Neuroanatomy — MCQs
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Which of the following murmurs increases with the Valsalva maneuver?
Which neuroanatomical part of the brain is involved in sexual drive?
Which is the commonest type of cartilage to ossify?
Pathological gambling is included in DSM 5 under which category?
What is true about the corpus callosum?
All of the following arise from neuroepithelial cells except:
Which bones ossify at the lower end?
Dystrophic calcification is seen in which of the following conditions?
Parasympathetic fibers of the vagus nerve supply which of the following structures?
A 55-year-old right-handed veteran received a small shrapnel wound in the head. Within 1 year of receiving his wound, the man complained of seizures and was treated with seizure medication. The medication was not effective, and a section of the anterior corpus callosum was performed. Which of the following neurologic deficits is most likely?
Neuroanatomy Indian Medical PG Practice Questions and MCQs
Question 941: Which of the following murmurs increases with the Valsalva maneuver?
- A. Mitral stenosis
- B. Hypertrophic obstructive cardiomyopathy (HOCM) (Correct Answer)
- C. Mitral regurgitation
- D. Aortic stenosis
Explanation: ### Explanation The **Valsalva maneuver** (specifically the strain phase) increases intrathoracic pressure, which decreases venous return to the heart. This leads to a **reduction in Left Ventricular (LV) end-diastolic volume** (preload). **Why HOCM is the correct answer:** In Hypertrophic Obstructive Cardiomyopathy, the pathology involves an asymmetrical septal hypertrophy that obstructs the LV outflow tract (LVOT). When the LV volume decreases (as during Valsalva), the ventricular walls and the anterior leaflet of the mitral valve move closer together. This **worsens the outflow obstruction**, thereby increasing the intensity of the systolic murmur. **Why the other options are incorrect:** * **Mitral Stenosis (A):** Decreased venous return reduces the flow across the stenotic mitral valve, thereby **decreasing** the intensity of the diastolic rumble [1]. * **Mitral Regurgitation (C) & Aortic Stenosis (D):** Both are "flow-dependent" systolic murmurs [1]. A decrease in preload leads to a lower stroke volume and less blood being ejected through the valves, resulting in a **decreased** murmur intensity [2]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Two":** Most murmurs *decrease* in intensity during the Valsalva maneuver and standing. The only two exceptions (which **increase**) are **HOCM** and **Mitral Valve Prolapse (MVP)**. * **Handgrip Exercise:** This increases afterload. It **decreases** the murmur of HOCM and AS but **increases** the murmur of MR, AR, and VSD. * **Squatting:** Increases both preload and afterload; it **decreases** the HOCM murmur (opposite of Valsalva). [1, 2, 3, 4, 5]
Question 942: Which neuroanatomical part of the brain is involved in sexual drive?
- A. Temporal lobe
- B. Limbic system (Correct Answer)
- C. Hypothalamus
- D. Frontal lobe
Explanation: The **Limbic System** (often called the "emotional brain") is the primary neuroanatomical region responsible for regulating sexual drive, emotions, motivation, and memory. It consists of a complex network including the amygdala, hippocampus, cingulate gyrus, and parts of the thalamus. Specifically, the **amygdala** and **septal nuclei** play pivotal roles in processing sexual arousal and pleasure. **Analysis of Options:** * **Limbic System (Correct):** It acts as the overarching functional unit for instinctual behaviors [1]. While sexual drive involves multiple areas, the limbic system integrates these signals to produce libido and emotional responses. * **Hypothalamus:** While the hypothalamus (specifically the preoptic area) is crucial for the *physical execution* of sexual behavior and hormonal regulation (GnRH release), the "drive" or emotional urge is primarily attributed to the limbic system [1], [2]. In many exams, if both are listed, the Limbic System is the broader, preferred answer for "drive/emotion." * **Temporal Lobe:** While it contains the amygdala and hippocampus, the lobe as a whole is primarily responsible for auditory processing and language. However, bilateral temporal lobe lesions can lead to **Klüver-Bucy Syndrome**, characterized by hypersexuality. * **Frontal Lobe:** This area is responsible for executive function and impulse control. It generally acts to *inhibit* inappropriate sexual behavior rather than generating the drive itself. **High-Yield NEET-PG Pearls:** * **Klüver-Bucy Syndrome:** Resulting from bilateral amygdala/temporal lesions; presents with hypersexuality, hyperphagia, and visual agnosia. * **Papez Circuit:** The classic pathway for emotional expression (Hippocampus → Mammillary bodies → Anterior Thalamus → Cingulate Gyrus → Hippocampus). * **Reward Center:** The **Nucleus Accumbens** (part of the limbic-striatal complex) is the key structure for the reinforcement of sexual pleasure via dopamine.
Question 943: Which is the commonest type of cartilage to ossify?
- A. Hyaline (Correct Answer)
- B. Elastic
- C. Fibrous
- D. Fibroelastic
Explanation: **Explanation:** **1. Why Hyaline Cartilage is the Correct Answer:** Hyaline cartilage is the most abundant type of cartilage in the human body and serves as the primary precursor for the skeletal system [1]. The majority of the skeleton is formed through **endochondral ossification**, a process where a hyaline cartilage model is gradually replaced by bone [2]. Furthermore, hyaline cartilage has a natural tendency to calcify and ossify with age, particularly in the costal cartilages and the laryngeal skeleton (except the epiglottis). Its matrix is rich in Type II collagen and lacks the dense elastic or thick fibrous bundles that inhibit mineralization in other types [1]. **2. Why the Other Options are Incorrect:** * **Elastic Cartilage:** Contains a dense network of elastic fibers. It is specifically designed for flexibility and resilience. It **never ossifies or calcifies**, even with advancing age (e.g., pinna of the ear, epiglottis). * **Fibrous Cartilage (Fibrocartilage):** Contains thick bundles of Type I collagen. It acts as a shock absorber in high-stress areas (e.g., intervertebral discs, pubic symphysis). While it may occasionally undergo pathological calcification, it does not routinely ossify as a physiological process. * **Fibroelastic:** This is a hybrid description and not a primary classification of cartilage in this context. **3. Clinical Pearls & High-Yield Facts:** * **Articular Cartilage:** A type of hyaline cartilage that covers joint surfaces; it is unique because it **does not have a perichondrium** and does not normally ossify (to maintain joint mobility) [1]. * **Laryngeal Cartilages:** The thyroid, cricoid, and arytenoid cartilages are hyaline and often appear radiopaque on X-rays in older adults due to ossification. * **Growth Plate:** The epiphyseal plate is composed of hyaline cartilage; its ossification marks the end of longitudinal bone growth [2].
Question 944: Pathological gambling is included in DSM 5 under which category?
- A. Impulse control disorder
- B. Obsessive compulsive disorder
- C. Substance use disorder (Correct Answer)
- D. Shared psychotic disorder
Explanation: **Explanation:** The classification of **Pathological Gambling** underwent a significant shift in the transition from DSM-IV to **DSM-5**. It is now officially categorized under **Substance-Related and Addictive Disorders** (specifically as a "Non-Substance Addictive Disorder"). **Why Substance Use Disorder is correct:** Neurobiological research has shown that pathological gambling activates the brain's **reward system** (mesolimbic dopaminergic pathway) in a manner remarkably similar to drugs of abuse. Patients exhibit clinical features synonymous with substance addiction, such as **tolerance** (needing to gamble with increasing amounts of money), **withdrawal** (restlessness/irritability when attempting to stop), and repeated unsuccessful efforts to quit despite negative consequences. **Why other options are incorrect:** * **Impulse Control Disorder:** In DSM-IV, gambling was classified here (alongside kleptomania and pyromania). However, DSM-5 moved it because its clinical course and genetic markers align more closely with addictions than with other impulse control disorders. * **Obsessive Compulsive Disorder (OCD):** While both involve repetitive behaviors, OCD is driven by anxiety-reduction (neutralizing obsessions), whereas gambling is driven by the pursuit of reward/pleasure (arousal). * **Shared Psychotic Disorder (Folie à deux):** This is a psychotic syndrome where a symptom is transmitted from one individual to another; it has no clinical relation to gambling. **High-Yield Clinical Pearls for NEET-PG:** * **Neurotransmitter:** Dopamine is the primary neurotransmitter involved in the "reward" aspect of gambling. * **Brain Region:** The **Ventromedial Prefrontal Cortex** and **Nucleus Accumbens** are key areas involved in the pathology. * **Pharmacotherapy:** Opioid antagonists like **Naltrexone** have shown efficacy in reducing the urge to gamble by modulating the reward pathway.
Question 945: What is true about the corpus callosum?
- A. Unites the far areas of the two sides of the brain. (Correct Answer)
- B. Connects the two frontal lobes.
- C. Unites the two hemispheres.
- D. Is superiorly related to the Indusium griseum.
Explanation: The **Corpus Callosum** is the largest commissural fiber bundle in the brain, consisting of approximately 200 million axons. Its primary function is to facilitate interhemispheric communication. ### **Explanation of Options** * **Correct Answer (A):** The corpus callosum primarily connects **homologous (mirror-image) areas** of the two cerebral hemispheres. However, its specific functional role is to integrate information between "far" or distant cortical regions across the midline, allowing the two sides of the brain to function as a single unit. * **Option B:** While it does connect the frontal lobes (via the *Genu* and *Rostrum*), it also connects the parietal, temporal, and occipital lobes. Restricting its function to only the frontal lobes is incomplete. * **Option C:** While it "connects" the hemispheres, the term "unites" in neuroanatomical nomenclature often refers to the functional integration of distant cortical points, making Option A a more precise description of its physiological role. * **Option D:** The **Indusium griseum** (a thin layer of primitive gray matter) and the medial/lateral longitudinal striae are located **superior** to the corpus callosum. Therefore, the corpus callosum is *inferiorly* related to the Indusium griseum, not superiorly. ### **High-Yield Clinical Pearls for NEET-PG** 1. **Parts (Anterior to Posterior):** Rostrum $\rightarrow$ Genu $\rightarrow$ Body (Trunk) $\rightarrow$ Splenium. 2. **Forceps Minor:** Fibers of the **Genu** connecting the frontal lobes. 3. **Forceps Major:** Fibers of the **Splenium** connecting the occipital lobes. 4. **Tapetum:** Fibers of the trunk and splenium that form the roof and lateral wall of the posterior and inferior horns of the lateral ventricle. 5. **Clinical Correlation:** Surgical sectioning (Callosotomy) is used to treat intractable epilepsy to prevent the spread of seizure activity (Split-brain syndrome).
Question 946: All of the following arise from neuroepithelial cells except:
- A. Neuron
- B. Oligodendrocyte
- C. Microglial cells (Correct Answer)
- D. Ependymal cells
Explanation: The development of the central nervous system (CNS) begins with the formation of the **neural tube**. The wall of the neural tube is composed of **neuroepithelial cells**, which serve as the multipotent stem cells for almost all CNS structures. **1. Why Microglial cells is the correct answer:** Unlike other CNS cells, **microglial cells** do not originate from the neuroepithelium [1]. They are derived from **mesenchymal cells** (specifically from yolk sac macrophages) that migrate into the developing brain during the fetal period [1]. Functionally, they are the resident macrophages of the CNS and are part of the mononuclear phagocyte system [1], [2]. **2. Why the other options are incorrect:** The neuroepithelium differentiates into two primary lineages: * **Neuroblasts:** These give rise to **Neurons (Option A)** [4]. Once neuroblasts form, they lose their ability to divide. * **Glioblasts:** These give rise to macroglial cells [1], including: * **Oligodendrocytes (Option B):** Responsible for myelination in the CNS [2], [3]. * **Astrocytes:** Provide structural and metabolic support [1], [4]. * **Ependymal cells (Option D):** When the neuroepithelium ceases production of neuroblasts and glioblasts, the remaining cells differentiate into ependymal cells, which line the ventricles of the brain and the central canal of the spinal cord [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Origin Summary:** All CNS cells are **ectodermal** (neuroectoderm) except Microglia, which are **mesodermal** [1]. * **PNS Exception:** Schwann cells and satellite cells are derived from **Neural Crest Cells**, not the neural tube neuroepithelium. * **Tumor Marker:** Glial Fibrillary Acidic Protein (GFAP) is a marker for cells of glial origin (Astrocytes, Ependymal cells), but *not* for Microglia.
Question 947: Which bones ossify at the lower end?
- A. Upper end of humerus
- B. Lower end of humerus
- C. Lower end of femur (Correct Answer)
- D. Lower end of tibia
Explanation: The correct answer is **Lower end of femur**. This question tests the knowledge of the **"Growing End"** of long bones and the specific timing of ossification centers, which is a high-yield topic for NEET-PG. **1. Why the Lower End of Femur is Correct:** The secondary ossification center for the lower end of the femur is unique because it appears just before birth (at approximately **9 months of intrauterine life**). In forensic medicine and pediatrics, the presence of this ossification center on an X-ray is a medico-legal indicator that a fetus has reached full-term maturity. **2. Analysis of Incorrect Options:** * **Upper end of humerus (Option A):** The growing end of the humerus is the upper end, but its ossification center typically appears shortly *after* birth (around 0–3 months). * **Lower end of humerus (Option B):** This is the non-growing end of the humerus. The ossification centers here (capitulum) appear around 1 year of age. * **Lower end of tibia (Option D):** The ossification center for the lower end of the tibia appears at approximately 6 months to 1 year of age. **3. NEET-PG Clinical Pearls & High-Yield Facts:** * **The Rule of Growing Ends:** "To the elbow I go, from the knee I flee." This means the growing ends are the upper end of the humerus, the lower ends of the radius/ulna, the upper end of the tibia/fibula, and the **lower end of the femur**. * **First Bone to Ossify:** Clavicle (5th–6th week of IU life; via intramembranous ossification) [1]. * **Last Bone to Ossify:** Pisiform (around 10–12 years). * **Medico-legal Importance:** The lower end of the femur and the upper end of the tibia are the only secondary centers present at birth, used to confirm neonatal maturity.
Question 948: Dystrophic calcification is seen in which of the following conditions?
- A. Atheroma (Correct Answer)
- B. Paget's disease
- C. Renal osteodystrophy
- D. Milk alkali syndrome
Explanation: Pathologic calcification is divided into two types: **Dystrophic** and **Metastatic**. **1. Why Atheroma is Correct:** Dystrophic calcification occurs in **dead, dying, or degenerated tissues** despite normal serum calcium levels. In an **atheroma** (advanced atherosclerosis), the necrotic core of the lipid plaque undergoes dystrophic calcification. This is a localized process where calcium salts deposit in damaged vessel walls, often leading to hardened arteries. **2. Why the Other Options are Incorrect:** Options B, C, and D are examples of **Metastatic Calcification**. This occurs in **normal tissues** due to a systemic derangement in calcium metabolism (**Hypercalcemia**). * **Paget’s Disease:** Involves excessive bone remodeling which can lead to elevated serum calcium [2]. * **Renal Osteodystrophy:** Chronic kidney disease leads to secondary hyperparathyroidism and hyperphosphatemia, causing calcium to deposit in healthy tissues (like blood vessels and lungs) [1]. * **Milk-Alkali Syndrome:** Caused by excessive ingestion of calcium and absorbable antacids, leading to hypercalcemia. **High-Yield NEET-PG Pearls:** * **Dystrophic Calcification:** Normal serum calcium; occurs in necrotic tissue (e.g., Caseous necrosis in TB, Psammoma bodies in papillary thyroid cancer, old infarcts, and damaged heart valves). * **Metastatic Calcification:** High serum calcium; occurs in healthy tissues, especially those with an internal alkaline environment (e.g., Gastric mucosa, Kidneys, Lungs, and Systemic arteries). * **Mnemonic for Metastatic sites:** "**K**idney, **L**ungs, **G**astric mucosa" (The **KLG** sites are prone due to acid excretion, making the tissue alkaline).
Question 949: Parasympathetic fibers of the vagus nerve supply which of the following structures?
- A. Heart (Correct Answer)
- B. Parotid gland
- C. Submandibular gland
- D. Ciliary muscles
Explanation: **Explanation:** The **Vagus nerve (CN X)** is the longest cranial nerve and provides extensive parasympathetic (craniosacral) innervation to thoracic and abdominal viscera [1]. Its preganglionic parasympathetic fibers originate in the **Dorsal Nucleus of Vagus** and the **Nucleus Ambiguus** [1]. 1. **Why Heart is Correct:** The vagus nerve provides parasympathetic supply to the heart via cardiac branches [1]. These fibers synapse in ganglia located within the cardiac plexus and the atrial walls [2]. Stimulation results in a decreased heart rate (negative chronotropy) and decreased conduction velocity through the AV node [3]. 2. **Why other options are incorrect:** * **Parotid Gland:** Supplied by the **Glossopharyngeal nerve (CN IX)**. Fibers originate in the inferior salivatory nucleus and synapse in the **otic ganglion** [2]. * **Submandibular Gland:** Supplied by the **Facial nerve (CN VII)** via the chorda tympani branch. Fibers originate in the superior salivatory nucleus and synapse in the **submandibular ganglion** [2]. * **Ciliary Muscles:** Supplied by the **Oculomotor nerve (CN III)**. Fibers originate in the Edinger-Westphal nucleus and synapse in the **ciliary ganglion** [2]. **High-Yield NEET-PG Pearls:** * **The "Rule of 2/3rds":** The vagus nerve supplies the midgut up to the junction of the proximal 2/3rds and distal 1/3rd of the transverse colon. Beyond this point (hindgut), parasympathetic supply is taken over by the **Pelvic Splanchnic Nerves (S2-S4)**. * **Nucleus Ambiguus:** This nucleus provides the special visceral efferent (SVE) fibers to the muscles of the larynx and pharynx, but also contains the cell bodies for preganglionic parasympathetic cardiac inhibitory fibers [1]. * **Vagal Maneuvers:** Clinical techniques (like carotid sinus massage) increase vagal tone to terminate Supraventricular Tachycardia (SVT).
Question 950: A 55-year-old right-handed veteran received a small shrapnel wound in the head. Within 1 year of receiving his wound, the man complained of seizures and was treated with seizure medication. The medication was not effective, and a section of the anterior corpus callosum was performed. Which of the following neurologic deficits is most likely?
- A. Alexia
- B. Gait ataxia
- C. Loss of binocular vision
- D. The inability, with closed eyes, to identify verbally an object held in the left hand (Correct Answer)
Explanation: This question tests the understanding of **interhemispheric communication** via the corpus callosum. The patient underwent a partial callosotomy (anterior section), which disrupts the transfer of somatosensory information between the two hemispheres. **Why Option D is Correct:** In a right-handed individual, the **left hemisphere** is typically dominant for language (speech production). When an object is held in the **left hand**, the sensory information is processed in the **right somatosensory cortex**. To name the object, this information must travel across the corpus callosum to the language centers in the left hemisphere (Broca’s area). Sectioning the corpus callosum prevents this transfer. Consequently, while the patient can feel and manipulate the object, they cannot "label" it verbally—a phenomenon known as **tactile anomia** [2]. **Analysis of Incorrect Options:** * **A. Alexia:** Alexia without agraphia usually occurs due to a lesion in the **posterior** corpus callosum (splenium) and the left occipital lobe, preventing visual information from reaching the language centers [1]. * **B. Gait ataxia:** This is a sign of cerebellar dysfunction or damage to the frontal gait centers, not a result of callosal sectioning. * **C. Loss of binocular vision:** Binocular vision depends on the optic chiasm and the primary visual cortex (V1). The corpus callosum is not involved in the primary pathway for binocularity. **NEET-PG High-Yield Pearls:** * **Corpus Callosum:** The largest commissural fiber bundle. * **Anterior 2/3 (Genu and Body):** Transfers motor and somatosensory information. * **Posterior 1/3 (Splenium):** Transfers visual information. * **Split-Brain Syndrome:** A collection of disconnection syndromes (like the one described) resulting from callosotomy, often performed for refractory "drop attack" seizures to prevent the spread of electrical activity between hemispheres [3].
Practice by Chapter
Organization of the Nervous System
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Spinal Cord Anatomy
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Brainstem Anatomy
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Cerebellum
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Cerebral Cortex
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Basal Ganglia
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Limbic System
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Cranial Nerves
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Autonomic Nervous System
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Neural Pathways and Tracts
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Neurovascular Anatomy
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