A 62 year old male patient presented with signs and symptoms of stroke. MR angiography revealed thrombus in the posterior cerebral aery. All of the following structures may be affected by the lesion except
**Core Concept**
The posterior cerebral artery (PCA) supplies a significant portion of the brain, including the occipital lobe, the medial and posterior aspects of the temporal lobe, and the thalamus. The PCA is closely related to the midbrain, the lateral geniculate body, and the choroid plexus of the third ventricle, but it has a more variable relationship with the pons.
**Why the Correct Answer is Right**
The pons is primarily supplied by the basilar artery, which is a direct continuation of the vertebral arteries. The basilar artery then bifurcates into the posterior cerebral arteries. Therefore, a lesion in the posterior cerebral artery is unlikely to affect the pons directly. However, it's essential to note that the PCA does have a variable relationship with the superior cerebellar arteries, which can supply the pons, but this is not the primary supply. The choroid plexus of the third ventricle, midbrain, and lentiform nucleus are all within the PCA's territory and can be affected by a PCA lesion.
**Why Each Wrong Option is Incorrect**
**Option A:** The choroid plexus of the third ventricle is closely related to the PCA and can be affected by a PCA lesion. The choroid plexus is responsible for producing cerebrospinal fluid, and a lesion in this area can lead to hydrocephalus or other cerebrospinal fluid-related complications.
**Option B:** The midbrain is supplied by the PCA, and a lesion in the PCA can affect the midbrain. The midbrain contains critical structures, including the oculomotor nerve (cranial nerve III), the trochlear nerve (cranial nerve IV), and the superior cerebellar peduncles.
**Option D:** The lentiform nucleus is part of the basal ganglia and is supplied by the lenticulostriate arteries, which are branches of the middle cerebral artery (MCA). However, the PCA can also supply a portion of the lentiform nucleus through the anterior choroidal artery, making it susceptible to PCA lesions.
**Clinical Pearl / High-Yield Fact**
In the context of stroke, it's essential to remember that the PCA's supply is more variable than the MCA or the anterior cerebral artery (ACA). A thorough understanding of the PCA's territory and its relationship with surrounding structures is crucial for accurate diagnosis and treatment.
✓ Correct Answer: C. Pons