Which of the following best describes the cavity indicated by the arrow in the image below?
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Options:
explanation: The image shows a dissected medial view of the right hemisphere, with the nose and frontal lobe towards the left of the image, and the occipital lobe and the cerebellum towards the right of the image. The third ventricle is a midline cavity of the ventricular system located at the level of the diencephalon, in between the left and the right thalami. It receives CSF from the lateral ventricles through the interventricular foramina of Monro and drains CSF through the cerebral aqueduct of Sylvius into the cavity indicated by the blue arrow, which is the fourth ventricle. The fourth ventricle is a midline cavity of the ventricular system which is located posterior to the pons and the medulla of the brainstem, and anterior to the cerebellum.
name: Third ventricle
label: b
answer: no
explanation: The image shows a dissected medial view of the right hemisphere, with the nose and frontal lobe towards the left of the image, and the occipital lobe and the cerebellum towards the right of the image. The interventricular foramen of Monro is a narrow passageway in between each of the lateral ventricles and the third ventricle, allowing CSF to drain. However, the blue arrow indicates the fourth ventricle, a midline cavity of the ventricular system which is located posterior to the pons and the medulla of the brainstem, and anterior to the cerebellum.
name: Interventricular foramen of Monro
label: e
answer: no
explanation: The image shows a dissected medial view of the right hemisphere, with the nose and frontal lobe towards the left of the image, and the occipital lobe and the cerebellum towards the right of the image. The blue arrow indicates the fourth ventricle, a midline cavity of the ventricular system which is located posterior to the pons and the medulla of the brainstem, and anterior to the cerebellum. It receives cerebrospinal fluid (CSF) from the third ventricle through the cerebral aqueduct of Sylvius and drains CSF into the spinal canal and the subarachnoid space (through the foramina of Luschka and Magendie).
name: Fourth ventricle
label: a
answer: yes
explanation: The image shows a dissected medial view of the right hemisphere, with the nose and frontal lobe towards the left of the image, and the occipital lobe and the cerebellum towards the right of the image. The cerebral aqueduct of Sylvius is a narrow passageway located immediately superior to the structure indicated by the arrow, which allows draining of CSF from the third ventricle into the fourth ventricle, which a midline cavity of the ventricular system which is located posterior to the pons and the medulla of the brainstem, and anterior to the cerebellum.
name: Cerebral aqueduct of Sylvius
label: d
answer: no
explanation: The image shows a dissected medial view of the right hemisphere, with the nose and frontal lobe towards the left of the image, and the occipital lobe and the cerebellum towards the right of the image. The lateral ventricles are two large cavities of the ventricular system, one in each cerebral hemisphere, containing choroid plexus producing CSF. They drain CSF into the third ventricle through the interventricular foramina of Monro. However, the blue arrow indicates the fourth ventricle, a midline cavity of the ventricular system which is located posterior to the pons and the medulla of the brainstem, and anterior to the cerebellum.
name: Lateral ventricle
label: c
answer: no

Correct answer: a