Upper Limb Practice Questions

Q: 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:

Pronator quadratus. ***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.

Q: Which tendon is frequently absent in the upper limb?

Palmaris longus. ***Palmaris longus*** - The **palmaris longus** tendon is frequently absent in the upper limb, with reported prevalence rates of absence varying between **10% and 15%** in various populations. - Its absence is generally considered a **normal anatomical variation** and does not typically result in significant functional deficit. - Clinically used as a donor tendon for reconstructive surgeries due to its dispensable nature. *Flexor carpi ulnaris* - The **flexor carpi ulnaris** is a critical muscle for **wrist adduction** and **flexion**, making its absence extremely rare and usually associated with severe developmental anomalies. - Its presence is crucial for the stability and function of the ulnar side of the wrist. *Extensor carpi radialis brevis* - The **extensor carpi radialis brevis** is a primary muscle involved in **wrist extension** and **radial deviation**. - It is consistently present due to its significant role in wrist mechanics, and its absence would severely compromise hand function. *Flexor digitorum profundus* - The **flexor digitorum profundus** is essential for **flexion of the distal interphalangeal joints** of the fingers. - Its absence would result in a profound inability to grasp and manipulate objects, making it an anatomically consistent and vital structure.

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

Adductor pollicis. ***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].

Q: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

Coracoclavicular ligament. ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong extra-articular ligament that connects the **coracoid process** of the scapula to the **inferior surface of the clavicle**, effectively suspending the scapula from the clavicle. - This ligament plays the **primary and crucial role** in transmitting forces from the upper limb through the **scapula and clavicle** to the **axial skeleton**, particularly during weight-bearing activities. - It is the key structure that maintains the connection between the upper limb (via scapula) and the axial skeleton (via clavicle). *Coracoacromial ligament* - The **coracoacromial ligament** forms the roof of the **subacromial space** and is primarily involved in preventing superior displacement of the humeral head. - It does not transmit the weight of the upper limb to the axial skeleton but rather protects structures within the subacromial space by forming the coracoacromial arch. *Costoclavicular ligament* - The **costoclavicular ligament** connects the **first rib to the clavicle**, stabilizing the **sternoclavicular joint**. - While it provides important stability at the sternoclavicular joint (part of the transmission pathway), the primary transmission of upper limb weight occurs through the **coracoclavicular ligament** connecting the scapula to clavicle. *Coracohumeral ligament* - The **coracohumeral ligament** connects the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**, reinforcing the shoulder joint capsule. - It primarily helps support the weight of the upper limb when the arm is adducted, but it does not transmit this weight to the axial skeleton.

Q: Loss of flexion in the interphalangeal joint of thumb in supracondylar fracture is due to involvement of which nerve?

Anterior interosseous. ***Anterior interosseous*** - The **anterior interosseous nerve (AIN)** is a branch of the median nerve and innervates the **flexor pollicis longus (FPL)**, which is responsible for **flexion of the interphalangeal (IP) joint of the thumb**. [1] - A supracondylar fracture of the humerus can compress or injure the AIN, leading to weakness or paralysis of the FPL. - In clinical practice, when isolated FPL weakness occurs, we specifically identify **AIN injury** rather than general median nerve injury. *Median* - While the **anterior interosseous nerve (AIN)** is a branch of the median nerve, the question asks for the **specific nerve involved** in isolated thumb IP joint flexion loss. [1] - A proximal median nerve injury at the supracondylar level would also affect other median nerve-innervated muscles like the **flexor digitorum superficialis**, **pronator teres**, and the thenar muscles (via recurrent motor branch). [1] - The **isolated loss of IP joint flexion of the thumb** indicates a specific injury to the **AIN** rather than the entire median nerve trunk, making "Anterior interosseous" the more precise and correct answer. *Ulnar* - The **ulnar nerve** primarily innervates the **flexor carpi ulnaris** and the ulnar half of the **flexor digitorum profundus**, as well as most intrinsic hand muscles. [1] - Injury to the ulnar nerve would primarily affect **flexion of the distal interphalangeal joints of the 4th and 5th digits** and intrinsic hand muscle function, not thumb IP joint flexion. [1] *Posterior interosseous* - The **posterior interosseous nerve (PIN)** is a deep motor branch of the radial nerve and innervates the **extensor muscles** of the forearm and hand. [1] - Injury to the PIN would result in the inability to **extend the wrist and digits**, which is not consistent with the presented symptom of loss of thumb IP joint flexion.

Q: Which artery becomes the axillary artery at the lateral border of the first rib?

Subclavian. ***Subclavian*** - The **subclavian artery** passes posterior to the clavicle and becomes the axillary artery once it crosses the **lateral border of the first rib**. [1] - This transition marks the beginning of the arterial supply to the upper limb in the axillary region. [1] *Radial* - The **radial artery** is a terminal branch of the brachial artery in the forearm, supplying the lateral forearm and hand. - It does not contribute to the formation of the axillary artery. *Brachial* - The **brachial artery** is a continuation of the axillary artery in the arm, beginning at the inferior border of the teres major muscle. - It does not precede or become the axillary artery. *Ulnar* - The **ulnar artery** is another terminal branch of the brachial artery in the forearm, supplying the medial forearm and hand. - Like the radial artery, it is a distal artery and is not involved in the formation of the axillary artery.

Q: In carpal tunnel syndrome, which nerve is compressed?

Median nerve. ***Median nerve*** - Carpal tunnel syndrome is caused by the **compression of the median nerve** as it passes through the **carpal tunnel** in the wrist [2]. - This compression leads to characteristic symptoms such as pain, numbness, and tingling in the thumb, index finger, middle finger, and radial half of the ring finger [2]. *Anterior interosseous nerve* - The **anterior interosseous nerve** is a branch of the median nerve that arises proximal to the carpal tunnel in the forearm [1]. - Compression of this nerve leads to **anterior interosseous syndrome**, characterized by weakness of the flexor pollicis longus and flexor digitorum profundus (to index finger), with **no sensory deficits** unlike carpal tunnel syndrome [1]. *Ulnar nerve* - The **ulnar nerve** passes through Guyon's canal at the wrist and its compression leads to conditions like ulnar neuropathy or Guyon's canal syndrome. - Ulnar nerve compression affects sensation in the little finger and ulnar half of the ring finger, and weakness of intrinsic hand muscles, distinct from carpal tunnel syndrome symptoms [2]. *Radial nerve* - The **radial nerve** controls muscles in the forearm and hand responsible for wrist and finger extension, and sensation over the back of the hand. - Compression of the radial nerve typically occurs higher up in the arm (e.g., Saturday night palsy) and results in **wrist drop** or sensory deficits on the back of the hand, not within the carpal tunnel.

Q: Which nerve is affected if a patient has weakness in wrist and finger extension?

Radial nerve. ***Radial nerve*** - The **radial nerve** innervates the muscles responsible for **wrist and finger extension**, such as the extensor digitorum and extensor carpi radialis [2]. - Weakness in these movements, often described as **wrist drop**, is a classic sign of radial nerve injury [2]. *Median nerve* - The **median nerve** primarily innervates muscles responsible for **flexion of the wrist and fingers**, as well as movements of the thumb [1],[2]. - Injury to the median nerve would typically result in weakness of thumb opposition, flexion of the index and middle fingers, and sensory deficits over the palmar aspect of the first three and a half digits [1]. *Ulnar nerve* - The **ulnar nerve** innervates most of the **intrinsic hand muscles** that control fine movements of the fingers, particularly abduction and adduction, and also controls flexion of the 4th and 5th digits [2]. - Damage to the ulnar nerve often leads to a "claw hand" deformity, which doesn't primarily manifest as weakness in wrist or finger extension [2]. *Musculocutaneous nerve* - The **musculocutaneous nerve** innervates the **biceps brachii** and brachialis muscles, which are primarily responsible for **elbow flexion**. - Weakness due to musculocutaneous nerve injury would therefore affect elbow flexion, and sensation over the lateral forearm.

Q: A 25-year-old male presents with weakness in his right arm and difficulty lifting it. An MRI reveals a lesion in the lateral cord of the brachial plexus. Which muscle is most likely to be affected?

Biceps brachii. ***Biceps brachii*** - The **lateral cord** of the brachial plexus gives rise to the **musculocutaneous nerve**, which innervates the biceps brachii, coracobrachialis, and brachialis. - The biceps brachii is **entirely dependent** on the musculocutaneous nerve for its innervation. - Injury to the lateral cord would lead to complete weakness in elbow flexion and forearm supination, which aligns with the clinical presentation of weakness and difficulty lifting the arm. *Pectoralis major* - The **pectoralis major** receives **dual innervation** from both the **lateral pectoral nerve** (from lateral cord, C5-C7) and **medial pectoral nerve** (from medial cord, C8-T1). - The lateral pectoral nerve primarily supplies the **clavicular head** of pectoralis major. - While a lateral cord lesion would affect the pectoralis major partially, the muscle would retain some function through its medial pectoral nerve supply, making isolated weakness less likely than with biceps brachii. *Deltoid* - The **deltoid muscle** is innervated by the **axillary nerve**, which arises from the **posterior cord** of the brachial plexus (C5-C6). - A lesion in the lateral cord would not directly affect the deltoid's function. *Triceps brachii* - The **triceps brachii** is innervated by the **radial nerve**, which is a terminal branch of the **posterior cord** of the brachial plexus (C6-C8). - A lesion in the lateral cord would not affect the triceps brachii's function.

Q: Which ligament is primarily involved in stabilizing the acromioclavicular joint?

Coracoclavicular ligament. ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is the primary stabilizer of the **acromioclavicular (AC) joint**, connecting the coracoid process of the scapula to the clavicle. - It consists of two parts, the **conoid** and **trapezoid ligaments**, which prevent superior displacement of the clavicle relative to the acromion. *Coracoacromial ligament* - The **coracoacromial ligament** forms the **coracoacromial arch** and protects the superior aspect of the glenohumeral joint, often implicated in impingement syndromes. - It does not directly stabilize the integrity of the **AC joint** itself against separation. *Glenohumeral ligament* - The **glenohumeral ligaments** (superior, middle, and inferior) are crucial for stabilizing the **glenohumeral joint** (shoulder joint), preventing dislocation of the humerus from the glenoid fossa. - These ligaments are internal to the shoulder joint capsule and do not have a direct role in the stability of the **AC joint**. *Transverse humeral ligament* - The **transverse humeral ligament** spans the bicipital groove of the humerus, holding the **long head of the biceps tendon** in place. - It plays no role in the stability of the **acromioclavicular joint**.

Question 1

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:

Accepted Answer

Pronator quadratus

Answer

Flexor carpi ulnaris

Answer

Flexor carpi radialis

Answer

Brachioradialis

Question 2

Which tendon is frequently absent in the upper limb?

Accepted Answer

Palmaris longus

Answer

Flexor carpi ulnaris

Answer

Extensor carpi radialis brevis

Answer

Flexor digitorum profundus

Question 3

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

Accepted Answer

Adductor pollicis

Answer

Lumbrical muscles to the middle finger

Answer

Lumbrical muscles to the Index finger

Answer

Muscles of the thenar eminence

Question 4

In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

Accepted Answer

Coracoclavicular ligament

Answer

Coracoacromial ligament

Answer

Costoclavicular ligament

Answer

Coracohumeral ligament

Question 5

Loss of flexion in the interphalangeal joint of thumb in supracondylar fracture is due to involvement of which nerve?

Accepted Answer

Anterior interosseous

Answer

Median

Answer

Ulnar

Answer

Posterior interosseous

Question 6

Which artery becomes the axillary artery at the lateral border of the first rib?

Accepted Answer

Subclavian

Answer

Radial

Answer

Brachial

Answer

Ulnar

Question 7

In carpal tunnel syndrome, which nerve is compressed?

Accepted Answer

Median nerve

Answer

Anterior interosseous nerve

Answer

Ulnar nerve

Answer

Radial nerve

Question 8

Which nerve is affected if a patient has weakness in wrist and finger extension?

Accepted Answer

Radial nerve

Answer

Median nerve

Answer

Ulnar nerve

Answer

Musculocutaneous nerve

Question 9

A 25-year-old male presents with weakness in his right arm and difficulty lifting it. An MRI reveals a lesion in the lateral cord of the brachial plexus. Which muscle is most likely to be affected?

Accepted Answer

Biceps brachii

Answer

Pectoralis major

Answer

Triceps brachii

Answer

Deltoid

Question 10

Which ligament is primarily involved in stabilizing the acromioclavicular joint?

Accepted Answer

Coracoclavicular ligament

Answer

Coracoacromial ligament

Answer

Glenohumeral ligament

Answer

Transverse humeral ligament

Upper Limb — MCQs

Upper Limb — MCQs

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