Upper Limb Practice Questions

Q: Axillary Nerve Injury is least likely in:

Improper use of crutch. Improper use of crutch - **Improper crutch usage** primarily affects the **radial nerve** in the axilla due to direct compression against the humerus. - While it can cause nerve damage, the **axillary nerve** is less commonly injured by crutch use as it lies more distally and laterally, protected by the deltoid muscle. *Intramuscular injection* - Injections in the **deltoid muscle** can directly injure the **axillary nerve** due to its superficial course around the surgical neck of the humerus. [1] - This risk is higher with improper technique or very deep injections, leading to **deltoid weakness** and **sensory loss** over the lateral shoulder. *Shoulder dislocation* - **Anterior shoulder dislocations** are a common cause of **axillary nerve injury** due to the stretching or tearing of the nerve as the humeral head displaces. - The nerve wraps around the **surgical neck of the humerus**, making it vulnerable during dislocation. *Fracture proximal humerus* - Fractures of the **surgical neck of the humerus** often lead to **axillary nerve damage** because the nerve lies in close proximity to this region. - The blunt force or displacement of bone fragments can directly compress or lacerate the nerve.

Q: What is the MOST characteristic feature of low ulnar nerve palsy? a) Claw hand b) Sensory loss of medial four digits c) Weakness of grip d) Inability to abduct the thumb

Claw hand. ***Claw hand*** - A **claw hand** (specifically an **ulnar claw**) is a classic sign of low ulnar nerve palsy, resulting from paralysis of the **interossei** and **medial two lumbricals**. - This leads to hyperextension at the **metacarpophalangeal (MCP) joints** and flexion at the **interphalangeal (IP) joints** of the 4th and 5th digits. *Sensory loss of lateral three digits* - Sensory loss in the **lateral three digits** (thumb, index, middle fingers) is characteristic of **median nerve palsy**, not ulnar nerve palsy. - The ulnar nerve supplies sensation to the **medial 1.5 digits** (half of the ring finger and the little finger). *Weakness of wrist flexion* - While the ulnar nerve contributes to wrist flexion via the **flexor carpi ulnaris**, significant weakness in overall wrist flexion alone is not its most characteristic distinguishing feature. - The median nerve and radial nerve also play crucial roles in wrist flexion and extension, respectively. *Inability to oppose the thumb* - The inability to **oppose the thumb** (touch the thumb to the tips of the other fingers) is a hallmark of **median nerve palsy**, specifically affecting the **opponens pollicis** muscle. - The ulnar nerve primarily affects adduction of the thumb via the **adductor pollicis**. *Inability to extend at M.C.P. joint* - The inability to extend at the **metacarpophalangeal (MCP) joint** is more characteristic of **radial nerve palsy**, which affects the **extensor muscles** of the fingers. - Ulnar nerve palsy causes increased extension at the MCP joints due to paralysis of the lumbricals and interossei.

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.

Q: All of the following are affected in Erb's palsy EXCEPT

Lower trunk of brachial plexus. ***Lower trunk of brachial plexus*** - Erb's palsy primarily involves the **upper trunk** of the brachial plexus (C5-C6 nerve roots), which affects muscles innervated by these roots. - The **lower trunk** (C8-T1 nerve roots) is typically spared in Erb's palsy, distinguishing it from **Klumpke's palsy**. *Dorsal scapular nerve* - The dorsal scapular nerve originates from the **C5 root of the brachial plexus** and innervates the **rhomboids** and **levator scapulae**. - As Erb's palsy involves the C5 root, the dorsal scapular nerve and its associated muscles are commonly affected. *Suprascapular nerve* - The suprascapular nerve arises from the **upper trunk** of the brachial plexus (C5-C6) and innervates the **supraspinatus** and **infraspinatus** muscles. - Damage to the upper trunk in Erb's palsy directly impacts the function of the suprascapular nerve. *Upper trunk of brachial plexus* - Erb's palsy is specifically defined by an injury to the **upper trunk** of the brachial plexus, involving the C5 and C6 nerve roots. - This damage leads to weakness in muscles such as the **deltoid**, **biceps**, and **brachialis**, resulting in the characteristic **"waiter's tip"** posture.

Q: Traumatic anterior dislocation of shoulder with sensory loss in lateral side of forearm and weakness of flexion of elbow joint, most likely injured nerve is:

Musculocutaneous nerve. ***Musculocutaneous nerve*** - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion**. - It also provides sensory innervation to the **lateral forearm** via the **lateral cutaneous nerve of the forearm**, explaining the sensory loss described. *Ulnar nerve* - The ulnar nerve primarily innervates muscles of the **hand** and gives sensory supply to the medial 1 and 1/2 digits. - Its injury would typically lead to weakness in **finger adduction/abduction** and sensory loss in the medial hand, not the lateral forearm. *Axillary nerve* - The axillary nerve innervates the **deltoid** and **teres minor** muscles, causing weakness in **shoulder abduction** and external rotation upon injury. - Sensory loss would be over the **regimental badge area** (lateral shoulder), not the lateral forearm. *Radial nerve* - The radial nerve innervates the **extensor muscles of the wrist and fingers**, and the triceps. - Injury would result in **wrist drop** and sensory loss over the **posterior arm, forearm, and hand**, not lateral forearm sensory loss.

Q: Posterolateral Anconeus triangle is formed by all, except

Medial epicondyle. ***Medial epicondyle*** - The **medial epicondyle** is part of the **medial column** of the distal humerus and is therefore not involved in forming the posterolateral anconeus triangle. - This triangle is specifically defined by structures on the posterior and lateral aspects of the elbow joint. *Lateral epicondyle* - The **lateral epicondyle** forms the **apex** or superior boundary of the anconeus triangle when viewed from the posterior aspect. - It serves as a key bony landmark for the posterolateral region of the elbow. *Olecranon* - The **olecranon** of the ulna constitutes the **inferomedial** boundary of the anconeus triangle. - It forms a prominent point on the posterior aspect of the elbow. *Head of the radius* - The **head of the radius** forms the **inferior-lateral** boundary of the anconeus triangle. - It is an important structure for defining the lateral and distal limits of this anatomical region.

Question 1

Axillary Nerve Injury is least likely in:

Accepted Answer

Improper use of crutch

Answer

Intramuscular injection

Answer

Shoulder dislocation

Answer

Fracture proximal humerus

Question 2

What is the MOST characteristic feature of low ulnar nerve palsy? a) Claw hand b) Sensory loss of medial four digits c) Weakness of grip d) Inability to abduct the thumb

Accepted Answer

Claw hand

Answer

Sensory loss of lateral three digits

Answer

Weakness of wrist flexion

Answer

Inability to oppose the thumb

Answer

Inability to extend at M.C.P. joint

Question 3

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 4

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 5

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 6

Strongest supinator muscle is -

Accepted Answer

Biceps

Answer

Brachialis

Answer

Supinator

Answer

Brachioradialis

Question 7

A 29-year-old patient comes in; he cannot flex the distal interphalangeal (DIP) joint of the index finger. His physician determines that he has nerve damage from a supracondylar fracture. Which of the following conditions is also a symptom of this nerve damage?

Accepted Answer

Loss of sensation over the distal part of the second digit

Answer

Paralysis of all the thumb muscles

Answer

Atrophy of the hypothenar eminence

Answer

Inability to flex the DIP joint of the ring finger

Question 8

All of the following are affected in Erb's palsy EXCEPT

Accepted Answer

Lower trunk of brachial plexus

Answer

Dorsal scapular nerve

Answer

Suprascapular nerve

Answer

Upper trunk of brachial plexus

Question 9

Traumatic anterior dislocation of shoulder with sensory loss in lateral side of forearm and weakness of flexion of elbow joint, most likely injured nerve is:

Accepted Answer

Musculocutaneous nerve

Answer

Ulnar nerve

Answer

Axillary nerve

Answer

Radial nerve

Question 10

Posterolateral Anconeus triangle is formed by all, except

Accepted Answer

Medial epicondyle

Answer

Lateral epicondyle

Answer

Olecranon

Answer

Head of the radius

Upper Limb — MCQs

Upper Limb — MCQs

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