Anatomy
6 questionsDevelopment of labia majora is from -
What type of joint is the 1st carpometacarpal joint?
Where is the neurovascular plane located in the anterior abdominal wall?
Which of these best describes the renal angle?
Which bone has the maximum anatomical contribution to the floor of the orbit?
Risorius is a muscle of?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 61: Development of labia majora is from -
- A. Urogenital sinus
- B. Mullerian duct
- C. Genital ridge
- D. Genital swelling (Correct Answer)
Explanation: ***Genital swelling*** - The **labia majora** develop from the **genital (labioscrotal) swellings** in females, which are homologous to the scrotum in males [3]. - These swellings enlarge and fuse anteriorly to form the mons pubis and posteriorly to form the posterior commissures of the labia majora. *Urogenital sinus* - The **urogenital sinus** gives rise to structures like the **bladder**, **urethra**, and parts of the **vagina** in females [2]. - It does not contribute to the formation of the external labial structures. *Mullerian duct* - The **Mullerian (paramesonephric) ducts** develop into the **fallopian tubes**, **uterus**, and the **upper third of the vagina** [1], [2]. - These structures are internal reproductive organs and do not form external genitalia like the labia majora. *Genital ridge* - The **genital ridge** is the embryonic precursor to the **gonads** (ovaries or testes). - It differentiates into either ovaries or testes and does not directly form external genital structures.
Question 62: What type of joint is the 1st carpometacarpal joint?
- A. Pivot
- B. Hinge
- C. Ball and Socket
- D. Saddle (Correct Answer)
Explanation: ***Saddle*** - The **1st carpometacarpal joint** (thumb CMC joint) is a classic example of a **saddle joint** due to the reciprocal concave-convex opposing surfaces of the trapezium and the first metacarpal [1]. - This unique shape allows for a wide range of motion, including **flexion/extension**, **abduction/adduction**, and **opposition**, which is crucial for thumb function. *Pivot* - A **pivot joint** allows for rotational movement around a single axis, like the **atlantoaxial joint** (C1-C2) or the **proximal radioulnar joint**. - This type of motion is not characteristic of the 1st carpometacarpal joint. *Hinge* - A **hinge joint** permits movement in only one plane, like the **elbow** or **interphalangeal joints**, allowing for **flexion and extension**. - The 1st carpometacarpal joint has a greater degree of freedom than a hinge joint. *Ball and Socket* - A **ball and socket joint** offers the greatest range of motion, allowing for movement in all planes, including **circumduction and rotation**, such as the **shoulder** and **hip joints**. - While the 1st carpometacarpal joint is highly mobile, it does not achieve the full range of motion of a ball and socket joint.
Question 63: Where is the neurovascular plane located in the anterior abdominal wall?
- A. Between external oblique and internal oblique
- B. Between internal oblique and transversus abdominis (Correct Answer)
- C. Below transversus abdominis
- D. Above external oblique
Explanation: ***Between internal oblique and transversus abdominis*** - This space, often referred to as the **transversus abdominis plane (TAP)**, contains the major neurovascular bundles supplying the anterior abdominal wall [1]. - The nerves here are the lower **thoracic (T7-T11)** and **iliohypogastric/ilioinguinal (L1) nerves**, along with accompanying blood vessels [1]. *Between external oblique and internal oblique* - This fascial plane primarily houses some superficial nerves and vessels but not the main neurovascular supply to the abdominal wall muscles. - The major neurovascular bundles for deeper muscle layers and skin are located deeper to the **internal oblique** [1]. *Below transversus abdominis* - Below the **transversus abdominis** muscle lies the **transversalis fascia**, an extraperitoneal fat layer, and then the **peritoneum**. - This deeper region primarily contains retroperitoneal structures and organs, not the main neurovascular plane for the abdominal wall. *Above external oblique* - The layer above the **external oblique** muscle is primarily subcutaneous tissue and skin. - While superficial nerves and vessels are present here, this is not the main neurovascular plane that supplies the muscles of the anterior abdominal wall.
Question 64: Which of these best describes the renal angle?
- A. The angle between the latissimus dorsi and the 12th rib
- B. The angle between the erector spinae and the iliac crest
- C. The angle between the 12th rib and the erector spinae (Correct Answer)
- D. The angle between the 12th rib and the rectus abdominis
Explanation: ***The angle between the 12th rib and the erector spinae*** - The **renal angle** (also known as the costovertebral angle) is the space formed by the junction of the **12th rib** and the **erector spinae muscles** laterally. - This anatomical landmark is clinically significant for assessing **kidney pain** or inflammation (e.g., in pyelonephritis) through percussion. *The angle between the latissimus dorsi and the 12th rib* - While the **latissimus dorsi** is a significant back muscle, it is not the primary anatomical landmark that defines the renal angle. - The renal angle specifically refers to the relationship between the rib cage and the deeper spinal muscles. *The angle between the erector spinae and the iliac crest* - This description refers to a region lower down on the back, closer to the **pelvis**, and not directly related to the position of the kidneys. - The **iliac crest** defines the upper border of the pelvis, far from the kidney's typical location relative to the 12th rib. *The angle between the 12th rib and the rectus abdominis* - The **rectus abdominis** muscle is located on the anterior (front) aspect of the abdomen, involved in trunk flexion. - This muscle is anatomically distinct and separate from the posterior flank region where the kidneys are located and where the renal angle is assessed.
Question 65: Which bone has the maximum anatomical contribution to the floor of the orbit?
- A. Maxillary (Correct Answer)
- B. Zygomatic
- C. Sphenoid
- D. Palatine
Explanation: ***Maxillary*** - The **maxilla** contributes the most significantly to the **orbital floor**, forming approximately **75%** of its surface area. - The orbital plate of the maxilla is a thin, triangular bone that also forms the roof of the **maxillary sinus**. *Zygomatic* - The **zygomatic bone** forms the **lateral wall** and the **lateral portion** of the **orbital floor**. - Its contribution to the overall floor is less extensive than that of the maxilla (approximately 20-25%). *Sphenoid* - The **sphenoid bone** does **NOT** contribute to the **orbital floor** at all. - It forms parts of the **posterior wall** and **lateral wall** (via greater and lesser wings) of the orbit, but has no anatomical contribution to the floor. *Palatine* - The **palatine bone** (via its orbital process) contributes a very small, **posterior-most part** of the **orbital floor**. - Its contribution is minimal (less than 5%) compared to the maxilla and zygomatic bone.
Question 66: 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.*
Physiology
4 questionsWhat is the consequence of tibial nerve injury/palsy?
In bladder injury, pain is referred to which of the following areas?
What is the average daily volume of pancreatic secretion in humans?
What is the duration of the second heart sound (S2)?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 61: What is the consequence of tibial nerve injury/palsy?
- A. Loss of plantar flexion (Correct Answer)
- B. Dorsiflexion of foot at ankle joint
- C. Loss of sensation of dorsum of foot
- D. Paralysis of muscles of anterior compartment of leg
Explanation: **Loss of plantar flexion** - The **tibial nerve** innervates the muscles of the **posterior compartment of the leg**, which are primarily responsible for **plantar flexion** of the foot. - Injury to this nerve directly impairs the function of muscles like the gastrocnemius, soleus, and tibialis posterior, leading to a significant loss of the ability to point the foot downwards. *Dorsiflexion of foot at ankle joint* - **Dorsiflexion** is primarily mediated by muscles in the **anterior compartment of the leg**, such as the tibialis anterior, which are innervated by the **deep fibular nerve**. - Tibial nerve injury would not directly affect these muscles or their function; rather, it leads to issues with the opposing action. *Loss of sensation of dorsum of foot* - Sensation to the **dorsum of the foot** is primarily supplied by the **superficial fibular nerve** (for most of the dorsum) and the **deep fibular nerve** (for the first web space). - While the tibial nerve provides sensation to the sole of the foot, it does not typically innervate the dorsum. *Paralysis of muscles of anterior compartment of leg* - The muscles of the **anterior compartment of the leg** (e.g., tibialis anterior, extensor digitorum longus, extensor hallucis longus) are innervated by the **deep fibular nerve**. - A tibial nerve injury would paralyze muscles in the posterior compartment, not the anterior compartment.
Question 62: In bladder injury, pain is referred to which of the following areas?
- A. Flank
- B. Upper part of thigh
- C. Lower abdominal wall (Correct Answer)
- D. Penis
Explanation: ***Correct Option: Lower abdominal wall*** - **Referred pain** from the bladder is typically felt in the **suprapubic region** of the lower abdominal wall due to shared visceral and somatic afferent innervation. - The **parietal peritoneum** overlying the bladder is innervated by somatic nerves that also supply the abdominal wall. - This convergence of visceral afferents from the bladder and somatic afferents from the abdominal wall at the spinal cord level (particularly S2-S4) results in referred pain to the suprapubic area. *Incorrect Option: Upper part of thigh* - Pain in the upper thigh is more commonly associated with conditions affecting the **hip joint**, **femoral nerve**, or **inguinal region**. - Bladder innervation does not primarily refer pain to the upper thigh. *Incorrect Option: Flank* - Flank pain is typically associated with conditions of the **kidneys** or **ureters**, such as **nephrolithiasis** or **pyelonephritis**. - The bladder's referred pain pattern does not usually extend to the flank. *Incorrect Option: Penis* - While bladder irritation can sometimes cause sensations in the penis, it is more often associated with conditions like **urethritis**, **cystitis**, or **prostatitis**. - Direct referred pain from bladder injury to the penis is less common than to the lower abdominal wall.
Question 63: 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.
Question 64: What is the duration of the second heart sound (S2)?
- A. 0.15 sec
- B. 0.1 sec
- C. 0.12 sec
- D. 0.08 sec (Correct Answer)
Explanation: ***0.08 sec*** - The second heart sound (S2) is composed of two components: A2 (aortic valve closure) and P2 (pulmonic valve closure). The normal duration of S2, encompassing both components, is approximately **0.08 seconds**. - This short duration reflects the rapid closure of the aortic and pulmonic valves at the beginning of **diastole**. *0.15sec* - A duration of **0.15 seconds** for S2 is significantly longer than normal, which could indicate abnormal valve function or conditions causing delayed valve closure. - Such prolonged duration might be observed in conditions like **severe pulmonic stenosis** or **pulmonic hypertension**, which are not the typical duration of a healthy S2. *0.12 sec* - A duration of **0.12 seconds** is also longer than the typical normal range for S2. - While still shorter than 0.15 seconds, it could suggest subtle delays in valve closure or splitting that exceeds the usual physiological splitting. *0.1 sec* - A duration of **0.1 seconds** is slightly prolonged but generally falls within a range that might be considered borderline or indicative of minimal physiological variations. - However, in typical healthy individuals, the S2 duration is closer to 0.08 seconds, making 0.1 seconds less precise for the most common duration.