Upper Limb Practice Questions

Q: Which muscle primarily forms the posterior wall of the axilla?

Subscapularis. ***Subscapularis*** - The **subscapularis** muscle forms the **largest and superior part of the posterior wall of the axilla**. - It arises from the subscapular fossa on the anterior surface of the scapula and its broad surface creates the majority of the posterior axillary wall. - It is a key component of the rotator cuff and passes through the axilla to insert on the lesser tubercle of the humerus. *Latissimus dorsi* - The **latissimus dorsi** contributes to the **inferior part of the posterior wall** of the axilla [1]. - Along with teres major, it forms the lower border of the posterior wall, but does not form the primary or largest component [1]. *Teres major* - The **teres major** also forms part of the **inferior portion of the posterior wall**, lying superior to latissimus dorsi. - Together with latissimus dorsi, it contributes to the lower aspect of the posterior wall. *Pectoralis major* - The **pectoralis major** forms the **anterior wall of the axilla**, not the posterior wall [1]. - It is a large, fan-shaped muscle essential for adduction and medial rotation of the humerus [1].

Q: Identify the marked muscle ‘A’ in the diagram.

Extensor carpi radialis longus. ***Extensor carpi radialis longus*** - Muscle 'A' originates from the **lateral supracondylar ridge of the humerus** and inserts into the base of the second metacarpal, consistent with the **extensor carpi radialis longus (ECRL)**. - The ECRL is part of the **superficial layer** of the posterior compartment of the forearm, responsible for **extension and abduction of the wrist**. *Brachioradialis* - While the brachioradialis also originates from the lateral supracondylar ridge, it is typically more superficial and inserts onto the **styloid process of the radius**, not the metacarpals. - Its primary action is **flexion of the elbow**, rather than wrist extension, and its belly is more anterior relative to the ECRL in this view. *Flexor carpi radialis* - This muscle is located in the **anterior compartment of the forearm** and functions as a **wrist flexor and abductor**. - It originates from the medial epicondyle and inserts into the base of the second and third metacarpals, completely different from the muscle marked 'A'. *Extensor carpi ulnaris* - The extensor carpi ulnaris (ECU) is found on the **ulnar side of the posterior forearm**, originating from the lateral epicondyle and posterior ulna, and inserting into the base of the fifth metacarpal. - Its position is medial to the marked muscle 'A', and it functions to **extend and adduct the wrist**.

Q: The patient is presenting with pain around the base of the thumb. Which tendons are likely involved?

APL & EPB. ***APL & EPB*** - Pain around the base of the thumb, especially with movement, is characteristic of De Quervain's tenosynovitis [1]. This condition involves the **abductor pollicis longus (APL)** and **extensor pollicis brevis (EPB)** tendons [1]. - These two tendons share a common synovial sheath as they pass through the first dorsal compartment of the wrist, making them susceptible to inflammation and friction [1]. *APB & EPL* - **APB (Abductor Pollicis Brevis)** is an intrinsic hand muscle found in the thenar eminence, primarily involved in thumb abduction, and is not typically associated with De Quervain's tenosynovitis. - **EPL (Extensor Pollicis Longus)** is part of the third dorsal compartment and its tendon crosses over the other thumb tendons, and is not inflamed in De Quervain's tenosynovitis. *APB & EPB* - As mentioned, **APB (Abductor Pollicis Brevis)** is an intrinsic hand muscle, not involved in De Quervain's tenosynovitis. - While **EPB (Extensor Pollicis Brevis)** is involved, its combination with APB incorrectly identifies the primary tendons affected in the first dorsal compartment. *APL & EPL* - **APL (Abductor Pollicis Longus)** is one of the correct tendons involved. - **EPL (Extensor Pollicis Longus)** belongs to the third dorsal compartment of the wrist and is not typically affected in De Quervain's tenosynovitis, differentiating it from the tendons in the first dorsal compartment [1].

Q: The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?

All of the above anatomical structures.. ***All of the above anatomical structures.*** - The image highlights the **anatomical snuffbox**, a triangular depression on the radial dorsal aspect of the hand. Its boundaries are formed by the tendons of the **extensor pollicis longus muscle** (ulnar side), and the **abductor pollicis longus** and **extensor pollicis brevis muscles** (radial side). - The **styloid process of the radius** forms the floor of the anatomical snuffbox along with the scaphoid and trapezium bones. All the options listed are key anatomical features associated with this region. *Extensor pollicis longus muscle.* - This muscle forms the **ulnar (medial) border** of the anatomical snuffbox. - Its tendon can be palpated during **thumb extension** and contributes to the overall structure of the highlighted area. *Abductor pollicis longus muscle.* - This muscle, along with the extensor pollicis brevis, forms the **radial (lateral) border** of the anatomical snuffbox. - Its tendon is visible and palpable on the radial side of the highlighted region when the thumb is abducted. *Styloid process of the radius.* - This bony prominence is located at the **distal end of the radius** on the radial side of the wrist. - It forms part of the **proximal floor** of the anatomical snuffbox, contributing to its definition.

Q: Which intrinsic muscles of the hand are paralyzed if there is hyperextension of the metacarpophalangeal joint and flexion of the interphalangeal joint?

Interossei and lumbricals (both). ***Interossei and lumbricals (both)*** - Paralysis of the **interossei and lumbricals** results in an inability to flex the metacarpophalangeal (MCP) joints and extend the interphalangeal (IP) joints [1]. - This leads to the characteristic "claw hand" deformity, which includes **hyperextension of the MCP joints** and **flexion of the IP joints**. *Thenar muscles* - The thenar muscles (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) are primarily responsible for movements of the **thumb** [1]. - Their paralysis would affect thumb function (e.g., opposition, abduction) but not directly cause the described deformity in the other digits. *Palmaris brevis* - The palmaris brevis tenses the skin of the palm and helps to deepen the hollow of the hand [1]. - Its paralysis would not have a significant impact on joint positioning or lead to a "claw hand" deformity. *Hypothenar muscles* - The hypothenar muscles (abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi) control movements of the **little finger** [1]. - Paralysis of these muscles would affect the little finger's function but would not cause the clawing pattern across all affected digits.

Q: Identify the muscles responsible for scapular retraction and elevation. What is their nerve supply?

Rhomboids and Levator Scapulae - Dorsal scapular nerve. ***Rhomboids and Levator Scapulae - Dorsal scapular nerve*** - The **rhomboid major** and **rhomboid minor** muscles are primarily responsible for **scapular retraction** (pulling the scapula towards the spine). - The **levator scapulae** muscle primarily acts to **elevate the scapula**. Both the rhomboids and levator scapulae are innervated by the **dorsal scapular nerve**. *Supraspinatus and Infraspinatus - Suprascapular nerve* - The **supraspinatus** muscle is involved in initial **abduction of the arm**, while the **infraspinatus** is involved in **external rotation** of the arm. - Both are innervated by the **suprascapular nerve** but are not the primary muscles for scapular retraction and elevation. *Serratus Anterior - Long thoracic nerve* - The **serratus anterior** muscle is primarily responsible for **protraction of the scapula** (pulling it forward) and stabilizing the scapula against the thoracic wall. - It is innervated by the **long thoracic nerve**, and its paralysis leads to **winged scapula**. *Latissimus Dorsi - Thoracodorsal nerve* - The **latissimus dorsi** is a large muscle of the back primarily involved in **adduction**, **extension**, and **internal rotation of the arm** [1]. - It is supplied by the **thoracodorsal nerve** and does not primarily contribute to scapular retraction or elevation [1].

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

Radial nerve. ***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.

Q: What is the nerve supply of the structure marked in the image?

Median nerve. ***Median nerve*** - The image likely points to one of the **thenar muscles** (e.g., abductor pollicis brevis, opponens pollicis, or superficial head of flexor pollicis brevis), which are primarily supplied by the **recurrent branch of the median nerve**. - The median nerve is crucial for **fine motor control** and **sensation** in the hand, particularly in the thenar region and radial digits. *Posterior interosseous nerve* - The posterior interosseous nerve is a branch of the **radial nerve** and primarily innervates muscles in the **posterior compartment of the forearm**, responsible for wrist and finger extension. - It does not innervate the intrinsic muscles of the thenar eminence. *Ulnar nerve* - The ulnar nerve mainly supplies most of the **intrinsic hand muscles** (e.g., hypothenar muscles, interossei, adductor pollicis), but crucially **not** the majority of the thenar muscles identified in this context. - Its motor distribution is primarily to the ulnar side of the hand. *Anterior interosseous nerve* - The anterior interosseous nerve is a branch of the **median nerve** that supplies deep muscles in the **anterior compartment of the forearm**, such as the **flexor pollicis longus**, pronator quadratus, and part of flexor digitorum profundus. - It does not supply the intrinsic muscles of the thenar eminence in the hand.

Q: What is the function of the Extensor Carpi Radialis Longus?

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 wrist **extension** [1]. - It also contributes significantly to **radial deviation** of the wrist [1]. - The ECRL works synergistically with the **Extensor Carpi Radialis Brevis (ECRB)** to produce powerful wrist extension with radial deviation [1]. *Extensor and ulnar deviator of the wrist* - This describes the action of the **Extensor Carpi Ulnaris (ECU)**, not the ECRL [1]. - The ECRL performs **radial deviation**, not ulnar deviation. *Flexor and radial deviator of the wrist* - This describes the action of the **Flexor Carpi Radialis (FCR)**, not the ECRL. - While both muscles cause radial deviation, the ECRL is an **extensor**, not a flexor. *Weak extensor of the wrist* - The **ECRL** is a **powerful primary extensor** of the wrist, especially when combined with the **Extensor Carpi Radialis Brevis (ECRB)** [1]. - It is one of the strongest wrist extensors and is not considered weak.

Q: Wrist drop is caused by injury to which nerve?

Radial nerve. ***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 1

Which muscle primarily forms the posterior wall of the axilla?

Accepted Answer

Subscapularis

Answer

Latissimus dorsi

Answer

Teres major

Answer

Pectoralis major

Question 2

Identify the marked muscle ‘A’ in the diagram.

Accepted Answer

Extensor carpi radialis longus

Answer

Brachioradialis

Answer

Flexor carpi radialis

Answer

Extensor carpi ulnaris

Question 3

The patient is presenting with pain around the base of the thumb. Which tendons are likely involved?

Accepted Answer

APL & EPB

Answer

APB & EPL

Answer

APB & EPB

Answer

APL & EPL

Question 4

The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?

Accepted Answer

All of the above anatomical structures.

Answer

Abductor pollicis longus muscle.

Answer

Styloid process of the radius.

Answer

Extensor pollicis longus muscle.

Question 5

Which intrinsic muscles of the hand are paralyzed if there is hyperextension of the metacarpophalangeal joint and flexion of the interphalangeal joint?

Accepted Answer

Interossei and lumbricals (both)

Answer

Thenar muscles

Answer

Hypothenar muscles

Answer

Palmaris brevis

Question 6

Identify the muscles responsible for scapular retraction and elevation. What is their nerve supply?

Accepted Answer

Rhomboids and Levator Scapulae - Dorsal scapular nerve

Answer

Supraspinatus and Infraspinatus - Suprascapular nerve

Answer

Latissimus Dorsi - Thoracodorsal nerve

Answer

Serratus Anterior - Long thoracic nerve

Question 7

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

Accepted Answer

Radial nerve

Answer

Ulnar nerve

Answer

Median nerve

Answer

Posterior interosseous nerve

Question 8

What is the nerve supply of the structure marked in the image?

Accepted Answer

Median nerve

Answer

Posterior interosseous nerve

Answer

Ulnar nerve

Answer

Anterior interosseous nerve

Question 9

What is the function of the Extensor Carpi Radialis Longus?

Accepted Answer

Extensor and radial deviator of the wrist

Answer

Extensor and ulnar deviator of the wrist

Answer

Flexor and radial deviator of the wrist

Answer

Weak extensor of the wrist

Question 10

Wrist drop is caused by injury to which nerve?

Accepted Answer

Radial nerve

Answer

Ulnar nerve

Answer

Median nerve

Answer

Axillary nerve

Upper Limb — MCQs

Upper Limb — MCQs

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