Upper Limb Practice Questions

Q: A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?

Intercostobrachial nerve. ***Intercostobrachial nerve*** - The **intercostobrachial nerve** (T2) is the nerve most commonly injured during **axillary lymph node dissection** - It provides **sensory innervation to the medial side of the upper arm**, specifically the skin over the medial and posterior aspects of the arm [1] - This nerve arises from the **lateral cutaneous branch of the second intercostal nerve** and crosses the axilla to reach the arm [1] - Injury during axillary surgery results in **numbness or paresthesia** in the medial upper arm region, which is a well-recognized complication of breast cancer surgery with axillary node dissection [1] - Studies show **30-80% of patients** undergoing axillary dissection experience intercostobrachial nerve injury *Long thoracic nerve* - The **long thoracic nerve** (C5-C7) innervates the **serratus anterior muscle**, which is crucial for scapular protraction and rotation - Damage to this nerve causes **"winged scapula"**, where the scapula protrudes posteriorly - This is a **motor nerve**, not sensory, so injury does not result in sensory deficits in the arm *Medial pectoral nerve* - The **medial pectoral nerve** (C8-T1) primarily innervates the **pectoralis major** and **pectoralis minor** muscles [1] - This is a **motor nerve** playing a role in muscle function rather than sensation [1] - Injury would result in weakness of these muscles, not sensory loss *Accessory nerve* - The **accessory nerve** (cranial nerve XI) innervates the **sternocleidomastoid** and **trapezius muscles** - This nerve is located in the **posterior triangle of the neck**, not in the axilla - Injury would lead to weakness in shrugging the shoulders or turning the head, not sensory loss in the arm during axillary dissection

Q: Which muscle of the arm has additional supinator action?

Biceps. ***Biceps*** - The **biceps brachii** powerfully supinates the forearm, especially when the elbow is flexed, due to its distal attachment on the **radial tuberosity**. - Its two heads originate from the scapula, contributing to both **flexion** at the elbow and supination. *Brachialis* - The **brachialis muscle** is the primary and most powerful flexor of the elbow joint. - It inserts onto the **ulna** and does not have any rotational or supinator action. *Coracobrachialis* - The **coracobrachialis** muscle primarily functions in adduction and flexion of the arm at the shoulder joint. - It has no attachments that allow for supination of the forearm. *Triceps* - The **triceps brachii** is the sole extensor of the elbow joint, located on the posterior aspect of the arm. - It is an antagonist to the biceps and has no supinator action.

Q: A patient has a herniated intervertebral disc impinging on the right C5 nerve roots. Which of the following movements would most likely be affected?

Flexion of the elbow. ***Flexion of the elbow*** - The **C5 nerve root** is a primary contributor to the innervation of the **biceps brachii** and **brachialis** muscles, which are the prime movers for elbow flexion. - The C5 myotome specifically includes elbow flexion as one of its key motor functions. - Impingement of the C5 nerve root would therefore most directly impact the strength and function of **elbow flexion**, leading to weakness in this movement. *Extension of the fingers* - Finger extension is primarily mediated by the **C7 and C8 nerve roots** via the posterior interosseous nerve (branch of the radial nerve). - C5 does not significantly contribute to finger extension. *Extension of the shoulder* - Shoulder extension involves muscles primarily innervated by the **C6, C7, and C8 nerve roots** (e.g., latissimus dorsi via thoracodorsal nerve, teres major). - While C5 contributes to some shoulder movements (particularly **shoulder abduction** via the deltoid), it is not primarily responsible for shoulder extension. *Flexion of the wrist* - Wrist flexion is primarily served by muscles innervated by the **C6, C7, and C8 nerve roots** (e.g., flexor carpi radialis - C6/C7, flexor carpi ulnaris - C7/C8). - The C5 nerve root has minimal to no role in wrist flexion.

Q: What is the characteristic upper limb deformity seen in Erb's palsy?

Adduction and medial rotation of arm. ***Adduction and medial rotation of arm*** - Erb's palsy, resulting from injury to the **upper brachial plexus** (C5-C6 nerve roots), primarily affects the **deltoid**, **supraspinatus**, **infraspinatus**, and **biceps** muscles. - The unopposed action of unaffected muscles, such as the **pectoris major** and **latissimus dorsi**, leads to the characteristic **waiter's tip position**, involving **adduction** and **medial rotation** of the arm. *Adduction and lateral rotation of arm* - This position would imply weakness of the **pectoralis major** and **latissimus dorsi** and stronger activity of the **infraspinatus** and **teres minor**, which is contrary to the muscle deficits in Erb's palsy. - **Lateral rotation** of the arm is typically impaired in Erb's palsy due to weakness of the **infraspinatus** and **teres minor**. *Abduction and lateral rotation of arm* - **Abduction** is severely impacted in Erb's palsy due to paralysis of the **deltoid** and **supraspinatus**. - This position would suggest intact function of muscles that are explicitly weakened or paralyzed in Erb's palsy. *Abduction and medial rotation of arm* - While **medial rotation** can be a component of the deformity, **abduction** is a movement that is significantly impaired in Erb's palsy, making this option incorrect. - The inability to abduct the arm is a hallmark of the condition due to weakness of the **deltoid** and **supraspinatus**.

Q: A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

Posterior Interosseous nerve injury. Posterior Interosseous Nerve (PIN) injury - The Posterior Interosseous Nerve is the deep motor branch of the radial nerve that specifically innervates the extensor muscles of the fingers and thumb - These muscles include: Extensor Digitorum, Extensor Indicis, Extensor Digiti Minimi, Extensor Pollicis Longus and Brevis [1] - PIN injury causes inability to extend the MCP joints and interphalangeal joints of the fingers [1] - Wrist extension is preserved because the Extensor Carpi Radialis Longus (ECRL) and often ECRB are innervated by the radial nerve proper before it gives off the PIN [1] - This results in a characteristic finger drop without wrist drop Radial nerve injury - A high radial nerve injury (proximal, above the elbow) would cause both wrist drop AND finger extension loss - However, radial nerve injury at the spiral groove (most common site) typically spares the PIN or affects it less severely - The question asks specifically about isolated inability to extend MCP joints, which is the hallmark of PIN injury, not general radial nerve injury - Radial nerve proper gives branches to triceps, brachioradialis, and ECRL before dividing into PIN and superficial branch Ulnar nerve injury - The ulnar nerve innervates intrinsic hand muscles (interossei, lumbricals to digits 4-5, hypothenar muscles, adductor pollicis) [1] - Ulnar nerve injury causes claw hand deformity with MCP hyperextension (not loss of extension) and IP joint flexion - This is the opposite of what is described in the question Median nerve injury - The median nerve innervates the thenar muscles, lateral two lumbricals, and forearm flexors [1] - Median nerve injury causes ape hand deformity with loss of thumb opposition and flexion - It does not affect MCP joint extension, which is an extensor function

Q: Tetracycline injection causes palsy of which nerve?

Radial. ***Radial*** - Tetracycline injections, especially when given in the deltoid region, can inadvertently injure the **radial nerve** due to its superficial course. - Damage to the radial nerve typically results in **wrist drop** and sensory deficits over the dorsum of the hand. *Ulnar* - The **ulnar nerve** is commonly injured at the elbow (cubital tunnel syndrome) or wrist (Guyon's canal). - Injury typically results in weakness of intrinsic hand muscles and sensory loss in the little finger and ulnar half of the ring finger, which is not characteristic of an injection injury in the deltoid region. *Median* - The **median nerve** is more frequently injured at the wrist (carpal tunnel syndrome) or elbow. - Injury causes difficulty with thumb opposition and sensation in the first three and a half digits on the palmar side. *Superficial peroneal* - The **superficial peroneal nerve** is found in the lower leg and foot, innervating the lateral compartment muscles and providing sensation to the dorsum of the foot. - It would not be affected by an injection in the upper arm or shoulder region.

Q: Which of the following muscles is not in the pectoral region?

Infraspinatus. ***Infraspinatus*** - The **infraspinatus** muscle is located in the **posterior scapular region**, specifically on the posterior aspect of the scapula, filling the infraspinous fossa. - Its primary function is **external rotation** of the humerus, and it is a key component of the **rotator cuff**. *Pectoralis major* - The **pectoralis major** is a large, superficial muscle located in the **anterior chest wall**, forming the bulk of the chest. [1] - It plays a significant role in **adduction**, **flexion**, and **medial rotation** of the humerus. *Pectoralis minor* - The **pectoralis minor** is a smaller, triangular muscle situated beneath the pectoralis major in the **anterior thoracic wall**. [1] - Its functions include **stabilizing the scapula** by pulling it inferiorly and anteriorly, and assisting in forced inspiration. [1] *Subclavius* - The **subclavius** is a small, triangular muscle located inferior to the clavicle in the **pectoral region**. - Its primary role is to **depress and stabilize the clavicle**, protecting the underlying neurovascular structures.

Q: Which of the following structures is not found in the midpalmar space?

1st lumbrical. ***1st lumbrical*** - The **1st lumbrical** is typically found within the **thenar space** or the **central compartment of the palm**, not the midpalmar space [1]. - Its position is associated with the **index finger's flexor tendons**, which do not traverse the midpalmar space. *2nd lumbrical* - The **2nd lumbrical** is located in the **midpalmar space**, situated on the radial side of the **flexor digitorum profundus (FDP) tendon** to the third digit [1]. - It arises from the radial side of the **FDP tendon** of the **middle finger** [1]. *FDP of 3rd finger* - The **flexor digitorum profundus (FDP) tendon** to the **third finger** (middle finger) passes through the **midpalmar space** [1]. - These tendons, along with their associated lumbricals, are key components of the **midpalmar space**. *FDP of 4th finger* - The **flexor digitorum profundus (FDP) tendon** to the **fourth finger** (ring finger) also travels through the **midpalmar space** [1]. - The midpalmar space contains the **FDP tendons** for the middle, ring, and little fingers, as well as their corresponding lumbricals (2nd, 3rd, and 4th).

Q: Axillary nerve is accompanied by which artery ?

Posterior circumflex humeral artery. ***Posterior circumflex humeral artery*** - The **axillary nerve** and the **posterior circumflex humeral artery** both pass through the **quadrangular space** in the axilla. - This anatomical relationship makes them vulnerable to injury together, particularly in cases of **shoulder dislocation** or **fractures of the surgical neck of the humerus**. *Axillary artery* - The **axillary artery** is the main arterial trunk of the axilla, but the axillary nerve is not typically described as directly accompanying the main trunk. - While branches of the axillary artery do supply the region where the axillary nerve travels, the specific artery that accompanies the nerve is a direct branch. *Subscapular artery* - The **subscapular artery** is the largest branch of the axillary artery and gives rise to the circumflex scapular and thoracodorsal arteries. - It does not directly accompany the axillary nerve through the quadrangular space; instead, it mostly supplies muscles like the **subscapularis** and **latissimus dorsi**. *Anterior circumflex humeral artery* - The **anterior circumflex humeral artery** also branches from the axillary artery and wraps around the surgical neck of the humerus. - However, it typically runs anteriorly and does not accompany the axillary nerve as it emerges from the quadrangular space posteriorly.

Q: Which muscle is not part of the superficial anterior compartment of the forearm?

Flexor pollicis longus (FPL). **Flexor pollicis longus (FPL)** - The **FPL** is located in the **deep anterior compartment** of the forearm, differentiating it from the superficial muscles [1]. - Its primary function is **flexion of the thumb's interphalangeal joint**, requiring a deeper anatomical position for mechanical advantage [1]. *FDS* - The **Flexor digitorum superficialis (FDS)** is a key muscle of the superficial anterior compartment, visible just beneath the skin and fascia. - It is responsible for **flexing the middle phalanges** of the medial four digits. *FCR* - The **Flexor carpi radialis (FCR)** is situated in the superficial anterior compartment, running obliquely across the forearm. - It functions in **flexion and abduction of the wrist**. *Palmaris longus* - The **Palmaris longus** is a superficial anterior compartment muscle, though it is absent in a significant portion of the population. - When present, its main action is **flexion of the wrist** and tightening of the palmar aponeurosis.

Question 1

A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?

Accepted Answer

Intercostobrachial nerve

Answer

Long thoracic nerve

Answer

Medial pectoral nerve

Answer

Accessory nerve

Question 2

Which muscle of the arm has additional supinator action?

Accepted Answer

Biceps

Answer

Brachialis

Answer

Coracobrachialis

Answer

Triceps

Question 3

A patient has a herniated intervertebral disc impinging on the right C5 nerve roots. Which of the following movements would most likely be affected?

Accepted Answer

Flexion of the elbow

Answer

Extension of the fingers

Answer

Extension of the shoulder

Answer

Flexion of the wrist

Question 4

What is the characteristic upper limb deformity seen in Erb's palsy?

Accepted Answer

Adduction and medial rotation of arm

Answer

Adduction and lateral rotation of arm

Answer

Abduction and lateral rotation of arm

Answer

Abduction and medial rotation of arm

Question 5

A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

Accepted Answer

Posterior Interosseous nerve injury

Answer

Radial nerve injury

Answer

Ulnar nerve injury

Answer

Median nerve injury

Question 6

Tetracycline injection causes palsy of which nerve?

Accepted Answer

Radial

Answer

Median

Answer

Ulnar

Answer

Superficial peroneal

Question 7

Which of the following muscles is not in the pectoral region?

Accepted Answer

Infraspinatus

Answer

Pectoralis major

Answer

Pectoralis minor

Answer

Subclavius

Question 8

Which of the following structures is not found in the midpalmar space?

Accepted Answer

1st lumbrical

Answer

2nd lumbrical

Answer

FDP of 4th finger

Answer

FDP of 3rd finger

Question 9

Axillary nerve is accompanied by which artery ?

Accepted Answer

Posterior circumflex humeral artery

Answer

Axillary artery

Answer

Subscapular artery

Answer

Anterior circumflex humeral artery

Question 10

Which muscle is not part of the superficial anterior compartment of the forearm?

Accepted Answer

Flexor pollicis longus (FPL)

Answer

FDS

Answer

FCR

Answer

Palmaris longus

Upper Limb — MCQs

Upper Limb — MCQs

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