Quick Overview
The posterior cerebral artery (PCA) is one of the four major arteries that supply blood to the brain. It originates from the basilar artery at the base of the brain and runs around the midbrain to supply blood to the occipital lobe, which is the part of the brain responsible for vision. The PCA also supplies blood to parts of the temporal lobe and thalamus.
Table of Contents
Anatomy of the Posterior Cerebral Artery:
According to the old books of general anatomy the PCA is divided into three distinct segments, which include P1, P2, and P3 but the recent classification also adds the P4 segment.
P1 refers to the proximal segment, P2 the ambient segment, P3 the quadrigeminal or choroidal segment and P4 represents the terminal branches found in the calcarine fissure.
| Artery | Description |
| Origin | Basilar Artery |
| Branches | Calcarine Artery, Thalamogeniculate Arteries, Medial and Lateral Posterior Choroidal Arteries |
| Supply | Occipital lobe, Temporal lobe, Thalamus, Midbrain, Choroid plexus |
Branches:
The PCA gives rise to several branches, including the:
- Calcarine Artery: Supplies the primary visual cortex.
- Thalamogeniculate Arteries: Nourish the thalamus.
- Medial and Lateral Posterior Choroidal Arteries: Supply the choroid plexus and midbrain structures.
Posterior Cerebral Artery Segments
The PCA is divided into four segments:
1- P1 Segment (Proximal Segment): The P1 segment is the initial part of the PCA, originating from the basilar artery. It supplies blood to the midbrain and helps nourish the posterior part of the thalamus.
2- P2 Segment (Ambient Segment): The P2 segment continues from the P1 segment and wraps around the cerebral peduncles. It supplies blood to the thalamus, midbrain structures, and the posterior part of the cerebral hemispheres.
3- P3 Segment (Quadrigeminal or Choroidal Segment): The P3 segment extends further into the brain, supplying the choroid plexus of the third and lateral ventricles. It also provides blood to parts of the thalamus and midbrain.
4- P4 Segment (Cortical or Calcarine Segment): The P4 segment is the distal portion of the PCA, and it is responsible for supplying the occipital lobes of the brain, particularly the primary visual cortex. This segment is crucial for processing visual information and supporting visual functions.
Right Posterior Cerebral Artery
The right PCA is one of the two main branches of the basilar artery. It supplies blood to the right occipital lobe, right temporal lobe, and right thalamus.
Left Posterior Cerebral Artery
The left PCA is the other main branch of the basilar artery. It supplies blood to the left occipital lobe, left temporal lobe, and left thalamus.
Posterior Cerebral Artery Supplies
The PCA supplies blood to the following parts of the brain:
- Occipital lobe
- Temporal lobe
- Thalamus
- Midbrain
- Choroid plexus
Posterior Cerebral Artery Syndrome
Posterior cerebral artery syndrome is a condition that occurs when there is a blockage in the PCA. This can cause a variety of symptoms, including:
- Vision loss
- Hemianopia (blindness in half of the visual field)
- Color blindness
- Cortical blindness (blindness without any damage to the eyes)
- Aphasia (difficulty speaking or understanding language)
- Agnosia (difficulty recognizing objects or people)
- Hemiparesis (weakness on one side of the body)
- Hemianesthesia (loss of sensation on one side of the body)
Posterior Cerebral Artery Stroke
A posterior cerebral artery stroke occurs when the blood supply to the PCA is blocked. This can cause a variety of symptoms, depending on the part of the brain that is affected. Symptoms of a PCA stroke may include vision loss, hemiparesis, hemianesthesia, aphasia, and agnosia.
Posterior Cerebral Artery Stenosis
Posterior cerebral artery stenosis is a narrowing of the PCA. This can be caused by a buildup of plaque, which is a fatty substance that can form on the walls of the arteries. PCA stenosis can increase the risk of a PCA stroke.
Symptoms of Fetal Origin of the Right and Left Posterior Cerebral Artery
The fetal origin of the PCA can lead to a number of abnormalities, including:
- Agenesis (absence of the PCA)
- Hypoplasia (underdevelopment of the PCA)
- Duplication of the PCA
- Persistent primitive hypoglossal artery
These abnormalities can cause a variety of symptoms, including vision loss, seizures, and developmental delays.
Questions
1. What symptoms might occur with bilateral Posterior Cerebral Artery occlusions?
Bilateral PCA occlusions may lead to severe symptoms such as vision loss, memory problems, altered consciousness, sensory and motor deficits, and headaches.
2. Which part of the brain is supplied by the Posterior Cerebral Artery?
The PCA supplies the occipital lobes (responsible for vision), parts of the thalamus, midbrain structures, and the choroid plexus of ventricles.
3. What does fetal origin of the right Posterior Cerebral Artery mean?
Fetal origin of the right PCA is an anatomical variation where blood supply to the right PCA comes from fetal-type circulation, potentially affecting blood flow patterns and causing neurological symptoms.
4. What symptoms might occur with bilateral Posterior Cerebral Artery occlusions?
Bilateral PCA occlusions can result in vision loss, memory issues, cognitive deficits, altered consciousness, sensory and motor problems, and headaches.
5. How do Posterior Cerebral Artery strokes affect vision?
PCA strokes impact vision significantly because they supply the occipital lobes. This can lead to visual disturbances such as hemianopia, visual hallucinations, visual agnosia, depth perception issues, and reading difficulties.