Anatomy
6 questionsRisorius is a muscle of?
Which of the following is an operculated sulcus ?
In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?
Renal papilla opens into -
Right ovarian artery is a branch of ?
Nutrient artery runs ?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 71: Risorius is a muscle of?
- A. Mastication
- B. Deglutition
- C. Facial expression (Correct Answer)
- D. Eye movement
Explanation: Facial expression - The **risorius muscle** retracts the **corner of the mouth** laterally, contributing to smiling or grimacing. - It falls under the category of **mimetic muscles**, all of which are innervated by the **facial nerve (cranial nerve VII)**. *Mastication* - Muscles of mastication, such as the **masseter**, **temporalis**, and **pterygoids**, are primarily involved in **chewing** and moving the mandible. - These muscles are innervated by the **trigeminal nerve (cranial nerve V)**, not the facial nerve. *Deglutition* - Deglutition refers to the process of **swallowing**, involving muscles of the **pharynx** and **larynx**. - Examples include the **palatoglossus**, **stylopharyngeus**, and **superior pharyngeal constrictor**. *Eye movement* - Muscles responsible for eye movement are the **extrinsic ocular muscles**, such as the **recti** and **oblique muscles** [1]. - These muscles are innervated by the **oculomotor (III)**, **trochlear (IV)**, and **abducens (VI)** cranial nerves. *Note: No provided references mention the risorius muscle, mimetic muscles, or muscles of mastication; citations are applied only to supported sub-topics.*
Question 72: Which of the following is an operculated sulcus ?
- A. Lunate
- B. Calcarine
- C. Central
- D. Sylvian fissure (lateral sulcus) (Correct Answer)
Explanation: ***Sylvian fissure (lateral sulcus)*** - The **lateral sulcus**, also known as the Sylvian fissure, is a deep groove on the lateral surface of the brain that **separates the frontal and parietal lobes from the temporal lobe**. - It is considered an **operculated sulcus** because its banks contain the insula, which is a buried part of the cerebral cortex covered by the surrounding cortical folds called opercula. *Calcarine* - The **calcarine sulcus** is located on the medial surface of the occipital lobe, forming the primary visual cortex, and is not an operculated sulcus. - It delineates the **upper and lower banks of the visual cortex** and does not involve overlying cortical structures. *Lunate* - The **lunate sulcus** is found on the posterior part of the occipital lobe and is not typically described as an operculated sulcus. - It represents a boundary in the visual cortex, but its banks do not hide a buried cortical region like the insula. *Central* - The **central sulcus** (Rolandic fissure) separates the frontal lobe from the parietal lobe and is a prominent sulcus, but it is not operculated. - Its banks contain the **precentral gyrus** (primary motor cortex) and **postcentral gyrus** (primary somatosensory cortex) directly facing each other.
Question 73: In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?
- A. Adductor muscles
- B. Quadriceps
- C. Gluteus medius and minimus (Correct Answer)
- D. Gluteus maximus
Explanation: ***Gluteus medius and minimus*** - The **gluteus medius** and **gluteus minimus** are essential **abductors** of the hip, primarily responsible for stabilizing the pelvis during the **single-limb support phase of gait**. - When one leg is lifted during walking, these muscles on the **stance leg side** contract to prevent the pelvis from tilting downwards on the unsupported swing leg side. *Adductor muscles* - **Adductor muscles** (adductor longus, brevis, magnus, pectineus, gracilis) primarily function to bring the thigh toward the midline of the body. - While they play a role in gait stability, their main action is not to prevent the lateral pelvic tilt described. *Quadriceps* - The quadriceps femoris group (rectus femoris, vastus lateralis, medialis, intermedius) are powerful **extensors of the knee**. - They are crucial for weight acceptance and propulsion during walking but do not directly prevent lateral pelvic tilt [1]. *Gluteus maximus* - The **gluteus maximus** is the largest and most powerful muscle of the hip, primarily responsible for **hip extension** and **external rotation**. - It is crucial for activities like climbing stairs or running, but its main role in normal walking is not to prevent lateral pelvic tilt; that function is more specific to the gluteus medius and minimus.
Question 74: Renal papilla opens into -
- A. Cortex
- B. Pyramid
- C. Minor calyx (Correct Answer)
- D. Major calyx
Explanation: ***Minor calyx*** - The **renal papilla** is the apex of the renal pyramid, which drains urine directly into a **minor calyx**. - Minor calyces then merge to form major calyces, eventually leading to the renal pelvis. *Cortex* - The **renal cortex** is the outer layer of the kidney, containing glomeruli and convoluted tubules, and does not directly receive urine from the papilla. - Urine is primarily formed and filtered in the cortex and then flows into the medulla. *Pyramid* - A **renal pyramid** is a conical structure within the renal medulla, and the renal papilla is its tip, but it doesn't open *into* the pyramid itself. - Instead, the pyramid *contains* the structures that contribute to the papilla. *Major calyx* - A **major calyx** is formed by the convergence of several minor calyces. - The renal papilla drains into the minor calyx, which then, in turn, drains into the major calyx.
Question 75: Right ovarian artery is a branch of ?
- A. Abdominal aorta (Correct Answer)
- B. Right internal iliac
- C. Common iliac
- D. External iliac
Explanation: ***Abdominal aorta*** - The **right ovarian artery** typically originates directly from the **abdominal aorta**, just inferior to the renal arteries [1]. - This is a direct branch, supplying blood to the **right ovary**, **fallopian tube**, and surrounding structures [1]. *Right internal iliac* - The **internal iliac artery** primarily supplies the **pelvic organs**, gluteal region, and medial thigh [1]. - While it has branches to pelvic structures, the ovarian artery does not originate from it. *Common iliac* - The **common iliac artery** bifurcates into the **internal and external iliac arteries** at the level of the sacroiliac joint. - It does not directly give off the ovarian artery. *External iliac* - The **external iliac artery** continues as the **femoral artery** below the inguinal ligament, primarily supplying the lower limb. - It does not give off branches to the ovary.
Question 76: 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
1 questionsWhat is the classification of the Y chromosome?
NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs
Question 71: What is the classification of the Y chromosome?
- A. Metacentric
- B. Submetacentric (Correct Answer)
- C. Acrocentric
- D. None of the options
Explanation: ***Submetacentric*** - The **Y chromosome** is classified as submetacentric because its **centromere** is located off-center, resulting in two arms of unequal length. - The short arm (Yp) is smaller than the long arm (Yq), but not as disproportionate as in acrocentric chromosomes. - The **X chromosome** is also submetacentric, making both sex chromosomes belong to this category. *Metacentric* - A **metacentric chromosome** has its **centromere** located in the middle, resulting in two arms of approximately equal length. - Examples include chromosomes 1, 3, 16, 19, and 20, which have nearly equal arm ratios unlike the Y chromosome. *Acrocentric* - An **acrocentric chromosome** has its **centromere** located very close to one end, creating one very short arm and one very long arm. - The five acrocentric human chromosomes are **13, 14, 15, 21, and 22**, which possess satellite DNA and nucleolar organizing regions (NORs) on their short arms. - The **Y chromosome is NOT acrocentric** despite historical confusion; it has a more centrally positioned centromere than true acrocentric chromosomes. *None of the options* - This option is incorrect because the Y chromosome has a specific and well-established classification as **submetacentric** based on its centromere position and arm ratio.
Obstetrics and Gynecology
1 questionsBlastocyst makes contact with endometrium on ?
NEET-PG 2012 - Obstetrics and Gynecology NEET-PG Practice Questions and MCQs
Question 71: Blastocyst makes contact with endometrium on ?
- A. < 3 days
- B. 5 - 7 days (Correct Answer)
- C. 8 - 11 days
- D. 15-16 days
Explanation: ***5-7 days*** - The **blastocyst makes initial contact** (apposition) with the **endometrium** around **day 5-6 after fertilization**. - **Implantation**, which includes adhesion and invasion, typically begins around day 6 and is complete by day 10. - This timeframe allows the blastocyst to travel from the fallopian tube to the uterus and for the uterine lining to be optimally prepared. *< 3 days* - Within the first few days after fertilization, the zygote is still undergoing **cleavage** and development into a **morula**, then a young blastocyst, while traveling down the fallopian tube. - It has not yet reached the uterus or developed sufficiently to interact with the endometrium. *8-11 days* - By 8-11 days, the process of implantation is usually **well underway or completed**, with the blastocyst already invading the endometrial wall. - Initial contact and attachment occur prior to this period. *15-16 days* - This timeframe is well beyond the typical window for initial blastocyst contact and implantation. - By 15-16 days post-fertilization, the embryo would be undergoing **gastrulation** and early organogenesis, assuming successful implantation.
Orthopaedics
1 questionsWhich of the following conditions can cause locking of the knee joint?
NEET-PG 2012 - Orthopaedics NEET-PG Practice Questions and MCQs
Question 71: Which of the following conditions can cause locking of the knee joint?
- A. Osgood Schlatter
- B. Tuberculosis of knee
- C. a and b both
- D. Loose body in knee joint (Correct Answer)
Explanation: ***Loose body in knee joint*** - A **loose body** (e.g., a fragment of cartilage or bone) can get trapped between the articular surfaces of the knee joint, mechanically obstructing its movement and causing sudden, painful **locking**. - This mechanical impingement prevents full extension or flexion of the knee until the loose body shifts, leading to episodic locking symptoms. *Osgood Schlatter* - This condition involves inflammation and potential avulsion of the **tibial tuberosity** where the patellar tendon inserts. - It primarily causes pain and swelling below the kneecap, especially during physical activity, but does not typically result in true mechanical locking of the joint. *Tuberculosis of knee* - **Tuberculosis of the knee joint** is an infectious arthritis that causes chronic pain, swelling, and gradual destruction of articular cartilage and bone. - While it can lead to pain and limited range of motion, it usually does not present with the sudden, intermittent mechanical locking characteristic of a loose body. *a and b both* - Neither **Osgood Schlatter** nor **Tuberculosis of the knee** typically cause the characteristic mechanical locking sensation described for a loose body in the joint. - Each of these conditions has distinct pathophysiological mechanisms and clinical presentations that do not involve a physical obstruction causing locking.
Physiology
1 questionsWhat is the average daily volume of pancreatic secretion in humans?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 71: What is the average daily volume of pancreatic secretion in humans?
- A. 5.0 L
- B. 10 L
- C. 1.5 L (Correct Answer)
- D. 2.5 L
Explanation: ***1.5 L*** - The **pancreas** produces approximately **1.5 liters (1200-1500 mL) of pancreatic juice** daily in humans. - This secretion is rich in **digestive enzymes** (amylase, lipase, proteases) and **bicarbonate** for neutralization of gastric acid in the duodenum. - This is the standard value cited in **major physiology textbooks** (Ganong, Guyton & Hall). *2.5 L* - **2.5 liters** overestimates the typical daily pancreatic secretion volume. - This value may represent **combined secretions** from multiple sources or confuse pancreatic output with total upper GI secretions. - Normal pancreatic secretion ranges from **1-2 liters**, making 2.5 L above the physiological range. *5.0 L* - **5.0 liters** represents an abnormally high volume for daily pancreatic secretion alone. - This volume is closer to the **total daily secretions** from stomach, pancreas, and bile combined. - Not consistent with **normal pancreatic physiology**. *10 L* - **10 liters** is grossly excessive for pancreatic secretion and represents approximately the **total volume of all gastrointestinal secretions** (saliva, gastric, pancreatic, bile, intestinal) combined daily. - This is **not physiologically realistic** for pancreatic output alone.