Forearm and Hand — MCQs

10 questions

All of the following muscles have dual nerve supply, EXCEPT?

A patient presents with loss of sensation on the lateral 3½ fingers and thenar atrophy. Which nerve is most likely involved?

Which muscle is not part of the superficial anterior compartment of the forearm?

Which of the following is NOT a symptom of carpal tunnel syndrome?

Which structure is NOT part of the anatomical snuffbox?

In a vehicle accident, the musculocutaneous nerve was completely severed, but still the person was able to weakly flex the elbow joint. All of the following muscles are responsible for this flexion, EXCEPT:

If median nerve is injured at the wrist then loss of function of all of the following will take place except

Ulnar nerve injury results in:

Which nerve supplies the area marked as ‘Area B’ in the image?

Q10

Which of the following statements about the anterior compartment of the forearm is correct?

Forearm and Hand Indian Medical PG Practice Questions and MCQs

Question 1: All of the following muscles have dual nerve supply, EXCEPT?

A. Flexor digitorum profundus
B. Pectineus
C. Brachialis
D. Flexor digitorum superficialis (Correct Answer)

Explanation: No changes were made to the original explanation because none of the provided references met the relevance criteria for the specific muscles and nerves discussed. ***Flexor digitorum superficialis*** - This muscle is solely innervated by the **median nerve**. - It works to **flex the middle phalanges** of the medial four digits. *Flexor digitorum profundus* - The medial half of the muscle, which supplies the ring and little fingers, is innervated by the **ulnar nerve**. - The lateral half, which supplies the index and middle fingers, is innervated by the **anterior interosseous nerve** (a branch of the median nerve). *Pectineus* - This muscle typically receives innervation from both the **femoral nerve** and the **obturator nerve**. - Its primary action is **adduction and flexion of the hip**. *Brachialis* - While primarily innervated by the **musculocutaneous nerve**, a small component also receives innervation from the **radial nerve**. - It is a powerful **flexor of the elbow joint**.

Question 2: A patient presents with loss of sensation on the lateral 3½ fingers and thenar atrophy. Which nerve is most likely involved?

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

Explanation: ***Median*** - The **median nerve** provides sensation to the **lateral 3½ fingers** (thumb, index, middle, and radial half of the ring finger) and innervates the **thenar muscles**, making its involvement consistent with the described symptoms [1]. - **Thenar atrophy** points directly to motor innervation loss of the thenar eminence, which is a key function of the median nerve. *Ulnar* - The **ulnar nerve** supplies sensation to the **medial 1½ fingers** (little finger and ulnar half of the ring finger) and innervates most of the **intrinsic hand muscles**, but not the thenar muscles [1]. - Damage typically causes **hypothenar atrophy** and **clawing** of the 4th and 5th digits, which are not described here. *Radial* - The **radial nerve** primarily provides sensation to the **dorsal aspect of the hand** and innervates the **extensor muscles of the forearm and hand**. - Its injury would typically lead to **wrist drop** and sensory loss in the dorsal hand, not thenar atrophy or lateral finger sensory loss. *Anterior interosseous nerve* - The **anterior interosseous nerve** is a **purely motor branch of the median nerve** that innervates muscles involved in **flexion of the thumb IP joint** and **index finger DIP joint**. - It does not have any sensory innervation, so loss of sensation in the lateral 3½ fingers would not be a symptom.

Question 3: Which muscle is not part of the superficial anterior compartment of the forearm?

A. FDS
B. FCR
C. Palmaris longus
D. Flexor pollicis longus (FPL) (Correct Answer)

Explanation: **Flexor pollicis longus (FPL)** - The **FPL** is located in the **deep anterior compartment** of the forearm, differentiating it from the superficial muscles [1]. - Its primary function is **flexion of the thumb's interphalangeal joint**, requiring a deeper anatomical position for mechanical advantage [1]. *FDS* - The **Flexor digitorum superficialis (FDS)** is a key muscle of the superficial anterior compartment, visible just beneath the skin and fascia. - It is responsible for **flexing the middle phalanges** of the medial four digits. *FCR* - The **Flexor carpi radialis (FCR)** is situated in the superficial anterior compartment, running obliquely across the forearm. - It functions in **flexion and abduction of the wrist**. *Palmaris longus* - The **Palmaris longus** is a superficial anterior compartment muscle, though it is absent in a significant portion of the population. - When present, its main action is **flexion of the wrist** and tightening of the palmar aponeurosis.

Question 4: Which of the following is NOT a symptom of carpal tunnel syndrome?

A. Phalen's sign
B. Pain & paraesthesia of wrist
C. Tinel sign
D. Ulnar nerve dysfunction (Correct Answer)

Explanation: ***Ulnar nerve dysfunction*** - Carpal tunnel syndrome specifically involves compression of the **median nerve**, not the ulnar nerve. - Symptoms related to the median nerve include numbness and tingling in the **thumb, index, middle, and radial half of the ring finger**, along with **thenar muscle wasting**. *Tinel sign* - The **Tinel sign** is a common physical examination finding in carpal tunnel syndrome, elicited by tapping over the **median nerve** at the wrist. - A positive sign involves tingling or electric shock-like sensations in the **median nerve distribution**. *Phalen's sign* - **Phalen's sign** is another classic physical maneuver used to diagnose carpal tunnel syndrome, where exaggerated wrist flexion for 60 seconds reproduces symptoms. - This maneuver increases pressure within the **carpal tunnel**, exacerbating median nerve compression. *Pain & paraesthesia of wrist* - **Pain and paraesthesia (numbness and tingling)** in the wrist and hand are hallmark symptoms of carpal tunnel syndrome. - These symptoms are often worse at night or with repetitive hand movements, reflecting **median nerve irritation**.

Question 5: Which structure is NOT part of the anatomical snuffbox?

A. Extensor pollicis brevis
B. Flexor carpi ulnaris (Correct Answer)
C. Abductor pollicis longus
D. Extensor pollicis longus

Explanation: ***Flexor carpi ulnaris*** - The **flexor carpi ulnaris** is located on the ulnar side of the forearm and wrist, contributing to wrist flexion and adduction. - It is not a boundary or content of the **anatomical snuffbox**, which is formed by tendons on the radial side of the wrist. *Extensor pollicis brevis* - This tendon forms the **lateral (radial) boundary** of the **anatomical snuffbox** along with the **abductor pollicis longus** [1]. - It extends the **metacarpophalangeal joint** of the thumb [1]. *Abductor pollicis longus* - This tendon forms the **lateral (radial) boundary** of the **anatomical snuffbox** along with the **extensor pollicis brevis** [1]. - It primarily **abducts** and **extends** the thumb at the **carpometacarpal joint** [1]. *Extensor pollicis longus* - This tendon forms the **medial (ulnar) boundary** of the **anatomical snuffbox** [1]. - It extends the **interphalangeal joint** of the thumb and contributes to its extension at the metacarpophalangeal and carpometacarpal joints.

Question 6: In a vehicle accident, the musculocutaneous nerve was completely severed, but still the person was able to weakly flex the elbow joint. All of the following muscles are responsible for this flexion, EXCEPT:

A. Flexor carpi ulnaris
B. Flexor carpi radialis
C. Pronator quadratus (Correct Answer)
D. Brachioradialis

Explanation: ***Pronator quadratus*** - The **pronator quadratus** primarily functions in **pronation of the forearm** and has no role in elbow flexion. - It is innervated by the **anterior interosseous nerve**, a branch of the median nerve, and not involved with elbow flexion. *Flexor carpi ulnaris* - While its main actions are **wrist flexion** and **adduction**, it can contribute *weakly* to elbow flexion due to its origin partially spanning the elbow joint. - It is innervated by the **ulnar nerve**. *Flexor carpi radialis* - The **flexor carpi radialis** acts as a primary **flexor of the wrist** and also assists in **abduction of the wrist**. - It provides a *minor* contribution to elbow flexion because it crosses the elbow joint, and is innervated by the **median nerve**. *Brachioradialis* - The **brachioradialis** is a significant elbow flexor, particularly when the forearm is in a **mid-prone position**. - It is innervated by the **radial nerve**, which explains why elbow flexion is still possible despite musculocutaneous nerve damage.

Question 7: If median nerve is injured at the wrist then loss of function of all of the following will take place except

A. Lumbrical muscles to the middle finger
B. Lumbrical muscles to the Index finger
C. Adductor pollicis (Correct Answer)
D. Muscles of the thenar eminence

Explanation: ***Adductor pollicis*** - The **adductor pollicis** muscle is primarily innervated by the **ulnar nerve**, not the median nerve [1]. - A median nerve injury at the wrist would therefore **not affect** the function of the adductor pollicis [1]. *Lumbrical muscles to the middle finger* - The **first and second lumbricals** (to the index and middle fingers) are typically innervated by the **median nerve** [1]. - An injury to the median nerve at the wrist would cause loss of function in these muscles. *Lumbrical muscles to the Index finger* - Similar to the middle finger lumbrical, the **lumbrical muscle to the index finger** is innervated by the **median nerve** [1]. - Its function would be compromised with a median nerve injury at the wrist. *Muscles of the thenar eminence* - Most muscles of the **thenar eminence** (e.g., abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) are innervated by the **recurrent branch of the median nerve** [1]. - An injury to the median nerve at the wrist, which provides this branch, would lead to significant loss of function in these muscles, affecting **thumb abduction, flexion, and opposition** [1].

Question 8: Ulnar nerve injury results in:

A. Pointing index
B. Ape thumb deformity
C. Clawing of fingers (Correct Answer)
D. Wrist drop

Explanation: ***Clawing of fingers*** - An ulnar nerve injury, particularly at the elbow, often leads to **paralysis of the interossei muscles** and the **medial two lumbricals**. [1] - This results in **hyperextension at the metacarpophalangeal joints** and **flexion at the interphalangeal joints** of the 4th and 5th fingers (and sometimes 3rd), creating the characteristic claw hand deformity. [1] *Pointing index* - **Pointing index**, also known as the **sign of benediction** or **preacher's hand**, occurs with **high median nerve lesions** affecting the lateral lumbricals and flexor digitorum superficialis. - The patient is unable to flex the index and middle fingers, especially when attempting to make a fist. *Ape thumb deformity* - **Ape thumb deformity** is caused by a **median nerve injury**, specifically affecting the **thenar muscles** (abductor pollicis brevis, opponens pollicis, and superficial head of flexor pollicis brevis). - This paralysis leads to the thumb being pulled laterally and into the same plane as the other fingers, losing its ability to oppose. *Wrist drop* - **Wrist drop** is a classic sign of **radial nerve injury**, which paralyzes the **extensor muscles of the wrist and fingers**. - This prevents the patient from extending their wrist and metacarpophalangeal joints.

Question 9: Which nerve supplies the area marked as ‘Area B’ in the image?

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

Explanation: ***Radial nerve*** - Area B represents the sensory distribution of the **radial nerve**, specifically its superficial branch. - The radial nerve provides sensory innervation to the **dorsal (back) aspect of the hand** over the radial (lateral) side, including the thumb, index, middle, and radial half of the ring finger up to the proximal interphalangeal joints. - The superficial branch of the radial nerve also innervates the **anatomical snuffbox** and the radial side of the dorsum of the hand. - **Note:** The radial nerve does NOT supply the palmar surface of the hand; its sensory distribution is limited to the dorsal aspect. *Ulnar nerve* - The ulnar nerve provides sensory innervation to the **medial 1.5 fingers** (little finger and ulnar half of ring finger) on both palmar and dorsal aspects. - It also supplies the **hypothenar eminence** and medial portion of the palm and dorsal hand. - This distribution corresponds to **Area C** in the image, not Area B. *Median nerve* - The median nerve provides sensory innervation to the **lateral 3.5 fingers** (thumb, index, middle, and radial half of ring finger) on the **palmar surface**. - It also supplies the **palmar aspect** of these digits and the **nail beds (dorsal tips)** of the same fingers. - This distribution corresponds to **Area A** in the image, not Area B. *Posterior interosseous nerve* - The **posterior interosseous nerve (PIN)** is a **motor branch** of the radial nerve with no cutaneous sensory distribution. - It supplies the extensor muscles of the posterior forearm compartment. - It does not provide sensory innervation to the skin of the hand.

Question 10: Which of the following statements about the anterior compartment of the forearm is correct?

A. Flexor pollicis longus is unipennate. (Correct Answer)
B. The ulnar nerve enters the forearm by passing between the two heads of pronator teres.
C. Flexor digitorum profundus originates from the radius.
D. The median nerve enters the forearm by passing between the two heads of flexor carpi ulnaris.

Explanation: The flexor pollicis longus is unipennate. - The **flexor pollicis longus** muscle has a **unipennate** architecture, meaning its muscle fibers insert obliquely into one side of a central tendon. - This specific arrangement provides efficient force generation for thumb flexion. *The ulnar nerve enters the forearm by passing between the two heads of pronator teres.* - This is **incorrect**. The **ulnar nerve** enters the forearm by passing **between the two heads of flexor carpi ulnaris** (humeral and ulnar heads), not pronator teres. - The nerve that passes between the heads of pronator teres is the **median nerve**. *Flexor digitorum profundus originates from the radius.* - This is **incorrect**. The **flexor digitorum profundus** originates primarily from the **anterior and medial surfaces of the ulna** and the **interosseous membrane**, not from the radius. - The muscle arising from the radius in the anterior compartment is the **flexor pollicis longus**. *The median nerve enters the forearm by passing between the two heads of flexor carpi ulnaris.* - This is **incorrect**. The **median nerve** enters the forearm by passing **between the two heads of pronator teres** (humeral and ulnar heads), not flexor carpi ulnaris [1]. - The nerve that passes between the heads of flexor carpi ulnaris is the **ulnar nerve** [1].

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