Neuroanatomy Practice Questions

Q: Juxtaglomerular cells are part of which structure?

Smooth muscle cells of the afferent arteriole. The **Juxtaglomerular (JG) apparatus** is a specialized structure formed by the distal convoluted tubule and the glomerular afferent arteriole. It plays a critical role in regulating blood pressure and the filtration rate of the glomerulus. **1. Why Option B is Correct:** Juxtaglomerular cells are **modified smooth muscle cells** located primarily in the tunica media of the **afferent arteriole** (and to a lesser extent, the efferent arteriole) [1]. These cells act as **baroreceptors** that sense changes in blood pressure. When blood pressure drops, JG cells synthesize, store, and secrete the enzyme **Renin**, initiating the Renin-Angiotensin-Aldosterone System (RAAS) [1],[2]. **2. Why Other Options are Incorrect:** * **Option A (Macula densa):** These are specialized columnar epithelial cells of the Distal Convoluted Tubule (DCT). They act as **chemoreceptors** sensing sodium chloride (NaCl) concentrations, not pressure [1]. * **Option C (Efferent arteriole):** While some JG cells can be found here, the primary and most significant concentration is in the afferent arteriole [1]. * **Option D (Islets of epithelial cells):** This is a distractor. However, **Lacis cells** (Extraglomerular mesangial cells) are located in the space between the afferent and efferent arterioles and the macula densa, acting as signaling intermediaries. **High-Yield Clinical Pearls for NEET-PG:** * **Granules:** JG cells contain pro-renin and renin granules (visible with Bowie stain) [1]. * **Innervation:** JG cells are innervated by **Sympathetic nerve fibers** (Beta-1 receptors), which stimulate renin release [2]. * **RAAS Trigger:** Renin release is triggered by: 1) Decreased renal perfusion pressure, 2) Increased sympathetic activity, and 3) Decreased NaCl delivery to the macula densa [2].

Q: Fournier's gangrene is typically seen in which of the following locations?

Scrotal skin. **Explanation:** **Fournier’s Gangrene** is a life-threatening, rapidly progressing **necrotizing fasciitis** of the perineal, perianal, and genital regions [1]. It is a polymicrobial infection (aerobes and anaerobes) that leads to obliterative endarteritis of the subcutaneous arteries, resulting in gangrene of the overlying skin and subcutaneous tissue. 1. **Why Scrotal Skin is Correct:** The infection typically originates from the skin, urethra, or rectum [1]. In males, it most commonly involves the **scrotum** and penis. The infection spreads along the anatomical planes defined by the superficial fascia. It travels between **Colles’ fascia** (perineum), **Scarpa’s fascia** (abdominal wall), and **Dartos fascia** (scrotum/penis). Because these fasciae are continuous, the gangrene can rapidly ascend from the scrotum to the anterior abdominal wall. 2. **Why Other Options are Incorrect:** * **Nose & Oral Cavity:** These areas are not associated with the specific urogenital/perineal fascial planes. Necrotizing infections in the head and neck are rare and usually classified as cervical necrotizing fasciitis, often secondary to odontogenic infections, but they are never termed "Fournier’s." **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Diabetes Mellitus (most common), chronic alcoholism, and immunosuppression. * **Anatomical Boundary:** The **testes are usually spared** because they have a separate blood supply (testicular artery from the abdominal aorta) and do not share the same venous/lymphatic drainage as the scrotal skin. * **Management:** This is a surgical emergency requiring aggressive **debridement**, broad-spectrum antibiotics, and often hemodynamic support [1]. * **Key Sign:** Crepitus on palpation (due to gas-forming organisms).

Q: The diaphragm is formed from the following components, except:

Splanchnopleuric mesoderm. The development of the diaphragm is a high-yield topic in embryology. The diaphragm is a composite structure derived from four distinct embryonic sources. ### **Why Splanchnopleuric Mesoderm is Correct** The **splanchnopleuric mesoderm** primarily contributes to the development of the wall of the primitive gut tube and the visceral layer of serous membranes (like the visceral pleura). It does **not** contribute to the formation of the diaphragm. ### **Explanation of Other Components (The "Four Sources")** The diaphragm develops from the following four components (Mnemonic: **S**ome **M**any **D**rive **E**verywhere): 1. **Septum Transversum (A):** This forms the **Central Tendon** of the diaphragm [1]. It is the largest contributor and initially lies opposite the C3-C5 somites. 2. **Mesoderm of the Body Wall (D):** This contributes to the **peripheral muscular parts** of the diaphragm. As the lungs expand, they "excavate" the body wall, incorporating this mesoderm. 3. **Dorsal Mesentery of the Esophagus (C):** This forms the **Crura** of the diaphragm. (Note: The ventral mesentery is usually not cited as a major contributor, but in the context of this question, the esophageal mesentery as a whole is a recognized source). 4. **Pleuroperitoneal Membranes:** These close the communication between the pleural and peritoneal cavities. ### **Clinical Pearls for NEET-PG** * **Congenital Diaphragmatic Hernia (Bochdalek Hernia):** Most commonly occurs due to the failure of the **pleuroperitoneal membrane** to fuse, usually on the **left side**. * **Nerve Supply:** The phrenic nerve (C3, C4, C5) supplies the diaphragm. Its cervical origin is explained by the fact that the septum transversum initially develops in the neck region before descending. * **Mnemonic for Diaphragm Openings:** **I Eat 10 Eggs At 12** (IVC at T8, Esophagus at T10, Aorta at T12).

Q: All are true about Wiskott-Aldrich syndrome except?

Large size platelets. **Explanation:** Wiskott-Aldrich Syndrome (WAS) is an **X-linked recessive** immunodeficiency caused by a mutation in the **WASP gene**, which leads to defective actin cytoskeleton reorganization in hematopoietic cells. **Why Option C is the correct answer (The "Except"):** In Wiskott-Aldrich Syndrome, platelets are characteristically **small in size** (microthrombocytopenia) and reduced in number. This is a high-yield diagnostic feature, as it is one of the few conditions where small platelets are seen. Large platelets (Option C) are seen in conditions like Bernard-Soulier Syndrome or ITP, making this statement false regarding WAS. **Analysis of other options:** * **Option A (Bloody diarrhea):** Due to profound thrombocytopenia and platelet dysfunction, infants often present with petechiae, purpura, and bloody diarrhea shortly after birth. * **Option B (Immunoglobulin profile):** The classic pattern is **low IgM**, normal to high IgG, and **elevated IgA and IgE**. This reflects the progressive decline in humoral and cellular immunity. * **Option D (Atopic dermatitis):** Severe, refractory eczema is a hallmark clinical feature of the classic triad. **NEET-PG High-Yield Pearls:** * **The Classic Triad:** (1) Thrombocytopenia/Bleeding, (2) Eczema, (3) Recurrent infections (due to T-cell and B-cell deficiency). * **Genetics:** X-linked recessive; WASP gene maps to **Xp11.22**. * **Complications:** Increased risk of **Non-Hodgkin Lymphoma** (especially EBV-related) and autoimmune hemolytic anemia. * **Treatment:** Bone marrow transplant is the definitive curative treatment.

Q: What is the term for words with a double meaning?

Puns. ### Explanation **Correct Answer: A. Puns** In the context of neuroanatomy and behavioral sciences, **puns** refer to the use of words that have a double meaning or sound similar but have different interpretations. In clinical neurology and psychiatry, an excessive tendency to make puns, jokes, or inappropriate facetiousness is known as **Witzelsucht**. This clinical sign is highly characteristic of a lesion in the **orbitofrontal cortex** (frontal lobe). **Analysis of Incorrect Options:** * **B. Echolalia:** This is the involuntary, parrot-like repetition of words or phrases spoken by another person. It is commonly seen in Autism Spectrum Disorder, Tourette syndrome, and certain types of aphasia (e.g., Transcortical Sensory Aphasia). * **C. Echopraxia:** This refers to the involuntary imitation of another person’s movements or actions. Like echolalia, it is often associated with frontal lobe damage or catatonic schizophrenia. * **D. Clang Association:** This is a thought disorder where word choice is governed by the sound of the words (rhyming or punning) rather than their logical meaning. While it involves sounds, it is specifically a feature of the "flight of ideas" seen in **Mania**. **Clinical Pearls for NEET-PG:** * **Frontal Lobe Syndrome:** Characterized by disinhibition, personality changes, and **Witzelsucht** (pathological punning). * **Orbitofrontal Cortex:** Responsible for impulse control and social behavior; damage leads to the "disinhibited" subtype of frontal lobe syndrome. * **High-Yield Distinction:** While "puns" are the words themselves, the *compulsion* to tell them is Witzelsucht. If a patient rhymes words without logical connection, think **Clang Association** (Mania).

Q: What is the largest organelle in a eukaryotic cell?

Nucleus. In eukaryotic cells, the **nucleus** is the largest and most prominent organelle. It typically occupies about 10% of the total cell volume and measures approximately 5–10 μm in diameter. It serves as the control center of the cell, housing the genetic material (DNA) and coordinating activities such as growth, metabolism, and protein synthesis [1]. **Analysis of Incorrect Options:** * **A. Endoplasmic Reticulum (ER):** While the ER is the largest membrane system in the cell and can occupy a significant portion of the cytoplasm, it is a network of tubules and sacs rather than a single discrete organelle larger than the nucleus [2]. * **C. Cytoskeleton:** This is a complex network of protein filaments (microtubules, microfilaments, and intermediate filaments). It provides structural framework but is categorized as a structural component rather than a membrane-bound organelle. * **D. Golgi Body:** The Golgi apparatus is involved in modifying and packaging proteins. While essential, it is significantly smaller in volume compared to the nucleus and the ER. **High-Yield Facts for NEET-PG:** * **Largest Organelle:** Nucleus. * **Second Largest Organelle:** Mitochondria (in animal cells) or Chloroplasts (in plant cells) [1]. * **Smallest Organelle:** Ribosome (non-membrane bound; approx. 20-30 nm). * **Clinical Correlation:** In cytology (e.g., Pap smears or malignancy grading), the **Nucleus-to-Cytoplasm (N:C) ratio** is a critical diagnostic marker. An increased N:C ratio is a hallmark of dysplastic and malignant cells. * **RBC Exception:** Mature human erythrocytes (RBCs) lack a nucleus to maximize space for hemoglobin, making them an important exception in human anatomy [3].

Q: The visual pathway consists of all of the following except:

Inferior colliculus. The visual pathway is the anatomical route that transmits visual information from the retina to the primary visual cortex. The correct answer is **Inferior colliculus** because it is a relay center for the **auditory pathway**, not the visual pathway [1]. **Why Inferior Colliculus is the correct answer:** The inferior colliculus (IC) is located in the midbrain and receives auditory input from the lateral lemniscus, relaying it to the Medial Geniculate Body (MGB) [1]. In contrast, the **Superior Colliculus** is the structure involved in visual reflexes (like tracking moving objects) [2]. **Analysis of other options:** * **Optic tract (A):** These are the nerve fibers that extend from the optic chiasm to the Lateral Geniculate Body (LGB). They carry information from the contralateral visual field [3]. * **Geniculocalcarine tract (B):** Also known as **optic radiations**, these fibers travel from the LGB to the primary visual cortex (Area 17) in the occipital lobe [3], [4]. * **Lateral geniculate body (D):** This is the primary relay nucleus in the thalamus for the visual system. It receives input from the optic tract and projects to the visual cortex [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic:** **M**GB is for **M**usic (Hearing); **L**GB is for **L**ight (Vision). * **Meyer’s Loop:** The part of the optic radiation that loops into the temporal lobe; a lesion here causes "Pie in the sky" (Superior Quadrantanopia). * **Baum’s Loop:** The part of the optic radiation in the parietal lobe; a lesion here causes "Pie on the floor" (Inferior Quadrantanopia). * **Macular Sparing:** Often seen in PCA (Posterior Cerebral Artery) strokes due to collateral supply from the Middle Cerebral Artery to the occipital pole [4].

Question 1

Juxtaglomerular cells are part of which structure?

Accepted Answer

Smooth muscle cells of the afferent arteriole

Answer

Macula densa

Answer

Smooth muscle cells of the efferent arteriole

Answer

Islets of epithelial cells

Question 2

Fournier's gangrene is typically seen in which of the following locations?

Accepted Answer

Scrotal skin

Answer

Nose

Answer

Oral cavity

Answer

All are true

Question 3

The diaphragm is formed from the following components, except:

Accepted Answer

Splanchnopleuric mesoderm

Answer

Septum transversum

Answer

Ventral and dorsal mesentery of the esophagus

Answer

Mesoderm of the body wall

Question 4

What is a characteristic feature of a superantigen?

Accepted Answer

Binds to the beta chain of the T cell receptor (TCR) and MHC class II molecules on antigen-presenting cells, stimulating T cell activation.

Answer

Binds to B7 and CD8 co-stimulatory molecules.

Answer

Binds to CD4 molecules, causing T cell activation.

Answer

Is presented by macrophages to a larger than normal number of T helper CD4 lymphocytes.

Question 5

All are true about Wiskott-Aldrich syndrome except?

Accepted Answer

Large size platelets

Answer

Bloody diarrhea during infancy

Answer

Low IgM and elevated IgA and IgE

Answer

Atopic dermatitis

Question 6

What stains are used for amyloid detection?

Accepted Answer

Thioflavin

Answer

Congo red

Answer

Eosin

Answer

Auramine

Question 7

What is the term for words with a double meaning?

Accepted Answer

Puns

Answer

Echolalia

Answer

Echopraxia

Answer

Clang association

Question 8

What is the largest organelle in a eukaryotic cell?

Accepted Answer

Nucleus

Answer

Endoplasmic reticulum

Answer

Cytoskeleton

Answer

Golgi body

Question 9

The visual pathway consists of all of the following except:

Accepted Answer

Inferior colliculus

Answer

Optic tract

Answer

Geniculocalcarine tract

Answer

Lateral geniculate body

Question 10

Which of the following is NOT a neuronal structure?

Accepted Answer

Common peroneal nerve

Answer

Optic nerve

Answer

SA node

Answer

Sciatic nerve

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?