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One-third of the cerebral blood supply is from the vertebral arteries.
Vertebral Artery
- First branches of the subclavian arteries on either side, entering the transverse process at C6.
- Ascends through the foramina in the transverse processes of the upper six cervical vertebrae to C1, where they enter the foramen magnum in front of the medulla.
- Inside the skull, the two vertebral arteries join to form the basilar artery.
Branches
- Posterior Inferior Cerebellar Artery (PICA)
- The largest branch of the vertebral artery, supplying the lateral medulla and lateral cerebellum.
- Loops around the medulla to reach the inferior surface of the cerebellum.
- Occlusion can lead to Wallenberg's syndrome (Lateral medullary syndrome).
- Anterior Spinal Artery
- Supplies the ventral medulla and forms where the vertebral arteries fuse.
- Posterior Spinal Artery : Supplies the dorsal medulla.
- Basilar Artery : Formed at the lower border of the pons by the fusion of the two vertebral arteries.
- Anterior Inferior Cerebellar Artery (AICA) : Supplies the lateral pons and anteroinferior cerebellum.
- Superior Cerebellar Artery : Supplies the lateral pons and the superior surface of the cerebellum.
- Pontine Arteries : Approximately 12 small branches that supply the medial pons, coming off at right angles from either side of the basilar artery.
- Internal Auditory Artery : A slender branch that arises near the middle of the basilar artery; it travels with the acoustic nerve through the internal acoustic meatus to supply the internal ear.
- Posterior Cerebral Artery (PCA)
- Embryologically originates from the internal carotid artery.
- Passes laterally, joining the posterior communicating artery, then sweeps back around the cerebral peduncle to the occipital lobe.
PCA Branches
- Postero-medial Ganglionic Branches : Arise at the commencement of the PCA, along with branches from the posterior communicating artery, supplying the medial surfaces of the thalami and the walls of the third ventricle.
- Posterior Choroidal Branches : Run forward beneath the splenium of the corpus callosum, supplying the tela choroidea of the third ventricle and the choroid plexus.
- Postero-lateral Ganglionic Branches : Arise after the PCA turns around the cerebral peduncle, supplying portions of the thalamus.
- Anterior Temporal Branch : Supplies the uncus and anterior part of the fusiform gyrus.
- Posterior Temporal Branch : Supplies the inferior temporal gyri, the calcarine sulcus, the cuneus, the lingual gyrus, and the posterior convex surface of the occipital lobe.
- Parietooccipital Branch : Supplies the parietooccipital region.