Anatomy
5 questionsThe roof of the olfactory region is formed by?
Vertebral arteries of both sides unite to form
Which of the following is not a tributary of the cavernous sinus?
Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
Medulla oblongata arises from which of the following?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 331: The roof of the olfactory region is formed by?
- A. Nasal bone
- B. Sphenoid
- C. Temporal bone
- D. Cribriform plate of ethmoid (Correct Answer)
Explanation: ***Cribriform plate of ethmoid*** - The **cribriform plate** of the ethmoid bone forms the superior boundary, or roof, of the nasal cavity specifically in the olfactory region [1]. - It is perforated by numerous **olfactory foramina** through which the olfactory nerves pass from the nasal cavity to the olfactory bulb of the brain [2]. *Nasal bone* - The **nasal bones** form part of the bridge of the nose and contribute to the anterior part of the bony framework of the external nose. - They do not form the roof of the olfactory region within the nasal cavity. *Sphenoid* - The **sphenoid bone** is a complex bone at the base of the skull, contributing to the posterior wall of the nasal cavity and parts of the cranial floor. - It does not directly form the roof of the olfactory region. *Temporal bone* - The **temporal bones** are located on the sides and base of the skull, housing structures related to hearing and balance. - They are not involved in forming the roof of the nasal cavity or the olfactory region.
Question 332: Vertebral arteries of both sides unite to form
- A. Anterior spinal artery
- B. Posterior spinal artery
- C. Medullary artery
- D. Basilar artery (Correct Answer)
Explanation: Basilar artery - The paired vertebral arteries ascend through the neck via the transverse foramina of cervical vertebrae and enter the skull through the foramen magnum. - At the level of the pontomedullary junction, the two vertebral arteries merge to form a single basilar artery. Anterior spinal artery - The anterior spinal artery is formed by the union of two small branches derived from each vertebral artery near their intracranial origin. - It supplies the anterior two-thirds of the spinal cord, running along the anterior median fissure. Posterior spinal artery - The posterior spinal arteries are typically two vessels, one arising from each vertebral artery (or less commonly from the posterior inferior cerebellar artery). - They supply the posterior one-third of the spinal cord and do not form a single major merged vessel in the brainstem. Medullary artery - There is no single major artery termed the "medullary artery" formed by the union of the vertebral arteries. - The medulla oblongata is supplied by branches directly from the vertebral arteries and the basilar artery, such as the posterior inferior cerebellar artery (PICA) and direct medullary branches.
Question 333: Which of the following is not a tributary of the cavernous sinus?
- A. Central vein of retina
- B. Sphenoparietal sinus
- C. Inferior cerebral vein (Correct Answer)
- D. Superior ophthalmic vein
Explanation: Detailed anatomical knowledge of the dural venous sinuses is required to answer this question. Venous drainage from the brain by way of the deep veins and dural sinuses typically empties principally into the internal jugular veins, though blood also drains via the ophthalmic and pterygoid venous plexuses [1]. ***Inferior cerebral vein*** - The **inferior cerebral veins** drain the inferior surface of the cerebral hemispheres and typically empty into the **basal vein of Rosenthal**, **transverse sinus**, or other dural sinuses. - They do **not directly drain** into the cavernous sinus, making this the correct answer. - While some small inferior cerebral veins may occasionally communicate with the cavernous sinus, they are not considered standard tributaries. *Central vein of retina* - The **central vein of retina** drains the retina and exits the eye through the optic nerve. - It drains into the **superior ophthalmic vein**, which then empties into the cavernous sinus. - It is an **indirect tributary** via the superior ophthalmic vein, not a direct tributary itself. *Sphenoparietal sinus* - The **sphenoparietal sinus** is a dural venous sinus that runs along the posterior edge of the lesser wing of the sphenoid bone. - It is a **direct tributary** that drains anteriorly into the cavernous sinus. - This is one of the standard tributaries listed in anatomical texts. *Superior ophthalmic vein* - The **superior ophthalmic vein** is the **major tributary** draining orbital structures including the eyeball, extraocular muscles, and eyelids. - It passes posteriorly through the **superior orbital fissure** to drain directly into the cavernous sinus. - This is the most clinically significant tributary, as infections can spread from the face to the cavernous sinus via this route.
Question 334: Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
- A. Intralaminar
- B. Anterior
- C. Pulvinar (Correct Answer)
- D. None of the options
Explanation: ***Pulvinar*** - The **pulvinar nucleus** is the largest thalamic nucleus and has the most extensive **妥reciprocal connections** with the **association cortices** of the parietal, temporal, and occipital lobes. - It plays a crucial role in **visual attention**, integration of visual and other sensory information, and facilitating cortico-cortical communication. - The pulvinar is unique in its dense, bidirectional connectivity with higher-order association areas, distinguishing it from other thalamic nuclei. *Intralaminar* - **Intralaminar nuclei** (centromedian, parafascicular) project **diffusely and non-specifically** to widespread cortical areas and the striatum [1]. - They are involved in arousal, attention, and consciousness but lack the **specific, reciprocal connections** with association cortices that characterize the pulvinar. - Their projections are more related to generalized cortical activation rather than specific sensory or cognitive processing [1]. *Anterior* - The **anterior nuclear group** (anteromedial, anterodorsal, anteroventral) projects primarily to the **cingulate gyrus** as part of the limbic system [1]. - While the cingulate is cortical tissue, it is **limbic cortex** with specific emotional and memory functions, not association neocortex involved in higher-order sensory integration. - Receives input from mammillary bodies and is part of the Papez circuit for memory and emotion. *None of the options* - This is incorrect because the **pulvinar nucleus** has well-established, extensive reciprocal connections with association areas of the neocortex. - The pulvinar is considered a "higher-order" thalamic nucleus specifically connecting cortical areas to each other via the thalamus.
Question 335: Medulla oblongata arises from which of the following?
- A. Mesencephalon
- B. Myelencephalon (Correct Answer)
- C. Rhombencephalon
- D. None of the options
Explanation: ***Myelencephalon*** - The **myelencephalon** is the most caudal of the three primary brain vesicles and is the developmental origin of the **medulla oblongata**. - It differentiates from the **rhombencephalon** (hindbrain) and is responsible for vital autonomic functions. *Rhombencephalon* - The **rhombencephalon** is the hindbrain and is a primary brain vesicle that further divides into the **metencephalon** and **myelencephalon**. - While it is the parent structure, it does not directly give rise to the medulla oblongata as a final differentiated structure without further division. *Mesencephalon* - The **mesencephalon** is the midbrain, a primary brain vesicle that develops into structures like the **tectum** and **tegmentum** [1]. - It is located rostral to the rhombencephalon and is not involved in the development of the medulla oblongata [1]. *None of the options* - This option is incorrect because the **myelencephalon** is the direct embryonic precursor of the medulla oblongata.
Internal Medicine
2 questionsType 3 respiratory failure occurs due to ?
Which of the following statements about obesity is FALSE?
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 331: Type 3 respiratory failure occurs due to ?
- A. Post-operative atelectasis (Correct Answer)
- B. Kyphoscoliosis
- C. Flail chest
- D. Pulmonary fibrosis
Explanation: ***Post-operative atelectasis*** - **Type 3 respiratory failure**, also known as **perioperative respiratory failure**, is characterized by hypoxemia occurring typically after surgery. - **Atelectasis**, the collapse of lung tissue, is a common cause of hypoxemia in the post-operative period due to shallow breathing, pain, and anesthesia affecting lung volumes. *Kyphoscoliosis* - This condition leads to a **restrictive lung disease** due to chest wall deformity, causing chronic respiratory failure. [1] - It more typically results in **Type 2 respiratory failure** (hypercapnic) due to impaired ventilation over time. [1] *Flail chest* - Flail chest is a severe chest wall injury causing paradoxical movement, leading to **acute respiratory failure**. - It is often associated with **Type 1 (hypoxemic)** or **Type 2 (hypercapnic)** respiratory failure due to trauma-induced lung injury and impaired mechanics. *Pulmonary fibrosis* - This is a progressive interstitial lung disease causing **restrictive ventilatory defect** and impaired gas exchange. - It leads to chronic **Type 1 respiratory failure** (hypoxemic) as the lung tissue becomes stiff and scarred.
Question 332: Which of the following statements about obesity is FALSE?
- A. There is no genetic predisposition to obesity. (Correct Answer)
- B. Smoking is associated with weight loss
- C. Obesity affects only females.
- D. The prevalence of obesity decreases with age.
Explanation: There is no genetic predisposition to obesity. - This statement is false because genetic factors play a significant role in an individual's susceptibility to obesity, influencing metabolism, appetite, and fat storage [1]. - While environment and lifestyle are crucial, polygenic influences and certain single-gene disorders can heavily predispose individuals to weight gain [1]. *Smoking is associated with weight loss* - Smoking can lead to appetite suppression and an increased metabolic rate, which may result in weight loss or lower body weight compared to non-smokers. - However, this is not a healthy or recommended method for weight control due to the numerous severe health risks associated with smoking. *Obesity affects only females.* - This statement is false; obesity affects both males and females across all age groups and demographics [2]. - Although there can be differences in fat distribution and associated health risks between sexes, obesity is a global health issue impacting everyone [2]. *The prevalence of obesity decreases with age.* - This statement is generally false; the prevalence of obesity tends to increase with age through middle adulthood before possibly leveling off or slightly declining in older age. - Factors like decreased physical activity, changes in metabolism, and chronic disease accumulation contribute to weight gain later in life [3].
Pathology
2 questionsWhat is the typical bone marrow finding in myelofibrosis?
MALT lymphoma is positive for which of the following markers?
NEET-PG 2013 - Pathology NEET-PG Practice Questions and MCQs
Question 331: What is the typical bone marrow finding in myelofibrosis?
- A. Megaloblastic cells
- B. Microcytic cells
- C. Thrombocytosis
- D. Dry tap (hypocellular) (Correct Answer)
Explanation: ***Dry tap (hypocellular)*** - In myelofibrosis, the bone marrow is often **hypocellular** due to fibrosis [1][2], leading to a **dry tap** during aspiration. - The presence of **reticulin** and collagen deposition replaces normal hematopoietic cells [2], resulting in ineffective hematopoiesis. *Thrombocytosis* - Myelofibrosis typically leads to **thrombocytopenia**, not thrombocytosis, due to ineffective megakaryopoiesis and splenic sequestration. - Though elevated platelets can occur, they are generally a **secondary response** to the disease and not a hallmark finding. *Megaloblastic cells* - Megaloblastic changes are associated with **vitamin B12** or **folate deficiencies**, which do not occur in myelofibrosis. - In myelofibrosis, the predominant issue is **marrow fibrosis** [1][2], which does not lead to megaloblastosis. *Microcytic cells* - Microcytic cells are commonly linked to **iron deficiency anemia**, not myelofibrosis. - Myelofibrosis typically results in **variable red cell morphology** [1], but microcytic anemia is not a primary characteristic. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 628-629. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 615-616.
Question 332: MALT lymphoma is positive for which of the following markers?
- A. CD20 (Correct Answer)
- B. CD19
- C. CD43
- D. CD5
Explanation: ***CD20*** - MALT lymphoma is a type of **B-cell non-Hodgkin lymphoma**, and CD20 is a **pan B-cell marker consistently expressed** in MALT lymphomas. - CD20 positivity is **crucial for diagnosis** and is the **primary therapeutic target** for anti-CD20 monoclonal antibody therapy (Rituximab). - In diagnostic practice, **CD20 is the most important B-cell marker** for identifying MALT lymphoma and guiding treatment decisions. *CD19* - CD19 is also a **pan B-cell marker** and is **typically positive in MALT lymphoma** along with CD20. - However, in the context of this question, **CD20 is the preferred answer** because it is the **standard diagnostic marker emphasized in clinical practice** and the **primary therapeutic target**. - Both markers are positive, but CD20 has greater **clinical and therapeutic significance** in MALT lymphoma management. *CD43* - CD43 is primarily a **T-cell and myeloid marker**, but can show **aberrant expression in 40-50% of MALT lymphomas**. - While it may be positive in some cases, it is **not a defining B-cell lineage marker** and is not used as a primary diagnostic criterion for MALT lymphoma. - Its variable expression makes it **less reliable** than consistent B-cell markers like CD20. *CD5* - CD5 is typically associated with **T-cells** and certain B-cell lymphomas, particularly **chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL)** and **mantle cell lymphoma**. - **MALT lymphoma is characteristically CD5-negative**, which is an important feature for **differentiating it from CD5+ B-cell lymphomas**.
Physiology
1 questionsWhat does Boyle's Law state?
NEET-PG 2013 - Physiology NEET-PG Practice Questions and MCQs
Question 331: What does Boyle's Law state?
- A. Pressure divided by temperature is constant.
- B. Volume divided by temperature is constant.
- C. PV = constant (Correct Answer)
- D. Pressure multiplied by volume equals the number of moles times the gas constant times temperature.
Explanation: ***PV = constant*** - **Boyle's Law** states that at constant temperature, the pressure and volume of a gas are inversely proportional. - Mathematically expressed as **PV = constant** or **P₁V₁ = P₂V₂** - This means that if the volume of a gas decreases, its pressure increases proportionally, and vice versa. - **Clinically relevant** in understanding lung mechanics during respiration - as thoracic volume increases during inspiration, intrapulmonary pressure decreases, allowing air to flow in. *Pressure divided by temperature is constant.* - This describes **Gay-Lussac's Law** (P/T = constant), which relates pressure and temperature at constant volume. - Shows the direct relationship between pressure and temperature. *Volume divided by temperature is constant.* - This statement describes **Charles's Law** (V/T = constant), which relates the volume and temperature of a gas at constant pressure. - Indicates a direct relationship between volume and temperature. *Pressure multiplied by volume equals the number of moles times the gas constant times temperature.* - This represents the **Ideal Gas Law**: PV = nRT - Combines Boyle's, Charles's, and Avogadro's laws to relate pressure, volume, temperature, and the number of moles of a gas.