Nerves of Upper Limb — MCQs

10 questions

Which of the following is true about nerve injuries?

Which of the following muscles is not supplied by the Median Nerve?

A young boy presents with multiple humerus fractures, resulting in loss of sensation over the lateral side of the forearm, along with difficulty in elbow flexion and forearm supination. What is the most likely nerve injury responsible for these symptoms?

Which statement considering the relations of nerves to the humerus is the most accurate?

Damage to median nerve produces:

Which of the following is not a branch of the posterior cord of the brachial plexus?

Which of the following statements about the brachial plexus is true?

Axillary Nerve Injury is least likely in:

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

Q10

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

Nerves of Upper Limb Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following is true about nerve injuries?

A. Froment sign seen in median nerve palsy is due to Flexor pollicis longus action
B. All lumbricals are supplied by median nerve
C. Waenburg sign is seen in median nerve palsy
D. Median nerve is also named as labourer's nerve (Correct Answer)

Explanation: ***Median nerve is also named as labourer's nerve*** - The median nerve is sometimes called the "laborer's nerve" because it innervates many of the muscles essential for **fine motor control** and **dexterous hand movements** predominantly used in manual labor. [1] - It supplies most of the **flexors in the forearm** and several intrinsic hand muscles, making it crucial for a strong grip and coordinated hand actions. [1] *Froment sign seen in median nerve palsy is due to Flexor pollicis longus action* - **Froment's sign** is observed in **ulnar nerve palsy**, not median nerve palsy. - It occurs when the adductor pollicis is weak, and the **flexor pollicis longus** (median nerve-innervated) compensates by hyperflexing the interphalangeal joint of the thumb to grasp an object. *All lumbricals are supplied by median nerve* - The **first two lumbricals** (from the radial side) are typically supplied by the **median nerve**. [1] - The **third and fourth lumbricals** (from the ulnar side) are supplied by the **ulnar nerve**. [1] *Waenburg sign is seen in median nerve palsy* - There is no widely recognized clinical sign called "Waenburg sign" associated with median nerve palsy. - Common signs of **median nerve palsy** include **ape hand deformity**, **hand of benediction**, and sensory loss in the radial three and a half digits. [1]

Question 2: Which of the following muscles is not supplied by the Median Nerve?

A. Opponens pollicis
B. Adductor pollicis (Correct Answer)
C. Abductor pollicis brevis
D. Flexor pollicis brevis

Explanation: **Adductor pollicis** - The **adductor pollicis** muscle is primarily supplied by the **deep branch of the ulnar nerve**. - Its main function is to adduct the thumb towards the palm, which is crucial for a strong grip. *Opponens pollicis* - The **opponens pollicis** is supplied by the **recurrent branch of the median nerve** [1]. - This muscle allows for **opposition of the thumb**, bringing the thumb's tip to touch the tips of other fingers. *Flexor pollicis brevis* - The **flexor pollicis brevis** typically has a **dual innervation**; however, its superficial head is supplied by the **median nerve** [1], while its deep head can be supplied by the ulnar nerve. - Its primary action is **flexion of the thumb** at the metacarpophalangeal joint [1]. *Abductor pollicis brevis* - The **abductor pollicis brevis** is innervated by the **recurrent branch of the median nerve** [1]. - It is responsible for **abducting the thumb**, moving it away from the palm.

Question 3: A young boy presents with multiple humerus fractures, resulting in loss of sensation over the lateral side of the forearm, along with difficulty in elbow flexion and forearm supination. What is the most likely nerve injury responsible for these symptoms?

A. Median nerve
B. Axillary
C. Radial nerve
D. Musculocutaneous nerve (Correct Answer)
E. Ulnar nerve

Explanation: ***Musculocutaneous nerve*** - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion** and **forearm supination**, and provides sensation to the **lateral forearm** via the lateral cutaneous nerve of the forearm. - A fracture of the humerus can damage this nerve, leading to the observed **motor and sensory deficits**. *Median nerve* - The median nerve primarily controls **flexion of the wrist and fingers**, and **pronation of the forearm**, as well as sensation to the palmar aspect of the thumb, index, middle, and radial half of the ring finger. - Its injury would not typically cause difficulty with **elbow flexion** or sensory loss over the **lateral forearm**. *Axillary* - The axillary nerve primarily innervates the **deltoid** and **teres minor muscles**, important for shoulder abduction and external rotation. - An injury would lead to **weakness in shoulder abduction** and sensory loss over the lateral shoulder (regimental badge area), not the lateral forearm. *Radial nerve* - The radial nerve controls **extension of the wrist and fingers** and sensation over the posterior arm, forearm, and hand. - Injury typically results in **wrist drop** and difficulty extending the arm, not primarily elbow flexion or lateral forearm sensation. *Ulnar nerve* - The ulnar nerve innervates intrinsic hand muscles and flexor carpi ulnaris, controlling **finger abduction/adduction** and **ulnar wrist flexion**. - Sensory distribution includes the medial hand and medial 1.5 fingers, not the **lateral forearm**. - Injury causes **claw hand deformity** and sensory loss in the medial hand, not the symptoms described.

Question 4: Which statement considering the relations of nerves to the humerus is the most accurate?

A. Deltoid may atrophy following shoulder dislocation. (Correct Answer)
B. The median nerve runs in the spiral groove.
C. The axillary nerve runs around the anatomical neck.
D. Mid-shaft humeral fractures will usually result in complete paralysis of triceps.

Explanation: **Deltoid may atrophy following shoulder dislocation.** - **Shoulder dislocations**, particularly anterior dislocations, frequently injure the **axillary nerve** due to its close proximity to the humeral head and surgical neck. - Damage to the axillary nerve, which innervates the **deltoid muscle**, can lead to deltoid paralysis and subsequent **atrophy**, resulting in a flattened shoulder contour and impaired abduction. *The median nerve runs in the spiral groove.* - The **radial nerve**, not the median nerve, runs in the **spiral groove** (radial groove) of the humerus [1]. - The median nerve travels more anteriorly in the arm, alongside the brachial artery. *The axillary nerve runs around the anatomical neck.* - The **axillary nerve** wraps around the **surgical neck** of the humerus, not the anatomical neck. - The surgical neck is a common site for fractures, making the axillary nerve vulnerable to injury in such cases. *Mid-shaft humeral fractures will usually result in complete paralysis of triceps.* - Mid-shaft humeral fractures primarily risk damage to the **radial nerve**, which innervates the lateral and medial heads of the triceps [1]. - However, the **long head of the triceps** is innervated by the radial nerve more proximally and may remain partially functional, preventing complete paralysis of the entire triceps muscle.

Question 5: Damage to median nerve produces:

A. Ape thumb (Correct Answer)
B. Winging of scapula
C. Claw hand
D. Wrist drop

Explanation: Ape thumb - Damage to the median nerve specifically affects the thenar muscles (via the recurrent branch): abductor pollicis brevis, opponens pollicis, and the superficial head of flexor pollicis brevis [1]. - Loss of these muscles results in the characteristic "ape thumb" deformity, where the thumb lies in the same plane as the palm and cannot be opposed [1]. - The patient loses the ability to perform thumb opposition, which is essential for precision grip and many hand functions [1]. Winging of scapula - Winging of the scapula is caused by damage to the long thoracic nerve, which innervates the serratus anterior muscle. - This condition is not associated with median nerve injury. Claw hand - A claw hand deformity is typically caused by damage to the ulnar nerve, affecting the lumbricals and interossei muscles. - It results in hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints, particularly of the 4th and 5th digits. - This is distinct from median nerve pathology. Wrist drop - Wrist drop is a classic sign of radial nerve damage, affecting the extensor muscles of the wrist and fingers. - It results in the inability to extend the wrist and digits, which is not a feature of median nerve injury.

Question 6: Which of the following is not a branch of the posterior cord of the brachial plexus?

A. Thoracodorsal nerve
B. Axillary nerve
C. Long thoracic nerve (Correct Answer)
D. Radial nerve

Explanation: ### Long thoracic nerve - The **long thoracic nerve** originates directly from the **nerve roots C5, C6, C7** of the brachial plexus, **NOT from the posterior cord**. - It innervates the **serratus anterior muscle**, crucial for scapular protraction and upward rotation. - Damage causes **winged scapula** deformity. ### Axillary nerve - The **axillary nerve** is a **terminal branch of the posterior cord**, formed from C5-C6. - It supplies the **deltoid** and **teres minor muscles**, and provides sensory innervation to the lateral shoulder (regimental badge area). - Commonly injured in anterior shoulder dislocations or humeral surgical neck fractures. ### Thoracodorsal nerve - The **thoracodorsal nerve** (nerve to latissimus dorsi) is a **branch of the posterior cord**, deriving from C6-C8 [1]. - It exclusively innervates the **latissimus dorsi muscle**, responsible for shoulder adduction, extension, and internal rotation [1]. - Important in breast reconstruction surgery (latissimus dorsi flap). ### Radial nerve - The **radial nerve** is the **largest terminal branch of the posterior cord**, formed from C5-T1. - It innervates the **triceps brachii** and all extensor muscles of the forearm (wrist and finger extensors). - Provides sensory innervation to the posterior arm, forearm, and anatomical snuffbox. - Most commonly injured nerve of the upper limb (spiral groove fractures).

Question 7: 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 8: Axillary Nerve Injury is least likely in:

A. Intramuscular injection
B. Shoulder dislocation
C. Improper use of crutch (Correct Answer)
D. Fracture proximal humerus

Explanation: 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.

Question 9: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

A. Coracoclavicular ligament (Correct Answer)
B. Costoclavicular ligament
C. Coracohumeral ligament
D. Coracoacromial ligament

Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong fibrous band connecting the **coracoid process** of the scapula to the **undersurface of the clavicle**, effectively suspending the scapula and upper limb from the clavicle. - This ligament is crucial as it transmits the **weight of the upper limb** to the clavicle, which then articulates with the axial skeleton (sternum) via the sternoclavicular joint. *Costoclavicular ligament* - This ligament connects the **first rib** to the **undersurface of the clavicle**, stabilizing the sternoclavicular joint. - While important for sternoclavicular joint stability, it primarily functions to limit **clavicular elevation** and does not directly transmit the primary weight of the upper limb to the axial skeleton in the same way as the coracoclavicular ligament. *Coracohumeral ligament* - The **coracohumeral ligament** is located in the shoulder joint, connecting the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**. - Its main roles are to **strengthen the superior part of the joint capsule** and prevent inferior displacement of the humeral head, not to transmit the overall weight of the upper limb to the axial skeleton. *Coracoacromial ligament* - This ligament extends between the **coracoid process** and the **acromion of the scapula**, forming the **coracocromial arch**. - Its primary function is to protect the superior aspect of the **glenohumeral joint** and prevent superior displacement of the humeral head; it does not bear the weight of the upper limb to the axial skeleton.

Question 10: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

A. Coracoacromial ligament
B. Costoclavicular ligament
C. Coracoclavicular ligament (Correct Answer)
D. Coracohumeral ligament

Explanation: ***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.

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