Clinical Anatomy — MCQs

Clinical Anatomy Indian Medical PG Practice Questions and MCQs

Question 111: Low radial nerve palsy (just after the spiral groove) does not produce which of the following?

A. Loss of finger extension
B. Loss of wrist extension
C. Loss of elbow extension (Correct Answer)
D. Loss of thumb extension

Explanation: ***Loss of elbow extension*** - A low radial nerve palsy, occurring **distal to the spiral groove**, affects branches supplying the forearm and hand. - The nerves to the **triceps brachii**, responsible for elbow extension, branch off **proximal to the spiral groove**. *Loss of wrist extension* - The muscles responsible for **wrist extension** (e.g., extensor carpi radialis longus, brevis, and extensor carpi ulnaris) are innervated by the radial nerve or its deep branch **distal to the spiral groove**. - Therefore, a low radial nerve palsy would cause **loss of wrist extension**, leading to **wrist drop**. *Loss of finger extension* - The **extensor digitorum**, **extensor indicis**, and **extensor digiti minimi** muscles, which extend the fingers, are innervated by the posterior interosseous nerve (a continuation of the deep radial nerve) also **distal to the spiral groove**. - A low radial nerve palsy would result in the inability to **extend the fingers**. *Loss of thumb extension* - The muscles involved in **thumb extension** (e.g., abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) are also supplied by the posterior interosseous nerve, originating **distal to the spiral groove**. - Consequently, **loss of thumb extension** would be a feature of a low radial nerve palsy.

Question 112: Foreign body aspiration in supine position commonly affects which of the following parts of the lung?

A. Apical left lobe
B. Apical lobe of right lung
C. Posterobasal segment of left lung
D. Apical part of the lower lobe (Correct Answer)

Explanation: ***Apical part of the lower lobe*** - In a **supine position**, the **apical (superior) segment of the lower lobe** becomes the most posterior and gravity-dependent part of the lung. - The **right lower lobe apical segment** is most commonly affected due to the **right main bronchus** being wider, shorter, and more vertical compared to the left, providing a more direct pathway for aspirated material. - This anatomical orientation facilitates the entry of foreign bodies into this specific segment when the patient is lying flat on their back. *Apical left lobe* - The **apical segment of the left upper lobe** is located anteriorly and superiorly, making it non-gravity-dependent in the supine position. - Aspiration to this area is uncommon when lying flat, as gravity directs material posteriorly. *Apical lobe of right lung* - This refers to the **apical segment of the right upper lobe**, which is also located anteriorly and superiorly. - Despite the right bronchus being more favorable for aspiration overall, the **upper lobe** is not gravity-dependent in the supine position. - Foreign bodies preferentially travel to the **lower lobe** segments when supine. *Posterobasal segment of left lung* - While the **posterobasal segment** is gravity-dependent, aspiration to the **left lung** is less common than to the right due to the more acute angle (40-60°) of the left main bronchus compared to the right (20-25°). - In the **supine position**, the **apical segment of the lower lobe** is more directly aligned for aspiration than the basal segments, which become more anterior when lying flat.

Question 113: Pregnant uterus will compress ureters at ?

A. Pelvic brim (Correct Answer)
B. Ischial spine
C. Trigone
D. Ureterovesical junction

Explanation: ***Pelvic brim*** - The pregnant uterus typically compresses the ureters at the **pelvic brim**, where the ureters cross over the **iliac vessels** as they enter the true pelvis [1]. - This compression, coupled with **hormonal effects** (particularly progesterone-induced smooth muscle relaxation), contributes to the physiological hydronephrosis commonly seen in pregnancy. - The **right ureter** is more commonly affected than the left due to dextrorotation of the uterus. *Ischial spine* - The ischial spine is a pelvic landmark used in obstetrics to assess the level of fetal descent. - While the ureters pass through the pelvis, they do not pass near the ischial spines and are not compressed at this location by the pregnant uterus. *Trigone* - The trigone is a triangular region in the **base of the bladder** formed by the openings of the two ureters and the internal urethral orifice [2]. - While bladder changes occur in pregnancy, direct compression of the ureters at the trigone by the uterus is not the primary mechanism of obstruction leading to hydronephrosis. *Ureterovesical junction* - This is the point where the ureters enter the **urinary bladder**. - While this junction can be affected by bladder distention or other pathologies, the primary site of compression by the pregnant uterus is usually more proximal, at the **pelvic brim** where the ureters cross the iliac vessels.

Question 114: Most common site of a glomus tumor is?

A. Under fingernails (Correct Answer)
B. Under toenails
C. Neck
D. Axilla

Explanation: ***Under fingernails*** - The subungual region (under the fingernails) is the **most common site** for glomus tumors, accounting for about 75% of cases [1]. - These tumors often present with severe, paroxysmal pain, cold sensitivity, and focal tenderness in this location due to the high concentration of **glomus bodies** [1]. *Under toenails* - While glomus tumors can occur in the toes, they are **much less common** than in the fingers. - The diagnostic characteristics are similar to those in fingernails but with **lower incidence**. *Neck* - Glomus tumors are **rarely found** in the neck. - If a tumor occurs in the neck with characteristics of glomus cell origin, it is more likely to be a **paraganglioma** (chemodectoma), which originates from glomus caroticum or similar structures, rather than a typical glomus tumor of the skin. *Axilla* - The axilla is an **uncommon site** for glomus tumors. - Glomus tumors primarily arise from **neuromyoarterial glomus bodies**, which are found in highest concentrations in the distal extremities, particularly the digits.

Question 115: The back in 10-14 year olds contributes what percentage to total body surface area?

A. 13% (Correct Answer)
B. 15%
C. 16%
D. 19%

Explanation: ***13%*** - According to the **Lund-Browder chart**, which is the gold standard for pediatric burn assessment, the **back (posterior trunk)** in children aged **10-14 years** accounts for **13%** of total body surface area [1]. - This is the most accurate method for calculating body surface area in pediatric patients, as it accounts for age-related proportional changes during growth [1]. - The Lund-Browder chart divides the back into upper and lower segments, but the total posterior trunk remains 13% in this age group. *15%* - This percentage is not a standard value for the back in the Lund-Browder chart for ages 10-14. - While 15% might represent a lower limb in some adult burn estimation methods, it does not correspond to the back in pediatric patients. *16%* - This value does not align with the established Lund-Browder chart values for children aged 10-14 years. - The back accounts for 13%, not 16%, in this age group according to standard pediatric burn assessment protocols. *19%* - This percentage is too high for the back of a child aged 10-14 years. - In the adult "Rule of Nines," the entire back represents 18%, but this rule is not appropriate for pediatric populations due to different body proportions. - The Lund-Browder chart gives a more accurate assessment for children.

Question 116: Blowout fracture of the orbit most commonly involves?

A. Floor (Correct Answer)
B. Medial wall
C. Lateral wall
D. Roof

Explanation: ***Floor*** - The **orbital floor** is the most commonly fractured site in a blowout fracture due to its thinness and location, often leading to herniation of orbital contents into the maxillary sinus. - This type of fracture often results from a **sudden increase in intraorbital pressure** by a blunt trauma, causing the weakest part of the orbit to give way. *Medial wall* - While less common than floor fractures, the **medial wall** can also be fractured in a blowout injury, leading to herniation into the ethmoid sinuses. - Involvement of the medial wall can sometimes damage the **lacrimal drainage system** or the medial rectus muscle. *Lateral wall* - The **lateral wall** of the orbit is significantly thicker and more robust than the floor or medial wall, making isolated lateral wall fractures extremely rare. - Fractures of the lateral wall are usually associated with more extensive **zygomaticomaxillary complex (ZMC)** fractures or high-impact trauma. *Roof* - The **orbital roof** is composed of the frontal bone and is considerably stronger and thicker than the floor, making roof fractures uncommon in isolated blowout injuries. - Fractures of the orbital roof typically occur with **severe trauma** and are often associated with intracranial injury or damage to the frontal sinus.

Question 117: Wrist drop is caused by injury to which nerve?

A. Radial nerve (Correct Answer)
B. Ulnar nerve
C. Median nerve
D. Axillary nerve

Explanation: ***Radial nerve*** - The **radial nerve** innervates the muscles responsible for **extension of the wrist and fingers** [1]. - Injury to the radial nerve, often due to humeral shaft fractures or prolonged compression, leads to the characteristic inability to extend the wrist, known as **wrist drop** [1]. *Ulnar nerve* - The ulnar nerve primarily controls most of the **intrinsic hand muscles** and some forearm flexors [1]. - Injury typically results in **claw hand deformity** (inability to extend the 4th and 5th digits) and weakened grip, not wrist drop. *Median nerve* - The median nerve innervates most of the **forearm flexors** and several intrinsic hand muscles, including those of the thenar eminence [1]. - Injury can lead to the **"ape hand" deformity** (inability to abduct and oppose the thumb) and sensory deficits in the first three fingers, but not wrist drop [1]. *Axillary nerve* - The axillary nerve primarily innervates the **deltoid muscle** and **teres minor**. - Injury results in **shoulder abduction weakness** and sensory loss over the deltoid region, with no direct involvement in wrist movement.

Question 118: Transplanted kidney is relocated to which region in the recipient's body?

A. Lumbar region
B. Epigastrium
C. Beside the dysfunctional kidney
D. Retroperitoneal region (Correct Answer)

Explanation: ***Retroperitoneal region*** - The transplanted kidney is typically placed in the **iliac fossa** within the **retroperitoneal space** of the recipient [2]. - This location provides adequate space and a convenient site for connecting the transplant's renal artery and vein to the recipient's **iliac vessels**, and the ureter to the bladder [2]. *Lumbar region* - The native kidneys are located in the lumbar region, but a transplanted kidney is not usually placed there due to the complexity of vascular anastomoses and limited access [1]. - Positioning in the lumbar region would require more extensive surgical dissection and potentially longer vascular connections. *Epigastrium* - The epigastrium is the upper central part of the abdomen, above the navel. - This location is not suitable for kidney transplantation due to anatomical constraints and the lack of readily accessible large blood vessels for connection. *Beside the dysfunctional Kidney* - The dysfunctional native kidneys are usually left in place unless they are causing severe complications like uncontrolled hypertension or infection. - Placing the transplanted kidney directly beside the native dysfunctional kidney is not the standard procedure due to space limitations and to avoid operating near potentially diseased native organs.

Question 119: What is the shape of caecum in the newborn?

A. Ovoid
B. Trapezoid
C. Globular
D. Conical (Correct Answer)

Explanation: ***Conical*** - In newborns, the **caecum** is typically described as having a **conical** shape. - This shape gradually changes as the individual grows and develops. *Ovoid* - The ovoid shape is more characteristic of the adult **caecum**, which tends to be broader and less pointed. - This shape is not typically observed in newborns. *Globular* - A globular shape implies a more rounded and spherical form, which is not accurate for the newborn **caecum**. - This term is sometimes used to describe the general appearance of some organs but not the specific shape of the neonatal caecum. *Trapezoid* - A trapezoid shape is defined by four sides with at least one pair of parallel sides, which does not accurately describe the normal anatomical configuration of the **caecum** at any age. - This shape is completely inconsistent with the morphology of the **caecum**.

Question 120: The sternocleidomastoid muscle is examined by

A. Shrugging of shoulder
B. Overhead abduction
C. Turning the head towards the same side to assess the muscle on that side
D. Turning the head towards the opposite side to assess the muscle on that side (Correct Answer)

Explanation: ***Turning the head towards the opposite side to assess the muscle on that side*** - The **sternocleidomastoid muscle** unilaterally acts to rotate the head to the **contralateral side**. - To palpate or visually inspect the right sternocleidomastoid, the patient would turn their head to the left, making the right muscle prominent. *Turning the head towards the same side to assess the muscle on that side* - Turning the head towards the same side primarily engages the **ipsilateral deep neck flexors** and **splenius capitis**, not the sternocleidomastoid. - This action would relax the sternocleidomastoid on the side towards which the head is turned, making it difficult to assess. *Shrugging of shoulder* - Shrugging the shoulder is primarily an action of the **trapezius** and **levator scapulae muscles**. - The sternocleidomastoid does not contribute significantly to shoulder elevation. *Overhead abduction* - Overhead abduction of the arm is primarily performed by the **deltoid muscle** and assisted by the **supraspinatus**. - This movement is entirely unrelated to the function of the sternocleidomastoid muscle.

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