Brain and Neuroanatomy Practice Questions

Q: Hemiballismus is due to lesion of

Subthalamic nucleus. Subthalamic nucleus [1] - **Hemiballismus** is characterized by **unilateral, involuntary, violent, flinging movements** of the proximal musculature, primarily affecting the limbs. - This symptom complex is classically associated with a lesion in the **contralateral subthalamic nucleus (STN)**, which is part of the basal ganglia circuit [1]. *Putamen* - Lesions of the putamen are more commonly associated with other movement disorders such as **dystonia** or **parkinsonian symptoms**, not hemiballismus. - The putamen plays a key role in **motor learning and habit formation**, and its dysfunction leads to a range of motor control problems. *Caudate nucleus* - Damage to the caudate nucleus is often linked to **Huntington's disease**, which involves **chorea** (irregular, rapid, uncontrolled movements) and cognitive decline [1]. - While it is part of the basal ganglia loop, its primary role in movement control is distinct from the STN's involvement in hemiballismus. *Globus pallidus* - Lesions of the globus pallidus are associated with different movement disorders, such as **dystonia** and **bradykinesia**. [1] - The globus pallidus (particularly the internal segment) is the primary output nucleus of the basal ganglia, but its dysfunction does not typically produce hemiballismus.

Q: A 68-year-old man has many months history of progressive hearing loss, unsteady gait, tinnitus, and facial pain. An MRI scan reveals a tumor at the cerebellopontine angle. Which of the following cranial nerves is this tumor most likely to affect?

eighth cranial nerve. ***eighth cranial nerve*** - The **eighth cranial nerve (vestibulocochlear nerve)** is located in the **cerebellopontine angle** and is responsible for **hearing and balance**. [1], [2] - Symptoms like **progressive hearing loss, tinnitus, and unsteady gait (vertigo)** are classic signs of compression or damage to this nerve, often caused by an **acoustic neuroma (vestibular schwannoma)** in this region. [2], [3] - **CN VIII is the FIRST and MOST COMMONLY affected nerve** in cerebellopontine angle tumors, making it the correct answer. - The **facial pain** mentioned suggests compression of the **trigeminal nerve (CN V)** by a large tumor, which can occur as the tumor expands, but CN VIII remains the primary nerve affected. *sixth cranial nerve* - The **sixth cranial nerve (abducens nerve)** innervates the **lateral rectus muscle**, responsible for **abduction of the eye**. - Damage would typically result in **diplopia** and an inability to move the eye laterally, which is not described. - This nerve is **rarely affected** by CPA tumors due to its anatomical location. *tenth cranial nerve* - The **tenth cranial nerve (vagus nerve)** controls **pharyngeal and laryngeal muscles**, as well as **parasympathetic innervation to many organs**. - Damage would typically cause **dysphagia**, **hoarseness**, or autonomic dysfunction, none of which are presented. - The vagus nerve is **not typically affected** by CPA tumors. *fourth cranial nerve* - The **fourth cranial nerve (trochlear nerve)** innervates the **superior oblique muscle**, aiding in **eye movement**. - Damage would primarily lead to **vertical diplopia**, particularly when looking down and in, which is not mentioned as a symptom. - This nerve is **not affected** by CPA tumors due to its location.

Q: A child presented with weakness of limbs, cannot sit properly and swaying both sides while walking. The lesion is in

Cerebellar vermis. ***Cerebellar vermis*** - Lesions in the **cerebellar vermis** typically cause **truncal ataxia**, leading to difficulty sitting upright and a wide-based gait with swaying [1]. - The vermis is responsible for coordinating **proximal and trunk movements**, which are essential for maintaining balance and posture. *Neocerebellum* - The neocerebellum (lateral hemispheres) is primarily involved in **fine motor coordination** and planning of voluntary movements [1]. - Lesions here typically result in **appendicular ataxia**, affecting movements of the limbs (e.g., dysmetria, dysdiadochokinesia), rather than truncal instability [1]. *Cerebellopontine area* - The cerebellopontine angle (CPA) is a region at the base of the brain where the cerebellum, pons, and medulla meet. - Lesions in this area often present with **cranial nerve palsies** (especially CNs VII and VIII), along with ataxia, but not specifically isolated truncal ataxia. *Cerebellar hemisphere* - Similar to the neocerebellum, the cerebellar hemispheres are primarily involved in **coordinating limb movements**. - Lesions here would typically cause **ipsilateral appendicular ataxia**, affecting the limbs on the same side as the lesion, rather than severe truncal instability [1].

Q: Auditory pathway passes through -

Medial geniculate body. ***Medial geniculate body*** - The **medial geniculate body (MGB)** is the **thalamic relay nucleus** for the **auditory pathway** [1] - It receives input from the **inferior colliculus** and projects to the **primary auditory cortex** (Heschl's gyrus) in the temporal lobe [1], [3] - Essential for processing and relaying auditory information from the brainstem to the cortex *Fornix* - The **fornix** is a C-shaped white matter tract that is part of the **limbic system**, connecting the hippocampus to the mammillary bodies and septal nuclei [2] - It is primarily involved in **memory consolidation** and emotional processing, not auditory function - Not a component of the auditory pathway *Lateral geniculate body* - The **lateral geniculate body (LGB)** is the **thalamic relay nucleus** for the **visual pathway** - It receives input from the retina via the optic tract and projects to the primary visual cortex - Dedicated exclusively to visual processing, not auditory information *Reticular formation* - The **reticular formation** is a diffuse network of neurons in the brainstem involved in **arousal, consciousness, sleep-wake cycles**, and autonomic regulation [2] - While it can modulate attention to auditory stimuli through ascending reticular activating system (ARAS), it is not part of the **primary ascending auditory pathway** - The dedicated auditory pathway goes: cochlear nuclei → superior olivary complex → lateral lemniscus → inferior colliculus → medial geniculate body → auditory cortex [1], [3]

Q: Wallenberg syndrome involves which artery?

Posterior inferior cerebellar artery. ***Posterior inferior cerebellar artery*** - **Wallenberg syndrome**, also known as **lateral medullary syndrome**, is most commonly caused by an infarction in the territory supplied by the **posterior inferior cerebellar artery (PICA)**. - The PICA supplies the **lateral medulla**, which contains several crucial nuclei and tracts, including the nucleus ambiguus, trigeminal nucleus, vestibular nuclei, and spinothalamic tract, leading to the characteristic clinical presentation of Wallenberg syndrome. *Subclavian artery* - The **subclavian artery** is a large artery in the upper thorax that supplies blood to the upper limbs, head, and neck. - While it can be involved in conditions like **subclavian steal syndrome**, it does not directly supply the lateral medulla responsible for Wallenberg syndrome. *Posterior cerebral artery* - The **posterior cerebral artery** primarily supplies the occipital lobe, temporal lobe, and parts of the thalamus and midbrain. - Infarction in the PCA territory typically leads to symptoms like **hemianopia**, visual field defects, and memory deficits, not the constellation of symptoms seen in Wallenberg syndrome. *Anterior inferior cerebellar artery* - The **anterior inferior cerebellar artery (AICA)** supplies the anterior and lateral parts of the cerebellum and the pontomedullary junction, leading to **lateral pontine syndrome** when infarcted. - Symptoms of AICA infarction include ipsilateral facial paralysis, hearing loss, and cerebellar ataxia, which are distinct from Wallenberg syndrome.

Q: During surgery for meningioma, the left paracentral lobule was injured. It would lead to paresis of:

Right Leg and perineum. Right Leg and perineum - The **paracentral lobule** is located in the medial aspect of the cerebral hemispheres and contains the cortical representations for the leg and perineum. [1] - Injury to the **left paracentral lobule** would therefore affect motor control on the contralateral side, specifically the **right leg and perineum**. *Left face* - Motor control for the face is primarily located in the **lateral aspects of the precentral gyrus**, not the paracentral lobule. - A left-sided lesion affecting the face would typically cause **contralateral (right) facial weakness**, not ipsilateral (left). *Right shoulder & trunk* - The motor cortex for the shoulder and trunk is located more **superior and lateral** in the precentral gyrus, distal to the paracentral lobule. - Injury to the paracentral lobule specifically spares these regions. *Right face* - As mentioned, the motor control for the face resides in the **lateral precentral gyrus**. - While this is the contralateral side, the specific anatomical location of the paracentral lobule does not typically involve the face.

Q: Fibers reaching directly to Purkinje cells of cerebellum arise from which of the following:

Inferior olivary nucleus. ***Inferior olivary nucleus*** - The **inferior olivary nucleus** gives rise to **climbing fibers**, which form powerful **excitatory synapses** directly onto the **Purkinje cells** of the cerebellum [1]. - Each Purkinje cell receives input from a single climbing fiber, which produces a characteristic **complex spike** response [1]. *Locus ceruleus* - The **locus ceruleus** is a nucleus in the pons that is the primary source of **noradrenaline** in the brain. - Its fibers project widely throughout the cerebrum, cerebellum, and spinal cord, modulating neuronal activity rather than forming direct, primary excitatory synapses on Purkinje cells. *Vestibular nucleus* - The **vestibular nuclei** send mossy fiber inputs to the cerebellum, particularly to the **flocculonodular lobe** and uvula, influencing balance and eye movements [2]. - These are **mossy fibers**, not climbing fibers, and they synapse indirectly via granule cells onto Purkinje cells, not directly [1]. *Raphe nucleus* - The **raphe nuclei** are a group of serotonin-producing nuclei located in the brainstem. - They project widely throughout the central nervous system, including the cerebellum, impacting mood, sleep, and pain perception, but their fibers do not directly synapse on Purkinje cells in the manner of climbing fibers.

Q: Cranial nerve that is involved in olfaction:

Trigeminal. ***Trigeminal*** - The **trigeminal nerve (CN V)** carries sensory information from the face and contributes to olfactory perception through its **ophthalmic (V1) and maxillary (V2) divisions** [1]. - These divisions detect **chemical irritants, pungency, cooling, and warming sensations** in the nasal cavity (chemesthesis), contributing to the overall perception of smells. - Examples include the stinging sensation of **ammonia**, cooling of **menthol**, and burning of **capsaicin** - all part of the smell experience. - This is distinct from true olfaction (CN I) but is an essential component of how we perceive "smell" in daily life. *Hypoglossal* - The **hypoglossal nerve (CN XII)** is purely a **motor nerve** that controls the intrinsic and extrinsic muscles of the **tongue**. - It is essential for **speech, swallowing, and tongue movement** but has **no role in olfaction or smell perception**. *Glossopharyngeal* - The **glossopharyngeal nerve (CN IX)** mediates **taste sensation from the posterior third of the tongue**, swallowing, and salivation. - While important for taste, it has **no role in olfactory pathways or smell detection**. *Vagus* - The **vagus nerve (CN X)** has extensive **parasympathetic functions** and carries taste sensation from the **epiglottis and pharynx**. - It innervates thoracic and abdominal organs but is **not involved in olfactory perception**.

Q: Arrange the sequence of auditory pathway from peripheral to central: Inferior colliculus, Cochlear nucleus, Auditory cortex, Medial geniculate body

B>A>D>C. ***B>A>D>C*** - This sequence represents the correct path of auditory information from the cochlea to the brain: **Cochlear nucleus** (B), then **Inferior colliculus** (A), followed by the **Medial geniculate body** (D), and finally the **Auditory cortex** (C) [1]. - This pathway allows for processing and integration of sound as it ascends through various brainstem and thalamic nuclei before reaching the cortex [1]. *A>D>B>C* - This sequence incorrectly places the **Inferior colliculus** (A) before the **Cochlear nucleus** (B) and the **Medial geniculate body** (D) before the Inferior colliculus, disrupting the normal ascending pathway. - The auditory signal originates from the cochlea and first synapses in the cochlear nucleus, not the inferior colliculus [1]. *C>A>B>D* - This sequence starts with the **Auditory cortex** (C), which is the final destination, indicating an inverted or incorrect order of information flow. - It also places the **Cochlear nucleus** (B) after the **Inferior colliculus** (A), which is the reverse of the true ascending pathway. *B>D>C>A* - This sequence correctly starts with the **Cochlear nucleus** (B) but then skips directly to the **Medial geniculate body** (D), omitting the **Inferior colliculus** (A) as an essential intermediate relay [1]. - It also places the **Auditory cortex** (C) before the Inferior colliculus, which is incorrect.

Q: Which of the following projects efferent fibers through the marked structure (fornix)?

Hippocampus. ***Hippocampus*** - The **fornix** is the major efferent pathway of the **hippocampus**, carrying signals from the hippocampus to various subcortical areas. - It plays a crucial role in memory formation by transmitting hippocampal output to the **mammillary bodies** and septal nuclei. *Amygdala* - The **amygdala's** primary efferent pathways are the **stria terminalis** and the **ventral amygdalofugal pathway**, not the fornix. - It is primarily involved in processing emotions, fear, and memory of emotional events. *Mammillary body* - The **mammillary bodies** receive input from the **fornix** (from the hippocampus) but they do not project efferent fibers *through* the fornix. - They primarily project to the **anterior thalamic nuclei** via the mammillothalamic tract. *Caudate nucleus* - The **caudate nucleus** is part of the **basal ganglia** and its efferent projections are directed towards the **globus pallidus** and substantia nigra, primarily involved in motor control and learning. - It is not connected to the **fornix**.

Question 1

Hemiballismus is due to lesion of

Accepted Answer

Subthalamic nucleus

Answer

Putamen

Answer

Caudate nucleus

Answer

Globus pallidus

Question 2

A 68-year-old man has many months history of progressive hearing loss, unsteady gait, tinnitus, and facial pain. An MRI scan reveals a tumor at the cerebellopontine angle. Which of the following cranial nerves is this tumor most likely to affect?

Accepted Answer

eighth cranial nerve

Answer

sixth cranial nerve

Answer

tenth cranial nerve

Answer

fourth cranial nerve

Question 3

A child presented with weakness of limbs, cannot sit properly and swaying both sides while walking. The lesion is in

Accepted Answer

Cerebellar vermis

Answer

Neocerebellum

Answer

Cerebellopontine area

Answer

Cerebellar hemisphere

Question 4

Auditory pathway passes through -

Accepted Answer

Medial geniculate body

Answer

Fornix

Answer

Lateral geniculate body

Answer

Reticular formation

Question 5

Wallenberg syndrome involves which artery?

Accepted Answer

Posterior inferior cerebellar artery

Answer

Subclavian artery

Answer

Posterior cerebral artery

Answer

Anterior inferior cerebellar artery

Question 6

During surgery for meningioma, the left paracentral lobule was injured. It would lead to paresis of:

Accepted Answer

Right Leg and perineum

Answer

Left face

Answer

Right shoulder & trunk

Answer

Right face

Question 7

Fibers reaching directly to Purkinje cells of cerebellum arise from which of the following:

Accepted Answer

Inferior olivary nucleus

Answer

Locus ceruleus

Answer

Vestibular nucleus

Answer

Raphe nucleus

Question 8

Cranial nerve that is involved in olfaction:

Accepted Answer

Trigeminal

Answer

Hypoglossal

Answer

Glossopharyngeal

Answer

Vagus

Question 9

Arrange the sequence of auditory pathway from peripheral to central: Inferior colliculus, Cochlear nucleus, Auditory cortex, Medial geniculate body

Accepted Answer

B>A>D>C

Answer

A>D>B>C

Answer

C>A>B>D

Answer

B>D>C>A

Question 10

Which of the following projects efferent fibers through the marked structure (fornix)?

Accepted Answer

Hippocampus

Answer

Amygdala

Answer

Mammillary body

Answer

Caudate nucleus

Brain and Neuroanatomy — MCQs

Brain and Neuroanatomy — MCQs

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