Neuroanatomy — MCQs
On this page
Amphotericin B causes deficiency of which electrolyte?
The Broca's area is situated in which part of the brain?
A 65-year-old woman with diabetes mellitus presents for examination. When the right side of her pharynx is touched with a tongue blade, the palate elevates symmetrically. However, when the left side of the pharynx is touched, the palate does not elevate at all. Which of the following cranial nerves is most likely responsible for this finding?
Primordial germ cells are seen in which structure by the 3rd week of development?
A 35-year-old male cannot adduct his left eye while looking to the right. Where is the lesion located?
The medial geniculate body is associated with which sense?
Stellate cells of von Kuffer are seen in the sinusoids of which of the following organs?
What is a disadvantage of the cold water treatment of burns?
The accessory pancreatic duct opens on which of the following structures?
In which intrauterine week do tertiary chorionic villi develop?
Neuroanatomy Indian Medical PG Practice Questions and MCQs
Question 1021: Amphotericin B causes deficiency of which electrolyte?
- A. Sodium
- B. Calcium
- C. Potassium (Correct Answer)
- D. Chloride
Explanation: Amphotericin B is a potent antifungal agent known for its significant renal toxicity, specifically affecting the distal renal tubules. **Why Potassium is the Correct Answer:** Amphotericin B acts by binding to ergosterol in fungal cell membranes, creating pores. However, it also binds to cholesterol in human cell membranes, particularly in the renal tubular epithelium. This increases the permeability of the distal tubule and collecting duct, leading to a "leak" of intracellular ions. The drug causes **Type 1 (Distal) Renal Tubular Acidosis (RTA)**, which results in significant wasting of **Potassium (Hypokalemia)** and Magnesium (Hypomagnesemia). The increased membrane permeability allows potassium to flow down its concentration gradient out of the cell and into the tubular lumen, leading to its excretion. **Analysis of Incorrect Options:** * **A. Sodium:** While Amphotericin B can cause a decrease in Glomerular Filtration Rate (GFR) due to afferent arteriolar vasoconstriction, it does not typically cause a primary deficiency (hyponatremia) in the same characteristic way it causes potassium loss. * **B. Calcium:** Nephrotoxicity may lead to some changes in divalent cation handling, but hypocalcemia is not the hallmark electrolyte derangement associated with Amphotericin B. * **D. Chloride:** The primary acid-base disturbance is a normal anion gap metabolic acidosis (due to RTA), which often involves a relative increase in chloride (hyperchloremia) rather than a deficiency. **NEET-PG High-Yield Pearls:** * **"Amphoterrible":** A common mnemonic for its side effects, including nephrotoxicity, infusion-related reactions (fever/chills), and anemia (decreased EPO). * **Electrolyte Triad:** Always monitor for **Hypokalemia, Hypomagnesemia, and Nephrogenic Diabetes Insipidus** when a patient is on Amphotericin B. * **Prevention:** Pre-loading the patient with **Normal Saline (0.9% NaCl)** infusion is a high-yield strategy used to reduce the risk of Amphotericin-induced nephrotoxicity. * **Liposomal Amphotericin B:** This formulation is preferred as it significantly reduces renal toxicity compared to the conventional deoxycholate form.
Question 1022: The Broca's area is situated in which part of the brain?
- A. Temporal lobe
- B. Posterior part of the Inferior frontal gyrus (Correct Answer)
- C. Occipital calcarine fissure
- D. Mammillary body region
Explanation: **Explanation:** **Broca’s area** (Motor Speech Area) is located in the **posterior part of the inferior frontal gyrus** of the dominant hemisphere (usually the left). It corresponds to **Brodmann areas 44 and 45**. Area 44 (Pars opercularis) and Area 45 (Pars triangularis) are responsible for the production of speech and the grammatical structure of language. **Analysis of Options:** * **Option A (Temporal lobe):** This lobe contains **Wernicke’s area** (posterior part of the superior temporal gyrus, Brodmann area 22), which is responsible for the comprehension of speech, not production [1]. * **Option C (Occipital calcarine fissure):** This region houses the **Primary Visual Cortex** (Brodmann area 17). It is responsible for receiving and processing visual information [1]. * **Option D (Mammillary body region):** Part of the diencephalon/limbic system, these are involved in recollective memory. Damage here (often due to Thiamine deficiency) is associated with Wernicke-Korsakoff syndrome. **Clinical Pearls for NEET-PG:** 1. **Broca’s Aphasia (Motor/Expressive Aphasia):** Characterized by "non-fluent," halting speech. Patients have intact comprehension but struggle to produce words (broken speech) [1]. 2. **Blood Supply:** Broca’s area is supplied by the **superior division of the Middle Cerebral Artery (MCA)**. 3. **Connection:** Broca’s and Wernicke’s areas are connected by a bundle of nerve fibers called the **Arcuate Fasciculus** [1]. Damage to this leads to *Conduction Aphasia* (impaired repetition).
Question 1023: A 65-year-old woman with diabetes mellitus presents for examination. When the right side of her pharynx is touched with a tongue blade, the palate elevates symmetrically. However, when the left side of the pharynx is touched, the palate does not elevate at all. Which of the following cranial nerves is most likely responsible for this finding?
- A. Cranial nerve VIII
- B. Cranial nerve IX (Correct Answer)
- C. Cranial nerve X
- D. Cranial nerve XII
Explanation: ### Explanation This clinical scenario describes a deficit in the **Gag Reflex** (Pharyngeal Reflex). To identify the affected nerve, one must understand the reflex arc components: * **Afferent (Sensory) Limb:** Glossopharyngeal nerve (**CN IX**) * **Efferent (Motor) Limb:** Vagus nerve (**CN X**) **Why Option B is Correct:** The patient has a normal response when the right side is touched, meaning the right CN IX (afferent) and both sides of CN X (efferent) are intact. However, when the **left** side is touched, there is **no elevation at all**. This indicates that the sensory signal is not being perceived or transmitted from the left pharyngeal mucosa to the brainstem. Therefore, the **left Glossopharyngeal nerve (CN IX)** is the site of the lesion. **Why the Other Options are Incorrect:** * **Option A (CN VIII):** The Vestibulocochlear nerve is responsible for hearing and equilibrium; it plays no role in the gag reflex. * **Option C (CN X):** If the Vagus nerve (motor limb) were damaged on the left, touching the right side would have resulted in **asymmetrical** palate elevation (the palate would pull toward the healthy right side). Since the palate elevates symmetrically when the right side is touched, CN X is functioning bilaterally. * **Option D (CN XII):** The Hypoglossal nerve provides motor supply to the tongue muscles. Damage would cause tongue deviation, not a loss of the gag reflex. **NEET-PG High-Yield Pearls:** * **Gag Reflex:** Sensory = IX, Motor = X. * **Uvula Deviation:** In a CN X lesion, the uvula deviates **away** from the side of the lesion (toward the healthy side). * **Tongue Deviation:** In a CN XII lesion, the tongue deviates **toward** the side of the lesion ("The tongue licks the wound"). * **CN IX Functions:** Sensory to the posterior 1/3 of the tongue, oropharynx, and carotid sinus/body; motor to the stylopharyngeus muscle.
Question 1024: Primordial germ cells are seen in which structure by the 3rd week of development?
- A. Neural crest
- B. Splanchnic mesoderm
- C. Genital ridge
- D. Yolk sac (Correct Answer)
Explanation: ### Explanation **Correct Answer: D. Yolk sac** **1. Why Yolk Sac is Correct:** Primordial germ cells (PGCs) are the precursors of gametes (oocytes and spermatozoa). They originate from the **epiblast** during the second week of development. During the **3rd week**, these cells migrate through the primitive streak and reside in the **endodermal lining of the wall of the yolk sac**, specifically near the exit of the allantois [1]. Between the 4th and 6th weeks, they migrate via the dorsal mesentery to reach the primitive gonads (genital ridges). **2. Analysis of Incorrect Options:** * **A. Neural crest:** These cells arise from the edges of the neural tube and give rise to structures like the dorsal root ganglia, adrenal medulla, and melanocytes, but not germ cells. * **B. Splanchnic mesoderm:** While this layer contributes to the heart, circulatory system, and the wall of the gut, it is not the initial site where PGCs are visualized in the 3rd week. * **C. Genital ridge:** This is the **destination** of the PGCs, not their 3rd-week location. PGCs do not reach the genital ridges until the **5th week** of development. If PGCs fail to reach the ridges, the gonads will not develop. **3. NEET-PG High-Yield Pearls:** * **Ectopic Germ Cells:** If PGCs stray from their migratory path and survive in mediastinal or sacrococcygeal regions, they can give rise to **Teratomas** (most common: Sacrococcygeal teratoma). * **Timeline:** * 2nd Week: Epiblast origin. * 3rd Week: Yolk sac wall [1]. * 5th Week: Arrival at Genital Ridge. * **Inductive Influence:** The PGCs have an inductive effect on the development of the gonad into an ovary or testis.
Question 1025: A 35-year-old male cannot adduct his left eye while looking to the right. Where is the lesion located?
- A. Abducens nerve
- B. Oculomotor nerve (Correct Answer)
- C. Trochlear nerve
- D. Trigeminal nerve
Explanation: ### Explanation The patient presents with an inability to **adduct** the left eye during rightward gaze. Adduction of the eyeball is primarily the function of the **Medial Rectus** muscle [1]. **1. Why Oculomotor Nerve is Correct:** The **Oculomotor nerve (CN III)** provides motor innervation to the Medial Rectus, Superior Rectus, Inferior Rectus, and Inferior Oblique muscles. A lesion of the left CN III results in paralysis of the left medial rectus, making it impossible for the left eye to move toward the midline (adduction) when the patient attempts to look toward the opposite side [1]. **2. Why Other Options are Incorrect:** * **Abducens Nerve (CN VI):** This nerve innervates the **Lateral Rectus**. A lesion here would cause an inability to **abduct** the eye (move it outward) [1]. In this scenario, a right CN VI palsy would prevent the right eye from looking right, but the question specifies a left-sided adduction deficit. * **Trochlear Nerve (CN IV):** This nerve innervates the **Superior Oblique**. Its primary action is depression of the eye in the adducted position and intorsion [1]. It does not control horizontal adduction. * **Trigeminal Nerve (CN V):** This is primarily a sensory nerve for the face and motor nerve for the muscles of mastication. It has no role in extraocular eye movements. **3. NEET-PG High-Yield Pearls:** * **Formula:** Remember **LR6(SO4)3**: Lateral Rectus (CN VI), Superior Oblique (CN IV), and all others (CN III). * **Clinical Correlation:** If adduction is lost *only* during conjugate lateral gaze but remains intact during convergence, the lesion is in the **Medial Longitudinal Fasciculus (MLF)**, a condition known as **Internuclear Ophthalmoplegia (INO)**. * **CN III Palsy Presentation:** "Down and Out" eye position, ptosis (levator palpebrae superioris), and a dilated pupil (loss of parasympathetics).
Question 1026: The medial geniculate body is associated with which sense?
- A. Vision
- B. Hearing (Correct Answer)
- C. Balance
- D. Smell
Explanation: The **Medial Geniculate Body (MGB)** is a specialized nucleus of the thalamus that serves as the final subcortical relay station for the **auditory pathway** [1]. ### Why Hearing is Correct The MGB receives auditory information from the **inferior colliculus** via the brachium of the inferior colliculus [1]. It then projects these signals to the **primary auditory cortex** (Heschl’s gyri, Brodmann areas 41 and 42) in the temporal lobe [2]. It plays a crucial role in processing sound frequency, intensity, and binaural properties [2]. ### Explanation of Incorrect Options * **Vision (A):** Visual information is relayed through the **Lateral Geniculate Body (LGB)**, not the medial. The LGB receives input from the optic tract and projects to the primary visual cortex (Area 17). * **Balance (C):** Vestibular (balance) signals primarily relay through the **vestibular nuclei** in the brainstem and the **ventral posterior nuclei** of the thalamus, rather than the MGB [4]. * **Smell (D):** Olfaction is unique because it is the only sense that reaches the cerebral cortex (olfactory cortex) **without** a mandatory primary relay in the thalamus [3]. ### NEET-PG High-Yield Pearls * **Mnemonic:** **M**edial for **M**usic (Hearing); **L**ateral for **L**ight (Vision). * **The Auditory Pathway (E-COLI-MA):** **E**ighth nerve → **C**ochlear nuclei → **O**livary nucleus (Superior) → **L**ateral lemniscus → **I**nferior colliculus → **M**edial geniculate body → **A**uditory cortex [1]. * The **Inferior Colliculus** is for hearing, while the **Superior Colliculus** is for visual reflexes.
Question 1027: Stellate cells of von Kuffer are seen in the sinusoids of which of the following organs?
- A. Spleen
- B. Bone marrow
- C. Liver (Correct Answer)
- D. Adrenal
Explanation: The **Stellate cells of von Kupffer** (commonly known as Kupffer cells) are specialized, fixed macrophages located within the **liver sinusoids**. They are derived from monocytes and form part of the Mononuclear Phagocyte System (MPS). Their primary function is to filter the portal blood by phagocytosing aged red blood cells, bacteria, and particulate matter, thereby acting as the liver's first line of immune defense [1]. **Analysis of Options:** * **Liver (Correct):** Kupffer cells are anchored to the endothelial lining of the hepatic sinusoids [2]. Note: They should not be confused with *Hepatic Stellate Cells (Ito cells)*, which reside in the Space of Disse and store Vitamin A [1]. * **Spleen:** While the spleen is rich in macrophages (located in the Red Pulp), they are referred to as splenic macrophages, not Kupffer cells [3]. * **Bone Marrow:** Contains "Hofbauer-like" macrophages and hematopoietic stem cells, but the resident phagocytes here do not carry the "von Kupffer" eponym. * **Adrenal:** The adrenal cortex contains sinusoids, but the resident macrophages do not have a specific eponymous designation like those in the liver. **High-Yield Clinical Pearls for NEET-PG:** * **Kupffer Cells:** Largest population of tissue macrophages in the body; involved in iron metabolism by recycling hemoglobin. * **Ito Cells (Stellate Cells):** Located in the Space of Disse; primary site for Vitamin A storage. In chronic liver injury, they transform into myofibroblasts and produce collagen, leading to **liver fibrosis** [1]. * **Space of Disse:** The perisinusoidal space between hepatocytes and sinusoids where nutrient exchange occurs [1].
Question 1028: What is a disadvantage of the cold water treatment of burns?
- A. Vesicle formation
- B. Infection (Correct Answer)
- C. Pain
- D. Scar formation
Explanation: **Explanation:** The primary disadvantage of using cold water (especially non-sterile or stagnant water) in the immediate treatment of burns is the significantly increased risk of **Infection** [1]. While cool running water is the gold standard for first aid to limit thermal spread, prolonged exposure or the use of contaminated water can macerate the skin and introduce pathogens into the compromised dermal barrier. Furthermore, extreme cold can cause vasoconstriction, which reduces the delivery of immune cells to the site, potentially promoting bacterial colonization [1]. **Analysis of Options:** * **Infection (Correct):** Burn wounds are highly susceptible to sepsis [1]. Cold water treatment, if not performed with potable water or if applied for too long, creates a moist environment conducive to microbial growth and impairs local perfusion. * **Vesicle formation:** This is a clinical feature of second-degree (partial-thickness) burns caused by the thermal injury itself, not a disadvantage of the cold water treatment. In fact, cooling can sometimes limit the extent of blistering. * **Pain:** Cold water is actually an **analgesic**. It numbs the nerve endings and reduces the release of inflammatory mediators, thereby decreasing pain. * **Scar formation:** Cooling the burn helps limit "zone of stasis" progression to the "zone of necrosis," which can actually reduce the depth of the wound and potentially *decrease* long-term scarring. **Clinical Pearls for NEET-PG:** * **The Rule of 15:** Apply cool running tap water (15°C) for approximately 15 minutes within the first 30 minutes of injury. * **Avoid Ice:** Never apply ice directly to a burn; it causes "frostbite" type injury and intense vasoconstriction, worsening tissue ischemia. * **Zone of Jackson:** Cooling aims to save the **Zone of Stasis** (the area surrounding the central necrotic core) from becoming irreversible.
Question 1029: The accessory pancreatic duct opens on which of the following structures?
- A. Major duodenal papillae
- B. Minor duodenal papillae (Correct Answer)
- C. Arch of plica semicircularis
- D. Plica longitudinalis
Explanation: **Explanation:** The pancreas is drained by two main systems: the **Main Pancreatic Duct (Duct of Wirsung)** and the **Accessory Pancreatic Duct (Duct of Santorini)**. 1. **Why Option B is correct:** The **Accessory Pancreatic Duct (Santorini)** drains the upper part of the head of the pancreas and opens into the second part of the duodenum at the **Minor Duodenal Papilla** [1]. This papilla is located approximately 2 cm proximal (superior) to the major duodenal papilla. 2. **Why Option A is incorrect:** The **Major Duodenal Papilla** is the site where the Main Pancreatic Duct and the Common Bile Duct (CBD) join to form the Ampulla of Vater (hepatopancreatic ampulla) before opening into the duodenum [1]. 3. **Why Option C is incorrect:** The **Plica Semicircularis** (Valvulae conniventes) are large valvular flaps/folds of the intestinal mucous membrane. They are general anatomical features of the small intestine, not specific opening sites for ducts. 4. **Why Option D is incorrect:** The **Plica Longitudinalis** is a vertical fold of mucous membrane found in the lower part of the posterior wall of the second part of the duodenum. The major duodenal papilla is situated at the lower end of this fold. **High-Yield NEET-PG Pearls:** * **Embryology:** The main duct (Wirsung) is derived from the **ventral pancreatic bud** and the distal part of the dorsal bud [1]. The accessory duct (Santorini) is derived from the proximal part of the **dorsal pancreatic bud** [1]. * **Pancreas Divisum:** This is the most common congenital anomaly of the pancreas, where the dorsal and ventral ducts fail to fuse. In this condition, the majority of pancreatic secretions drain through the **Accessory Duct into the Minor Papilla**, which can lead to obstructive pancreatitis. * **Location:** Both papillae are located in the **second (descending) part** of the duodenum.
Question 1030: In which intrauterine week do tertiary chorionic villi develop?
- A. 3rd week (Correct Answer)
- B. 5th week
- C. 7th week
- D. 9th week
Explanation: The development of chorionic villi is a hallmark of early placentation, occurring during the **3rd week** of intrauterine life [1]. This process follows a specific chronological sequence: 1. **Primary Villi (End of 2nd week):** Consist of a core of cytotrophoblast covered by a layer of syncytiotrophoblast [1]. 2. **Secondary Villi (Early 3rd week):** Extraembryonic mesoderm invades the core of the primary villi. 3. **Tertiary Villi (End of 3rd week):** Mesodermal cells differentiate into blood capillaries and blood cells, establishing the embryonic cardiovascular system. By the end of the 3rd week, embryonic blood begins to flow through these capillaries, facilitating nutrient and gas exchange [1]. **Analysis of Incorrect Options:** * **B (5th week):** By this stage, the placenta is already well-established, and the embryo undergoes rapid organogenesis (e.g., limb buds and heart development). * **C (7th week):** This marks the period of facial development and the beginning of digit separation. * **D (9th week):** This marks the transition from the embryonic period to the fetal period. **High-Yield Facts for NEET-PG:** * **Rule of 2s (2nd Week):** Two layers of trophoblast (Cyto and Syncytio), two layers of embryoblast (Epiblast and Hypoblast), and two cavities (Amniotic and Yolk sac). * **Gastrulation:** Occurs in the 3rd week, converting the bilaminar disc into a trilaminar disc (Ectoderm, Mesoderm, Endoderm). * **Clinical Correlation:** Hydatidiform moles result from the abnormal proliferation of trophoblasts; if villi fail to vascularize (staying at the primary/secondary stage), they may become cystic.
Practice by Chapter
Organization of the Nervous System
Practice Questions
Spinal Cord Anatomy
Practice Questions
Brainstem Anatomy
Practice Questions
Cerebellum
Practice Questions
Diencephalon
Practice Questions
Cerebral Cortex
Practice Questions
Basal Ganglia
Practice Questions
Limbic System
Practice Questions
Cranial Nerves
Practice Questions
Autonomic Nervous System
Practice Questions
Neural Pathways and Tracts
Practice Questions
Neurovascular Anatomy
Practice Questions
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free