Blood Supply of Brain and Spinal Cord

Blood Supply of Brain and Spinal Cord

• Brain is 2% of total body water (TBW)
• Brain consumes 15% of normal cardiac output
• Brain consumes 25% of body's oxygen
• Over 90% of blood is distributed to cortical (gray matter) tissue.
• Brain receives blood from two sources: internal carotid arteries and vertebral arteries.
• Internal carotid artery: arises from the common carotid artery, enters the skull via the carotid canal, and bifurcates into the anterior and middle cerebral arteries.
  • Extracranial part: from the origin of the ICA to the skull base
  • Intracranial part: subdivided into petrous, cavernous, and subarachnoid portions
• Vertebral arteries: arise at the root of the neck from the first part of the subclavian artery.
  • Ascends through foramina transversarium of cervical vertebrae.
  • Enter the skull through the foramen magnum.
• Circle of Willis: an arterial ring at the base of the brain formed by the basilar artery and internal carotids.
• Middle cerebral artery: continuation of the internal carotid, emerges from the lateral sulcus to supply the superior lateral surface of the brain.
• Exclusions: most of the superior and inferior parts
• Supplies: all motor and sensory areas, excluding the lower limb, deep nuclei, internal capsules, and lateral/third ventricles.
• Anterior cerebral artery: supplies the medial aspect of the brain, superior margin of the cortex, which supply the foot, and motor/sensory areas for the lower limb, and corpus callosum.
• Posterior cerebral artery: supplies the posterior cortex and brainstem, entire visual cortex, center of smell in the uncus, most of the thalamus and midbrain, and most of the choroid plexuses.
• Blood Supply to Cerebellum:
  • Superior cerebellar artery (SCA) from basilar artery
  • Anterior inferior cerebellar artery (AICA) from basilar artery
  • Posterior inferior cerebellar artery (PICA) from vertebral artery
• Blood Supply to Spinal Cord: supplied by three longitudinal arteries (anterior spinal artery, and right and left posterior spinal arteries).
• Travel in the subarachnoid space, sending branches to the spinal cord.
• Anastomose via the anterior and posterior segmental medullary arteries, entering the spinal cord at various points.
• Extra-dural hemorrhage: results from injury to meningeal arteries/veins, most commonly the anterior branch of the middle meningeal artery.
• Sub-dural hemorrhage: results from tearing of superior cerebral veins at entrance to the superior sagittal sinus. Caused by a blow to the front or back of the head, causing an anteroposterior displacement of the brain.

Arterial Territories (of the brain)

• Anterior cerebral artery: supplies the front part
• Middle cerebral artery: supplies the middle part, lateral surface
• Posterior cerebral artery: supplies the back part of the brain

Explore the complex blood supply system of the brain and spinal cord. This quiz covers essential information about blood flow, arterial sources, and anatomical structures involved. Test your knowledge on the roles of the internal carotid and vertebral arteries, as well as the significance of the Circle of Willis.