Blood Supply of the Brain Quiz

Blood Supply of the Brain

• The brain receives its blood supply from two sets of arteries:
  • Vertebral arteries
  • Internal carotid arteries

Arterial Supply of the Brain

• Vertebral Arteries:

  • Originate as branches from the first part of the subclavian artery.
  • Have 4 parts; the 4th part passes through the foramen magnum, ascends upward and medially on the medulla to reach the lower border of the pons.
  • The two vertebral arteries unite to form the basilar artery at the lower border of the pons.

• Internal Carotid Arteries:

  • Enter the skull through the carotid canal.
  • Pass through the cavernous sinus.
  • End at the base of the brain, dividing into two terminal branches:
    • Anterior cerebral artery
    • Middle cerebral artery

Internal Carotid Artery

• Originates as one of the two terminal branches of the common carotid artery.
• Course is divided into 4 parts: cervical, petrous, cavernous and supracavernous.
• Terminates on the lateral side of the optic chiasma just below the anterior perforated substance, dividing into the anterior cerebral and middle cerebral arteries.

Basilar Artery

• Formed by the union of the two vertebral arteries.
• Ascends in the basilar groove of the pons.
• Terminates at the upper border of the pons, dividing into two posterior cerebral arteries.

Circle of Willis

• An anastomosis (connection) of the branches of the two internal carotid arteries and the basilar artery.
• Located at the base of the brain in the interpeduncular fossa
• Formed by six large arteries and three communicating arteries
• Function as an important link between the internal carotid and the vertebrobasilar system, crucial for blood supply to the brain.

Branches of Cranial Part of Vertebral Artery

• Anterior spinal artery
• Posterior spinal artery
• Posterior inferior cerebellar artery (largest branch)
• Meningeal arteries (supply dura matter of the posterior cranial fossa)
• Medullary arteries (supply medulla oblongata)

Middle Cerebral Artery

• Supplies the lateral surface of the cerebral hemisphere, specifically excluding the upper border, from the frontal pole to the parieto-occipital sulcus.
• Also supplies a narrow strip of the temporal lobe along the lower border.
• Clinical Importance: Supplies the following areas: motor, and sensory areas for the whole body except lower limbs, auditory area in the superior temporal gyrus, Broca's area and sensory area of speech and the internal capsule, insula.

Anterior Cerebral Artery

• Supplies the medial surface of the cerebral hemisphere from the frontal pole to the parieto-occipital sulcus.
• Clinical Importance: Supplies motor and sensory areas for the lower limb and perineum, septal area (plays a role in prolonged unconsciousness), and the corpus callosum (lesions can produce apraxia).

Posterior Cerebral Artery

• Supplies the posterior surface of the cerebral hemisphere, primarily the occipital lobe.
• Clinical Importance: Supplies the whole visual cortex, the center of smell in the uncus, most of the thalamus and midbrain, and most of the choroid plexuses.

The Cerebellum

• Superior Surface: Supplied by the superior cerebellar branch of the basilar artery.
• Inferior Surface: Supplied by
  • Posterior inferior cerebellar artery (main part)
  • Anterior inferior cerebellar branch of the basilar artery (small anterior part)

The Midbrain

• Supplied by central branches of the posterior cerebral artery (terminal branch of the basilar artery), plus the superior cerebellar artery and the posterior communicating artery.

The Pons

• Anterior Part (basis pontis): Supplied by pontine branches of the basilar artery.
• Posterior Part (tegmentum):
  • Lower pons: posterior inferior cerebellar artery.
  • Upper pons: superior cerebellar artery.

The Medulla Oblongata

• Supplied by branches of the vertebral artery.
• Anterolateral Surface: Supplied by medullary branches of anterior spinal artery (medially) and the 4th part of vertebral artery (laterally).
• Posterolateral Surface: Posterior inferior cerebellar artery.
• Gracile and cuneate tracts and nuclei: Supplied by the posterior spinal artery.