Neuroanatomy — MCQs

Neuroanatomy Indian Medical PG Practice Questions and MCQs

Question 131: Which of the following tracts is concerned with pain and temperature sensation?

A. Pyramidal tract
B. Anterior spinothalamic tract
C. Lateral spinothalamic tract (Correct Answer)
D. Dorsal column

Explanation: ### Explanation The sensory pathways of the spinal cord are divided into specific tracts based on the modalities they carry. **1. Why the Lateral Spinothalamic Tract is Correct:** The **Lateral Spinothalamic Tract (LSTT)** is the primary pathway for **pain and temperature** [1], [2]. The first-order neurons reside in the dorsal root ganglion; they synapse in the dorsal horn (Substantia Gelatinosa). The second-order neurons **decussate immediately** in the anterior white commissure and ascend in the lateral funiculus to the thalamus (VPL nucleus) [2]. **2. Analysis of Incorrect Options:** * **Pyramidal Tract (Corticospinal Tract):** This is a **descending motor pathway** responsible for voluntary muscle control, not sensory perception [3]. * **Anterior Spinothalamic Tract:** This tract primarily carries **crude touch and pressure**. While related to the LSTT, it is anatomically and functionally distinct. * **Dorsal Column (Medial Lemniscus Pathway):** This pathway carries **fine touch, vibration, conscious proprioception, and two-point discrimination** [1]. It decussates in the medulla (internal arcuate fibers), not the spinal cord [1]. **3. Clinical Pearls for NEET-PG:** * **Syringomyelia:** Classically affects the anterior white commissure first, leading to a "cape-like" loss of pain and temperature (LSTT) while sparing fine touch (Dorsal Column)—a phenomenon known as **dissociated sensory loss**. * **Brown-Séquard Syndrome:** Hemisection of the cord results in **contralateral** loss of pain/temperature (LSTT) and **ipsilateral** loss of vibration/proprioception (Dorsal Column) below the level of the lesion. * **Lamination:** In the spinothalamic tract, fibers are arranged somatotopically with sacral fibers being most lateral and cervical fibers being most medial.

Question 132: Stratified cuboidal epithelium is typically found in which of the following locations?

A. Ovaries
B. Cervix
C. Ovarian follicles (Correct Answer)
D. Larynx

Explanation: **Explanation:** **Correct Answer: C. Ovarian follicles** Stratified cuboidal epithelium is a rare type of epithelium consisting of two or more layers of cube-shaped cells. In the human body, it is primarily found in the **larger ducts of sweat glands, mammary glands, and salivary glands**, as well as in the **developing ovarian follicles**. As a primordial follicle matures into a primary and then a secondary follicle, the single layer of follicular cells becomes multilayered (stratified) and cuboidal in shape; these are then referred to as **granulosa cells**. **Analysis of Incorrect Options:** * **A. Ovaries:** The surface of the ovary (germinal epithelium) is covered by a **simple cuboidal** (or sometimes simple squamous) epithelium, not stratified [1]. * **B. Cervix:** The cervix has two types of epithelium: the endocervix is lined by **simple columnar** epithelium, while the ectocervix is lined by **non-keratinized stratified squamous** epithelium [2]. * **C. Larynx:** The larynx is primarily lined by **pseudostratified ciliated columnar** epithelium (respiratory epithelium), though the true vocal folds are lined by stratified squamous epithelium to withstand mechanical stress. **NEET-PG High-Yield Pearls:** * **Simple Cuboidal:** Found in thyroid follicles, surface of the ovary, and renal tubules (PCT/DCT). * **Simple Columnar:** Found in the GI tract (stomach to anus) and gallbladder. * **Pseudostratified Ciliated Columnar:** Found in the trachea and bronchi. * **Transitional Epithelium (Urothelium):** Found in the ureter, urinary bladder, and prostatic urethra. * **Stratified Cuboidal/Columnar:** Always think of **large exocrine ducts**.

Question 133: Gustatory cortex is situated in which of the following locations?

A. Superior temporal gyrus
B. Inferior frontal gyrus
C. Superior frontal gyrus
D. Inferior parietal gyrus (Correct Answer)

Explanation: **Explanation:** The **Gustatory Cortex** (Primary Taste Area) is responsible for the perception of taste. It is primarily located in the **anterior insula** and the **frontal operculum**. In the context of cortical anatomy, this region corresponds to the **inferior parietal gyrus** (specifically the parietal operculum) and the lower part of the postcentral gyrus (Brodmann area 43) [1]. **Why the correct answer is right:** * **Brodmann Area 43:** This area is situated at the base of the postcentral gyrus, extending into the **parietal operculum** (part of the inferior parietal lobule/gyrus). It receives taste sensations from the ventral posteromedial (VPM) nucleus of the thalamus [1]. **Why the incorrect options are wrong:** * **Superior temporal gyrus:** This contains the **Primary Auditory Cortex** (Heschl’s gyri, Areas 41 and 42) and Wernicke’s area (Area 22). * **Inferior frontal gyrus:** This contains **Broca’s Motor Speech Area** (Areas 44 and 45) in the dominant hemisphere. * **Superior frontal gyrus:** This is primarily involved in higher cognitive functions, motor planning (Supplementary Motor Area), and working memory. **High-Yield Facts for NEET-PG:** * **Taste Pathway:** Receptors → Cranial Nerves VII, IX, X → Nucleus Tractus Solitarius (NTS) → VPM Nucleus of Thalamus → Primary Gustatory Cortex (Area 43) [1]. * **Insula:** Often considered the "fifth lobe" of the brain; it is hidden deep within the lateral sulcus and is the primary site for visceral and gustatory integration. * **Ageusia:** The clinical term for the loss of taste sensation.

Question 134: Clinical features of Conus Medullaris syndrome include all of the following, except:

A. Plantar extensor (Babinski sign positive)
B. Absent knee and ankle jerks (Correct Answer)
C. Sacral anesthesia
D. Lower sacral and coccygeal involvement

Explanation: To understand **Conus Medullaris Syndrome (CMS)**, one must localize the lesion to the terminal end of the spinal cord (usually at the **L1-L2 vertebral level**). CMS typically involves the sacral segments (S3-S5) and the coccygeal segment. ### **Why "Absent knee and ankle jerks" is the correct answer (The Exception):** In CMS, the lesion occurs at the distal tip of the spinal cord. The **Knee jerk (L2-L4)** is usually **preserved** because the segments responsible for it are located higher up in the lumbar cord, above the site of injury. While the **Ankle jerk (S1-S2)** may be affected if the lesion extends slightly higher, it is not a defining feature of pure CMS. Therefore, the statement that *both* are absent is incorrect. ### **Analysis of Incorrect Options:** * **Plantar extensor (Babinski sign):** Since the Conus Medullaris is part of the spinal cord (CNS), a lesion here can manifest **Upper Motor Neuron (UMN)** signs, such as a positive Babinski reflex. * **Sacral anesthesia:** CMS characteristically presents with "saddle anesthesia" (sensory loss over S3-S5 dermatomes) due to damage to the sacral cord segments. * **Lower sacral and coccygeal involvement:** This is the anatomical hallmark of the syndrome, leading to early onset of bladder/bowel dysfunction and impotence. ### **Clinical Pearls for NEET-PG:** | Feature | Conus Medullaris Syndrome | Cauda Equina Syndrome | | :--- | :--- | :--- | | **Level** | L1-L2 (Spinal Cord) | Below L2 (Nerve Roots) | | **Motor Signs** | Symmetric, UMN + LMN | Asymmetric, Pure LMN | | **Reflexes** | Knee preserved; Ankle may be absent | Both Knee and Ankle absent | | **Onset** | Sudden/Abrupt | Gradual/Radicular | | **Bladder/Bowel** | Early involvement | Late involvement | **High-Yield Note:** If a question mentions **symmetrical** symptoms and **perianal** sensory loss, think Conus Medullaris. If it mentions **asymmetrical** leg pain and **absent knee/ankle jerks**, think Cauda Equina.

Question 135: Which muscle does not contribute to the pes anserinus?

A. semimembranosus (Correct Answer)
B. semitendinosus
C. gracilis
D. sartorius

Explanation: **Explanation:** The **Pes Anserinus** (Latin for "Goose's Foot") is a high-yield anatomical landmark referring to the conjoined tendons of three specific muscles that insert onto the **anteromedial (medial) surface of the proximal tibia**. **Why Semimembranosus is the Correct Answer:** The **Semimembranosus** does not contribute to the pes anserinus. Instead, it inserts primarily on the **posteromedial** aspect of the medial tibial condyle. While it is a medial hamstring muscle, its insertion point is distinct and deeper than the pes anserinus complex. **Analysis of Incorrect Options:** The pes anserinus is formed by the "SGT" muscles, which represent three different compartments of the thigh: * **Sartorius (Option D):** The most superficial component; represents the **Anterior** compartment (Femoral nerve). * **Gracilis (Option C):** The middle component; represents the **Medial** compartment (Obturator nerve). * **Semitendinosus (Option B):** The deepest component of the three; represents the **Posterior** compartment (Sciatic nerve/Tibial division). **NEET-PG High-Yield Pearls:** 1. **Mnemonic:** Remember **"Say Grace before Tea"** (Sartorius, Gracilis, semitendinosus) to recall the order from anterior to posterior. 2. **Nerve Supply:** A favorite examiner trick is noting that these three muscles are supplied by three different nerves (Femoral, Obturator, and Sciatic). 3. **Clinical Correlation:** **Pes Anserine Bursitis** is a common cause of medial knee pain, often seen in runners or patients with osteoarthritis, located just below the joint line. 4. **Surgical Significance:** The tendons of the Gracilis and Semitendinosus are frequently harvested as autografts for **ACL reconstruction**.

Question 136: Which of the following is a complete sulcus?

A. Central sulcus
B. Paracentral sulcus
C. Collateral sulcus (Correct Answer)
D. Post calcarine sulcus

Explanation: ### Explanation In neuroanatomy, a **complete sulcus** is defined as a deep groove that is so profound it causes a corresponding elevation or inward bulging in the wall of the lateral ventricle. **Why Collateral Sulcus is correct:** The **collateral sulcus** is located on the tentorial surface of the brain, separating the parahippocampal gyrus from the medial occipitotemporal gyrus. It is a classic example of a complete sulcus because its depth produces a longitudinal elevation on the floor of the temporal horn of the lateral ventricle, known as the **collateral eminence**. **Analysis of Incorrect Options:** * **A. Central sulcus:** This is a limiting sulcus (separating motor and sensory areas) but does not indent the ventricular system. * **B. Paracentral sulcus:** This is a minor sulcus on the medial surface of the hemisphere and does not reach the ventricular wall. * **D. Post-calcarine sulcus:** While the **calcarine sulcus** itself is a complete sulcus (producing the *calcar avis* in the posterior horn of the lateral ventricle), the *post-calcarine* portion is generally considered a continuation that does not consistently produce a ventricular indentation in the same manner as the main trunk or the collateral sulcus. **High-Yield Facts for NEET-PG:** * **The Two Main Complete Sulci:** 1. **Collateral Sulcus** $\rightarrow$ produces **Collateral Eminence**. 2. **Calcarine Sulcus** $\rightarrow$ produces **Calcar Avis** (Hippocampus minor). * **Limiting Sulcus:** A sulcus that separates two different functional/histological areas (e.g., Central Sulcus). * **Operculated Sulcus:** A sulcus whose lips contain a third area hidden in its depths (e.g., Lunate sulcus). * **Crucial Landmark:** The collateral sulcus begins near the occipital pole and runs forward, parallel to the calcarine sulcus.

Question 137: Nerve fibers in the greater, lesser, and least splanchnic nerves are primarily composed of which type of fibers?

A. Preganglionic sympathetic (Correct Answer)
B. Postganglionic sympathetic fibers
C. Postganglionic parasympathetic fibers
D. Both preganglionic and postganglionic sympathetic fibers

Explanation: The thoracic splanchnic nerves (Greater, Lesser, and Least) are unique because they are composed of **preganglionic sympathetic fibers** that pass through the sympathetic chain without synapsing [1]. **1. Why Option A is Correct:** The sympathetic outflow originates from the lateral horn of the spinal cord (T1–L2). While most sympathetic fibers synapse in the paravertebral ganglia (sympathetic chain), the fibers destined for the abdominal viscera pass through the chain as **white rami communicantes** and exit as splanchnic nerves [1]. They remain preganglionic until they reach **prevertebral (collateral) ganglia** (such as the celiac, superior mesenteric, or aorticorenal ganglia), where they finally synapse. **2. Why the Other Options are Incorrect:** * **Option B & D:** Postganglionic sympathetic fibers typically arise *after* synapsing in the sympathetic chain and travel via gray rami communicantes to spinal nerves or directly to thoracic organs (like the heart). Splanchnic nerves are defined by their "pre-synaptic" status. * **Option C:** Parasympathetic supply to the foregut and midgut is provided by the **Vagus nerve (CN X)**, not the thoracic splanchnic nerves. **High-Yield Facts for NEET-PG:** * **Greater Splanchnic Nerve:** T5–T9 (synapses in Celiac ganglion). * **Lesser Splanchnic Nerve:** T10–T11 (synapses in Superior Mesenteric ganglion). * **Least Splanchnic Nerve:** T12 (synapses in Aorticorenal ganglion). * **Clinical Pearl:** These nerves also carry **GVA (General Visceral Afferent)** fibers. This is the anatomical basis for **referred pain**; for example, pain from the gallbladder (T5-T9) is often felt in the epigastrium.

Question 138: In ICD-10, dementia is classified under which category?

A. F00 (Correct Answer)
B. F10
C. F20
D. F30

Explanation: In the ICD-10 (International Classification of Diseases, 10th Revision), Chapter V focuses on **Mental and Behavioral Disorders**, using the prefix **'F'**. **Correct Option: A (F00)** The code **F00** specifically refers to **Dementia in Alzheimer's disease**. The broader category **F00–F09** encompasses "Organic, including symptomatic, mental disorders." Dementia is classified here because it is characterized by a clinically identifiable cerebral disease or systemic dysfunction affecting the brain. **Explanation of Incorrect Options:** * **F10 (Mental and behavioral disorders due to use of alcohol):** This category (F10–F19) covers disorders resulting from the use of psychoactive substances (e.g., opioids, cocaine, tobacco). * **F20 (Schizophrenia):** The F20–F29 block covers Schizophrenia, schizotypal, and delusional disorders. F20 specifically denotes Schizophrenia. * **F30 (Manic episode):** The F30–F39 block covers Mood [affective] disorders. F30 refers to a single manic episode, while F31 refers to Bipolar Affective Disorder and F32 to Depressive episodes. **High-Yield Clinical Pearls for NEET-PG:** * **ICD-11 Update:** Note that in the newer ICD-11, Dementia is classified under "Neurocognitive Disorders." * **Most Common Cause:** Alzheimer’s disease is the most common cause of dementia worldwide (associated with amyloid plaques and tau tangles) [1]. * **Key Diagnostic Feature:** For a diagnosis of dementia in ICD-10, symptoms must be present for at least **6 months**. * **Memory vs. Consciousness:** In dementia, there is a decline in memory and thinking, but **consciousness remains clear** (unlike Delirium, where consciousness is clouded).

Question 139: The most common cause of tricuspid regurgitation is secondary to?

A. Rheumatoid heart disease
B. Dilation of the right ventricle (Correct Answer)
C. Coronary artery disease
D. Endocarditis due to intravenous drug abuse

Explanation: **Explanation:** Tricuspid Regurgitation (TR) is classified into primary (organic) and secondary (functional) causes. **Secondary TR is the most common form**, accounting for approximately 80% of cases [1]. **1. Why "Dilation of the Right Ventricle" is correct:** Functional TR occurs without structural defects in the valve leaflets themselves [2]. When the right ventricle (RV) dilates—often due to pulmonary hypertension or left-sided heart failure—it causes **annular dilation** and displacement of the papillary muscles [1]. This prevents the leaflets from coapting (closing) properly, leading to regurgitation [2]. **2. Why the other options are incorrect:** * **Rheumatoid heart disease:** While Rheumatic Heart Disease (RHD) is a common cause of organic TR in developing countries, it almost never occurs in isolation and is significantly less common than functional TR [1]. * **Coronary artery disease:** This more frequently leads to mitral regurgitation (due to papillary muscle dysfunction in the left ventricle) rather than tricuspid issues. * **Endocarditis (IV drug abuse):** This is the most common cause of *isolated primary* (organic) TR [3], but it is far less frequent in the general population than secondary TR caused by RV dilation. **Clinical Pearls for NEET-PG:** * **Physical Exam:** Look for a holosystolic murmur at the left lower sternal border that increases with inspiration (**Carvallo’s sign**). * **Jugular Venous Pulse (JVP):** Characterized by a prominent **'v' wave** and a steep 'y' descent. * **Pulsatile Liver:** Severe TR can cause congestive hepatomegaly with palpable systolic pulsations [2]. * **Ebstein’s Anomaly:** A high-yield congenital cause of TR characterized by "atrialization" of the right ventricle [1].

Question 140: Collecting tubules of the kidney develop from which embryonic structure?

A. Ureteric bud (Correct Answer)
B. Mesonephric duct
C. Paramesonephric duct
D. Wolffian duct

Explanation: The development of the permanent kidney (metanephros) begins in the 5th week of gestation and arises from two distinct sources: the **Ureteric Bud** and the **Metanephric Blastema**. [1] ### 1. Why the Ureteric Bud is Correct The **Ureteric Bud** is an outgrowth from the distal end of the mesonephric duct. It undergoes repeated branching to form the **collecting system** of the kidney. Its derivatives include: * Ureter * Renal Pelvis [1] * Major and Minor Calyces * **Collecting Tubules** and Collecting Ducts [1] ### 2. Why the Other Options are Incorrect * **Mesonephric Duct (Wolffian Duct):** While the ureteric bud originates from this duct, the duct itself primarily gives rise to male reproductive structures (Epididymis, Vas deferens, Seminal vesicles, and Ejaculatory duct) under the influence of testosterone. * **Paramesonephric Duct (Müllerian Duct):** This structure gives rise to the female reproductive tract (Fallopian tubes, Uterus, and upper 1/3rd of the Vagina). It does not contribute to the renal system. * **Wolffian Duct:** This is simply another name for the Mesonephric duct. ### 3. NEET-PG High-Yield Pearls * **Metanephric Blastema (Cap):** This forms the **excretory system** (Nephrons), including Bowman’s capsule, Proximal Convoluted Tubule (PCT), Loop of Henle, and Distal Convoluted Tubule (DCT). * **Reciprocal Induction:** The interaction between the ureteric bud and metanephric blastema is essential for kidney development. Failure of this interaction leads to **Renal Agenesis**. * **Potter Sequence:** Often caused by bilateral renal agenesis, leading to oligohydramnios, pulmonary hypoplasia, and limb deformities.

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