Neuroanatomy Practice Questions

Q: Injury to the corpus striatum leads to which of the following motor disorders?

Chorea. The **Corpus Striatum** (comprising the Caudate Nucleus and Putamen) is the primary input station of the Basal Ganglia [1]. It plays a crucial role in regulating voluntary movement by inhibiting unwanted motor activity. **1. Why Chorea is the Correct Answer:** Chorea is characterized by brief, semi-directed, irregular, and involuntary movements. It is classically associated with lesions of the **Corpus Striatum** (specifically the Caudate Nucleus). In conditions like **Huntington’s Disease**, the degeneration of GABAergic neurons in the striatum leads to a loss of inhibitory control over the motor thalamus, resulting in the hyperkinetic movements seen in Chorea [1]. **2. Analysis of Incorrect Options:** * **Parkinsonism:** This is primarily caused by the degeneration of dopaminergic neurons in the **Substantia Nigra pars compacta (SNpc)**, leading to a deficiency of dopamine in the striatum [1]. * **Hemiballismus:** This involves violent, flinging movements of the limbs and is specifically caused by a lesion in the **Subthalamic Nucleus (STN)**. * **Athetosis:** This refers to slow, writhing, "worm-like" movements, typically associated with lesions in the **Globus Pallidus**. **Clinical Pearls for NEET-PG:** * **Caudate Nucleus + Putamen** = Neostriatum (Corpus Striatum) [2]. * **Putamen + Globus Pallidus** = Lentiform Nucleus. * **Wilson’s Disease** typically affects the Putamen (Lenticular degeneration). * **Sydenham’s Chorea** is a major criterion for Rheumatic Fever, caused by autoimmune damage to the basal ganglia.

Q: The transtubercular plane lies at which vertebral level?

L5. The **transtubercular plane** is a horizontal anatomical plane passing through the iliac tubercles on the iliac crest of the pelvis. It is located at the level of the **L5 vertebral body**. This plane is clinically significant as it marks the upper boundary of the hypogastric (pubic) and iliac (inguinal) regions in the nine-region classification of the abdomen. **Analysis of Options:** * **L1 (Incorrect):** This is the level of the **Transpyloric plane** (of Addison). It is a high-yield landmark passing through the pylorus of the stomach, the hila of the kidneys, and the beginning of the duodenum. * **L3 (Incorrect):** This is the level of the **Subcostal plane**, which joins the lowest points of the costal margins (10th costal cartilage). It is also the level of the inferior mesenteric artery origin. * **L5 (Correct):** The transtubercular plane passes through the tubercles of the iliac crest, corresponding to the L5 vertebra. It also roughly corresponds to the level where the **Inferior Vena Cava (IVC) is formed** by the union of the common iliac veins. * **S3 (Incorrect):** This level marks the beginning of the rectum and the end of the sigmoid colon. **NEET-PG High-Yield Pearls:** 1. **Supracristal Plane (L4):** Passes through the highest points of the iliac crests; used as a landmark for lumbar punctures. 2. **Umbilicus:** Usually located at the L3-L4 disc level. 3. **Aortic Bifurcation:** Occurs at the L4 level, just above the transtubercular plane. 4. **IVC Formation:** Occurs at the L5 level, coinciding with the transtubercular plane.

Q: What is mirabegron?

Beta 3 agonist. **Explanation:** **Mirabegron** is a potent and selective **Beta-3 ($\beta_3$) adrenergic receptor agonist**. In the context of neuroanatomy and autonomic pharmacology, $\beta_3$ receptors are primarily located on the **detrusor muscle** of the urinary bladder. Activation of these receptors stimulates adenylyl cyclase, increasing intracellular cAMP, which leads to detrusor muscle relaxation [1]. This increases bladder capacity and provides symptomatic relief for **Overactive Bladder (OAB)** without the dry mouth and constipation typically associated with anticholinergics. **Analysis of Incorrect Options:** * **Option A (Alpha-2 agonist):** These agents (e.g., Clonidine) act on presynaptic receptors in the CNS to decrease sympathetic outflow. They are used for hypertension or sedation, not bladder relaxation. * **Option C (Beta-1 agonist):** These receptors are primarily located in the heart. Agonists (e.g., Dobutamine) increase heart rate and contractility [1]. * **Option D (Beta-2 agonist):** These receptors are found in bronchial smooth muscle. Agonists (e.g., Salbutamol) are used for bronchodilation in asthma/COPD. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Use:** First-line alternative for Overactive Bladder (OAB) in patients who cannot tolerate antimuscarinics (like Oxybutynin). * **Side Effects:** The most significant side effect is **Hypertension**; it should be avoided in patients with severe uncontrolled high blood pressure. * **Mechanism:** It enhances the "filling/storage" phase of micturition by mimicking sympathetic stimulation of the detrusor.

Q: Taste fibres from the anterior two-thirds of the tongue are carried by which nerve?

Facial nerve. The tongue’s innervation is a high-yield topic for NEET-PG, requiring a clear distinction between general sensation and special sensation (taste). [1] ### **Explanation** The **Facial nerve (CN VII)** is responsible for carrying taste fibers from the **anterior two-thirds** of the tongue. Specifically, these fibers travel via the **chorda tympani** nerve (a branch of CN VII), which joins the lingual nerve to reach the tongue. The cell bodies for these taste fibers are located in the **geniculate ganglion**, and they ultimately synapse in the nucleus tractus solitarius (NTS) in the brainstem. [1] ### **Analysis of Incorrect Options** * **A. Trigeminal nerve (CN V):** The lingual nerve (a branch of the mandibular division, V3) carries **general sensation** (touch, pain, temperature) from the anterior two-thirds, not taste. * **C. Hypoglossal nerve (CN XII):** This is a purely motor nerve responsible for the movements of all intrinsic and extrinsic muscles of the tongue (except the palatoglossus). * **D. Glossopharyngeal nerve (CN IX):** This nerve carries **both** taste and general sensation from the **posterior one-third** of the tongue, including the vallate papillae. [1] ### **High-Yield Clinical Pearls** * **Vagus Nerve (CN X):** Carries taste and general sensation from the extreme posterior part of the tongue (epiglottic region) via the internal laryngeal nerve. [1] * **Nucleus Tractus Solitarius (NTS):** The "sensory nucleus of the viscera" where all taste fibers (VII, IX, X) terminate. * **Clinical Correlation:** Damage to the facial nerve proximal to the branching of the chorda tympani (as seen in Bell’s Palsy) results in **ageusia** (loss of taste) in the anterior two-thirds of the tongue.

Q: Which of the following is a branch of the third part of the subclavian artery?

Dorsal scapular artery. The subclavian artery is divided into three parts by the **scalenus anterior muscle**: the first part is medial, the second part is posterior, and the third part is lateral to the muscle. ### **Explanation of the Correct Answer** **B. Dorsal Scapular Artery:** This is the most common branch of the **third part** of the subclavian artery. It passes through the brachial plexus to supply the levator scapulae and rhomboid muscles. *Note:* In about 30% of individuals, it arises as a deep branch of the transverse cervical artery (from the thyrocervical trunk); however, for NEET-PG purposes, it is classically taught as the branch of the third part. ### **Analysis of Incorrect Options** * **A. Thyrocervical Trunk:** Arises from the **first part** of the subclavian artery. It further divides into the inferior thyroid, suprascapular, and transverse cervical arteries. * **C. Vertebral Artery:** Arises from the **first part** (superior aspect). it ascends through the foramina transversaria of the cervical vertebrae to enter the cranial cavity. * **D. Internal Thoracic Artery:** Arises from the **first part** (inferior aspect). It descends behind the costal cartilages to supply the anterior chest wall and breast. ### **High-Yield NEET-PG Pearls** * **Mnemonic for Branches:** * **1st Part:** **V**ertebral, **I**nternal thoracic, **T**hyrocervical trunk (**VIT**). * **2nd Part:** **C**ostocervical trunk (**C**). * **3rd Part:** **D**orsal scapular artery (**D**). * **The Second Part:** Usually gives off only the **Costocervical trunk** (which divides into the superior intercostal and deep cervical arteries). * **Clinical Correlation:** The third part of the subclavian artery is the most superficial and can be compressed against the first rib to control bleeding in the upper limb.

Q: Section 174 of the Criminal Procedure Code deals with which type of inquest?

Police inquest. Explanation: In India, an **inquest** is a legal inquiry into the cause of death in cases that are sudden, suspicious, or unnatural. **Correct Option: A. Police Inquest** Under **Section 174 of the Criminal Procedure Code (CrPC)**, a police officer (usually the Station House Officer) conducts an investigation to determine the apparent cause of death. They prepare a report known as the **Panchnama**, which is signed by two or more respectable witnesses (Panchas). This is the most common type of inquest in India. **Incorrect Options:** * **B. Magistrate Inquest:** This is conducted under **Section 176 CrPC**. It is mandatory in specific high-risk scenarios such as custodial deaths, deaths in police firing, dowry deaths (within 7 years of marriage), or exhumations. It is superior to a police inquest. * **C. Coroner’s Inquest:** This system was abolished in India (previously active in Mumbai and Kolkata). It is currently practiced in countries like the UK and USA, where a specialized official (Coroner) investigates the death. * **D. Summons:** This is not a type of inquest; it is a legal document issued by a court ordering a person to appear as a witness or to produce documents. **High-Yield Clinical Pearls for NEET-PG:** * **Section 174 CrPC:** Police Inquest (Most common). * **Section 176 CrPC:** Magistrate Inquest (Custodial deaths/Dowry deaths). * **Section 175 CrPC:** Empowers the police to summon witnesses for the inquest. * **Medical Examiner System:** Considered the best system of inquest (practiced in parts of the USA), but not currently used in India.

Q: What is the mechanism of action of pralidoxime?

Deactivation of acetylcholinesterase enzyme. ### Explanation **Mechanism of Action: The Correct Answer** Pralidoxime (2-PAM) is a **cholinesterase reactivator** [1]. In organophosphate (OP) poisoning, the OP compound binds to the anionic site of the acetylcholinesterase (AChE) enzyme, phosphorylating it and rendering it inactive. Pralidoxime has a high affinity for the phosphate group; it binds to the enzyme-inhibitor complex, removes the phosphate group, and restores the enzyme's ability to degrade acetylcholine [1]. This process is known as **deactivation of the phosphorylated enzyme** (reactivation of the functional enzyme). **Analysis of Incorrect Options** * **Option A:** Pralidoxime does not stimulate receptors; its effect is indirect by restoring the enzyme that controls neurotransmitter levels. * **Option B:** This describes the effect of Organophosphates or Carbamates themselves, which lead to a cholinergic crisis [2]. Pralidoxime does the opposite. * **Option C:** This is the mechanism of **Atropine**, which competitively blocks muscarinic receptors to manage symptoms but does not fix the underlying enzyme inhibition. **NEET-PG High-Yield Pearls** * **The "Aging" Phenomenon:** Pralidoxime must be administered early [1]. Once the enzyme-OP bond "ages" (dealkylation), the bond becomes permanent, and oximes can no longer reactivate the enzyme [1]. * **Blood-Brain Barrier:** Pralidoxime is a quaternary ammonium compound and **does not cross the BBB**; therefore, it does not reverse central CNS symptoms (unlike Atropine) [1]. * **Specific Use:** It is effective in Organophosphate poisoning but is generally **not recommended for Carbamate poisoning** (as the carbamate-enzyme bond is reversible and oximes may worsen the inhibition). * **The "Double Therapy":** Management of OP poisoning always requires Atropine (to treat symptoms) + Pralidoxime (to restore enzyme function) [1].

Q: Fanconi Bickel syndrome is associated with which of the following?

GLUT 2. **Explanation:** **Fanconi-Bickel Syndrome (FBS)** is a rare autosomal recessive disorder of carbohydrate metabolism caused by a mutation in the **SLC2A2 gene**, which encodes the **GLUT 2** transporter. **Why GLUT 2 is the Correct Answer:** GLUT 2 is a high-capacity, low-affinity glucose transporter found primarily in the **liver, pancreas (beta cells), intestines, and proximal renal tubules** [1]. In FBS, the deficiency of GLUT 2 leads to: 1. **Impaired Glucose Export:** Glucose cannot leave the liver or kidneys, leading to glycogen accumulation (Hepatorenal Glycogenosis). 2. **Proximal Renal Tubular Dysfunction:** Failure to reabsorb glucose, amino acids, and phosphates, resulting in Fanconi syndrome (glycosuria, phosphaturia, and aminoaciduria) [1]. **Analysis of Incorrect Options:** * **GLUT 1:** Found in RBCs and the Blood-Brain Barrier [1]. Deficiency leads to encephalopathy and seizures (De Vivo disease). * **GLUT 3:** Primarily found in neurons (high affinity) [1]. It ensures glucose uptake in the brain even during hypoglycemia. * **GLUT 4:** The only **insulin-dependent** transporter, found in skeletal muscle and adipose tissue [1]. It is sequestered intracellularly and translocates to the membrane in response to insulin. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Triad of FBS:** Hepatomegaly (due to glycogen storage), Vitamin D-resistant rickets (due to phosphate loss), and fasting hypoglycemia with postprandial hyperglycemia. * **GLUT 2 Function:** Acts as a "glucose sensor" in pancreatic beta cells for insulin secretion [1]. * **SGLT vs. GLUT:** Remember that SGLT (1 & 2) are active transporters (sodium-dependent), while GLUTs are facilitated diffusion transporters [1].

Question 1

Injury to the corpus striatum leads to which of the following motor disorders?

Accepted Answer

Chorea

Answer

Parkinsonism

Answer

Hemiballismus

Answer

Athetosis

Question 2

The transtubercular plane lies at which vertebral level?

Accepted Answer

L5

Answer

L1

Answer

L3

Answer

S3

Question 3

What is mirabegron?

Accepted Answer

Beta 3 agonist

Answer

Alpha 2 agonist

Answer

Beta 1 agonist

Answer

Beta 2 agonist

Question 4

Taste fibres from the anterior two-thirds of the tongue are carried by which nerve?

Accepted Answer

Facial nerve

Answer

Trigeminal nerve

Answer

Hypoglossal nerve

Answer

Glossopharyngeal nerve

Question 5

Which of the following is a branch of the third part of the subclavian artery?

Accepted Answer

Dorsal scapular artery

Answer

Thyrocervical trunk

Answer

Vertebral artery

Answer

Internal thoracic artery

Question 6

A 75-year-old coal miner complains of progressive loss of vision. Visual field examination shows visual loss in the upper right quadrant in both visual fields. The lesion would most likely be in which location?

Accepted Answer

Left temporal lobe

Answer

Left cuneus

Answer

Right angular gyrus

Answer

Right lingual gyrus

Question 7

Section 174 of the Criminal Procedure Code deals with which type of inquest?

Accepted Answer

Police inquest

Answer

Magistrate inquest

Answer

Coroner's inquest

Answer

Summons

Question 8

All of the following are true about an expert witness except?

Accepted Answer

Responsibility is less.

Answer

A skilled person in a particular field.

Answer

Drawing inferences from observation.

Answer

Can claim conduct money.

Question 9

What is the mechanism of action of pralidoxime?

Accepted Answer

Deactivation of acetylcholinesterase enzyme

Answer

Stimulation of acetylcholine receptors

Answer

Inhibition of acetylcholine breakdown

Answer

Blockade of acetylcholine receptors

Question 10

Fanconi Bickel syndrome is associated with which of the following?

Accepted Answer

GLUT 2

Answer

GLUT 1

Answer

GLUT 3

Answer

GLUT 4

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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