Neuroanatomy Practice Questions

Q: Bipolar cells are seen in which of the following structures?

Retina. **Explanation:** Bipolar neurons are specialized sensory neurons characterized by having two processes extending from the cell body: one axon and one dendrite [2]. In the human body, these are rare and are primarily associated with the **special senses** (vision, hearing, and equilibrium) [3]. **Why Option B is Correct:** In the **retina**, bipolar cells serve as the critical intermediate layer of the visual pathway [1]. They receive input from photoreceptors (rods and cones) and transmit these signals to the ganglion cells, whose axons form the optic nerve. This is the most classic example of bipolar neurons cited in medical exams [1]. **Analysis of Incorrect Options:** * **A & D (Sympathetic and Parasympathetic Ganglia):** These autonomic ganglia contain **multipolar neurons**, which have one axon and multiple dendrites. This is the most common neuronal type in the nervous system [2]. * **C (Cochlear Ganglion):** While the cochlear (spiral) and vestibular ganglia are often associated with bipolar cells in early development, in adults, they are specifically classified as **bipolar neurons** as well. However, in the context of standard NEET-PG questions where only one option must be chosen, the **Retina** is the primary and most definitive textbook answer. *Note: If this were a "Multiple Correct" type question, both B and C would be technically accurate.* **High-Yield Clinical Pearls for NEET-PG:** * **Unipolar neurons:** Found primarily in the mesencephalic nucleus of the Trigeminal nerve (CN V). * **Pseudounipolar neurons:** Found in the **Dorsal Root Ganglia (DRG)** and sensory ganglia of cranial nerves [2]. * **Locations of Bipolar Neurons (The "Big Three"):** 1. Retina (Vision) [1], 2. Olfactory epithelium (Smell) [3], 3. Vestibulocochlear nerve ganglia (Hearing/Balance). * **Purkinje Cells:** These are large multipolar neurons found specifically in the cerebellum [2].

Q: What is the effect of Interleukin-1 (IL-1)?

All the above. **Explanation:** Interleukin-1 (IL-1) is a pivotal pro-inflammatory cytokine primarily produced by activated macrophages. It serves as a key mediator of the acute inflammatory response and tissue repair processes. **Why "All the above" is correct:** IL-1 exerts pleiotropic effects across various cell types to coordinate the body's response to injury or infection: * **Increased Leukocyte Adhesion:** IL-1 induces the expression of adhesion molecules (like E-selectin and ligands for integrins) on vascular endothelial cells [1]. This is a critical step in leukocyte recruitment, allowing white blood cells to roll, adhere, and migrate into the extravascular space [1]. * **Fibroblast Proliferation:** In the context of chronic inflammation and wound healing, IL-1 acts as a mitogen for fibroblasts [1]. It stimulates their growth to ensure the structural integrity of the healing tissue. * **Increased Collagen Synthesis:** IL-1 promotes the synthesis of collagen and other extracellular matrix components by fibroblasts, facilitating the formation of granulation tissue and eventual scarring (fibrosis) [1]. **Analysis of Options:** Since IL-1 simultaneously promotes the recruitment of immune cells (Option A) and initiates the proliferative phase of healing (Options B and C), all three physiological actions are characteristic of its function. **High-Yield Clinical Pearls for NEET-PG:** * **Endogenous Pyrogen:** IL-1 (along with TNF-α and IL-6) acts on the hypothalamus to induce fever by increasing prostaglandin (PGE2) synthesis [2]. * **Synergy:** IL-1 often works synergistically with **TNF-α**; both are major mediators of septic shock [2]. * **Acute Phase Response:** It stimulates the liver to produce acute-phase proteins (e.g., C-reactive protein). * **Bone Resorption:** In chronic inflammatory states (like Rheumatoid Arthritis), IL-1 promotes osteoclast activity, leading to bone resorption [1].

Q: What is the resting membrane potential of cardiac muscle?

-90 mV. ### Explanation **Correct Answer: A. -90 mV** The resting membrane potential (RMP) of a cardiac ventricular muscle fiber is approximately **-90 mV** [2]. This value is determined primarily by the high permeability of the resting membrane to potassium ions ($K^+$) relative to sodium ions ($Na^+$). The RMP is very close to the equilibrium potential for $K^+$ (calculated by the Nernst equation), as $K^+$ leaks out of the cell through "inward rectifier" $K^+$ channels [1]. This creates a significant electrical gradient, keeping the interior of the cell strongly negative. **Analysis of Incorrect Options:** * **B. -60 mV:** This is the approximate threshold potential for firing an action potential in the **Sinoatrial (SA) node**. The SA node does not have a "resting" potential; instead, it has a "pre-potential" or pacemaker potential that starts at -60 mV and drifts upward. * **C. -70 mV:** This is the typical RMP for **large myelinated nerve fibers**. While still negative, it is less negative than cardiac muscle because nerves have a slightly higher relative permeability to $Na^+$ at rest compared to cardiac myocytes. * **D. All of the above:** Incorrect, as RMP is a specific physiological constant for a given cell type. **High-Yield Clinical Pearls for NEET-PG:** * **SA Node RMP:** -55 to -60 mV (less negative due to "leaky" sodium channels). * **Skeletal Muscle RMP:** Similar to cardiac muscle, approximately -80 to -90 mV. * **Phase 4:** In cardiac muscle, Phase 4 of the action potential corresponds to the RMP. * **Hyperkalemia:** An increase in extracellular $K^+$ makes the RMP **less negative** (depolarized), which can lead to cardiac arrest in diastole [3].

Q: Defect in any of the following may result in renal agenesis except?

Failure of descent of nephrogenic tissue of lumbar area. Renal development depends on a complex reciprocal induction between two key embryological structures: the **Ureteric Bud** and the **Metanephric Blastema** (nephrogenic tissue). **Why Option D is the correct answer:** Renal agenesis is a failure of the kidney to form. The kidneys actually develop in the **sacral/pelvic region** and subsequently **ascend** to the lumbar area. A failure of descent is embryologically impossible; rather, a failure of *ascent* results in an **Ectopic Kidney** (often a Pelvic Kidney), not agenesis. Since the kidney has already formed but is simply in the wrong location, it is not considered agenesis. **Analysis of Incorrect Options:** * **A & C (Nephrogenic bud/Blastoma):** The metanephric blastema (nephrogenic tissue) forms the nephrons (excretory part). If this tissue is absent or defective, no kidney tissue can develop. * **B (Ureteric bud):** The ureteric bud (a diverticulum of the Wolffian duct) must penetrate the metanephric blastema to induce it to form the kidney [1]. If the ureteric bud fails to develop or reach the blastema, the result is **Renal Agenesis**. **NEET-PG High-Yield Pearls:** * **Reciprocal Induction:** Ureteric bud (forms collecting system: ureter, pelvis, calyces, collecting ducts) $\leftrightarrow$ Metanephric blastema (forms excretory system: Bowman’s capsule to DCT). * **Potter’s Sequence:** Bilateral renal agenesis leads to oligohydramnios, pulmonary hypoplasia, and characteristic flattened facies [2]. * **Unilateral Agenesis:** Often asymptomatic; usually associated with a single umbilical artery. * **Blood Supply:** As the kidney ascends, it receives new arterial branches from the aorta at higher levels; failure of lower vessels to degenerate results in **Accessory Renal Arteries**.

Q: The efferent fiber bundle of substantia nigra transmits dopamine to which area?

Corpus striatum. The **Substantia Nigra (SN)**, located in the midbrain, is a critical component of the basal ganglia circuitry [1]. It is divided into two parts: the *pars reticulata* and the *pars compacta*. ### Why Option B is Correct The **Substantia Nigra pars compacta (SNpc)** contains pigmented, dopaminergic neurons [1]. These neurons project their axons to the **Corpus Striatum** (which consists of the Caudate nucleus and Putamen) [1]. This pathway is known as the **Nigrostriatal pathway**. It plays a vital role in modulating the "Direct" and "Indirect" pathways of the basal ganglia to facilitate smooth, coordinated motor movement. ### Why Other Options are Incorrect * **A. Thalamus:** While the Substantia Nigra *pars reticulata* (SNpr) sends GABAergic (inhibitory) projections to the thalamus (Nigrothalamic tract) [1], these are not dopaminergic. * **C. Tegmentum of pons:** This area contains various cranial nerve nuclei and the reticular formation, but it is not the primary target for dopaminergic efferents from the SN. * **D. Tectum of midbrain:** The tectum (Superior and Inferior colliculi) is involved in visual and auditory reflexes, not the dopaminergic motor control circuit. ### Clinical Pearls for NEET-PG * **Parkinson’s Disease:** Caused by the degeneration of dopaminergic neurons in the SNpc [1]. This leads to a deficiency of dopamine in the striatum, resulting in the classic triad of tremors, rigidity, and bradykinesia. * **Histology:** On gross examination, the SN appears black due to **Neuromelanin** (a byproduct of dopamine synthesis). * **MPTP:** A neurotoxin that specifically destroys dopaminergic neurons in the SN, leading to irreversible Parkinsonian symptoms [1].

Q: Derivatives of the mesonephric duct are all except?

Appendix of testis. The **Mesonephric (Wolffian) duct** is the precursor for the male internal genital tract, developing under the influence of testosterone [1]. The **Paramesonephric (Müllerian) duct** is the precursor for the female internal genital tract [1]. ### **Explanation of the Correct Answer** **D. Appendix of testis:** This is the correct answer because it is a **vestigial remnant of the Paramesonephric (Müllerian) duct** in males. It is located at the upper pole of the testis. In females, the Paramesonephric duct forms the fallopian tubes, uterus, and upper vagina [2]. ### **Analysis of Incorrect Options** * **A. Epididymis:** The cranial part of the mesonephric duct becomes convoluted to form the duct of the epididymis. * **B. Ductus deferens:** The straight portion of the mesonephric duct distal to the epididymis develops thick muscular walls to become the vas deferens [1]. * **C. Ureter:** The **ureteric bud**, which gives rise to the ureter, renal pelvis, calyces, and collecting ducts, is a diverticulum that arises directly from the caudal end of the mesonephric duct. ### **High-Yield Clinical Pearls for NEET-PG** * **Mnemonic for Mesonephric derivatives (SEED):** **S**eminal vesicles, **E**pididymis, **E**jaculatory duct, **D**uctus deferens. (Note: The Prostate is NOT a Wolffian derivative; it arises from the urogenital sinus). * **Appendix of Epididymis:** Unlike the appendix of the testis, the appendix of the epididymis is a derivative of the **Mesonephric duct**. * **Prostatic Utricle:** This is the other male remnant of the Paramesonephric duct (homologous to the female uterus/vagina). * **Gartner’s Duct Cyst:** A clinical remnant of the mesonephric duct found in the lateral wall of the vagina in females.

Q: Which of the following is NOT a B-cell marker?

CD15. The identification of cell surface markers (Cluster of Differentiation or CD) is a high-yield topic in NEET-PG, particularly for differentiating lymphocyte lineages. **Why CD15 is the correct answer:** **CD15** is primarily a marker for **Granulocytes** (Neutrophils and Eosinophils) and is also expressed on **Reed-Sternberg cells** in Hodgkin Lymphoma (along with CD30). It is not expressed on B-cells. Therefore, it is the correct "NOT" option. **Why the other options are incorrect (B-cell markers):** * **CD19:** This is the most ubiquitous B-cell marker. It is expressed from the earliest stages of B-cell development (pro-B cell) until just before terminal differentiation into plasma cells. * **CD21:** Also known as Complement Receptor 2 (CR2). It is found on mature B-cells and serves as the receptor for the **Epstein-Barr Virus (EBV)**. * **CD24:** This is a glycoprotein expressed on the surface of B-lymphocytes from the pre-B to the mature B-cell stage. **High-Yield Clinical Pearls for NEET-PG:** * **Pan-B cell markers:** CD19, CD20, CD22. * **CD10:** Also known as **CALLA** (Common Acute Lymphoblastic Leukemia Antigen), found on pre-B cells. * **CD5:** Normally a T-cell marker, but its expression on B-cells is characteristic of **Chronic Lymphocytic Leukemia (CLL)** and **Mantle Cell Lymphoma**. * **CD15 & CD30:** The classic "duo" for identifying Reed-Sternberg cells in Hodgkin Lymphoma (except for the Lymphocyte Predominant type).

Q: Which statement is true about valves in the portal venous system?

The whole system is valveless. The portal venous system is a unique circulatory pathway that drains blood from the gastrointestinal tract and spleen to the liver. The defining anatomical feature of the portal vein and its tributaries (the superior mesenteric, inferior mesenteric, and splenic veins) is that they are **entirely valveless** [1]. **Why the correct answer is right:** In the human body, most systemic veins contain valves to prevent the backflow of blood against gravity. However, the portal system lacks these valves [1]. This absence is physiologically significant because it allows for the bidirectional flow of blood depending on pressure gradients. Under normal conditions, blood flows toward the liver (hepatopetal). In pathological states like cirrhosis, increased resistance in the liver causes pressure to rise (portal hypertension), and because there are no valves to stop it, blood flows backward (hepatofugal) toward porto-systemic watersheds. **Analysis of Incorrect Options:** * **Option A:** This describes arteries (SMA and Splenic artery), not veins. Furthermore, valves are a feature of veins, not the arterial system. * **Option B & D:** These are incorrect because the lack of valves is not localized; it is a characteristic of the entire system, from the small mesenteric tributaries to the main portal vein trunk and its intrahepatic branches. **High-Yield Clinical Pearls for NEET-PG:** * **Porto-systemic Anastomoses:** Because the system is valveless, portal hypertension leads to the opening of collateral channels at specific sites: Lower esophagus (Esophageal varices), Umbilicus (Caput medusae), and Rectum (Hemorrhoids). * **Direction of Flow:** Normal flow is **hepatopetal**; reversed flow in portal hypertension is **hepatofugal**. * **Formation:** The portal vein is formed behind the neck of the pancreas by the union of the Superior Mesenteric Vein and the Splenic Vein [1].

Question 1

Bipolar cells are seen in which of the following structures?

Accepted Answer

Retina

Answer

Sympathetic ganglion

Answer

Cochlear ganglion

Answer

Parasympathetic ganglion

Question 2

What is the effect of Interleukin-1 (IL-1)?

Accepted Answer

All the above

Answer

Increased leukocyte adhesion

Answer

Fibroblast proliferation

Answer

Increased collagen synthesis

Question 3

Which muscle will be spared in median nerve injury at the elbow?

Accepted Answer

Adductor pollicis longus

Answer

Pronator quadratus

Answer

Abductor pollicis brevis

Answer

Flexor pollicis longus

Question 4

What is the resting membrane potential of cardiac muscle?

Accepted Answer

-90 mV

Answer

-60 mV

Answer

-70 mV

Answer

All of the above

Question 5

Defect in any of the following may result in renal agenesis except?

Accepted Answer

Failure of descent of nephrogenic tissue of lumbar area

Answer

Nephrogenic bud

Answer

Ureteric bud

Answer

Blastoma of nephrogenic tissue

Question 6

The efferent fiber bundle of substantia nigra transmits dopamine to which area?

Accepted Answer

Corpus striatum

Answer

Thalamus

Answer

Tegmentum of pons

Answer

Tectum of midbrain

Question 7

Derivatives of the mesonephric duct are all except?

Accepted Answer

Appendix of testis

Answer

Epididymis

Answer

Ductus deferens

Answer

Ureter

Question 8

Which of the following structures attains adult size before puberty?

Accepted Answer

Ear ossicles

Answer

Maxilla

Answer

Mastoid process

Answer

Parietal bone

Question 9

Which of the following is NOT a B-cell marker?

Accepted Answer

CD15

Answer

CD19

Answer

CD21

Answer

CD24

Question 10

Which statement is true about valves in the portal venous system?

Accepted Answer

The whole system is valveless

Answer

Present at the junction of the superior mesenteric artery with the splenic artery

Answer

Within the portal vein only

Answer

In the intrahepatic portion of the portal vein

Neuroanatomy — MCQs

Neuroanatomy — MCQs

On this page

Practice by Chapter

Want unlimited practice?