Brain and Neuroanatomy Practice Questions

Q: Identify the marked structure.

Corpus callosum. ***Corpus callosum*** - The **corpus callosum** is a prominent, thick bundle of white matter fibers that connects the two cerebral hemispheres, located just superior to the **lateral ventricles** and **septum pellucidum**. - It is typically identified in sagittal brain imaging as a C-shaped structure forming the roof of the **lateral ventricles** and contributing to the **major commissures** of the brain. *Septum pellucidum* - The **septum pellucidum** is a thin, triangular, vertical membrane that separates the anterior horns of the left and right **lateral ventricles**. - It is located inferior to the body of the **corpus callosum** and superior to the **fornix**, rather than being the large, dense band of fibers itself. *Globus pallidus* - The **globus pallidus** is a subcortical structure located deep within the cerebral hemispheres, specifically medial to the **putamen** in the **lentiform nucleus**. - It is a key component of the **basal ganglia** involved in motor control and is not part of the midline sagittal structures typically identified in this context. *Fornix* - The **fornix** is a C-shaped bundle of nerve fibers in the brain that acts as the primary output tract from the **hippocampus** to the **mammillary bodies**. - It follows an arch-like course inferior to the **septum pellucidum** and is distinct from the **corpus callosum** which lies superior to the ventricles.

Q: Identify the marked structure:

Body. ***Body*** - It is the central and largest portion of the **corpus callosum**, situated between the **genu** anteriorly and the **splenium** posteriorly. - It forms the roof of the **lateral ventricles** and connects the cortical areas of the frontal and parietal lobes across the midline. *Rostrum* - This is the thin, beak-like extension located most anteriorly and inferiorly, continuous with the **lamina terminalis**. - It represents the most anterior and inferior part of the **corpus callosum**, positioned ahead of the genu. *Splenium* - This is the thick, posterior-most bulbous part of the **corpus callosum** that overhangs the **midbrain**. - It contains fibers that primarily interconnect the **occipital lobes** and the temporal lobes. *Genu* - This is the anterior, knee-shaped bend of the **corpus callosum** that connects the two **frontal lobes**. - It is located between the rostrum and the body, serving as a distinct anatomical landmark in the midline sagittal section of the brain.

Q: Which artery supplies the deep cerebellar nuclei?

Superior cerebellar artery. **Explanation:** The **Superior Cerebellar Artery (SCA)** is the primary blood supply to the **deep cerebellar nuclei** (Dentate, Emboliform, Globose, and Fastigial). Arising from the distal part of the basilar artery, the SCA supplies the superior surface of the cerebellar cortex, the superior cerebellar peduncle, and the deep-seated nuclei before they project to the thalamus and red nucleus. **Analysis of Options:** * **Superior Cerebellar Artery (Correct):** It provides the deep penetrating branches that reach the cerebellar core and nuclei. * **Anterior Inferior Cerebellar Artery (AICA):** Supplies the anterior-inferior surface of the cerebellum, the middle cerebellar peduncle, and the CN VII and VIII nerves. It does not typically supply the deep nuclei. * **Anterior Spinal Artery:** Supplies the anterior two-thirds of the spinal cord and the medial medulla (including the pyramids and medial lemniscus). * **Posterior Cerebral Artery (PCA):** Supplies the visual cortex (occipital lobe) and the inferior surface of the temporal lobe. While it is part of the Circle of Willis, it does not supply the cerebellum. **High-Yield Facts for NEET-PG:** * **The Dentate Nucleus** is the largest and most clinically significant deep nucleus; its blood supply is almost exclusively from the **SCA**. * **PICA (Posterior Inferior Cerebellar Artery)** supplies the postero-inferior surface and the **Lateral Medulla**. Occlusion leads to **Wallenberg Syndrome**. * **AICA** occlusion leads to **Lateral Pontine Syndrome**, uniquely characterized by **ipsilateral facial paralysis and deafness** (due to involvement of CN VII, VIII, and the labyrinthine artery). * **Rule of Thumb:** The SCA supplies the "top," AICA the "middle/front," and PICA the "bottom/back" of the cerebellum.

Q: Which thalamic nucleus projects to the striatum?

Centromedian nucleus. The **Centromedian (CM) nucleus** is the largest of the **intralaminar nuclei** of the thalamus [1]. Unlike the specific relay nuclei, the intralaminar nuclei have widespread connections. The CM nucleus specifically functions as a part of the **basal ganglia circuit**, receiving inputs from the globus pallidus and projecting primarily to the **striatum** (caudate nucleus and putamen) [3]. This pathway is crucial for regulating cortical excitability and motor functions [2]. **Analysis of Incorrect Options:** * **B. Mediodorsal nucleus:** This nucleus is part of the limbic system. It receives input from the amygdala and olfactory tract and projects to the **prefrontal cortex**. It is involved in memory, emotion, and executive function. * **C. Ventral anterior (VA) nucleus:** This is a motor relay nucleus. It receives input from the basal ganglia (globus pallidus) and projects to the **premotor cortex** and supplementary motor area. * **D. Ventral lateral (VL) nucleus:** Another motor relay nucleus, it receives major input from the **cerebellum** (dentate nucleus) and projects to the **primary motor cortex** (Brodmann area 4). **High-Yield Facts for NEET-PG:** * **Mnemonic for CM:** **C**entromedian = **C**onnects to **C**audate/Striatum. * The **Ventral Postero-Lateral (VPL)** nucleus relays sensory information from the body (Spinothalamic and DCML). * The **Ventral Postero-Medial (VPM)** nucleus relays sensory information from the face (Trigeminal pathway). * **Lateral Geniculate Body (LGB)** is for Vision (**L**ight); **Medial Geniculate Body (MGB)** is for Hearing (**M**usic).

Q: Which of the following is NOT a branch of the basilar artery?

Posterior communicating artery. **Explanation:** The **basilar artery** is formed by the union of the two vertebral arteries at the lower border of the pons. It ascends in the pontine sulcus and terminates at the upper border of the pons by dividing into the two posterior cerebral arteries. **1. Why the Correct Answer is Right:** The **Posterior Communicating Artery (PCoA)** is a branch of the **Internal Carotid Artery (ICA)**. It forms a vital part of the Circle of Willis by connecting the ICA system with the posterior cerebral artery (a terminal branch of the basilar system). Since it originates from the ICA, it is not a branch of the basilar artery. **2. Analysis of Incorrect Options (Branches of the Basilar Artery):** * **Pontine Artery:** Multiple small vessels that supply the pons. * **Anterior Inferior Cerebellar Artery (AICA):** Arises from the lower part of the basilar artery to supply the anterior-inferior aspect of the cerebellum. * **Labyrinthine Artery:** Usually arises from the AICA (85% of cases) or directly from the basilar artery. It accompanies the CN VII and VIII into the internal acoustic meatus. * *Note:* The **Superior Cerebellar Artery** is also a major branch arising just before the terminal bifurcation. **3. NEET-PG High-Yield Pearls:** * **Terminal Branches:** The basilar artery ends by dividing into two **Posterior Cerebral Arteries (PCA)**. * **Clinical Correlation:** Occlusion of the basilar artery can lead to **"Locked-in Syndrome,"** where the patient is conscious but paralyzed (except for vertical eye movements). * **Aneurysm Site:** The PCoA is a common site for berry aneurysms, which can cause **third nerve palsy** (mydriasis and ptosis) due to its proximity to the oculomotor nerve.

Question 1

Identify the marked structure.

Accepted Answer

Corpus callosum

Answer

Septum pellucidum

Answer

Globus pallidus

Answer

Fornix

Question 2

Identify the marked structure:

Accepted Answer

Body

Answer

Rostrum

Answer

Splenium

Answer

Genu

Question 3

Which artery supplies the deep cerebellar nuclei?

Accepted Answer

Superior cerebellar artery

Answer

Anterior inferior cerebellar artery

Answer

Anterior spinal artery

Answer

Posterior cerebral artery

Question 4

Which thalamic nucleus projects to the striatum?

Accepted Answer

Centromedian nucleus

Answer

Mediodorsal nucleus

Answer

Ventral anterior nucleus

Answer

Ventral lateral nucleus

Question 5

Which of the following is NOT a branch of the basilar artery?

Accepted Answer

Posterior communicating artery

Answer

Labyrinthine artery

Answer

Anterior inferior cerebellar artery

Answer

Pontine artery

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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