Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 801: Ulnar nerve injury at the wrist involves all of the following except:

A. Palmar interossei
B. Dorsal interossei
C. Adductor pollicis
D. Opponens pollicis (Correct Answer)

Explanation: ***Opponens pollicis*** - The **opponens pollicis** is innervated by the **median nerve**, specifically its recurrent branch, therefore it would not be affected by an ulnar nerve injury at the wrist [1]. - Its action is to **oppose the thumb**, a function preserved if only the ulnar nerve is damaged. *Palmar interossei* - The **palmar interossei** muscles are entirely innervated by the **deep branch of the ulnar nerve** [1]. - Injury to the ulnar nerve at the wrist would therefore directly affect the function of these muscles, leading to loss of **adduction of the fingers**. *Dorsal interossei* - The **dorsal interossei** muscles are also innervated by the **deep branch of the ulnar nerve** [1]. - Damage to the ulnar nerve at the wrist would impair their function, resulting in difficulty with **abduction of the fingers**. *Adductor pollicis* - The **adductor pollicis** muscle is innervated by the **deep branch of the ulnar nerve** [1]. - An ulnar nerve injury at the wrist would cause weakness or paralysis of this muscle, affecting **thumb adduction** and strength [1].

Question 802: The lateral boundary of the cubital fossa is formed by

A. Biceps
B. Brachialis
C. Brachioradialis (Correct Answer)
D. Pronator teres

Explanation: ***Brachioradialis*** - The **brachioradialis muscle** forms the **lateral boundary** of the cubital fossa. - It originates from the lateral supracondylar ridge of the humerus and inserts on the distal radius. - This muscle is a **flexor of the elbow** and assists in bringing the forearm to a neutral position from pronation or supination. *Pronator teres* - The **pronator teres muscle** forms the **medial boundary** of the cubital fossa. - It originates from the medial epicondyle of the humerus and coronoid process of the ulna, inserting on the lateral surface of the radius. - This muscle is primarily responsible for **pronation of the forearm** and assists in elbow flexion. *Brachialis* - The **brachialis muscle** forms part of the **floor of the cubital fossa** (along with the supinator muscle). - It lies deep to the biceps brachii and inserts on the coronoid process and ulnar tuberosity. - It is a powerful **elbow flexor**, acting directly on the ulna. *Biceps* - The **biceps brachii** does not form a boundary of the cubital fossa. - Its **tendon passes through the fossa** as content, while the **bicipital aponeurosis** contributes to the roof. - The biceps is a major flexor and supinator of the forearm.

Question 803: What is the potential anatomical space that can be infected when there is an infection of the index finger?

A. Radial bursa
B. Dorsum of hand
C. Thenar space
D. Mid-palmar space (Correct Answer)

Explanation: ***Mid-palmar space*** - Infections of the index, middle, and ring fingers can track along their **flexor tendon sheaths** and potentially drain into the mid-palmar space due to anatomical connections [1]. - This space is a potential pathway for infection spread as some **flexor tendons** become contiguous with the fibrous septa of the mid-palmar space, allowing pus to collect there [1]. *Radial bursa* - The radial bursa surrounds the **flexor pollicis longus tendon** of the thumb. - An infection of the index finger would not typically spread directly to the radial bursa unless there is a significant, complex, or unusually extensive infection crossing fascial planes. *Thenar space* - The thenar space is located around the **thenar muscles** and communicates with the flexor tendon sheath of the thumb [1]. - Infection of the index finger is unlikely to track into the thenar space, which is primarily associated with thumb infections or deeper palmar infections. *Dorsum of hand* - The dorsum of the hand is usually affected by direct trauma or superficial infections, or due to severe, uncontrolled palmar infections that perforate [1]. - Infection from a **flexor tendon sheath** of the index finger would typically spread within the palmar fascial compartments, rather than directly to the dorsum of the hand.

Question 804: Following an incised wound in the front of the wrist, the subject is unable to oppose the tips of the little finger and the thumb. The nerve(s) involved are

A. Ulnar nerve alone
B. Median nerve alone
C. Median and ulnar nerves (Correct Answer)
D. Radial and ulnar nerves

Explanation: ***Median and ulnar nerves*** - **Opposition of the thumb** (touching the tip of the thumb to the tips of other fingers) is primarily mediated by the **recurrent branch of the median nerve** supplying the thenar muscles (e.g., **opponens pollicis**) [1]. - While the median nerve is crucial for thumb opposition, the inability to oppose the thumb and *little finger* implies involvement of the **ulnar nerve** as well, which innervates the **opponens digiti minimi** muscle, essential for opposing the little finger [2]. *Ulnar nerve alone* - The ulnar nerve innervates most intrinsic hand muscles, including those responsible for adduction of the thumb and flexion of the ring and little fingers [1]. - However, **opposition of the thumb** itself is a specific function of the median nerve, making ulnar nerve involvement alone insufficient to explain the complete described deficit [1]. *Median nerve alone* - The median nerve is essential for **thumb opposition** (via the opponens pollicis) and sensation of the palmar aspect of the thumb, index, middle, and radial half of the ring finger [1]. - While a median nerve injury would impair thumb opposition, it would not directly affect the ability to oppose the little finger, which is innervated by the ulnar nerve [1]. *Radial and ulnar nerves* - The radial nerve primarily supplies muscles for **wrist and finger extension**, and sensation over the dorsal hand [1]. - Involvement of the radial nerve would not typically present with a primary deficit in **thumb and little finger opposition**, which are functions of the median and ulnar nerves, respectively.

Question 805: Movements of supination and pronation take place at all of the following joints, except:

A. Superior radioulnar joint
B. Inferior radioulnar joint
C. Middle radioulnar joint (stabilizing joint)
D. Radio-carpal joint (flexion and extension joint) (Correct Answer)

Explanation: The radio-carpal joint is primarily responsible for flexion, extension, radial deviation, and ulnar deviation of the wrist. While it contributes to wrist movement, it does not directly facilitate the rotational movements of supination and pronation. Superior radioulnar joint - This pivot joint allows the head of the radius to rotate within the anular ligament, essential for supination and pronation. - It works in conjunction with the inferior radioulnar joint to produce these crucial forearm movements. Middle radioulnar joint (stabilizing joint) - While not a synovial joint, the interosseous membrane connecting the radius and ulna, along with the oblique cord, forms the middle radioulnar joint. - This structure primarily acts as a stabilizer and attachment site for muscles, and its fibers transmit forces between the bones during supination and pronation. Inferior radioulnar joint - This pivot joint allows the distal end of the ulna to articulate with the ulnar notch of the radius, enabling the radius to cross over the ulna during pronation. - It is a key component for the coordinated rotational movements of the forearm required for supination and pronation.

Question 806: Which of the following statements about the brachial plexus is true?

A. Formed by spinal nerves C5-C8 and T1 (Correct Answer)
B. The radial nerve arises from the medial cord of the brachial plexus.
C. Injury to the brachial plexus may occur during shoulder dystocia, often affecting the lower trunk.
D. The lower trunk is a common site of injury in brachial plexus trauma.

Explanation: ***Formed by spinal nerve C5- C8 and T1*** - The brachial plexus is indeed formed by the **ventral rami** of spinal nerves **C5, C6, C7, C8, and T1**. - These roots then arrange into **trunks, divisions, cords, and branches** to innervate the upper limb. *The radial nerve arises from the medial cord of the brachial plexus.* - The **radial nerve** is the largest branch of the **posterior cord** of the brachial plexus, not the medial cord. - The **ulnar nerve** and medial root of the median nerve arise from the medial cord. *Injury to the brachial plexus may occur during shoulder dystocia, often affecting the lower trunk.* - **Shoulder dystocia** typically causes injury to the **upper roots (C5-C6)**, leading to **Erb's palsy**, not the lower trunk. - Injury to the lower trunk (C8-T1) is more commonly associated with **Klumpke's palsy**, which is rarer and often due to traction on an abducted arm. *The lower trunk is a common site of injury in brachial plexus trauma.* - The **upper trunk (C5-C6)** is the most common site of injury in brachial plexus trauma, especially in conditions like **Erb's palsy**. - While the lower trunk can be injured, it is much less frequent than upper trunk injuries.

Question 807: The largest branch of the axillary artery is which one of the following?

A. Lateral thoracic artery
B. Subscapular artery (Correct Answer)
C. Superior thoracic artery
D. Thoracoacromial artery

Explanation: ***Subscapular artery*** - The **subscapular artery** is the largest branch of the **axillary artery**, originating from its third part. - It gives off the **circumflex scapular artery** and the **thoracodorsal artery**, both of which supply muscles of the back and shoulder. *Lateral thoracic artery* - The **lateral thoracic artery** typically arises from the second part of the axillary artery and supplies the seratus anterior muscle and pectoral muscles. - While significant, it is generally smaller in caliber and distribution compared to the subscapular artery. *Superior thoracic artery* - The **superior thoracic artery** is usually the first and smallest branch of the **axillary artery**, arising from its first part. - It supplies the first two intercostal spaces and parts of the pectoralis major and minor muscles. *Thoracoacromial artery* - The **thoracoacromial artery** arises from the second part of the axillary artery and divides into pectoral, deltoid, acromial, and clavicular branches. - Although it has multiple branches, its overall size and vascular territory are less extensive than those of the subscapular artery.

Question 808: What is the primary function of the extensor carpi radialis longus muscle?

A. Wrist extensor (Correct Answer)
B. Wrist adductor
C. Extensor of MCP joint
D. Extensor of IP joint

Explanation: ***Wrist extensor*** - The **extensor carpi radialis longus** originates from the **lateral supracondylar ridge of the humerus** and inserts at the **base of the second metacarpal** [2]. - Its primary action is **extension and abduction of the wrist** (along with the extensor carpi radialis brevis) [2]. *Wrist adductor* - **Wrist adduction** (ulnar deviation) is primarily performed by the **flexor carpi ulnaris** and **extensor carpi ulnaris** muscles [2]. - The extensor carpi radialis longus contributes to wrist abduction (radial deviation), not adduction [2]. *Extensor of MCP joint* - **Extension of the metacarpophalangeal (MCP) joints** is mainly carried out by the **extensor digitorum**, **extensor indicis**, and **extensor digiti minimi** muscles [1], [2]. - The extensor carpi radialis longus acts on the wrist joint, not directly on the MCP joints [2], [3]. *Extensor of IP joint* - **Extension of the interphalangeal (IP) joints** is primarily performed by the **lumbricals**, **interossei**, and the more distal actions of the **extensor digitorum** [1]. - The extensor carpi radialis longus does not have attachments or direct actions on the IP joints [2].

Question 809: Physical examination reveals weakness of medial deviation of the wrist (adduction), loss of sensation on the medial side of the hand, and clawing of the fingers. Where is the most likely place of injury?

A. Compression of a nerve passing between the humeral and ulnar heads of origin of flexor carpi ulnaris (Correct Answer)
B. Compression of a nerve passing through the carpal tunnel
C. Compression of a nerve passing between the humeral and ulnar heads of origin of flexor digitorum superficialis
D. Compression of a nerve at Guyon's canal between the pisiform bone and the hook of the hamate.

Explanation: ***Compression of a nerve passing between the humeral and ulnar heads of origin of flexor carpi ulnaris*** - The described symptoms of weakness in **medial deviation of the wrist** (due to paralysis of the **flexor carpi ulnaris**), **loss of sensation on the medial side of the hand**, and **clawing of the fingers** (specifically digits 4 and 5) are classic signs of an **ulnar nerve injury**. - The ulnar nerve passes between the two heads of origin of the **flexor carpi ulnaris (FCU)** in the **cubital tunnel** at the elbow, making this a common site for compression and injury. - This **proximal lesion** affects the ulnar nerve before it gives off the branch to FCU, explaining the weakness in wrist adduction. *Compression of a nerve passing through the carpal tunnel* - Compression in the **carpal tunnel** affects the **median nerve**, leading to symptoms like numbness and tingling in the **thumb, index, middle, and radial half of the ring finger** [1], along with **weakness of thumb abduction** and **opposition**. - This symptom complex does not match the patient's presentation of **ulnar nerve deficit**. *Compression of a nerve passing between the humeral and ulnar heads of origin of flexor digitorum superficialis* - The **flexor digitorum superficialis** is primarily innervated by the **median nerve**, not the ulnar nerve. [2] - Compression in this location would not cause the specific **ulnar nerve** symptoms described. *Compression of a nerve at Guyon's canal between the pisiform bone and the hook of the hamate* - Compression at **Guyon's canal** also affects the **ulnar nerve**, but it typically spares the **flexor carpi ulnaris** and the **dorsal cutaneous branch of the ulnar nerve** (which provides sensation to the dorsomedial hand). [1] - The patient's symptom of **weakness in medial deviation of the wrist** indicates a more proximal lesion affecting the ulnar nerve before the branch to the **FCU**.

Question 810: Regimental badge anesthesia is due to a lesion of:

A. Axillary nerve (Correct Answer)
B. Long thoracic nerve
C. Spinal accessory nerve
D. Musculocutaneous nerve

Explanation: ***Axillary nerve*** - A lesion of the **axillary nerve** causes sensory loss over the lateral part of the shoulder, often described as a **regimental badge anesthesia**, due to damage to its **superior lateral cutaneous nerve** branch. - The axillary nerve can be injured in cases of **anterior shoulder dislocation** or **fractures of the surgical neck of the humerus**. *Long thoracic nerve* - Injury to the long thoracic nerve primarily leads to weakness and paralysis of the **serratus anterior muscle**, causing **scapular winging**. - It does not typically present with sensory deficits on the shoulder. *Spinal accessory nerve* - A lesion of the spinal accessory nerve results in weakness of the **sternocleidomastoid** and **trapezius muscles**, leading to difficulty shrugging the shoulder and turning the head. - This nerve is purely motor and does not carry sensory fibers for the shoulder region. *Musculocutaneous nerve* - A lesion of the musculocutaneous nerve causes weakness in forearm flexion (biceps brachii, brachialis) and sensory loss over the **lateral forearm** (lateral antebrachial cutaneous nerve). - It does not innervate the shoulder for sensation.

Practice by Chapter

Pectoral Region and Axilla

Practice Questions

Arm and Cubital Fossa

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Forearm and Hand

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Joints of Upper Limb

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Nerves of Upper Limb

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Arterial Supply and Venous Drainage

Practice Questions

Lymphatic Drainage

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Muscles and Their Actions

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Applied Anatomy and Clinical Correlations

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Surface Anatomy and Landmarks

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Upper Limb — MCQs

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