veins drain into the internal vertebral plexus of veins.

Internal Structure of the Spinal Cord

• Gray Matter:
  • Composed primarily of neuron cell bodies.
  • H-shaped or butterfly-like.
  • Gray commissure: contains the central canal.
  • Anterior horns: contain cell bodies of motor neurons.
  • Posterior (dorsal) horns: consists of interneurons (contain sensory nuclei).
  • Lateral horn: present only in thoracic and lumbar segments (T1-L2) for sympathetic nuclei, and sacral segments (S2, 3, 4) for parasympathetic nuclei.
• White Matter:
  • Composed of nerve fibers (ascending and descending tracts) with myelin sheaths.

Commissures of the Spinal Cord

• The two halves of the spinal cord are connected by three commissures:
  • White commissure
  • Anterior gray commissure (infront of the central canal)
  • Posterior gray commissure (behind the central canal)

Gray Matter of the Spinal Cord & Spinal Roots

• Motor Neurons:
  • Ventral Horn: - Medial group: for trunk muscles (L1 to S3). - Lateral group: supply the limb muscles (L1 to S3). - Central group: in cervical region only (phrenic nerve and spinal accessory nerve).
  • Dorsal horn (sensory) afferent:
    • Substantia Gelatinosa of Rolandi (SGR): pain, temperature, and touch.
    • Nucleus proprius: crude touch, light pressure (all levels).
    • Postromarginal nucleus: pain and temperature (all levels).
    • Clarke’s Nucleus: proprioception (C8-L2).
• Lateral horn:
  • Present only in thoracic and lumbar segments (T1-L2) for sympathetic nuclei, and sacral segments (S2, 3, 4) for parasympathetic nuclei.

White Matter of the Spinal Cord

• Composed of axons of nerve cells, forming tracts or fasciculi.
• Three types of fibers:
  • Ascending (ventral) columns
  • Descending (dorsal) columns
  • Lateral columns

Explore the intricate blood supply system of the spinal cord, including the roles of the anterior spinal artery, posterior spinal arteries, and segmental spinal arteries. This quiz examines the pathways and functions of these key arteries essential for spinal cord health and function.