Anatomy
4 questionsAll pass through jugular foramen except
Which muscle is the deepest in the anterior neck region?
Which of the following structures pass through the superior orbital fissure?
Vertebral arteries of both sides unite to form
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 201: All pass through jugular foramen except
- A. Mandibular nerve (Correct Answer)
- B. Vagus nerve
- C. Internal jugular vein
- D. Glossopharyngeal nerve
Explanation: ***Mandibular nerve*** - The **mandibular nerve** (CN V3) exits the skull through the **foramen ovale**, not the jugular foramen. - It is a branch of the **trigeminal nerve** and is responsible for motor innervation to muscles of mastication and sensory innervation to the lower face and mouth. *Glossopharyngeal nerve* - The **glossopharyngeal nerve** (CN IX) is one of the three cranial nerves that exit through the **jugular foramen**. - It provides motor, sensory, and parasympathetic innervation including taste from posterior third of tongue and motor to stylopharyngeus muscle. *Vagus nerve* - The **vagus nerve** (CN X) is one of the major cranial nerves that exits the skull through the **jugular foramen**. - It provides extensive motor, sensory, and parasympathetic innervation to the head, neck, thorax, and abdomen. *Internal jugular vein* - The **internal jugular vein** is formed at the jugular foramen by the continuation of the **sigmoid sinus**, and it exits the skull through this foramen. - It is one of the primary venous drainage pathways for the brain.
Question 202: Which muscle is the deepest in the anterior neck region?
- A. Sternocleidomastoid
- B. Platysma
- C. Longus colli (Correct Answer)
- D. Trapezius
Explanation: ***Longus colli*** - The **longus colli** muscle is the **deepest muscle** located in the anterior neck region, running along the front of the cervical vertebral column from C1 to T3. - It lies in the **prevertebral layer**, deep to all other anterior neck structures including the carotid sheath, visceral compartment, and superficial muscles. - Its position directly anterior to the vertebral bodies makes it the deepest anterior neck muscle. *Platysma* - The platysma is the **most superficial muscle** of the neck, located just beneath the skin in the superficial fascia. - It is not a deep muscle and lies superficial to all other neck muscles. *Sternocleidomastoid* - The sternocleidomastoid is enclosed within the **investing layer of deep cervical fascia**, making it relatively superficial. - While prominent in the anterior and lateral neck, it is not the deepest anterior neck muscle. *Trapezius* - The trapezius is a large, **superficial muscle of the back and posterior neck**. - It is not located in the anterior neck and is a superficial, not deep, muscle.
Question 203: Which of the following structures pass through the superior orbital fissure?
- A. Oculomotor nerve
- B. Trochlear nerve
- C. Superior ophthalmic vein
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The **superior orbital fissure** is a key opening in the skull that allows passage of several important cranial nerves and vessels into the orbit. - The **oculomotor nerve**, **trochlear nerve**, and **superior ophthalmic vein** are all established structures that pass through this fissure. *Oculomotor nerve* - The **oculomotor nerve (CN III)** passes through the superior orbital fissure to innervate most of the extrinsic eye muscles. - It controls movements such as **adduction**, **elevation**, and **depression** of the eyeball, and also innervates the **levator palpebrae superioris** muscle for eyelid elevation [1]. *Trochlear nerve* - The **trochlear nerve (CN IV)**, which innervates the **superior oblique muscle**, also passes through the superior orbital fissure. - The superior oblique muscle is responsible for **intorsion** and **depression** of the eye, particularly when the eye is adducted [1]. *Superior ophthalmic vein* - The **superior ophthalmic vein** drains blood from structures within the orbit and passes through the superior orbital fissure to drain into the **cavernous sinus**. - This vein provides a connection between the facial veins and the cavernous sinus, which can be clinically relevant in cases of infection spread.
Question 204: 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.
Microbiology
1 questionsPersons with heterozygous sickle cell trait are protected from infection by:
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 201: Persons with heterozygous sickle cell trait are protected from infection by:
- A. Pneumococcus
- B. P. falciparum (Correct Answer)
- C. P. vivax
- D. Salmonella
Explanation: ***P. falciparum*** - Individuals with heterozygous sickle cell trait have a **protective effect** against severe malaria caused by *P. falciparum* due to altered red blood cell morphology [1][2]. - The sickle hemoglobin (HbAS) provides a **selective advantage**, reducing the severity of malaria infections and the parasitic load [2][3]. *P. vivax* - Sickle cell trait does not confer significant protection against *P. vivax*, which primarily infects non-sickled red blood cells [2]. - The infection still occurs in individuals with the trait because it specifically affects the reticulocyte count, which is less impacted by sickling. *Salmonella* - While sickle cell disease is linked with increased susceptibility to **Salmonella infections**, the sickle cell trait itself does not provide protection against it [2]. - The trait does not influence immunity or susceptibility to bacterial pathogens like *Salmonella*. *Pneumococcus* - Individuals with sickle cell trait still have a normal risk of **invasive pneumococcal disease**, similar to those without the trait [2]. - Protection against *Pneumococcus* primarily relates to vaccination status and not to hemoglobinopathies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 398-400. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 598-599. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 50-51.
Pathology
2 questionsWhich of the following statements is false regarding hereditary spherocytosis?
Which of the following statements about sickle cell anemia is false?
NEET-PG 2013 - Pathology NEET-PG Practice Questions and MCQs
Question 201: Which of the following statements is false regarding hereditary spherocytosis?
- A. Defect in ankyrin
- B. Reticulocytosis
- C. Decreased MCHC (Correct Answer)
- D. Normal to increased MCV
Explanation: ***Decreased MCHC*** - Hereditary spherocytosis typically presents with an **increased MCHC** due to the spherocytes being more concentrated. - MCHC is a measure of the hemoglobin concentration in red blood cells, and in spherocytosis, this value is often elevated rather than decreased. *Defect in ankyrin* - This is a true statement; hereditary spherocytosis is associated with a defect in **ankyrin**, a protein that helps maintain the cell's membrane structure [2]. - Mutations in ankyrin lead to instability of the red blood cell membrane, resulting in spherocyte formation [2]. *Decreased MCV* - In hereditary spherocytosis, MCV is often **normal or slightly increased**, as it reflects the volume of red blood cells, which can be misinterpreted due to the presence of spherocytes. - Spherocytes are smaller cells, which can mistakenly suggest a falsely decreased MCV if not properly interpreted [1]. *Reticulocytosis* - This condition typically presents with **reticulocytosis** as a response to hemolysis, indicating the bone marrow is producing more red blood cells to compensate [1]. - The presence of reticulocytosis is a common finding in hereditary spherocytosis due to increased destruction of spherocytes. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 597-598. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 640-641.
Question 202: Which of the following statements about sickle cell anemia is false?
- A. Sickle cells are present in sickle cell anemia.
- B. Target cells are commonly seen in sickle cell anemia.
- C. Ringed sideroblasts are associated with sickle cell anemia. (Correct Answer)
- D. Howell Jolly bodies can be found in sickle cell anemia.
Explanation: ***Ringed sideroblast*** - **Ringed sideroblasts** are not typically associated with sickle cell anemia; they are indicative of disorders like **sideroblastic anemia**. - In sickle cell anemia, the primary findings include **hemolysis** and ineffective erythropoiesis, not ringed sideroblasts [3]. *Howell jolly bodies* - These bodies are remnants of nuclear material and can be found in individuals with **spleen dysfunction**, which can occur in sickle cell anemia [1]. - They are actually a common finding due to **hyposplenism** or **asplenia** in patients with sickle cell disease [2]. *Sickle cells* - The presence of **sickle-shaped red blood cells** is a hallmark of sickle cell anemia, caused by the mutation in the **beta-globin chain** [3]. - These sickle cells are responsible for the characteristic complications of the disease, such as **vaso-occlusive crises** [1][3]. *Target cells* - Target cells, or **codocytes**, are often seen in disorders like **thalassemia** and liver disease, and can also be present in sickle cell anemia. - They are formed due to an increase in the **surface area to volume ratio** of red blood cells, often secondary to **membrane abnormalities** seen in sickle cell changes [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 644-646. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 570-571. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 598-599.
Pharmacology
3 questionsWhat is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
Which of the following drugs is known to have low first pass metabolism?
Which drug has the highest plasma protein binding?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 201: What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
- A. First pass kinetics
- B. First order kinetics
- C. Zero order kinetics (Correct Answer)
- D. Second order kinetics
Explanation: ***Zero order kinetics*** - This mechanism occurs when the **metabolic enzymes become saturated at high drug concentrations**, leading to a constant amount (not a constant percentage) of drug being eliminated per unit time. - Alcohol, aspirin, and phenytoin are examples of drugs that exhibit **saturable metabolism**, transitioning from first-order to zero-order kinetics at higher doses. *First pass kinetics* - This describes the **metabolism of a drug by the liver or gut wall enzymes before it reaches systemic circulation** after oral administration. - While relevant to the oral bioavailability of these drugs, it does not describe the specific mechanism of elimination at high doses. *First order kinetics* - In this mechanism, a **constant fraction or percentage of the drug is eliminated per unit of time**, meaning the rate of elimination is directly proportional to the drug concentration. - Most drugs follow first-order kinetics at therapeutic doses because metabolizing enzymes are not saturated. *Second order kinetics* - This is a **less common pharmacokinetic model** where the rate of elimination is proportional to the square of the drug concentration or involves two reactants. - It does not typically describe the common elimination patterns of most drugs, including alcohol, aspirin, and phenytoin.
Question 202: Which of the following drugs is known to have low first pass metabolism?
- A. Lidocaine
- B. Propranolol
- C. Theophylline (Correct Answer)
- D. Morphine
Explanation: ***Theophylline*** - **Theophylline** exhibits **low first-pass metabolism**, meaning a significant portion of the orally administered drug reaches systemic circulation unchanged. - This characteristic contributes to its relatively **high bioavailability** when given orally. *Lidocaine* - **Lidocaine** undergoes extensive **first-pass metabolism** in the liver, leading to very low oral bioavailability. - Due to this, it is typically administered **parenterally** (e.g., intravenously or topically) to achieve therapeutic concentrations. *Propranolol* - **Propranolol** is known for its significant **first-pass metabolism**, which results in a much lower bioavailability after oral administration compared to intravenous. - This extensive metabolism necessitates higher oral doses to achieve the same therapeutic effect as parenteral administration. *Morphine* - **Morphine** also undergoes substantial **first-pass metabolism** in the liver, where it is primarily glucuronidated. - This leads to a lower oral bioavailability compared to other routes of administration and contributes to a higher oral dose requirement.
Question 203: Which drug has the highest plasma protein binding?
- A. Warfarin (Correct Answer)
- B. Verapamil
- C. Aspirin
- D. GTN
Explanation: ***Warfarin*** - **Warfarin** exhibits very **high plasma protein binding**, typically greater than 99%, primarily to albumin. - This high binding capacity means that only a small fraction of the drug is free and pharmacologically active. - Due to high protein binding, warfarin is susceptible to drug interactions when displaced from albumin. *Verapamil* - **Verapamil** has a relatively high plasma protein binding, around 90%, but it is not as high as warfarin. - Its binding is predominantly to **albumin** and alpha-1-acid glycoprotein. *Aspirin* - **Aspirin** (acetylsalicylic acid) has moderate plasma protein binding, usually between 50-90%, depending on the dosage. - It binds to **albumin** and can displace other protein-bound drugs. *GTN* - **Glyceryl trinitrate (GTN)** has moderate plasma protein binding, approximately 60%. - Its rapid onset and short duration of action are primarily due to its extensive first-pass metabolism and quick redistribution, rather than protein binding characteristics.