Upper Limb Practice Questions

Q: A 35-year-old patient presents with weakness in wrist flexion and numbness in the little finger following elbow trauma. Which nerve is most likely to be affected?

Ulnar nerve. ***Ulnar nerve*** - The **ulnar nerve** innervates the **flexor carpi ulnaris** and the medial half of the **flexor digitorum profundus**, responsible for wrist flexion and flexion of the 4th and 5th digits. [1] - It also provides sensory innervation to the **little finger** and the ulnar half of the ring finger, explaining the reported numbness. [1] The **cubital tunnel** at the elbow is a common site of ulnar nerve compression or injury following trauma. *Median nerve* - The **median nerve** primarily innervates the forearm flexors (excluding the flexor carpi ulnaris and medial flexor digitorum profundus) and most of the thenar muscles. - Sensory innervation of the **median nerve** includes the thumb, index finger, middle finger, and radial half of the ring finger. [1] Injury would typically affect these areas and spare the little finger. *Radial nerve* - The **radial nerve** is responsible for **wrist and finger extension**, not flexion. - Injury to the **radial nerve** would result in **wrist drop** and sensory deficits over the dorsum of the hand, not numbness in the little finger. *Musculocutaneous nerve* - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion** and forearm supination. - It provides sensory innervation to the lateral forearm, but not the little finger or wrist flexion.

Q: A 35-year-old female with carpal tunnel syndrome undergoes surgical release. Which structure is incised during the procedure?

Flexor retinaculum. ***Flexor retinaculum*** - The **flexor retinaculum** (also known as the **transverse carpal ligament**) forms the roof of the carpal tunnel. - Incising this ligament during surgery relieves pressure on the **median nerve**, which is entrapped in carpal tunnel syndrome. *Extensor retinaculum* - The **extensor retinaculum** is located on the dorsal aspect of the wrist and holds the extensor tendons in place. - It is not involved in carpal tunnel syndrome, which affects structures on the palmar side. *Palmar aponeurosis* - The **palmar aponeurosis** is a thick fibrous fascia in the palm of the hand, superficial to the carpal tunnel. - While it can be involved in conditions like Dupuytren's contracture, it does not form the boundaries of the carpal tunnel directly. *Ulnar bursa* - The **ulnar bursa** is a synovial sheath that encloses the flexor digitorum superficialis and profundus tendons within the carpal tunnel. - It lies within the carpal tunnel but incising it would not relieve the primary compression on the median nerve.

Q: A child presents with a 'claw hand' deformity after a fall. Which nerve is most likely to be injured?

Ulnar nerve. ***Ulnar nerve*** - A **claw hand deformity** (or ulnar claw) is characterized by **hyperextension of the metacarpophalangeal joints** and **flexion of the interphalangeal joints** of the 4th and 5th digits, due to paralysis of the **interossei** and **lumbricals** to these digits. - The ulnar nerve innervates most of the intrinsic hand muscles, including the **interossei** and the medial two **lumbricals**, which are crucial for flexing the MCP joints and extending the IP joints of the ring and little fingers. *Median nerve* - Injury to the median nerve would typically result in a **"hand of benediction"** or **ape hand deformity**, where the thumb is adducted and externally rotated, and there is an inability to flex the index and middle fingers. - It primarily affects the **thenar muscles** and lateral two **lumbricals**, which would not cause a claw hand deformity of the 4th and 5th digits. *Radial nerve* - Damage to the radial nerve leads to **wrist drop** and an inability to extend the wrist and fingers. - This nerve is responsible for innervating the **extensor muscles** of the forearm and hand, not the intrinsic hand muscles that cause a claw hand. *Musculocutaneous nerve* - The musculocutaneous nerve primarily innervates the muscles of the anterior compartment of the arm, such as the **biceps brachii** and **brachialis**. - Injury would result in weakness in **forearm flexion** and **supination**, not hand deformities.

Q: A patient reports a loss of sensation along the medial side of their hand. This symptom suggests an injury to which nerve?

Ulnar nerve. ***Ulnar nerve*** - The **ulnar nerve** innervates the **medial side of the hand**, including the little finger and the medial half of the ring finger [1]. - A loss of sensation in this area, often described as the **"ulnar side"** of the hand, is a classic sign of ulnar nerve injury [1]. *Radial nerve* - The **radial nerve** primarily supplies sensation to the **posterior surface of the arm and forearm**, and the **dorsal aspect of the lateral 3.5 fingers**. - Injury typically results in wrist drop and sensory loss over the dorsal aspect of the hand. *Median nerve* - The **median nerve** provides sensation to the **lateral side of the palm**, thumb, index finger, middle finger, and the lateral half of the ring finger [1]. - Injury to this nerve leads to sensory deficits in this distribution, often associated with carpal tunnel syndrome [1]. *Musculocutaneous nerve* - The **musculocutaneous nerve** solely innervates the skin of the **lateral forearm** as the lateral cutaneous nerve of the forearm. - It does not supply any sensory innervation to the hand itself.

Q: What action is most affected by severing the tendon of the long head of the biceps brachii?

Forearm supination. ***Forearm supination*** - The **long head of the biceps brachii** is the **most powerful supinator** of the forearm, especially when the elbow is flexed. - The biceps has a **longer moment arm** for supination compared to the supinator muscle, making it biomechanically more effective. - Severing its tendon results in **significant weakness (20-30% loss)** in supination strength, particularly during resisted supination. - While the **supinator muscle** can still perform this action, it is considerably weaker and cannot fully compensate. *Elbow flexion* - Although the biceps contributes to elbow flexion, the **brachialis** is the primary elbow flexor (the "workhorse" of elbow flexion). - The **brachioradialis** also assists significantly. - Loss of the long head of biceps results in only **5-10% loss** of elbow flexion strength, as other muscles compensate effectively. *Shoulder abduction* - **Shoulder abduction** is primarily performed by the **deltoid** and **supraspinatus** muscles. - The biceps brachii is not a primary mover for shoulder abduction. *Wrist extension* - **Wrist extension** is controlled by muscles in the posterior compartment of the forearm, such as the **extensor carpi radialis longus** and **brevis**, and **extensor carpi ulnaris**. - The biceps brachii has no direct action on the wrist.

Q: Which nerve is affected in carpal tunnel syndrome, resulting in symptoms such as numbness, tingling, and muscle weakness in the hand?

Median nerve. ***Median nerve*** - The **median nerve** passes through the **carpal tunnel** in the wrist [1], and its compression leads to the characteristic symptoms of **numbness**, **tingling**, and **weakness** in the hand. - This nerve innervates the **thumb**, **index**, **middle**, and **half of the ring finger** [1], along with some muscles responsible for thumb movement. *Ulnar nerve* - The **ulnar nerve** provides sensation to the **little finger** and the **other half of the ring finger**, and its compression (e.g., at the **cubital tunnel**) causes symptoms in these specific digits, which are not typical for carpal tunnel syndrome [1]. - It also innervates most of the **intrinsic hand muscles**, affecting fine motor control and grip strength. *Radial nerve* - The **radial nerve** primarily provides sensation to the **back of the hand** and controls muscles that **extend the wrist and fingers**. - Its compression typically results in **wrist drop** or sensory changes on the dorsal aspect of the hand, not the classic carpal tunnel symptoms. *Axillary nerve* - The **axillary nerve** innervates the **deltoid muscle** and provides sensation over the **lateral shoulder**. - Compression or injury to this nerve affects **shoulder abduction** and sensation in the shoulder region, not the hand.

Q: What is the primary function of the deltoid muscle?

Abduction of the shoulder. ***Abduction of the shoulder*** - The **deltoid muscle** is the major muscle responsible for **abducting the arm** at the shoulder joint, particularly after the initial 15-20 degrees. - Its different parts (anterior, middle, posterior) also contribute to flexion, extension, and rotation, but **abduction** is its primary and most powerful action. *Adduction of the shoulder* - **Adduction of the shoulder** involves moving the arm towards the midline of the body, which is primarily performed by muscles such as the **latissimus dorsi** and **pectoralis major**. - While some fibers of the deltoid can assist in adduction from certain positions, it is not its primary function. *Flexion of the elbow* - **Flexion of the elbow** involves bending the arm at the elbow joint and is primarily performed by muscles like the **biceps brachii**, **brachialis**, and **brachioradialis**. - The deltoid muscle is located at the shoulder and has no direct action on the elbow joint. *Extension of the wrist* - **Extension of the wrist** involves bending the hand backward at the wrist joint and is primarily performed by muscles in the forearm such as the **extensor carpi radialis** and **extensor digitorum**. - The deltoid muscle is a shoulder muscle and does not act on the wrist joint.

Q: A patient complains of pain during the abduction of the shoulder. Which muscle is likely involved?

Supraspinatus. ***Supraspinatus*** - The **supraspinatus muscle** is crucial for **initiating shoulder abduction**, particularly the first 15-20 degrees. - Pain during abduction strongly suggests involvement or injury to the supraspinatus due to its primary role in this movement. *Pectoralis major* - The **pectoralis major** is primarily responsible for **adduction, medial rotation, and flexion of the humerus**, not abduction. - Pain related to this muscle would typically manifest during activities involving pushing or chest movements. *Infraspinatus* - The **infraspinatus muscle** primarily functions in **external (lateral) rotation of the humerus**. - While it is part of the rotator cuff, its main role is not shoulder abduction. *Trapezius* - The **trapezius muscle** primarily **elevates, retracts, and rotates the scapula**, and assists in neck movements. - Its role in shoulder abduction is indirect, primarily by stabilizing the scapula, and it is not a direct force generator for the movement.

Q: Which muscle's function is primarily assessed to evaluate damage to the axillary nerve?

Deltoid. ***Deltoid*** - The **axillary nerve** innervates the **deltoid muscle**, which is responsible for **shoulder abduction** (lifting the arm away from the body) and some flexion/extension. - Damage to the axillary nerve typically results in **weakness** or **paralysis** of the deltoid, leading to impaired shoulder abduction. *Teres major* - The teres major muscle is primarily innervated by the **lower subscapular nerve**, not the axillary nerve. - Its main actions are **adduction** and **internal rotation** of the humerus. *Pectoralis major* - The pectoralis major is innervated by the **medial and lateral pectoral nerves** [1]. - This muscle is responsible for **adduction**, **flexion**, and **internal rotation** of the humerus. *Latissimus dorsi* - The latissimus dorsi muscle is innervated by the **thoracodorsal nerve** [1]. - Its functions include **extension**, **adduction**, and **internal rotation** of the humerus.

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

Radial nerve. ***Radial nerve*** - The radial nerve provides **sensory innervation to the dorsum of the hand**, specifically the radial side including the dorsal aspect of the **thumb, index, middle, and radial half of the ring finger** (excluding the distal phalanges) - This anatomical snuffbox region and dorsal hand area is the characteristic **sensory distribution of the superficial branch of the radial nerve** - The radial nerve also provides **motor innervation to extensor muscles of the forearm** via its posterior interosseous branch *Ulnar nerve* - Supplies sensory innervation to the **ulnar 1.5 digits** (little finger and ulnar half of ring finger) on both palmar and dorsal surfaces - Provides motor innervation to **most intrinsic hand muscles** (hypothenar muscles, interossei, medial lumbricals) - Would not innervate a radial-sided area on the dorsum of the hand *Median nerve* - Provides sensory innervation primarily to the **palmar surface** of the lateral 3.5 digits (thumb, index, middle, and radial half of ring finger) - On the dorsum, only supplies the **distal phalanges (nail beds)** of index and middle fingers - Supplies motor innervation to **thenar muscles** and lateral lumbricals - Does not provide primary sensory innervation to broad dorsal hand areas *Posterior interosseous nerve* - This is the **deep motor branch of the radial nerve** that passes through the supinator muscle - Provides **motor innervation** to extensor muscles in the posterior forearm compartment - Has minimal sensory function, limited to **proprioceptive innervation of wrist joint capsule** - Does not provide cutaneous sensory innervation to skin areas

Question 1

A 35-year-old patient presents with weakness in wrist flexion and numbness in the little finger following elbow trauma. Which nerve is most likely to be affected?

Accepted Answer

Ulnar nerve

Answer

Median nerve

Answer

Radial nerve

Answer

Musculocutaneous nerve

Question 2

A 35-year-old female with carpal tunnel syndrome undergoes surgical release. Which structure is incised during the procedure?

Accepted Answer

Flexor retinaculum

Answer

Extensor retinaculum

Answer

Palmar aponeurosis

Answer

Ulnar bursa

Question 3

A child presents with a 'claw hand' deformity after a fall. Which nerve is most likely to be injured?

Accepted Answer

Ulnar nerve

Answer

Median nerve

Answer

Radial nerve

Answer

Musculocutaneous nerve

Question 4

A patient reports a loss of sensation along the medial side of their hand. This symptom suggests an injury to which nerve?

Accepted Answer

Ulnar nerve

Answer

Radial nerve

Answer

Median nerve

Answer

Musculocutaneous nerve

Question 5

What action is most affected by severing the tendon of the long head of the biceps brachii?

Accepted Answer

Forearm supination

Answer

Shoulder abduction

Answer

Elbow flexion

Answer

Wrist extension

Question 6

Which nerve is affected in carpal tunnel syndrome, resulting in symptoms such as numbness, tingling, and muscle weakness in the hand?

Accepted Answer

Median nerve

Answer

Ulnar nerve

Answer

Radial nerve

Answer

Axillary nerve

Question 7

What is the primary function of the deltoid muscle?

Accepted Answer

Abduction of the shoulder

Answer

Adduction of the shoulder

Answer

Flexion of the elbow

Answer

Extension of the wrist

Question 8

A patient complains of pain during the abduction of the shoulder. Which muscle is likely involved?

Accepted Answer

Supraspinatus

Answer

Pectoralis major

Answer

Infraspinatus

Answer

Trapezius

Question 9

Which muscle's function is primarily assessed to evaluate damage to the axillary nerve?

Accepted Answer

Deltoid

Answer

Teres major

Answer

Pectoralis major

Answer

Latissimus dorsi

Question 10

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

Upper Limb — MCQs

Upper Limb — MCQs

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