Nervous Tissue — MCQs
A 35-year-old female experiences a tingling sensation in her arm after watching TV for long hours with her hands under her head. Which type of nerve fibers is most likely to be affected due to this position?
Multiple sclerosis is characterized by all EXCEPT -
All the following nerves are involved in entrapment neuropathy except -
Match the following: A) Glossopharyngeal nerve B) Spinal accessory nerve C) Facial nerve D) Mandibular nerve 1) Shrugging of shoulder 2) Touch sensation from the posterior one-third of the tongue 3) Chewing 4) Taste from the anterior two-thirds of the tongue
What is the characteristic feature of neuropraxia?
A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
Which of the following is NOT a glial cell?
Which of the following cell types is neuroectodermal in origin?
Oncocytes are found in all of the following organs, except:
What is the cell lining of the common bile duct?
Nervous Tissue Indian Medical PG Practice Questions and MCQs
Question 1: A 35-year-old female experiences a tingling sensation in her arm after watching TV for long hours with her hands under her head. Which type of nerve fibers is most likely to be affected due to this position?
- A. B - fibers (autonomic)
- B. C - fibers (pain and temperature)
- C. Sympathetic nerve fibers
- D. A-beta (Aβ) sensory nerve fibers (Correct Answer)
Explanation: ***A-beta (Aβ) sensory nerve fibers*** - The tingling sensation (paresthesia) described is a classic symptom of **A-beta fiber compression**. - **A-beta fibers** are large, myelinated sensory fibers that transmit light touch, pressure, vibration, and proprioception. - These fibers are **most susceptible to mechanical compression** due to their position and structure. - Positioning the hands under the head for extended periods compresses superficial nerves, causing temporary A-beta fiber dysfunction, which manifests as the characteristic "pins and needles" sensation. *B-fibers (autonomic)* - **B-fibers** are preganglionic autonomic fibers that mediate visceral functions, such as organ control and glandular secretions. - Compression of these fibers would lead to symptoms related to autonomic dysfunction (e.g., changes in sweating, blood pressure), not a tingling sensation in the arm. *C-fibers (pain and temperature)* - **C-fibers** are unmyelinated fibers that transmit slow, dull, aching pain and contribute to temperature sensation. - They are **less susceptible to compression** than larger myelinated fibers. - The primary sensation described (tingling/paresthesia) is characteristic of large myelinated fiber (A-beta) dysfunction, not C-fiber involvement. *Sympathetic nerve fibers* - **Sympathetic nerve fibers** regulate involuntary functions like heart rate, blood pressure, and sweating. - Their compression would cause symptoms such as changes in skin temperature, altered sweating, or blood vessel constriction (Horner's syndrome if severe), not a tingling sensation.
Question 2: Multiple sclerosis is characterized by all EXCEPT -
- A. Demyelination
- B. Grey-tan plaques in the white matter
- C. Increased protein concentration in CSF
- D. Oligodendrocytes (Correct Answer)
Explanation: ***Oligodendrocytes*** - Multiple sclerosis is characterized by the **loss or destruction** of oligodendrocytes, not by their presence [1]. - The mere presence of oligodendrocytes is normal in CNS tissue and does not characterize MS. - What characterizes MS is **oligodendrocyte damage** leading to demyelination, but oligodendrocytes themselves as a cell type are not a characteristic feature of the disease [1]. - This makes "Oligodendrocytes" alone the correct answer to this EXCEPT question. *Demyelination* - **Demyelination** is the hallmark pathological feature of multiple sclerosis [2], [3]. - Progressive destruction of myelin sheaths disrupts nerve impulse conduction. - This is a defining characteristic of MS pathology. *Grey-tan plaques in the white matter* - Characteristic **plaques** (sclerotic lesions) in CNS white matter are pathognomonic for MS [2]. - These lesions appear **grey-tan** on gross examination at autopsy [2]. - Represent areas of chronic demyelination, inflammation, and gliosis [3]. - The term "multiple sclerosis" literally refers to these multiple sclerotic plaques [2]. *Increased protein concentration in CSF* - CSF analysis in MS typically shows **increased protein**, particularly **immunoglobulins (IgG)**. - **Oligoclonal bands** on CSF electrophoresis are found in ~95% of MS patients. - Reflects intrathecal immune activation and inflammation within the CNS. - This is a characteristic laboratory finding in MS. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1255-1256. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1286-1287. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 713-715.
Question 3: All the following nerves are involved in entrapment neuropathy except -
- A. Median nerve
- B. Femoral nerve (Correct Answer)
- C. Ulnar nerve
- D. Lateral cutaneous nerve of thigh
Explanation: ***Femoral nerve*** - While the femoral nerve can be injured, it is **uncommonly involved** in entrapment neuropathy compared to other nerves. - Entrapment of the femoral nerve is rare and typically occurs in the **pelvis** or **inguinal region**, often due to trauma or mass effect. *Median nerve* - The median nerve is classically involved in **carpal tunnel syndrome**, where it is compressed at the wrist [1], [2]. - Symptoms include pain, numbness, and tingling in the thumb, index, middle, and radial half of the ring finger [1]. *Ulnar nerve* - The ulnar nerve is commonly entrapped at the **cubital tunnel** (elbow) or the **Guyon's canal** (wrist) [1]. - This leads to symptoms such as numbness and weakness in the small finger and ulnar half of the ring finger [1]. *Lateral cutaneous nerve of thigh* - This nerve is frequently entrapped as it passes under the **inguinal ligament**, causing **meralgia paresthetica**. - Symptoms include burning pain and numbness on the lateral aspect of the thigh.
Question 4: Match the following: A) Glossopharyngeal nerve B) Spinal accessory nerve C) Facial nerve D) Mandibular nerve 1) Shrugging of shoulder 2) Touch sensation from the posterior one-third of the tongue 3) Chewing 4) Taste from the anterior two-thirds of the tongue
- A. A-3 , B-1 , C-4 , D-2
- B. A-2 , B-3 , C-4 , D-1
- C. A-4 , B-1 , C-2 , D-3
- D. A-2 , B-1 , C-4 , D-3 (Correct Answer)
Explanation: ***A-2 , B-1 , C-4 , D-3*** - **A) Glossopharyngeal nerve (CN IX)** is responsible for **general sensation and taste from the posterior one-third of the tongue** [1]. (2). - **B) Spinal Accessory nerve (CN XI)** innervates the **sternocleidomastoid** and **trapezius muscles**, which are involved in shrugging the shoulders (1). - **C) Facial nerve (CN VII)** carries **taste sensation from the anterior two-thirds of the tongue** [1] (4) via the chorda tympani. - **D) Mandibular nerve (V3)**, a branch of the trigeminal nerve, innervates the muscles of mastication, enabling **chewing** (3). *A-3 , B-1 , C-4 , D-2* - This option incorrectly associates the **glossopharyngeal nerve** with chewing, which is a function of the mandibular nerve (V3). - It also incorrectly associates the **mandibular nerve** with touch sensation from the posterior one-third of the tongue, which is a function of the glossopharyngeal nerve [1]. *A-2 , B-3 , C-4 , D-1* - This option incorrectly links the **spinal accessory nerve** with chewing; this nerve primarily controls shoulder and neck movements. - It also incorrectly assigns shrugging of the shoulder to the **mandibular nerve** instead of the spinal accessory nerve. *A-4 , B-1 , C-2 , D-3* - This choice incorrectly attributes **taste from the anterior two-thirds of the tongue** to the glossopharyngeal nerve, which supplies the posterior one-third [1]. - It also incorrectly links **touch sensation from the posterior one-third of the tongue** to the facial nerve, which is involved in taste from the anterior two-thirds [1].
Question 5: What is the characteristic feature of neuropraxia?
- A. Damage to the endoneurium
- B. Damage to the epineurium
- C. No structural damage to the nerve (Correct Answer)
- D. Damage to the axon
Explanation: ***No structural damage to the nerve*** - **Neuropraxia** is the mildest form of nerve injury, characterized by a **temporary block in nerve conduction** without structural damage to the axon or surrounding connective tissues. - This typically results in **temporary sensory and/or motor deficits** that fully resolve within weeks to months. *Damage to the endoneurium* - Damage to the **endoneurium** would indicate a more severe injury, such as **axonotmesis**, where the axon is damaged but the connective tissue sheaths are preserved. - This level of injury suggests that wallerian degeneration would occur distal to the lesion, leading to **slower and incomplete recovery**. *Damage to the epineurium* - Damage to the **epineurium**, along with the endoneurium and perineurium, signifies **neurotmesis**, the most severe nerve injury. - This involves a **complete transection of the nerve**, requiring surgical intervention for any chance of functional recovery. *Damage to the axon* - Damage to the **axon** itself, often alongside preserved connective tissues, is characteristic of **axonotmesis**. - While recovery is possible through axonal regeneration, it is **slower and less complete** than in neuropraxia.
Question 6: A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?
- A. Grade I (Mild claudication)
- B. Grade II (Moderate claudication) (Correct Answer)
- C. Grade III (Severe claudication)
- D. Grade IV (Ischemic rest pain)
Explanation: ***Grade II (Moderate claudication)*** - **Grade II claudication** is characterized by **intermittent claudication** where the patient experiences pain while walking but can **continue walking with effort**. - This level of claudication reflects a moderate degree of peripheral arterial disease, where blood flow is sufficiently compromised to cause pain with exertion but not severe enough to force immediate cessation of activity. - The patient in this scenario can continue ambulation despite discomfort, which is the defining feature of this grade. *Grade I (Mild claudication)* - **Grade I claudication** involves discomfort or pain that the patient can **tolerate without significantly altering their gait or pace**. - In this stage, the pain is minimal, and the patient may perceive it as a dull ache or mild fatigue rather than true pain. - Walking can continue without significant effort or limitation. *Grade III (Severe claudication)* - **Grade III claudication** is marked by pain that is **severe enough to stop the patient from walking within a short distance** (typically less than 200 meters). - The pain forces the patient to rest and recover before they can resume walking. - This represents significant functional limitation in daily activities. *Grade IV (Ischemic rest pain)* - **Grade IV**, also known as **critical limb ischemia**, involves **pain even at rest**, especially in the feet or toes, often worsening at night when the limb is elevated. - This stage indicates severe arterial obstruction and is frequently associated with **ulcers, non-healing wounds, or gangrene**. - This represents advanced peripheral arterial disease requiring urgent intervention. **Note:** This grading system is a simplified clinical classification. The standard medical classifications for peripheral arterial disease are the **Fontaine classification** (Stages I-IV) and **Rutherford classification** (Categories 0-6).
Question 7: Which of the following is NOT a glial cell?
- A. Oligodendrocytes
- B. Neurons (Correct Answer)
- C. Microglia
- D. Astrocytes
Explanation: ***Neurons*** - **Neurons** are the primary cells responsible for transmitting electrical and chemical signals throughout the nervous system [3]. - They are distinctly different from glial cells, which primarily provide **support and protection** to neurons [1]. *Oligodendrocytes* - **Oligodendrocytes** are a type of glial cell found in the **central nervous system** (CNS) [1]. - Their main function is to produce **myelin sheaths** that insulate axons, enhancing the speed of nerve impulse transmission [2]. *Microglia* - **Microglia** are the resident **immune cells** of the central nervous system, acting as its primary form of **active immune defense** [1]. - They scavenge for plaques, damaged neurons, and infectious agents, playing a critical role in neuroinflammation and tissue repair [2]. *Astrocytes* - **Astrocytes** are star-shaped glial cells found in the **brain and spinal cord** [1]. - They perform numerous functions, including providing **nutritional support**, maintaining the **blood-brain barrier**, and regulating the **extracellular environment** by controlling ion concentrations.
Question 8: Which of the following cell types is neuroectodermal in origin?
- A. Smooth muscle cells (Correct Answer)
- B. Skeletal muscle cells
- C. Endothelial cells
- D. Cardiac muscle cells
Explanation: ***Smooth muscle cells*** - This is the **correct answer** based on a **specific exception**: smooth muscle cells of the **iris dilator and sphincter muscles** and the **ciliary muscle** in the eye are derived from **neuroectoderm** (specifically from the **optic cup**, an outgrowth of the neural tube). - **Important note:** The vast majority of smooth muscle in the body is of **mesodermal origin** (e.g., in blood vessels, GI tract, respiratory tract). This question tests knowledge of this **notable embryological exception**. - In the context of the given options, this is the only cell type with any neuroectodermal component. *Skeletal muscle cells* - Skeletal muscle cells are entirely derived from the **paraxial mesoderm**, specifically from **somites** (myotome portion). - They form the voluntary muscles of the body and are **never** of neuroectodermal origin. *Endothelial cells* - Endothelial cells lining blood vessels and lymphatic vessels are derived from the **mesoderm** (specifically from **angioblasts**). - They are part of the cardiovascular system and are **entirely mesodermal** in origin. *Cardiac muscle cells* - Cardiac muscle cells are derived from the **splanchnic mesoderm** (lateral plate mesoderm). - The heart musculature is **entirely mesodermal** with no neuroectodermal contribution. **Clinical Pearl:** Classic neuroectodermal derivatives include neurons, glial cells (astrocytes, oligodendrocytes), ependymal cells, and neural crest derivatives (Schwann cells, melanocytes, chromaffin cells). The smooth muscle of the iris represents an important exception to the general rule that smooth muscle is mesodermal.
Question 9: Oncocytes are found in all of the following organs, except:
- A. Thyroid
- B. Kidneys
- C. Pituitary
- D. Pineal body (Correct Answer)
Explanation: **Explanation:** **Oncocytes** (also known as oxyphil cells or Askanazy cells) are large, polygonal epithelial cells characterized by an abundant, granular, eosinophilic cytoplasm. This distinct appearance is due to the presence of a massive number of **mitochondria**. 1. **Why Pineal Body is the correct answer:** The pineal body consists primarily of pinealocytes and glial cells. It does not contain oncocytes. While it may contain "brain sand" (corpora arenacea) with age, oncocytic transformation is not a feature of this neuroendocrine gland. 2. **Analysis of Incorrect Options:** * **Thyroid (Option A):** Oncocytes in the thyroid are known as **Hürthle cells**. They are commonly seen in Hashimoto’s thyroiditis and Hürthle cell tumors. * **Kidneys (Option B):** Oncocytes are found in the renal tubules. A benign tumor arising from these cells is called a **Renal Oncocytoma**, which typically shows a characteristic "central stellate scar" on imaging. * **Pituitary (Option C):** Oncocytic changes can occur in the anterior pituitary gland, particularly in older individuals or within specific adenomas (Oncocytomas). **High-Yield Clinical Pearls for NEET-PG:** * **Salivary Glands:** The **Warthin’s tumor** (Adenolymphoma) of the parotid gland is classically composed of a double layer of oncocytic epithelium. * **Parathyroid:** Oxyphil cells appear after puberty and increase with age; they are larger and darker than chief cells but their exact function remains unknown [1]. They are characterized by being tightly packed with mitochondria [1]. * **Staining:** Due to high mitochondrial content, oncocytes stain strongly with **phosphotungstic acid-hematoxylin (PTAH)**. * **Mnemonic:** Oncocytes are common in **"T-P-K-S"** (Thyroid, Parathyroid/Pituitary, Kidney, Salivary glands).
Question 10: What is the cell lining of the common bile duct?
- A. Stratified columnar
- B. Stratified squamous
- C. Simple cuboidal
- D. Simple columnar (Correct Answer)
Explanation: ### Explanation The correct answer is **D. Simple columnar**. **1. Why Simple Columnar is Correct:** The entire extrahepatic biliary tree, including the hepatic ducts, cystic duct, and the **common bile duct (CBD)**, is lined by a **simple columnar epithelium**. These cells, often called cholangiocytes, are specialized for the transport of water and electrolytes, helping to modify the bile as it flows toward the duodenum. The tall, columnar shape provides a protective barrier against the detergent properties of bile while allowing for active secretion and absorption. **2. Analysis of Incorrect Options:** * **A. Stratified columnar:** This is a rare epithelium found only in specific transition zones (e.g., parts of the male urethra or conjunctiva). It is not found in the biliary system. * **B. Stratified squamous:** This epithelium is designed for protection against mechanical friction (e.g., esophagus, skin). If found in the CBD, it would represent **squamous metaplasia**, usually due to chronic irritation from gallstones. * **C. Simple cuboidal:** While the smaller, intrahepatic bile ductules (Canals of Hering) are lined by simple cuboidal epithelium, the epithelium becomes taller (columnar) as the ducts increase in diameter toward the CBD. **3. Clinical Pearls for NEET-PG:** * **The Mucosa:** Unlike the intestine, the CBD mucosa lacks a muscularis mucosae and a distinct submucosa. * **Rokistansky-Aschoff Sinuses:** These are mucosal herniations into the muscular wall, specifically characteristic of the gallbladder (often seen in chronic cholecystitis), not the CBD. * **Ampulla of Vater:** At its distal end, the CBD joins the pancreatic duct; the epithelium remains simple columnar but transitions to the intestinal type at the Major Duodenal Papilla. * **High-Yield Fact:** The gallbladder also shares this **simple columnar** lining, but it is characterized by prominent microvilli for concentrating bile.
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