Upper Limb Practice Questions

Q: No man's land in palm corresponds to -

Zone II. ***Zone II*** - **Zone II** of the flexor tendons, extending from the distal palmar crease to the mid portion of the middle phalanx, is known as "no man's land" due to the historical difficulty in achieving good outcomes after tendon repair. - This zone houses both the **flexor digitorum superficialis** and **flexor digitorum profundus** tendons within a single fibro-osseous sheath, making repairs complex and prone to adhesions. *Zone I* - **Zone I** extends from the insertion of the **flexor digitorum profundus** (distal to the middle phalanx) to the midportion of the middle phalanx [1]. - Injuries in this zone typically involve only the **profundus tendon**, allowing for more straightforward repair due to lack of the superficialis tendon. *Zone IV* - **Zone IV** constitutes the carpal tunnel, where nine flexor tendons and the median nerve pass through a confined space. - While injuries here can be severe due to potential nerve involvement, they are not typically referred to as "no man's land" in the context of tendon repair due to better outcomes historically compared to Zone II. *Zone III* - **Zone III** extends from the distal end of the carpal tunnel to the beginning of the A1 pulley (distal palmar crease). - This zone is predominantly in the palm and offers more space for tendon repair, leading to better outcomes than Zone II, as the tendons diverge here and are not yet constrained within a common sheath.

Q: Extensor carpi radialis longus is

Extensor and radial deviator of the wrist. ***Extensor and radial deviator of the wrist*** - The **extensor carpi radialis longus (ECRL)** is one of the primary muscles responsible for **extension of the wrist**. [1] - Due to its anatomical position on the radial side of the forearm, it also contributes significantly to **radial deviation** (abduction) of the wrist. [1] *Weak extensor of the wrist* - While it is an extensor, the ECRL is considered a **strong extensor** of the wrist, especially when acting with other extensors like the Extensor Carpi Radialis Brevis (ECRB). [1] - Its strength is crucial for tasks requiring **grip and wrist stabilization**. *Extensor and ulnar deviator of the wrist* - The ECRL performs wrist extension but causes **radial deviation**, not ulnar deviation. [1] - **Ulnar deviation** is primarily performed by the **extensor carpi ulnaris** and **flexor carpi ulnaris**. *Injured in Posterior interosseous nerve injury* - The ECRL is innervated by the **radial nerve** **before** it divides into the superficial and deep (posterior interosseous) branches. [2] - Therefore, ECRL function is typically **spared in isolated posterior interosseous nerve injuries**, which mainly affect muscles in the deep compartment of the posterior forearm. [2]

Q: In interphalangeal joint, the capsule is thinnest on the -

Dorsal side. ***Dorsal side*** - The interphalangeal joint capsule is thinnest on the **dorsal side** due to the need for flexibility during **flexion** and the presence of the **extensor tendon** covering this aspect. - This anatomical arrangement allows for a greater range of motion for finger flexion, as the dorsal capsule offers less resistance. *Palmar side* - The capsule on the palmar side is reinforced by the **volar plate** and accessory **collateral ligaments**, making it thicker and stronger to prevent hyperextension. - This thickening provides crucial stability to the joint during gripping and other hand functions. *Medial side* - The medial side of the interphalangeal joint capsule is reinforced by the **collateral ligament**, which provides significant stability against sideways forces. - This ligament helps prevent excessive abduction or adduction of the finger. *Lateral side* - Similar to the medial side, the lateral aspect of the joint capsule is strengthened by the **collateral ligament**. - This reinforcement is vital for maintaining joint integrity and preventing dislocation during lateral stresses.

Q: Partial claw hand is caused by lesion involving the:

Ulnar nerve. ***Ulnar nerve*** - A lesion of the **ulnar nerve** causes a **partial claw hand** (also called "ulnar claw") because the **medial two lumbricals** (which flex the MCP joints and extend the IP joints of the 4th and 5th digits) and the **interossei** are paralyzed [1]. - This leads to hyperextension at the **metacarpophalangeal (MCP) joints** and flexion at the **interphalangeal (IP) joints** of the **4th and 5th fingers only** (hence "partial") [1]. - The lateral two fingers (index and middle) are spared because their lumbricals are supplied by the median nerve [1]. *Anterior interosseous nerve* - Injury to the **anterior interosseous nerve** primarily affects the **flexor pollicis longus**, **flexor digitorum profundus** (index and middle fingers), and **pronator quadratus**. - This results in the inability to make an "OK" sign (pinch sign) and does not typically cause a claw hand deformity. *Radial nerve* - A **radial nerve** lesion leads to **wrist drop** and the inability to extend the wrist and fingers. - This deformity is distinct from a claw hand, which involves hyperextension at the MCP joints and flexion at the IP joints. *Median nerve* - A **median nerve** lesion results in a "hand of benediction" or "ape hand" deformity, affecting the **thenar muscles** and the **lateral two lumbricals** [1]. - This involves paralysis of the thumb's opposition and the inability to flex the index and middle fingers, not the characteristic clawing of the 4th and 5th digits.

Q: In cubital fossa, which structure is the most medial

Median nerve. ***Median nerve*** - The **median nerve** is the most medial structure within the cubital fossa, positioned medial to the brachial artery. - Its medial position is crucial for understanding its vulnerability to injury in this region, especially during venipuncture or supracondylar fractures of the humerus. - It runs along the medial border of the brachial artery throughout its course in the cubital fossa. *Brachial artery* - The **brachial artery** lies lateral to the median nerve and medial to the biceps tendon in the cubital fossa. - It is a major vessel used for blood pressure measurement and is a common site for arterial punctures. - It bifurcates into radial and ulnar arteries at the level of the radial neck. *Radial nerve* - The **radial nerve** is the most lateral structure in the cubital fossa, positioned deep to the brachioradialis muscle. - It divides into deep (posterior interosseous) and superficial branches just distal to the lateral epicondyle. - The deep branch is at risk during surgical approaches to the radial head. *Biceps tendon* - The **biceps tendon** is located centrally within the cubital fossa, lying lateral to the brachial artery. - It inserts into the radial tuberosity and is an important landmark for palpation in the fossa. - The bicipital aponeurosis (lacertus fibrosus) arises from its medial side and protects the median nerve and brachial artery.

Q: The commonly injured carpal bone next to the scaphoid is:

Triquetrum. ***Triquetrum*** - The **scaphoid** is the most commonly fractured carpal bone [1]. After the scaphoid, the **triquetrum** is the next most frequently injured carpal bone. - Injuries to the triquetrum often occur due to **hyperextension of the wrist** with ulnar deviation, typically resulting from falls onto an outstretched hand (FOOSH). *Trapezoid* - The trapezoid is a carpal bone in the **distal row** of the wrist, located medial to the trapezium and lateral to the capitate. - While it can be injured, it is **much less commonly fractured** than the scaphoid or triquetrum due to its protected position and strong ligamentous attachments. *Capitate* - The capitate is the **largest carpal bone** and the central bone in the distal row of the carpus. - Fractures of the capitate are **relatively rare**, often occurring in conjunction with other carpal injuries or dislocations, and are less frequent than triquetral fractures. *Lunate* - The lunate bone is located in the **proximal row** of carpal bones, articulating with the radius and contributing to wrist stability. - While the lunate is crucial in wrist mechanics, it is more commonly associated with **dislocations** or **Kienböck's disease** (avascular necrosis) rather than simple fractures, and is not the next most common fracture after the scaphoid.

Q: A patient presents with winging of the scapula. Which nerve is most likely involved?

Long thoracic nerve. ### Long thoracic nerve - The long thoracic nerve innervates the **serratus anterior muscle**, which is responsible for scapular protraction and upward rotation. - Damage to this nerve paralyzes the serratus anterior, leading to **winging of the scapula** as the medial border and inferior angle of the scapula become prominent. ### Thoracodorsal nerve - This nerve supplies the **latissimus dorsi muscle**, which is involved in adduction, extension, and internal rotation of the humerus [1]. - Injury to the thoracodorsal nerve would weaken movements of the shoulder, but not directly cause **scapular winging**. ### Lateral pectoral nerve - The lateral pectoral nerve innervates the **pectoralis major muscle** (upper and middle parts) [1]. - Damage to this nerve primarily affects shoulder adduction and internal rotation, but does not result in **scapular winging**. ### Musculocutaneous nerve - This nerve innervates the **coracobrachialis**, **biceps brachii**, and **brachialis muscles** in the anterior compartment of the arm. - Injury to the musculocutaneous nerve would impair elbow flexion and forearm supination, and is unrelated to **scapular movement**.

Q: Only finger drop and no wrist drop in Posterior interosseous nerve injury, is due to sparing of

Extensor carpi radialis longus. ***Extensor carpi radialis longus*** - The **extensor carpi radialis longus (ECRL)** is innervated by the **radial nerve proper** before its division into superficial and deep branches. - Spared ECRL function allows for continued **wrist extension**, preventing a full wrist drop, although finger extension is lost due to **posterior interosseous nerve (PIN)** damage. *Triceps* - The **triceps** muscle is innervated much higher up by the **radial nerve** in the arm, prior to the elbow joint. - Injury to the PIN, which is a branch of the radial nerve below the elbow, would not affect triceps function. *Anconeus* - The **anconeus** muscle receives its innervation from the **radial nerve** proximal to the division into the superficial and deep branches. - Thus, it would usually be spared in an isolated **posterior interosseous nerve** injury. *Brachioradialis* - The **brachioradialis** muscle is innervated by the **radial nerve** in the upper arm, before the deep branch (PIN) originates. - Therefore, its function in elbow flexion would be preserved in a purely PIN lesion.

Q: Injury to the Ulnar nerve at the wrist causes paralysis of-

Adduction of the thumb. ***Adduction of the thumb*** - The **adductor pollicis muscle** is innervated by the deep branch of the **ulnar nerve**. Injury to the ulnar nerve at the wrist would paralyze this muscle, leading to an inability to powerfully **adduct the thumb** [1]. - Weakness in thumb adduction is a hallmark sign of ulnar nerve palsy, often demonstrated by **Froment's sign** where the patient compensates by flexing the IP joint of the thumb using the median-innervated flexor pollicis longus [1]. *Abduction of the carpo-metacarpal joint of the thumb* - **Abduction of the thumb** at the **CMC joint** is primarily performed by the **abductor pollicis longus** (radial nerve) and the **abductor pollicis brevis** (median nerve). - An **ulnar nerve injury** would not directly affect these muscles, thus preserving the ability to abduct the thumb. *Apposition of the thumb* - **Apposition** (opposition) of the thumb, which involves composite movements of abduction, flexion, and medial rotation, is primarily carried out by the **opponens pollicis muscle**, which is innervated by the **median nerve** [1]. - While other muscles contribute, the core movement of opposition is **median nerve dependent**, not ulnar nerve dependent. *Flexion of the MCP joint of the middle finger* - **Flexion of the MCP joints** is primarily controlled by the **lumbricals** and **interossei muscles**. - The **lumbricals** of the middle finger are typically innervated by the **median nerve**, while the **palmar and dorsal interossei** are supplied by the **ulnar nerve** [1]. An ulnar nerve injury would affect the interossei, but not all flexion of the MCP joint of the middle finger is lost, and lumbricals can still flex it.

Q: Strongest supinator muscle is -

Biceps. ***Biceps*** - The **biceps brachii** is the most powerful supinator of the forearm, especially when the elbow is flexed at 90 degrees. - Its long lever arm and direct attachment to the **radial tuberosity** give it significant mechanical advantage for supination. *Brachialis* - The **brachialis** is the primary flexor of the elbow joint and plays a minimal role in forearm supination. - Its insertion on the **ulna** means it has no direct action on the rotation of the radius. *Supinator* - The **supinator muscle** is a primary supinator of the forearm, particularly when the elbow is extended or during slow, unresisted supination. - However, it is less powerful than the biceps brachii, especially against resistance or with the elbow flexed. *Brachioradialis* - The **brachioradialis** is primarily a flexor of the elbow, particularly active during rapid movements or against resistance. - Its main action is to bring the forearm to a neutral position between pronation and supination, not to strongly supinate.

Question 1

No man's land in palm corresponds to -

Accepted Answer

Zone II

Answer

Zone I

Answer

Zone IV

Answer

Zone III

Question 2

Extensor carpi radialis longus is

Accepted Answer

Extensor and radial deviator of the wrist

Answer

Weak extensor of the wrist

Answer

Extensor and ulnar deviator of the wrist

Answer

Injured in Posterior interosseous nerve injury

Question 3

In interphalangeal joint, the capsule is thinnest on the -

Accepted Answer

Dorsal side

Answer

Palmar side

Answer

Medial side

Answer

Lateral side

Question 4

Partial claw hand is caused by lesion involving the:

Accepted Answer

Ulnar nerve

Answer

Anterior interosseous nerve

Answer

Radial nerve

Answer

Median nerve

Question 5

In cubital fossa, which structure is the most medial

Accepted Answer

Median nerve

Answer

Brachial artery

Answer

Radial nerve

Answer

Biceps tendon

Question 6

The commonly injured carpal bone next to the scaphoid is:

Accepted Answer

Triquetrum

Answer

Trapezoid

Answer

Capitate

Answer

Lunate

Question 7

A patient presents with winging of the scapula. Which nerve is most likely involved?

Accepted Answer

Long thoracic nerve

Answer

Thoracodorsal nerve

Answer

Lateral pectoral nerve

Answer

Musculocutaneous nerve

Question 8

Only finger drop and no wrist drop in Posterior interosseous nerve injury, is due to sparing of

Accepted Answer

Extensor carpi radialis longus

Answer

Triceps

Answer

Anconeus

Answer

Brachioradialis

Question 9

Injury to the Ulnar nerve at the wrist causes paralysis of-

Accepted Answer

Adduction of the thumb

Answer

Abduction of the carpo-metacarpal joint of the thumb

Answer

Apposition of the thumb

Answer

Flexion of the MCP joint of the middle finger

Question 10

Strongest supinator muscle is -

Accepted Answer

Biceps

Answer

Brachialis

Answer

Supinator

Answer

Brachioradialis

Upper Limb — MCQs

Upper Limb — MCQs

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