Clinical Anatomy — MCQs
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The image shows performance of the Cremasteric Reflex with ipsilateral elevation of testis. Which nerve mediates this reflex? Additional information: - Afferent: Femoral branch of genitofemoral nerve - Efferent: Genital branch of genitofemoral nerve - The reflex is elicited by lightly stroking the skin on the medial aspect of the superior part of the thigh - Rapid elevation of the testis on the same side confirms the cremasteric reflex - This reflex is extremely active in children
The image shows a triangular anatomical region with the following boundaries: 1. Confluence of cystic duct with common hepatic duct 2. Junction of head and body of pancreas 3. Junction of second and third parts of duodenum. Identify the structure:
Which artery shown here should be avoided during paracentesis?
Which of the nerves shown in yellow color is not a part of the triangle of pain?
In this diagram, identify the structure whose paralysis causes decrease in respiratory movements: (AIIMS May 2016)
Identify the nerve damaged in the picture:
Identify the scientist. (Recent NEET Pattern 2016-17)
The following instrument is sterilized using:
The suture material shown below is sterilized by which method?
All are correct about the method of sterilization shown here except:
Clinical Anatomy Indian Medical PG Practice Questions and MCQs
Question 41: The image shows performance of the Cremasteric Reflex with ipsilateral elevation of testis. Which nerve mediates this reflex? Additional information: - Afferent: Femoral branch of genitofemoral nerve - Efferent: Genital branch of genitofemoral nerve - The reflex is elicited by lightly stroking the skin on the medial aspect of the superior part of the thigh - Rapid elevation of the testis on the same side confirms the cremasteric reflex - This reflex is extremely active in children
- A. Genitofemoral nerve (Correct Answer)
- B. Iliohypogastric nerve
- C. Ilioinguinal nerve
- D. Obturator nerve
Explanation: ***Genitofemoral nerve*** - The **cremasteric reflex** involves both the afferent (sensory) and efferent (motor) limbs mediated by branches of the **genitofemoral nerve**. - The afferent limb is the **femoral branch of the genitofemoral nerve**, which senses the stimulation on the inner thigh, and the efferent limb is the **genital branch of the genitofemoral nerve**, which causes the cremaster muscle to contract.
Question 42: The image shows a triangular anatomical region with the following boundaries: 1. Confluence of cystic duct with common hepatic duct 2. Junction of head and body of pancreas 3. Junction of second and third parts of duodenum. Identify the structure:
- A. Gastrinoma triangle (Correct Answer)
- B. Hesselbach's triangle
- C. Triangle of Petit
- D. Calot's triangle
Explanation: ***Correct: Gastrinoma triangle (Passaro's triangle)*** - The **Gastrinoma triangle** or **Passaro's triangle** is a triangular region in the abdomen where the majority of gastrinomas (tumors that secrete gastrin) are found - Its boundaries are: - **Superiorly**: Confluence of the cystic duct with the common hepatic duct - **Inferiorly**: Junction of the head and body of the pancreas - **Medially**: Junction of the second and third parts of the duodenum - This is the most common location for **gastrinomas** in Zollinger-Ellison syndrome - Approximately **90% of gastrinomas** are found within this triangle *Incorrect: Calot's triangle* - Also known as the **hepatocystic triangle** - Boundaries: Cystic duct, common hepatic duct, and inferior surface of the liver - Important surgical landmark during **cholecystectomy** for identifying the cystic artery *Incorrect: Hesselbach's triangle* - Also known as the **inguinal triangle** - Boundaries: Inferior epigastric vessels laterally, rectus abdominis medially, and inguinal ligament inferiorly - Site of **direct inguinal hernias** *Incorrect: Triangle of Petit* - Also known as the **inferior lumbar triangle** - Boundaries: Iliac crest inferiorly, latissimus dorsi medially, and external oblique laterally - Potential site of **lumbar hernias**
Question 43: Which artery shown here should be avoided during paracentesis?
- A. Superior epigastric artery
- B. Inferior epigastric artery (Correct Answer)
- C. Superior hypogastric artery
- D. Inferior hypogastric artery
Explanation: ***Inferior epigastric artery*** - The image depicts the **inferior epigastric artery** and its branches, which run on the anterior abdominal wall. These vessels are susceptible to injury during paracentesis, particularly if the needle is inserted lateral to the rectus abdominis muscle. - Injury to the inferior epigastric artery can lead to **significant bleeding** and **hematoma formation**, even after careful technique. *Superior epigastric artery* - The **superior epigastric artery** is a continuation of the internal thoracic artery and supplies the upper rectus abdominis muscle. It is located more superiorly and less commonly injured during **paracentesis** which is typically performed in the lower abdomen. - While it anastomoses with the inferior epigastric artery, its anatomical position makes it a less likely candidate for direct injury during standard paracentesis procedures which are usually performed below the umbilicus. *Superior hypogastric artery* - The **superior hypogastric artery** (also known as the median sacral artery) originates from the posterior aspect of the aorta and is involved in the arterial supply of structures within the pelvis. - This artery is located **deep within the pelvis**, far from the anterior abdominal wall where paracentesis is performed, making it anatomically irrelevant to this procedure. *Inferior hypogastric artery* - The term **inferior hypogastric artery** is not a standard anatomical term for a major artery; the primary pelvic arterial supply is from the internal iliac artery, sometimes referred to as the hypogastric artery, which branches into numerous smaller vessels. - Regardless of specific nomenclature, any such vessel would be located **deep in the pelvis** and not in the abdominal wall where injury during paracentesis would be a concern.
Question 44: Which of the nerves shown in yellow color is not a part of the triangle of pain?
- A. Lateral femoral cutaneous nerve
- B. Femoral branch of Genitofemoral nerve
- C. Genital branch of Genitofemoral nerve
- D. Femoral nerve (Correct Answer)
Explanation: ***Femoral nerve*** The **femoral nerve** is located laterally to the **femoral artery** and typically runs within the **iliopsoas groove**, outside the boundaries of the **triangle of pain**. Its position is more posterior and lateral, making it less vulnerable to injury during inguinal hernia repair compared to the nerves that traverse the "triangle of pain". *Lateral femoral cutaneous nerve* The **lateral femoral cutaneous nerve** is consistently found within the boundaries of the **triangle of pain**, increasing its susceptibility to injury during Lichtenstein hernia repair. Damage to this nerve can lead to **meralgia paraesthetica**, characterized by burning pain and numbness in the lateral thigh. *Femoral branch of Genitofemoral nerve* The **femoral branch of the genitofemoral nerve** typically crosses the **deep inguinal ring** and lies within the lateral part of the **triangle of pain**. Injury to this nerve during hernia repair can result in numbness or altered sensation in the anterior thigh. *Genital branch of Genitofemoral nerve* The **genital branch of the genitofemoral nerve** is located within the medial and inferior aspects of the **triangle of pain**. Damage to this nerve most commonly causes numbness or pain in the scrotum/labia majora and medial thigh.
Question 45: In this diagram, identify the structure whose paralysis causes decrease in respiratory movements: (AIIMS May 2016)
- A. A
- B. B
- C. C (Correct Answer)
- D. D
Explanation: ***C*** - Structure C points to the **phrenic nerve** (C3-C5: "C3, 4, 5 keeps the diaphragm alive"), which primarily innervates the **diaphragm**. - The diaphragm is the **most important muscle of respiration**, responsible for approximately **70-80% of the work of breathing** during quiet respiration. - Paralysis of the phrenic nerve leads to **diaphragmatic paralysis**, significantly decreasing respiratory movements and causing respiratory compromise. *A* - Structure A points to a nerve arising from the **carotid sheath region**, likely representing a branch of the **cervical plexus** or a sympathetic nerve. - While these nerves have various functions (e.g., cutaneous innervation, vasomotor control), their paralysis does not directly cause a significant decrease in overall respiratory movements. *B* - Structure B points to the **subclavian artery**, which is a major blood vessel supplying blood to the upper limb and head/neck region. - Paralysis is a neurological term and does not apply to an artery; therefore, its occlusion or damage would lead to **ischemia** of supplied tissues, not a direct decrease in respiratory movements. *D* - Structure D points to the **trachea**, which is the main airway leading to the lungs. - The trachea is a cartilaginous tube, not a nerve or muscle that can be paralyzed; its obstruction would lead to **dyspnea** and respiratory distress, not decreased movements due to paralysis.
Question 46: Identify the nerve damaged in the picture:
- A. Radial
- B. Ulnar
- C. Median (Correct Answer)
- D. Posterior interosseous nerve
Explanation: ***Median*** - The image illustrates a patient unable to form a perfect "O" shape with their thumb and index finger, a sign known as the **"A-OK" sign** or **"pinch sign"**, indicating weakness of the **flexor pollicis longus** and **flexor digitorum profundus** (index finger) muscles. - These muscles are innervated by the **anterior interosseous nerve (AIN)**, which is a pure motor branch of the **median nerve**. *Radial* - Radial nerve damage typically results in a **wrist drop** due to paralysis of the wrist extensors and finger extensors. - The patient in the image is holding their wrist and fingers in flexion, which is not characteristic of radial nerve palsy. *Ulnar* - Ulnar nerve damage would result in a **"claw hand" deformity**, where the 4th and 5th fingers are hyperextended at the metacarpophalangeal joints and flexed at the interphalangeal joints. - It would also affect the **adduction of the thumb** (Froment's sign) and the intrinsic muscles of the hand, which are not the primary issues depicted. *Posterior interosseous nerve* - Damage to the posterior interosseous nerve (PIN), a branch of the radial nerve, primarily affects the **extensors of the fingers and thumb** leading to an inability to extend them. - It does not typically affect the **flexor pollicis longus** or **flexor digitorum profundus to the index finger**, which are responsible for the 'pinch' movement shown.
Question 47: Identify the scientist. (Recent NEET Pattern 2016-17)
- A. Louis Pasteur
- B. Robert Koch (Correct Answer)
- C. Christiaan Barnard
- D. William Osler
Explanation: ***Robert Koch*** - The image provided is a portrait of **Robert Koch**, a German physician and microbiologist. - He is known for his work on identifying the **causative agents of diseases** such as tuberculosis, cholera, and anthrax. *Louis Pasteur* - **Louis Pasteur** was a French chemist and microbiologist, known for his discoveries of the principles of **vaccination, microbial fermentation, and pasteurization**. - His appearance, particularly his facial features and style of beard, is distinct from the person in the image. *Christiaan Barnard* - **Christiaan Barnard** was a South African cardiac surgeon who performed the **world's first successful human-to-human heart transplant**. - He lived much later than the person pictured and has a distinct appearance. *William Osler* - **William Osler** was a Canadian physician and one of the four founding professors of **Johns Hopkins Hospital**. He is often called the "Father of Modern Medicine". - While a prominent figure in medicine, his physical appearance in historical photographs is different from the individual shown.
Question 48: The following instrument is sterilized using:
- A. Ortho-phthalaldehyde (Correct Answer)
- B. Ethylene oxide
- C. Beta-propiolactone
- D. Formaldehyde
Explanation: ***Ortho-phthalaldehyde (OPA)*** - The instrument shown is an **endoscope**, which is a heat-sensitive, semi-critical device requiring high-level disinfection. - **OPA** is a common and effective high-level disinfectant used for endoscopes, as it offers a rapid disinfection time, broad microbicidal activity, and is stable. *Ethylene dioxide* - **Ethylene oxide (EO)** is a gas sterilant primarily used for heat and moisture-sensitive medical devices that cannot be effectively disinfected by liquid chemicals. - EO sterilization requires specific, highly controlled chambers and aeration periods to remove toxic residuals, making it less practical for routine endoscope disinfection in clinical settings compared to liquid agents. *Beta-propiolactone* - **Beta-propiolactone** is a chemical sterilant with broad-spectrum activity but is notable for being a probable human carcinogen and a strong irritant. - Due to its significant toxicity and potential health risks, its use in medical sterilization, particularly for instruments like endoscopes, has largely been phased out or is very restricted. *Formaldehyde* - **Formaldehyde** is a strong disinfectant and sterilant that can be used in both liquid and gaseous forms; however, it is a known carcinogen and has strong irritating fumes. - While effective, its high toxicity and safety concerns limit its routine use for endoscopes, especially when less hazardous high-level disinfectants like OPA are available.
Question 49: The suture material shown below is sterilized by which method?
- A. Dry heat sterilization
- B. Autoclave (moist heat)
- C. Ethylene oxide
- D. Gamma radiation (Correct Answer)
Explanation: ***Gamma radiation*** - **Catgut sutures**, being made from natural, collagen-based materials, are **heat-sensitive** and cannot withstand high temperatures or steam. - **Ionizing radiation**, specifically gamma radiation, is effective for sterilizing heat-sensitive medical devices and materials without causing thermal damage, while still effectively killing microorganisms. *Dry heat sterilization* - Dry heat sterilization requires high temperatures for extended periods, which would **damage the protein structure of catgut**, leading to degradation and loss of tensile strength. - This method is typically used for items that can withstand high heat but are sensitive to moisture, such as powders, oils, and some glassware. *Autoclave (moist heat)* - While highly effective for many surgical instruments, **autoclaving (moist heat)** would cause the **collagen fibers of catgut to denature** and melt, destroying the suture material. - Catgut is highly susceptible to hydrolysis and degradation in the presence of heat and moisture. *Chemical sterilization with ethylene oxide* - Although ethylene oxide can be used for heat-sensitive materials, its use is often limited due to **toxic residue concerns** and the need for a lengthy aeration process. - While technically possible for some heat-sensitive items, **gamma radiation** is generally preferred for catgut due to its efficiency and lack of toxic residues.
Question 50: All are correct about the method of sterilization shown here except:
- A. Hold time of $180^{\circ}$ Celsius for 3 hours
- B. Swab sticks should be placed inside test tubes
- C. Chemical indicator of sterilization is Browne's tube number 3
- D. Biological indicator is Bacillus subtilis strips containing spores (Correct Answer)
Explanation: ***Biological indicator is Bacillus subtilis strips containing spores*** - This statement is **INCORRECT** for hot air oven (dry heat) sterilization, making it the correct answer to this EXCEPT question. - The appropriate biological indicator for dry heat sterilization is **Bacillus atrophaeus** (formerly *Bacillus subtilis var. niger*), which has spores with high heat resistance. - *Bacillus subtilis* strips are used as biological indicators for **ethylene oxide sterilization**, not dry heat. *Hold time of 180° Celsius for 3 hours* - While this temperature-time combination is **excessive**, it would still achieve sterilization (though inefficient). - Standard protocols: **180°C for 30 minutes**, 170°C for 1 hour, or 160°C for 2 hours. - The extended time doesn't make the statement fundamentally incorrect for sterilization purposes. *Swab sticks should be placed inside test tubes* - This statement is **CORRECT** for dry heat sterilization. - Swab sticks are placed in test tubes with cotton plugs or loose caps to allow heat penetration while preventing recontamination after sterilization. *Chemical indicator of sterilization is Browne's tube number 3* - While **Browne's tube No. 1** is more specific for hot air ovens, Browne's tube No. 3 can indicate exposure to high temperatures. - However, Browne's tube No. 3 is specifically designed for **steam sterilization at 121°C**, making this statement technically imprecise but not the primary exception. - The biological indicator error is more fundamentally incorrect.
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