Neuroanatomy Practice Questions

Q: A 58-year-old male with a history of diabetes mellitus, hypertension, and hypercholesterolemia presents with loss of sensation below the level of the umbilicus. There is no motor loss and his bowel and bladder function are intact. An MRI scan revealed spinal infarction affecting the posterior white columns in the tenth thoracic segment of the spinal cord. Which of the following sensations would be intact in this patient?

Pain. ### Explanation The patient presents with a spinal infarction localized to the **posterior white columns** (Dorsal Columns) at the T10 level. To answer this question, one must distinguish between the different sensory pathways of the spinal cord. **1. Why "Pain" is the Correct Answer:** Pain and temperature sensations are carried by the **Lateral Spinothalamic Tract** [1], while crude touch and pressure are carried by the **Anterior Spinothalamic Tract**. These tracts are located in the lateral and anterior funiculi of the spinal cord, respectively. Since the infarction is restricted to the posterior columns, the spinothalamic tracts remain functional. Therefore, the patient will still be able to perceive pain [2]. **2. Why the Other Options are Incorrect:** * **A, C, and D (Position sense, Touch, and Vibration):** These sensations are specifically mediated by the **Dorsal Column-Medial Lemniscal (DCML) pathway**, which consists of the Fasciculus Gracilis and Fasciculus Cuneatus. The DCML is responsible for: * **Fine (discriminative) touch** * **Conscious Proprioception** (Position sense) * **Vibration sense** * **Two-point discrimination** Because the MRI confirms damage to the posterior white columns, all these modalities will be lost below the level of the lesion. **Clinical Pearls for NEET-PG:** * **T10 Landmark:** The umbilicus corresponds to the T10 dermatome [1]. * **Blood Supply:** The posterior columns are supplied by the **Posterior Spinal Arteries**. An infarct here is rarer than an Anterior Spinal Artery syndrome (which spares the dorsal columns but causes motor and pain loss). * **Tabes Dorsalis:** A classic neurosyphilis manifestation that selectively involves the destruction of the posterior columns, leading to sensory ataxia and loss of vibration/position sense.

Q: Pain sensation from the lateral extremities is transmitted by which pathway?

Spinothalamic tract. ### Explanation The **Spinothalamic Tract (STT)** is the primary sensory pathway responsible for transmitting **pain, temperature, and crude touch** from the extremities and trunk to the brain [1]. **Why Option A is Correct:** The STT is part of the anterolateral system. First-order neurons (pseudounipolar) enter the spinal cord via the dorsal root ganglion and synapse in the **substantia gelatinosa**. Second-order neurons decussate immediately (within 1-2 spinal segments) via the anterior white commissure and ascend in the contralateral lateral funiculus to the **Ventral Posterolateral (VPL) nucleus** of the thalamus [1], [2]. **Analysis of Incorrect Options:** * **B. Dorsal Column-Medial Lemniscus (DCML):** This pathway carries **fine touch, vibration, and conscious proprioception** [1]. It decussates in the medulla (internal arcuate fibers), not the spinal cord. * **C. Corticospinal Tract:** This is a **descending motor pathway** responsible for voluntary movement of the distal extremities [3]. It does not carry sensory information. * **D. Spinocerebellar Tract:** This pathway carries **unconscious proprioception** from muscles and joints to the cerebellum to coordinate posture and movement. **High-Yield Clinical Pearls for NEET-PG:** 1. **Brown-Séquard Syndrome:** A hemisection of the spinal cord results in **contralateral** loss of pain and temperature (STT) and **ipsilateral** loss of vibration/proprioception (DCML) below the level of the lesion. 2. **Syringomyelia:** Expansion of the central canal first compresses the **anterior white commissure**, leading to a bilateral "cape-like" loss of pain and temperature, while sparing fine touch. 3. **Lissauer’s Tract:** Fibers of the STT may ascend or descend 1–2 levels before synapsing, explaining why clinical sensory levels are often lower than the actual anatomical lesion.

Q: Geniculate neuralgia is caused by damage to which of the following cranial nerves?

Cranial Nerve VII. **Explanation:** **Geniculate neuralgia** (also known as Ramsay Hunt syndrome type II when associated with Herpes Zoster) is a rare neuropathic pain syndrome caused by the involvement of the **Cranial Nerve VII (Facial Nerve)** [2]. Specifically, it involves the **geniculate ganglion**, which is the sensory ganglion of the facial nerve located in the facial canal of the temporal bone. This ganglion contains the cell bodies for taste (via chorda tympani) and somatic sensation from the external auditory canal and retroauricular area [3]. Damage or inflammation here results in paroxysmal, lancinating pain deep within the ear. [4] **Analysis of Options:** * **Cranial Nerve V (Trigeminal):** Damage leads to **Trigeminal Neuralgia** (Tic Douloureux), characterized by stabbing pain in the distribution of the ophthalmic, maxillary, or mandibular divisions (face/jaw), not the deep ear. * **Cranial Nerve VI (Abducens):** This is a purely motor nerve supplying the lateral rectus muscle. Damage results in medial strabismus and diplopia, not neuralgia. * **Cranial Nerve VIII (Vestibulocochlear):** Damage typically results in sensorineural hearing loss, tinnitus, or vertigo (e.g., Acoustic Neuroma), rather than a primary neuralgic pain syndrome [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Nervus Intermedius (of Wrisberg):** This is the specific sensory/parasympathetic branch of CN VII associated with geniculate neuralgia. * **Ramsay Hunt Syndrome:** Look for the triad of facial nerve palsy, ear pain, and vesicles in the external auditory canal (herpes zoster oticus) [2]. * **Sensory supply of CN VII:** Remember it supplies taste to the **anterior 2/3 of the tongue** and somatic sensation to a small part of the **external ear** [3].

Q: The geniculate ganglion is associated with which function?

Taste sensation. **Explanation:** The **Geniculate Ganglion** is the sensory ganglion of the **Facial Nerve (CN VII)**, located in the facial canal of the temporal bone. It contains the cell bodies of pseudo-unipolar neurons responsible for two primary sensory functions: **taste sensation** from the anterior two-thirds of the tongue (via the chorda tympani) and general somatic sensation from the external auditory canal. **Why Option B is Correct:** Taste fibers from the anterior 2/3 of the tongue travel via the chorda tympani to join the facial nerve [1]. The cell bodies for these special visceral afferent (SVA) fibers are located in the geniculate ganglion. From here, fibers project to the *nucleus tractus solitarius* in the medulla. **Analysis of Incorrect Options:** * **A & C (Lacrimation & Salivation):** These are parasympathetic (secretomotor) functions. While the preganglionic fibers pass *through* the geniculate ganglion, they **do not synapse** there. Lacrimation involves the Pterygopalatine ganglion, and salivation (submandibular/sublingual) involves the Submandibular ganglion. * **D (Sweating):** This is a sympathetic function. Facial sweating is mediated by postganglionic sympathetic fibers arising from the Superior Cervical Ganglion, traveling along the external carotid artery plexus. **High-Yield Clinical Pearls for NEET-PG:** * **Ramsay Hunt Syndrome:** Herpes Zoster infection involving the geniculate ganglion, presenting with facial palsy and vesicles in the external auditory canal/auricle. * **Nerve of Pterygoid Canal (Vidian Nerve):** Formed by the junction of the Great Petrosal Nerve (branch from geniculate ganglion) and Deep Petrosal Nerve. * **First branch of CN VII:** The Greater Petrosal Nerve arises directly from the geniculate ganglion.

Q: Which Brodmann area corresponds to the premotor cortex?

Area 6. The **Premotor Cortex** is located in the posterior part of the frontal lobe, immediately anterior to the primary motor cortex (Area 4) [1]. It corresponds to **Brodmann Area 6** [1]. **1. Why Area 6 is Correct:** Area 6 is divided into the **Premotor Cortex** (lateral surface) and the **Supplementary Motor Area** (medial surface) [1]. Its primary function is the planning and sequencing of complex movements and the regulation of posture [1]. It receives sensory input from the posterior parietal cortex and sends signals to the primary motor cortex to execute voluntary actions [2]. **2. Analysis of Incorrect Options:** * **Area 7:** Located in the **Superior Parietal Lobule** [3]. It is a sensory association area involved in visuospatial processing and hand-eye coordination [3]. * **Area 8:** Located anterior to Area 6, it contains the **Frontal Eye Field (FEF)**. It controls conjugate voluntary scanning movements of the eyes to the opposite side. * **Area 12:** Located on the orbitofrontal surface of the frontal lobe. It is part of the **Prefrontal Cortex**, involved in executive functions and emotional regulation. **High-Yield Clinical Pearls for NEET-PG:** * **Lesion of Area 6:** Results in **Apraxia** (inability to perform learned purposeful movements despite having normal muscle power). * **Lesion of Area 8:** Causes the eyes to deviate **towards** the side of the lesion (due to unopposed action of the opposite FEF). * **Jacksonian March:** Typically originates in Area 4 (Primary Motor Cortex), but Area 6 contributes to the refinement of these motor outputs. * **Giant Pyramidal Cells (Betz cells):** These are characteristic of Area 4, whereas Area 6 lacks these large cells.

Q: Personality changes are seen in lesions of which lobe?

Frontal lobe. The **Frontal lobe** is the correct answer because it houses the **Prefrontal Cortex (PFC)**, which is the center for higher executive functions. This region regulates social behavior, decision-making, emotional expression, and impulse control. A lesion here—most famously illustrated by the case of Phineas Gage—leads to "Frontal Lobe Syndrome," characterized by drastic personality changes, disinhibition, irritability, and loss of social decorum [2]. Additionally, the frontal lobe contains the motor cortex and Broca’s area (motor speech) [3]. **Why other options are incorrect:** * **Temporal lobe:** Primarily involved in auditory processing, memory (hippocampus), and language comprehension (Wernicke’s area). Lesions typically cause memory deficits, complex partial seizures, or sensory aphasia [1]. * **Parietal lobe:** Responsible for somatosensory perception and spatial awareness. Lesions lead to cortical sensory loss, astereognosis, or Gerstmann’s syndrome (acalculia, agraphia, finger agnosia). * **Occipital lobe:** Dedicated to visual processing. Lesions result in visual field defects like homonymous hemianopia or cortical blindness. **High-Yield Clinical Pearls for NEET-PG:** * **Phineas Gage:** The classic historical case associated with frontal lobe personality shifts. * **Foster Kennedy Syndrome:** Frontal lobe tumor causing ipsilateral optic atrophy, contralateral papilledema, and anosmia. * **Klüver-Bucy Syndrome:** Associated with bilateral **Temporal lobe** (amygdala) lesions, presenting with hypersexuality, hyperphagia, and visual agnosia. * **Wernicke’s Aphasia:** "Word Salad" (fluent but meaningless speech) occurs in the superior temporal gyrus [3].

Q: Mitral cells are characteristic of which brain structure?

Olfactory bulb. **Explanation:** **1. Why Olfactory Bulb is Correct:** Mitral cells are the primary output neurons of the **olfactory bulb** [2]. They are large, triangular cells located in the mitral cell layer. Their dendrites synapse with the axons of olfactory sensory neurons (Cranial Nerve I) within specialized structures called **glomeruli** [1], [2]. The axons of these mitral cells then bundle together to form the **olfactory tract**, which carries sensory information directly to the olfactory cortex without a primary relay in the thalamus [2]. **2. Why Other Options are Incorrect:** * **Basal Ganglia:** Characterized by **Medium Spiny Neurons (MSNs)** in the striatum (caudate and putamen), which utilize GABA as their primary neurotransmitter. * **Hippocampus:** Known for **Pyramidal cells** (found in the CA fields) and **Granule cells** (found in the dentate gyrus). These are essential for memory consolidation. * **Hypothalamus:** Composed of various nuclei (e.g., Supraoptic, Paraventricular) containing specialized neurosecretory cells that produce hormones like ADH and Oxytocin. **3. High-Yield Clinical Pearls for NEET-PG:** * **Glomerulus:** This is the functional unit of the olfactory bulb where first-order neurons (olfactory nerves) synapse with second-order neurons (**Mitral** and **Tufted cells**) [2]. * **Unique Pathway:** Olfaction is the only sensory modality that reaches the cerebral cortex (piriform cortex, amygdala) without passing through the thalamus first [2], [3]. * **Foster Kennedy Syndrome:** A classic exam topic involving an olfactory groove meningioma, leading to ipsilateral anosmia (due to olfactory bulb compression), ipsilateral optic atrophy, and contralateral papilledema.

Q: By what age does the mastoid fontanelle typically close?

11-12 months. **Explanation:** The fontanelles are membrane-filled gaps located at the junctions of the cranial sutures in neonates, allowing for brain growth and skull molding during birth [1]. **Correct Answer: C (11-12 months)** The **mastoid (posterolateral) fontanelle** is a paired structure located at the junction of the temporal, parietal, and occipital bones (the future asterion). While it begins to close shortly after birth, its definitive fibrous closure typically occurs by the end of the first year, specifically between **6 to 12 months** of age. **Analysis of Incorrect Options:** * **A (1-3 months):** This timeframe is characteristic of the **posterior fontanelle** (located at the lambda), which is the first to close, usually by 2–3 months. * **B (3-6 months):** The **sphenoidal (anterolateral)** fontanelle typically closes around 6 months of age. * **D (18-24 months):** This is the timeline for the **anterior fontanelle** (located at the bregma), which is the last to close (average 12–18 months, up to 24 months). **High-Yield Clinical Pearls for NEET-PG:** 1. **Sequence of Closure:** Posterior → Sphenoidal → Mastoid → Anterior. 2. **Clinical Significance:** A bulging fontanelle indicates increased intracranial pressure (e.g., hydrocephalus, meningitis), while a depressed fontanelle is a classic sign of dehydration. 3. **The Asterion:** The mastoid fontanelle marks the future site of the asterion, a surgical landmark for the transverse-sigmoid sinus junction. 4. **Third Fontanelle:** An accessory fontanelle between the anterior and posterior fontanelles is often associated with Trisomy 21 (Down Syndrome).

Q: Which cranial nerve emerges between the pyramid and the olive?

XII. **Explanation:** The medulla oblongata features two prominent longitudinal elevations on its anterior surface: the **pyramid** (medial) and the **olive** (lateral). The correct answer is **XII (Hypoglossal nerve)** because it is the only cranial nerve that emerges from the **anterolateral (pre-olivary) sulcus**, which is the groove situated specifically between the pyramid and the olive. **Analysis of Options:** * **Option A (VI - Abducens):** This nerve emerges from the pontomedullary junction, specifically at the upper end of the pyramid. * **Option B (VII - Facial):** This nerve emerges from the cerebellopontine angle (lateral part of the pontomedullary junction), lateral to the VIII nerve. * **Option C (XI - Accessory):** The cranial root of the accessory nerve emerges from the **posterolateral (post-olivary) sulcus**, which is located *behind* (lateral to) the olive. * **Option D (XII - Hypoglossal):** As stated, it emerges between the pyramid and olive. **High-Yield NEET-PG Pearls:** 1. **Post-olivary Sulcus:** Three nerves emerge here in descending order: **IX (Glossopharyngeal), X (Vagus), and XI (Cranial root of Accessory).** 2. **Medial Medullary Syndrome (Dejerine Syndrome):** Often involves the Hypoglossal nerve and the pyramid. Clinical sign: Ipsilateral tongue deviation and contralateral hemiplegia. 3. **Rule of 4s:** Cranial nerves IX, X, XI, and XII are all associated with the Medulla. However, only XII is medial (pre-olivary), while IX, X, and XI are lateral (post-olivary).

Question 1

A 58-year-old male with a history of diabetes mellitus, hypertension, and hypercholesterolemia presents with loss of sensation below the level of the umbilicus. There is no motor loss and his bowel and bladder function are intact. An MRI scan revealed spinal infarction affecting the posterior white columns in the tenth thoracic segment of the spinal cord. Which of the following sensations would be intact in this patient?

Accepted Answer

Pain

Answer

Position sense

Answer

Touch

Answer

Vibration

Question 2

Pain sensation from the lateral extremities is transmitted by which pathway?

Accepted Answer

Spinothalamic tract

Answer

Dorsal column

Answer

Corticospinal tract

Answer

Spinocerebellar tract

Question 3

Geniculate neuralgia is caused by damage to which of the following cranial nerves?

Accepted Answer

Cranial Nerve VII

Answer

Cranial Nerve V

Answer

Cranial Nerve VI

Answer

Cranial Nerve VIII

Question 4

The geniculate ganglion is associated with which function?

Accepted Answer

Taste sensation

Answer

Lacrimation

Answer

Salivation

Answer

Sweating

Question 5

Which Brodmann area corresponds to the premotor cortex?

Accepted Answer

Area 6

Answer

Area 7

Answer

Area 8

Answer

Area 12

Question 6

Personality changes are seen in lesions of which lobe?

Accepted Answer

Frontal lobe

Answer

Temporal lobe

Answer

Parietal lobe

Answer

Occipital lobe

Question 7

Mitral cells are characteristic of which brain structure?

Accepted Answer

Olfactory bulb

Answer

Basal ganglia

Answer

Hippocampus

Answer

Hypothalamus

Question 8

Which of the following statements is true regarding the trochlear nerve?

Accepted Answer

Is the only cranial nerve to emerge from the dorsal aspect of the brainstem

Answer

Supplies the inferior oblique muscle of the eyeball

Answer

Has its nucleus of origin in the midbrain at the level of the superior colliculus

Answer

Enters the orbit through the middle compartment of the superior orbital fissure

Question 9

By what age does the mastoid fontanelle typically close?

Accepted Answer

11-12 months

Answer

1-3 months

Answer

3-6 months

Answer

18-24 months

Question 10

Which cranial nerve emerges between the pyramid and the olive?

Accepted Answer

XII

Answer

VI

Answer

VII

Answer

XI

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?