Anatomy
5 questionsAll the following are characteristics of the oculomotor nerve except:
Anal valve is found in which part of anal canal?
Which lymph nodes are involved in the lymphatic drainage of the lateral wall of the nose?
Rouviere nodes are situated in?
Nutrient artery runs ?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 331: All the following are characteristics of the oculomotor nerve except:
- A. Carries parasympathetic nerve fibres
- B. Supplies inferior oblique muscle
- C. Enters orbit through the inferior orbital fissure (Correct Answer)
- D. Enters orbit through the superior orbital fissure
Explanation: ***Enters orbit through the inferior orbital fissure*** - The oculomotor nerve **does not** enter the orbit through the **inferior orbital fissure**; it enters via the **superior orbital fissure**. - The **inferior orbital fissure** transmits structures like the **maxillary nerve (V2)**, **zygomatic nerve**, and **inferior ophthalmic vein**. *Carries parasympathetic nerve fibres* - The oculomotor nerve contains **parasympathetic preganglionic fibers** that synapse in the **ciliary ganglion** [1]. - These fibers control **pupillary constriction** (via the **sphincter pupillae**) and **accommodation** (via the **ciliary muscle**) [1]. *Supplies inferior oblique muscle* - The **inferior oblique muscle** is one of the **extraocular muscles** innervated by the **oculomotor nerve (CN III)** [2]. - This muscle works to **elevate** and **externally rotate** the eye [2]. *Enters orbit through the superior orbital fissure* - The oculomotor nerve indeed passes through the **superior orbital fissure** to enter the orbit. - This fissure serves as the passage for several cranial nerves and vessels, including the **oculomotor (III)**, **trochlear (IV)**, **abducens (VI)**, and branches of the **ophthalmic nerve (V1)**.
Question 332: Anal valve is found in which part of anal canal?
- A. Lower
- B. At anus
- C. Middle (Correct Answer)
- D. Upper
Explanation: ***Middle*** - The **anal valves** are crescentic folds located at the level of the **pectinate (dentate) line** in the middle portion of the anal canal. - They mark the inferior limit of the **anal columns** and form small recesses called **anal sinuses**. *Lower* - The lower part of the anal canal, below the pectinate line, is lined by **anoderm** and lacks anal valves. - This region is sensitive to pain due to somatic innervation. *At anus* - The anus refers to the external opening and perianal skin, which does not contain anal valves. - The anal canal transitions into the perianal skin at the anocutaneous line. *Upper* - The upper part of the anal canal, above the pectinate line, contains the **anal columns (columns of Morgagni)** but not the anal valves themselves, which are located at the base of these columns. - This region is lined by columnar epithelium and is relatively insensitive to pain.
Question 333: Which lymph nodes are involved in the lymphatic drainage of the lateral wall of the nose?
- A. Deep cervical nodes
- B. Retropharyngeal nodes
- C. Submandibular nodes
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The lymphatic drainage from the **lateral wall of the nose** follows a sequential pathway involving **submandibular nodes**, **retropharyngeal nodes**, and ultimately the **deep cervical nodes**. - This question tests understanding of the complete lymphatic drainage pathway, not just the primary drainage site. - All three node groups are anatomically involved in draining lymph from the lateral nasal wall. **Drainage Pathway:** - **Submandibular nodes** (Primary): The anterior and middle portions of the lateral nasal wall drain primarily to the submandibular lymph nodes. - **Retropharyngeal nodes** (Secondary): The posterior portions of the lateral wall and areas near the nasal pharynx drain to retropharyngeal nodes. - **Deep cervical nodes** (Final pathway): Lymph from both submandibular and retropharyngeal nodes eventually drains into the deep cervical chain, particularly the jugulodigastric and juguloomohyoid nodes. *Why not just one node group?* - The lateral wall of the nose has an extensive lymphatic network with multiple drainage routes. - Different regions of the lateral wall have preferential drainage to different node groups. - Understanding the complete drainage pathway is clinically important for assessing spread of infections and malignancies from the nasal cavity.
Question 334: Rouviere nodes are situated in?
- A. Retropharynx (Correct Answer)
- B. Nasopharyngeal region
- C. Oral region
- D. Supraclavicular region
Explanation: ***Retropharynx*** - Rouviere nodes are a group of **retropharyngeal lymph nodes** located in the space behind the pharynx. - They are clinically significant as they are the **first station of lymphatic drainage** for the nasopharynx and can be involved in cancers of that region. *Nasopharyngeal region* - While Rouviere nodes drain the nasopharynx, they are **located *behind* the nasopharynx** in the retropharyngeal space, not within the nasopharyngeal region itself. - The nasopharynx is the superior part of the pharynx, above the soft palate. *Oral region* - The oral cavity drainage primarily involves **submandibular, submental, and deep cervical lymph nodes**. - Rouviere nodes are not typically involved in the initial lymphatic drainage of the oral region. *Supraclavicular region* - **Supraclavicular nodes** are located above the clavicle in the supraclavicular fossa and represent a distant drainage site. - Involvement of these nodes usually indicates more **advanced disease** or drainage from organs in the chest or abdomen.
Question 335: Nutrient artery runs ?
- A. Away from epiphysis (Correct Answer)
- B. Towards metaphysis
- C. None of the options
- D. Away from metaphysis
Explanation: ***Away from epiphysis*** - The **nutrient artery** runs away from the **dominant (faster-growing) epiphysis** towards the non-dominant end of the bone. - This follows the classic anatomical rule: **"To the elbow, from the knee"** - nutrient arteries point towards the elbow in upper limb bones and away from the knee in lower limb bones. - The **nutrient foramen** is directed obliquely away from the more actively growing end, established during bone development. - Examples: In the humerus, it runs towards the elbow (away from proximal epiphysis); in the femur, it runs away from the knee (away from distal epiphysis). *Towards metaphysis* - While the artery does course towards the metaphyseal region of the slower-growing end, this option is less anatomically precise. - The standard teaching emphasizes the relationship with the **dominant epiphysis** rather than the metaphysis. *Away from metaphysis* - This is **incorrect** - the nutrient artery actually runs **towards** the metaphysis of the non-dominant end. - It runs **away from** the dominant epiphysis, not away from the metaphysis. *None of the options* - This is incorrect as **"Away from epiphysis"** correctly describes the direction of the nutrient artery relative to the dominant growing end.
Biochemistry
2 questionsThe Watson-Crick model is for which type of DNA?
Which of the following is a ribozyme?
NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs
Question 331: The Watson-Crick model is for which type of DNA?
- A. B DNA (Correct Answer)
- B. A DNA
- C. C DNA
- D. Z DNA
Explanation: ***B DNA*** - The **Watson-Crick model** describes the most common and stable form of DNA found in living organisms under physiological conditions. - **B-DNA** is a right-handed double helix, characterized by a **major and minor groove**, with approximately 10-10.5 base pairs per turn. *A DNA* - **A-DNA** is a **right-handed double helix** that forms under dehydrating conditions and is shorter and wider than B-DNA. - It has a more tilted base pair arrangement and is not the primary form described by the Watson-Crick model. *C DNA* - **C-DNA** is a less common **right-handed double helix** that forms under even lower hydration conditions and in the presence of certain ions. - It has fewer base pairs per turn than B-DNA, typically around 9.3 base pairs. *Z DNA* - **Z-DNA** is unique because it is a **left-handed double helix**, unlike the right-handed forms of A, B, and C DNA. - It is transiently formed in regions with a high concentration of **GC base pairs** and has a zigzag backbone, hence its name.
Question 332: Which of the following is a ribozyme?
- A. Peptidyl transferase (Correct Answer)
- B. Elongation factor 2
- C. Primase
- D. RNA polymerase
Explanation: ***Peptidyl transferase*** - This enzyme is an integral part of the **large ribosomal subunit** and is responsible for catalyzing the formation of peptide bonds during protein synthesis. - While historically thought to be purely proteinaceous, it is now known that the **catalytic activity** of peptidyl transferase comes from its **rRNA component**, specifically the 23S rRNA in prokaryotes and 28S rRNA in eukaryotes, making it a ribozyme. *Elongation factor 2* - **Elongation Factor 2 (EF2)** is a **GTPase** that facilitates the translocation of the ribosome along the mRNA during protein synthesis. - It is a **protein**, not an RNA molecule, and thus does not possess catalytic activity as a ribozyme. *Primase* - **Primase** is an **RNA polymerase** that synthesizes short RNA primers required for the initiation of DNA replication. - It is a **protein enzyme** and not an RNA molecule with catalytic activity. *RNA polymerase* - **RNA polymerase** is a **protein enzyme** responsible for synthesizing RNA from a DNA template during transcription. - It uses a DNA template to produce an RNA strand, but its own catalytic activity is derived from its **protein structure**, not from an RNA component.
Internal Medicine
1 questionsWhich condition is most commonly associated with systemic amyloidosis?
NEET-PG 2012 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 331: Which condition is most commonly associated with systemic amyloidosis?
- A. Chronic Kidney Disease (Correct Answer)
- B. Multiple Myeloma
- C. Rheumatoid Arthritis
- D. Familial Mediterranean Fever
Explanation: Type II DM - Amyloidosis is commonly associated with **chronic diseases** like type II diabetes mellitus due to insulin resistance leading to amyloid deposition [4]. - The presence of **amiloid in the pancreas** often correlates with the complications of this type of diabetes [3]. *Maturity onset DM* - While maturity-onset diabetes can lead to complications, it is often synonymous with **type II DM**, making this distinction inaccurate regarding amyloidosis. - This term is less commonly used and does not emphasize the direct link to amyloidosis seen in type II diabetes. *HTN* - Hypertension itself is not a direct cause of amyloidosis; it typically results from other underlying conditions. - The association of amyloidosis with hypertension is usually **secondary**, not a primary condition leading to amyloid deposits [2]. *Type I DM* - Type I diabetes is primarily **autoimmune**, resulting in insulin-deficient states and does not strongly associate with amyloidosis like type II [1]. - The amyloid deposits seen in type I are much less common compared to type II or associated chronic conditions.
Microbiology
1 questionsWhat is the most common bacterial cause of multiple sinus tracts resulting from an infection of the great toe?
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 331: What is the most common bacterial cause of multiple sinus tracts resulting from an infection of the great toe?
- A. Tuberculosis
- B. Pseudomonas aeruginosa
- C. Staphylococcus aureus
- D. Actinomyces (Correct Answer)
Explanation: ***Actinomyces*** - **Actinomycosis** is known for causing **chronic suppurative infections** with **multiple draining sinus tracts** and characteristic **sulfur granules**. - The causative organism is **Actinomyces israelii**, an anaerobic, gram-positive, filamentous bacterium. - While rare, it can affect bones, leading to **osteomyelitis**, especially in the feet, presenting with these multifocal sinus tracts. *Tuberculosis* - **Tuberculosis of bone** is typically a **monoarticular affection**, often affecting larger joints, and does not commonly present with multiple draining sinus tracts like actinomycosis. - It is more common in the spine (**Pott's disease**) and large weight-bearing joints, rather than solely the great toe with multiple sinuses. *Staphylococcus aureus* - **Staphylococcus aureus** is the most common cause of **acute osteomyelitis** and can lead to draining sinuses. - However, it typically causes **single or localized sinus tracts** rather than the extensive, multiple sinus formation associated with actinomycosis. *Pseudomonas aeruginosa* - **Pseudomonas aeruginosa** is often associated with **osteomyelitis following puncture wounds** through footwear. - While it can cause chronic infections, it is not primarily known for forming the characteristic **multiple, long-standing sinus tracts** seen with Actinomyces.
Physiology
1 questionsCells most sensitive to hypoxia are?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 331: Cells most sensitive to hypoxia are?
- A. Myocardial cells
- B. Neurons (Correct Answer)
- C. Hepatocytes
- D. Renal tubular epithelial cells
Explanation: ***Neurons*** - Neurons have a very high metabolic rate and an **absolute requirement for oxygen** and glucose to maintain their complex electrochemical functions and ionic gradients. - Due to their lack of significant energy reserves and high metabolic demand, they can sustain **irreversible damage within minutes** (typically 3-5 minutes) of complete oxygen deprivation. *Myocardial cells* - While myocardial cells are highly susceptible to hypoxia and can undergo **ischemic necrosis** (e.g., in a myocardial infarction), they can often tolerate oxygen deprivation for somewhat longer periods than neurons due to some anaerobic metabolic capacity. - Significant damage to myocardial cells usually occurs after **20-30 minutes of severe ischemia**. *Hepatocytes* - Hepatocytes (liver cells) are relatively **resilient to hypoxia** compared to neurons, possessing significant metabolic flexibility and capacity for regeneration. - They can endure **longer periods of oxygen deprivation** before irreversible damage occurs, often hours. *Renal tubular epithelial cells* - Renal tubular epithelial cells are generally **sensitive to hypoxia**, especially those in the medulla, due to their high metabolic activity for reabsorption and secretion. - They are a common target for **acute tubular necrosis** in ischemic injury but generally have a **higher tolerance than neurons**, with damage becoming widespread after tens of minutes to an hour of severe ischemia.