Upper Limb Practice Questions

Q: Allen's test is performed to assess the patency of which artery before performing Coronary Artery Bypass Grafting (CABG)?

Ulnar artery. The **Allen’s test** is a clinical bedside test used to assess the **collateral circulation** of the hand via the **superficial palmar arch**. Before harvesting the **Radial artery** for use as a conduit in Coronary Artery Bypass Grafting (CABG) or performing radial artery cannulation, it is mandatory to ensure that the **Ulnar artery** is patent and capable of supplying the entire hand independently. If the ulnar artery is insufficient, harvesting the radial artery could lead to digital ischemia or gangrene. **2. Analysis of Incorrect Options:** * **B. Radial artery:** While the radial artery is the vessel being *tested for potential removal/cannulation*, the test specifically evaluates the *adequacy* of the ulnar artery to take over the blood supply. * **C & D. Anterior and Posterior Interosseous arteries:** These are branches of the common interosseous artery (from the ulnar artery). While they supply the deep structures of the forearm, they do not contribute significantly to the superficial palmar arch and cannot maintain hand perfusion if the radial and ulnar arteries are compromised. **3. Clinical Pearls for NEET-PG:** * **Procedure:** The clinician compresses both radial and ulnar arteries while the patient makes a fist. When the hand blanches, the pressure on the **ulnar artery** is released. * **Interpretation:** A "Positive" (Normal) test occurs if the hand flushes (re-perfuses) within **5–15 seconds**, indicating a patent ulnar artery. * **Modified Allen’s Test:** This is the version most commonly used in clinical practice today, performed on one hand at a time. * **High-Yield Anatomy:** The **Superficial Palmar Arch** is primarily formed by the **Ulnar artery**, whereas the **Deep Palmar Arch** is primarily formed by the **Radial artery**.

Q: A patient who has undergone a radical mastectomy with extensive axillary dissection exhibits winging of the scapula when she pushes against resistance on an immovable object, such as a wall. Injury of which of the following nerves would result in this condition?

Suprascapular nerve. **Explanation:** **Correct Answer: A. Long thoracic nerve** *(Note: There appears to be a discrepancy in the provided key. In clinical anatomy, winging of the scapula following axillary dissection is the classic presentation of Long Thoracic Nerve injury.)* **1. Why Long Thoracic Nerve is the Correct Answer:** The **Long thoracic nerve (Nerve of Bell)** arises from the roots of the brachial plexus (C5, C6, C7). It runs along the lateral thoracic wall on the superficial surface of the **serratus anterior muscle**, making it highly vulnerable during axillary lymph node dissection in radical mastectomies [1]. The serratus anterior is responsible for protracting the scapula and holding its medial border against the thoracic wall. Paralysis of this muscle causes the medial border of the scapula to project posteriorly—a clinical sign known as **"Winging of the Scapula"**—which becomes prominent when the patient pushes against a wall. **2. Why Other Options are Incorrect:** * **Spinal Accessory Nerve (CN XI):** Innervates the trapezius. Injury causes drooping of the shoulder and difficulty in shrugging, but not classic medial winging. * **Suprascapular Nerve:** Innervates the supraspinatus and infraspinatus. Injury leads to weakness in the initiation of abduction and external rotation of the arm, but does not cause winging. * **Musculocutaneous Nerve:** Innervates the anterior compartment of the arm (Biceps, Coracobrachialis, Brachialis). Injury results in loss of elbow flexion and forearm supination. **3. NEET-PG High-Yield Pearls:** * **Mnemonic for Roots:** C5, 6, 7 reach the heaven (Long thoracic nerve). * **Nerve at Risk in Mastectomy:** Long thoracic nerve (leads to winging) and Thoracodorsal nerve (innervates Latissimus dorsi; injury leads to weakness in extension, adduction, and internal rotation) [1]. * **Dynamic Test:** Winging is best demonstrated by asking the patient to perform a "wall push-up."

Q: Which of the following is a branch from the root of the brachial plexus?

Dorsal scapular nerve. The brachial plexus is organized into Roots, Trunks, Divisions, Cords, and Branches. Understanding the specific level at which nerves originate is a high-yield topic for NEET-PG. ### **Explanation** The **Dorsal Scapular Nerve** arises directly from the **Root of C5**. It is one of only two nerves that originate from the roots (the other being the Long Thoracic Nerve). It pierces the middle scalene muscle and supplies the Rhomboids (major and minor) and Levator scapulae. ### **Analysis of Incorrect Options** * **Nerve to Subclavius (A):** This nerve arises from the **Upper Trunk** (C5, C6). * **Suprascapular Nerve (B):** This nerve also arises from the **Upper Trunk** (C5, C6). It passes through the suprascapular notch to supply the Supraspinatus and Infraspinatus muscles. * **Anterior Thoracic Nerve (D):** Now more commonly known as the **Lateral Pectoral Nerve**, it arises from the **Lateral Cord** (C5–C7) [1]. The Medial Pectoral Nerve arises from the Medial Cord. ### **High-Yield Clinical Pearls for NEET-PG** 1. **Nerves from the Roots:** Only two: **Dorsal Scapular Nerve (C5)** and **Long Thoracic Nerve (C5, C6, C7)**. 2. **Erb’s Point:** This is the junction of six nerves at the Upper Trunk. Injury here (Erb's Palsy) results in a "waiter's tip" deformity. 3. **Long Thoracic Nerve:** Injury leads to **"Winging of Scapula"** due to paralysis of the Serratus Anterior. 4. **Post-fixed Plexus:** When the plexus receives a contribution from T2; **Pre-fixed Plexus** is when it receives a contribution from C4.

Q: Which structure lies superficial to the flexor retinaculum?

Ulnar artery. The **flexor retinaculum** (transverse carpal ligament) is a strong fibrous band that converts the anterior concavity of the carpus into the **carpal tunnel**. Understanding the spatial relationship of structures at the wrist is a high-yield topic for NEET-PG [1]. **Why the Ulnar Artery is Correct:** The ulnar artery and ulnar nerve enter the hand by passing **superficial** to the flexor retinaculum. They travel through a specialized fascial canal known as **Guyon’s canal** (ulnar canal), located medial to the pisiform bone [1]. Therefore, they are not contents of the carpal tunnel. **Analysis of Incorrect Options:** * **Flexor Digitorum Superficialis (FDS):** These four tendons lie deep to the retinaculum within the carpal tunnel, arranged in two layers (middle fingers superficial to index and little fingers). * **Flexor Pollicis Longus (FPL):** This tendon lies deep to the retinaculum, occupying the most lateral position within the carpal tunnel. * **Median Nerve:** This is the most clinically significant structure passing **deep** to the flexor retinaculum [1]. Compression of this nerve within the tunnel leads to Carpal Tunnel Syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Structures superficial to the retinaculum (Medial to Lateral):** Ulnar nerve, Ulnar artery, Palmar cutaneous branch of the ulnar nerve, Palmaris longus tendon, and Palmar cutaneous branch of the median nerve [1]. * **Carpal Tunnel Contents:** 10 structures (4 FDS tendons, 4 FDP tendons, 1 FPL tendon, and the Median nerve). * **Note:** The Flexor Carpi Radialis (FCR) tendon travels in a separate compartment within the lateral attachment of the retinaculum (not strictly "deep" or "superficial" in the standard tunnel context).

Q: In a patient with Erb's palsy, paralysis of which of the following muscles results in medial rotation of the arm?

Infraspinatus and teres minor. **Explanation:** **Erb’s Palsy** (Waiter’s Tip Deformity) results from an injury to the upper trunk of the brachial plexus (**C5-C6 roots**). The characteristic position of the limb—adducted and medially rotated at the shoulder—is a result of the loss of specific muscle groups. **1. Why Option C is Correct:** The arm is held in **medial rotation** because of the paralysis of the **lateral rotators** of the shoulder, specifically the **Infraspinatus** and **Teres minor** (both supplied by C5-C6). When these muscles are paralyzed, the medial rotators (like Pectoralis major and Latissimus dorsi) act unopposed, pulling the humerus into internal rotation. **2. Analysis of Incorrect Options:** * **Option A:** Paralysis of the **Supraspinatus and Deltoid** (abductors) leads to the **adducted** position of the arm, not specifically the medial rotation. * **Option B:** Teres major is a medial rotator; its paralysis would theoretically favor lateral rotation. Biceps brachii loss affects supination and elbow flexion. * **Option C:** Paralysis of the **Biceps brachii, Brachialis, and Brachioradialis** (elbow flexors and supinators) results in the **extended elbow** and **pronated forearm** seen in Erb's palsy. **Clinical Pearls for NEET-PG:** * **Site of Injury:** Erb’s Point (junction of 6 nerves). * **Deformity Summary:** * **Arm:** Adducted (loss of Abductors) and Medially Rotated (loss of Lateral Rotators). * **Forearm:** Extended (loss of Flexors) and Pronated (loss of Supinators). * **Reflexes:** Biceps and Supinator reflexes are lost. * **Sensory Loss:** Small area over the lower part of the deltoid (regimental badge area).

Q: All of the following show ulnar nerve injury EXCEPT?

Abductor pollicis palsy. **Explanation:** The ulnar nerve, often called the "musician’s nerve," is responsible for the fine motor movements of the hand. To answer this question, one must distinguish between the nerve supply of the **Thenar eminence** (Median nerve) and the **Adductor compartment** (Ulnar nerve) [2]. 1. **Why "Abductor pollicis palsy" is the correct answer:** The **Abductor Pollicis Brevis (APB)** is a thenar muscle supplied by the **Recurrent branch of the Median Nerve** [1]. Therefore, its palsy is a feature of Median nerve injury (Ape-thumb deformity), not ulnar nerve injury. Note: The *Abductor Pollicis Longus* is supplied by the Posterior Interosseous Nerve (Radial) [1]. 2. **Analysis of Incorrect Options:** * **Clawing of medial 2 digits:** The ulnar nerve supplies the medial two lumbricals [2]. Paralysis leads to the loss of extension at IP joints and flexion at MCP joints, resulting in the characteristic "Ulnar Claw Hand." * **Adductor pollicis palsy:** This is the only muscle of the thumb supplied by the **Deep branch of the Ulnar Nerve** [2]. Its paralysis leads to a positive **Froment’s Sign** (where the patient flexes the FPL to compensate for adductor weakness). * **Sensory loss on medial 1 1/2 fingers:** The ulnar nerve provides cutaneous innervation to the medial one and a half fingers (little finger and medial half of the ring finger) on both palmar and dorsal aspects. **High-Yield Clinical Pearls for NEET-PG:** * **Ulnar Paradox:** The higher the lesion (at the elbow), the less prominent the clawing because the FDP (medial half) is also paralyzed, reducing flexion at the IP joints. * **Froment’s Sign:** Tests Adductor Pollicis (Ulnar nerve). * **Mnemonic for Thenar muscles (Median Nerve):** **Meat** = **M**edian nerve: **E**lexor pollicis brevis (superficial head), **A**bductor pollicis brevis, **O**pponens pollicis.

Q: Which of the following nerves innervates a dermatome that does not lie superficial to its myotome?

Musculocutaneous nerve. The core concept tested here is the **spatial relationship between dermatomes (sensory) and myotomes (motor)**. In most peripheral nerves of the limbs, the skin area supplied by the nerve (dermatome) lies directly over the muscles it innervates (myotome). [1] **Why Musculocutaneous Nerve is the Correct Answer:** The Musculocutaneous nerve (C5–C7) provides motor innervation to the muscles of the **anterior compartment of the arm** (Biceps brachii, Coracobrachialis, and Brachialis). However, its sensory continuation, the **Lateral Cutaneous Nerve of the Forearm**, supplies the skin of the **lateral aspect of the forearm**. Because the myotome is in the arm and the dermatome is in the forearm, they do not overlap spatially. **Analysis of Incorrect Options:** * **Axillary Nerve (C5–C6):** Innervates the Deltoid muscle and the skin overlying it (Regimental Badge area). The dermatome lies directly over the myotome. * **Radial Nerve (C5–T1):** Innervates the triceps and extensors of the forearm; it also provides sensory supply to the posterior arm and forearm. These areas generally overlap. * **Ulnar Nerve (C8–T1):** Innervates the intrinsic muscles of the hand and the skin of the medial 1.5 fingers/palmar surface. The sensory and motor distributions are both concentrated in the hand. **High-Yield NEET-PG Pearls:** * **Musculocutaneous Nerve:** Pierces the Coracobrachialis muscle (frequent MCQ). * **Injury:** Results in loss of forearm flexion (Biceps/Brachialis) and loss of sensation on the lateral forearm. * **Rule of Thumb:** Most nerves of the Brachial Plexus follow the "superficiality" rule except for those that travel significantly distal to their motor targets, like the Musculocutaneous.

Q: Which of the following arm muscles is NOT supplied by the musculocutaneous nerve?

Triceps. The **Musculocutaneous nerve (C5–C7)** is the nerve of the anterior compartment of the arm. It originates from the lateral cord of the brachial plexus, pierces the coracobrachialis muscle, and supplies all three muscles in the flexor compartment. ### **Explanation of Options:** * **Triceps (Correct Answer):** The triceps brachii is the sole muscle of the **posterior compartment** of the arm. It functions as the primary extensor of the elbow and is supplied by the **Radial nerve (C5–T1)**, which is a branch of the posterior cord. * **Coracobrachialis:** This muscle is supplied by the musculocutaneous nerve before the nerve pierces it. * **Biceps Brachii:** Both the long and short heads are supplied by the musculocutaneous nerve. * **Brachialis:** This is a **hybrid (composite) muscle**. Its medial part (main bulk) is supplied by the musculocutaneous nerve, while its lateral part is supplied by the radial nerve. ### **High-Yield Clinical Pearls for NEET-PG:** 1. **Sensory Continuation:** After supplying the flexor muscles, the musculocutaneous nerve continues as the **Lateral Cutaneous Nerve of the Forearm**, supplying the skin of the lateral aspect of the forearm up to the base of the thumb. 2. **Injury Presentation:** Damage to this nerve results in weak elbow flexion and weak supination (due to loss of biceps), along with sensory loss on the lateral forearm. 3. **The "BBC" Mnemonic:** Remember **B**iceps, **B**rachialis, and **C**oracobrachialis as the muscles supplied by the Musculocutaneous nerve. 4. **Reflex:** The Musculocutaneous nerve mediates the **Biceps reflex (C5, C6)**.

Question 1

Allen's test is performed to assess the patency of which artery before performing Coronary Artery Bypass Grafting (CABG)?

Accepted Answer

Ulnar artery

Answer

Radial artery

Answer

Anterior interosseous artery

Answer

Posterior interosseous artery

Question 2

All of the following statements regarding intermuscular spaces are true EXCEPT:

Accepted Answer

The lateral boundary of the lower triangular intermuscular space is formed by the lateral margin of the long head of the triceps brachii muscle.

Answer

The superior boundary of the quadrangular intermuscular space is formed by the inferior margin of the subscapularis muscle.

Answer

The medial boundary of the quadrangular intermuscular space is formed by the lateral margin of the long head of the triceps brachii muscle.

Answer

The lateral boundary of the upper triangular intermuscular space is formed by the medial margin of the long head of the triceps brachii muscle.

Question 3

A patient who has undergone a radical mastectomy with extensive axillary dissection exhibits winging of the scapula when she pushes against resistance on an immovable object, such as a wall. Injury of which of the following nerves would result in this condition?

Accepted Answer

Suprascapular nerve

Answer

Long thoracic nerve

Answer

Spinal accessory nerve

Answer

Musculocutaneous nerve

Question 4

Which of the following is a branch from the root of the brachial plexus?

Accepted Answer

Dorsal scapular nerve

Answer

Nerve to subclavius

Answer

Suprascapular nerve

Answer

Anterior thoracic nerve

Question 5

Which structure lies superficial to the flexor retinaculum?

Accepted Answer

Ulnar artery

Answer

Flexor digitorum superficialis (FDS)

Answer

Flexor pollicis longus (FPL)

Answer

Median nerve

Question 6

In a patient with Erb's palsy, paralysis of which of the following muscles results in medial rotation of the arm?

Accepted Answer

Infraspinatus and teres minor

Answer

Supraspinatus and deltoid

Answer

Teres major and biceps brachii

Answer

Biceps brachii, brachialis and brachioradialis

Question 7

All of the following show ulnar nerve injury EXCEPT?

Accepted Answer

Abductor pollicis palsy

Answer

Clawing of medial 2 digits

Answer

Adductor pollicis palsy

Answer

Sensory loss on medial 1 1/2 fingers

Question 8

Which of the following nerves innervates a dermatome that does not lie superficial to its myotome?

Accepted Answer

Musculocutaneous nerve

Answer

Axillary nerve

Answer

Radial nerve

Answer

Ulnar nerve

Question 9

A 17-year-old boy fell from his motorcycle and complains of numbness of the lateral part of his arm. Examination reveals the axillary nerve is severed. Which of the following types of axons is most likely spared?

Accepted Answer

Preganglionic sympathetic axons

Answer

Postganglionic sympathetic axons

Answer

Somatic afferent axons

Answer

General somatic efferent axons

Question 10

Which of the following arm muscles is NOT supplied by the musculocutaneous nerve?

Accepted Answer

Triceps

Answer

Biceps

Answer

Brachialis

Answer

Coracobrachialis

Upper Limb — MCQs

Upper Limb — MCQs

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