The document details the vascular anatomy of the brain, describing the primary arteries, including the internal carotid and vertebral arteries, and their significant branches and functions. It highlights the importance of these arteries in supplying oxygen and nutrients to various brain regions and the potential consequences of occlusions. Additionally, the document mentions the arterial circle of Willis and its role in providing collateral circulation to the brain.

1. Arteries of the Brain

2. • Supply 15% of the cardiac output to the brain.
• Provide the brain with 20% of the oxygen used by the body.
• Consist of two pairs of vessels, the internal carotid arteries and the
vertebral arteries, and their divisions. At the junction between the
medulla and the pons, the two vertebral arteries fuse to form the
basilar artery.
Internal carotid artery
Vertebral artery
Basilar artery

3. Internal carotid artery
• Enters the cranium via the carotid canal of the temporal
bone.
• Lies within the cavernous sinus as the carotid siphon.
• Supplies tributaries to the dura, hypophysis, tympanic
cavity, and trigeminal ganglion.
• Provides direct branches to the optic nerve, optic
chiasm, hypothalamus, and genu of the internal
capsule.
• Hippocampus, amygdala, optic tract, lateral geniculate
body, globus pallidus, and posterior limb of the internal
capsule.

4. Internal carotid artery
• Divides into:
1. Ophthalmic artery: enters the orbit via the optic canal
with the optic nerve.
2. Central artery of the retina: is a branch of the
ophthalmic artery.
• Provides the only blood supply to the inner five layers of
the retina.
• Is an end artery; its occlusion results in blindness.
3. Posterior communicating artery: arises from the
carotid siphon and joins the posterior cerebral artery.
• Supplies the optic chiasm and tract, hypothalamus,
subthalamus, and anterior half of the ventral portion of
the thalamus.
• Is a common site of berry aneurysms.

5. Internal carotid artery
4. Anterior choroidal artery:
• Supplies the choroid plexus of the temporal
horn of the lateral ventricle
• Supplies the proximal portion of optic
radiations.
5. Anterior cerebral artery: originate at the
terminal bifurcation of the internal carotid artery.
• Gives direct branches to the optic chiasm.
• Supplies the medial surface of the frontal and
parietal lobes and carpus callosum.
• Supplies the leg and foot area of the motor and
sensory cortices (paracentral lobule).

6. Internal carotid artery
6. Anterior communicating artery: connects the
two anterior cerebral arteries.
• Is a common site of berry aneurysms.
7. Middle cerebral artery: begins at the
bifurcation of the internal carotid artery.
• Supplies the lateral convexity of the
hemisphere.
• Supplies the trunk, arm, and face areas of the
motor and sensory cortices.
• Supplies the Broca and Wernicke speech areas.

7. Vertebral artery
• Is a branch of the subclavian artery.
• Joins its opposite partner to form the basilar artery.
• Gives rise to:
1. Anterior spinal artery
2. Posterior spinal artery: is occasionally a branch of the vertebral
artery.
3. Posterior inferior cerebellar artery: gives rise to the posterior
spinal artery.
• Supplies the dorsolateral zone of the medulla.
• Supplies the inferior surface of the cerebellum and the choroid
plexus of the fourth ventricle.
• Supplies the medial and inferior vestibular nuclei, inferior
cerebellar peduncle, nucleus ambiguus, intra-axial fibers of the
glossopharyngeal nerve (CN IX) and the vagal nerve (CN X),
spinothalamic tract, and spinal trigeminal nucleus and tract.
• Supplies the hypothalamospinal tract.

8. Basilar artery
• Is formed by the two vertebral arteries.
• Spinal trigeminal nucleus and tract, vestibular nuclei, cochlear nuclei, vestibulocochlear
nerve, spinothalamic tract, and cerebellar peduncles.
• Gives rise to:
1. Pontine arteries:
Supplies corticospinal tracts and abducens nerve (CN VI).
2. Labyrinthine artery: arises from the basilar artery in 15% of the population.
• Perfuses the cochlea and the vestibular apparatus.
3. Anterior inferior cerebellar artery: supplies the inferior surface of the cerebellum.
• Gives rise to the labyrinthine artery in 85% of the population.
• Supplies the facial nucleus.
• Supplies the hypothalamospinal tract.

9. Basilar artery
4. Superior cerebellar artery: supplies the superior surface of the cerebellum and the
cerebellar nuclei (dentate nucleus).
• Supplies the rostral and lateral pons, including the superior cerebellar peduncle and
spinothalamic tract.
5. Posterior cerebral artery: originates from the internal carotid (fetal origin) in 20% of the
population.
• Is formed by bifurcation of the basilar artery.
• Provides the major blood supply to the midbrain.
• Supplies the posterior half of the thalamus and the medial and lateral geniculate bodies.
• Supplies the occipital lobe, visual cortex, and inferior surface of the temporal lobe,
including the hippocampal formation.
• Gives rise to the lateral and medial posterior choroidal arteries, which supply the dorsal
thalamus, pineal body, and choroid plexus of the third and lateral ventricles.

10. Arterial Circle of Willis
Is formed by:
• Anterior communicating
• Anterior cerebral
• Internal carotid
• Posterior communicating
• Posterior cerebral arteries
Gives off penetrating arteries to
supply the ventral diencephalon
(hypothalamus, subthalamus,
thalamus) and the midbrain.