Anatomy
8 questionsAll are derived from ectoderm except for which of the following?
Which muscle stabilizes the clavicle during movement of the shoulder?
Nutrient artery runs ?
What anatomical structures are involved in the closure of the fossa ovalis?
Which is derived from Wolffian duct?
Which of the following is a traction epiphysis ?
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 -
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 301: All are derived from ectoderm except for which of the following?
- A. Hair follicles
- B. Nails
- C. Lens of the eye
- D. Adrenal cortex (Correct Answer)
Explanation: ***Adrenal cortex*** - The adrenal cortex is derived from the **intermediate mesoderm**, specifically from the cells lining the posterior abdominal wall. The cells migrate to develop into the adrenal cortex. - It produces various steroid hormones, including **aldosterone**, **cortisol**, and **androgens**, which regulate diverse bodily functions. *Lens of the eye* - The lens of the eye is derived from the **surface ectoderm**. It forms from an invagination of the surface ectoderm called the lens placode. - Its primary function is to **focus light** onto the retina. *Hair follicles* - Hair follicles develop from the **surface ectoderm** [1]; they are invaginations of the epidermis that extend into the dermis. - They produce hair, which provides **insulation** and **protection** [1]. *Nails* - Nails are also derivatives of the **surface ectoderm**, forming thickened plates on the dorsal surface of the distal phalanges. - They provide **protection** to the fingertips and aid in grasping objects.
Question 302: Which muscle stabilizes the clavicle during movement of the shoulder?
- A. Pectoralis major
- B. Latissimus dorsi
- C. Subclavius (Correct Answer)
- D. Serratus anterior
Explanation: ***Subclavius*** - The **subclavius muscle** originates from the first rib and inserts into the inferior surface of the clavicle, acting to **depress the clavicle** and prevent its displacement, thus enhancing shoulder stability during movement. - It plays a crucial role in protecting the underlying **neurovascular structures** (brachial plexus and subclavian vessels) from external trauma to the shoulder. *Pectoralis major* - This large, fan-shaped muscle primarily functions in **adduction, medial rotation, and flexion of the humerus** at the shoulder joint [1]. - It does not directly stabilize the clavicle but rather acts on the arm. *Latissimus dorsi* - The **latissimus dorsi** is a broad muscle of the back responsible for **extension, adduction, and internal rotation of the humerus** [1]. - Its actions are mainly on the humerus and it does not directly stabilize the clavicle. *Serratus anterior* - The **serratus anterior** muscle primarily **protracts and rotates the scapula**, keeping it pressed against the thoracic wall. - While it's essential for **scapular stability** and overhead arm movements, it does not directly stabilize the clavicle.
Question 303: 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.
Question 304: What anatomical structures are involved in the closure of the fossa ovalis?
- A. Septum primum + Endocardial cushion
- B. Septum primum + Septum secundum (Correct Answer)
- C. Endocardial cushions + Septum secundum
- D. None of the options
Explanation: The septum primum acts as a valve, closing against the septum secundum postnatally due to changes in atrial pressure. This fusion effectively closes the foramen ovale, leading to the formation of the fossa ovalis. The endocardial cushions are important for the formation of the atrial and ventricular septa, as well as the AV valves, but not directly for the closure of the fossa ovalis. The septum primum is directly involved, but its apposition with the endocardial cushions doesn't close the foramen ovale. While both structures contribute to heart development, their direct interaction is not responsible for the closure of the fossa ovalis. The septum secundum forms the muscular rim of the fossa ovalis, and the endocardial cushions are critical for atrial septation, but not the final closure here. This option is incorrect because the specific combination of septum primum and septum secundum is indeed responsible for the closure of the fossa ovalis.
Question 305: Which is derived from Wolffian duct?
- A. Appendix of epididymis (Correct Answer)
- B. Appendix of the testis
- C. Uterine structure
- D. Hydatid of Morgagni
Explanation: The **appendix of the epididymis** is a vestigial structure directly derived from the mesonephric (Wolffian) duct in males. It is an embryological remnant of this duct, located at the head of the epididymis. *Appendix of the testis* - The **appendix of the testis** (hydatid of Morgagni) is a remnant of the paramesonephric (Müllerian) duct, not the Wolffian duct. - It is usually found on the upper pole of the testis, typically near the epididymis. *Uterine structure* - **Uterine structures** (uterus, fallopian tubes, and upper vagina) are derived from the paramesonephric (Müllerian) ducts in females [1]. - The Wolffian ducts largely regress in females due to the absence of testosterone. *Hydatid of Morgagni* - The term **hydatid of Morgagni** can refer to the appendix of the testis (Müllerian duct remnant) or, less commonly, to the appendix of the epididymis (Wolffian duct remnant). - However, in common clinical and anatomical usage, it almost exclusively refers to the **appendix of the testis**, which is a Müllerian duct derivative.
Question 306: Which of the following is a traction epiphysis ?
- A. Tibial condyles
- B. Head of femur
- C. Trochanter of femur
- D. Coracoid process of scapula (Correct Answer)
Explanation: ***Coracoid process of scapula*** - A **traction epiphysis** (also called atavistic epiphysis) serves as an attachment site for muscles and tendons, transferring muscle force to the bone without bearing significant weight or forming articular surfaces. - The **coracoid process** is a classic example, anchoring the **pectoralis minor, coracobrachialis, and short head of biceps brachii**, as well as important ligaments (coracoclavicular and coracoacromial). - It develops from a separate ossification center purely for muscle and ligament attachment, not for articulation or weight-bearing. *Tibial condyles* - The **tibial condyles** are **pressure epiphyses** (articular epiphyses) that form the superior articular surface of the tibia. - They articulate with the femoral condyles to form the knee joint and bear significant weight during standing and movement. - Their primary function is joint formation and contribution to longitudinal bone growth. *Trochanter of femur* - The **greater and lesser trochanters** are large bony prominences that serve as muscle attachment sites, but they are better classified as **apophyses** rather than true traction epiphyses. - An **apophysis** is a secondary ossification center that does not contribute to longitudinal bone growth and serves primarily for muscle attachment. - While functionally similar to traction epiphyses, the term "traction epiphysis" is more specifically applied to structures like the coracoid process, tibial tuberosity, and calcaneal tuberosity. *Head of femur* - The **head of femur** is a classic **pressure epiphysis** that articulates with the acetabulum to form the hip joint. - It bears significant body weight and contributes to the longitudinal growth of the femur. - Its primary functions are joint formation and weight transmission, not muscle attachment.
Question 307: 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 308: 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.
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 301: 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 questionsWhich isotope is used to measure RBC volume?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 301: Which isotope is used to measure RBC volume?
- A. Cr 51 (Correct Answer)
- B. H-3
- C. D2O
- D. I-135
Explanation: ***Cr 51*** - **Chromium-51** attaches irreversibly to the beta chain of hemoglobin, making it an ideal tracer for measuring **red blood cell volume** and survival. - After injection, the labeled red blood cells distribute throughout the circulation, and their dilution allows for the calculation of the total **RBC mass**. *H-3* - **Tritium (H-3)** is typically used as tritiated water to measure **total body water**, as it readily equilibrates throughout all fluid compartments. - It does not specifically bind to red blood cells for mass measurement. *D2O* - **D2O (heavy water)** is used to measure **total body water** content, similar to tritiated water. - It exchanges with water in the body and diffuses into all fluid compartments, rather than targeting red blood cells. *I-135* - While various **iodine isotopes** are used in medicine, such as **I-131** for thyroid imaging or therapy, **I-135** is not a commonly used isotope for measuring red blood cell volume. - Other tracers like **radio-iodinated human serum albumin** (e.g., I-125 HSA) can be used to measure plasma volume, not specifically RBC volume.