Upper Limb — MCQs

During a strenuous game of tennis, a 55-year-old woman complained of severe shoulder pain that forced her to quit the game. During physical examination, it was found that she could not initiate abduction of her arm, but if her arm was passively elevated to 45 degrees from the vertical (at her side) position, she had no trouble fully abducting it. Injury to which muscle was responsible?

Q363Medium

A patient presents with inability to flex her hand at the joint indicated by a black arrow. Which of the following muscles appears to be paralyzed upon further examination of her finger?

Q364Easy

Which of the following muscles of the scapula, functioning as retractors, is the exception?

Q365Medium

Which of the following muscles is NOT supplied by the radial nerve below the spiral groove?

Q366Medium

Which of the following statements about radial nerve palsy is NOT true?

Q367Easy

The dorsal scapular nerve supplies all of the following muscles except?

Q368Medium

Regarding the anatomical snuffbox, which of the following statements is true?

Q369Medium

What is the 'ulnar paradox'?

Q370Easy

What is the major nerve that innervates the intrinsic muscles of the hand?

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 361: All of the following muscles are used for the retraction of the scapula, EXCEPT?

A. Trapezius
B. Rhomboideus major
C. Rhomboideus minor
D. Levator scapulae (Correct Answer)

Explanation: **Explanation:** The movement of **scapular retraction** (bringing the medial borders of the scapulae toward the midline/spine) is primarily performed by muscles that originate from the vertebral column and insert into the medial border or acromion of the scapula with a horizontal or oblique pull. * **Why Levator Scapulae is the correct answer:** The primary action of the Levator scapulae is to **elevate** the superior angle of the scapula. While it attaches to the medial border, its fibers run vertically from the cervical transverse processes (C1-C4). Therefore, it contributes to elevation and downward rotation of the glenoid cavity, but it does **not** significantly contribute to retraction. * **Why the other options are incorrect:** * **Trapezius:** Specifically, the **middle fibers** of the trapezius are the most powerful retractors of the scapula. * **Rhomboideus Major & Minor:** These muscles run obliquely from the nuchal ligament and spinous processes (C7-T5) to the medial border of the scapula. Their contraction pulls the scapula medially and upward, making them essential retractors. **NEET-PG High-Yield Pearls:** 1. **Protraction:** The primary protractor is the **Serratus Anterior** (the "boxer's muscle"). Paralysis leads to "winging of the scapula." 2. **Upward Rotation:** Performed by the Trapezius (upper and lower fibers) and Serratus Anterior. This is essential for abducting the arm above 90°. 3. **Nerve Supply:** * Trapezius: Spinal accessory nerve (CN XI). * Rhomboids & Levator Scapulae: **Dorsal scapular nerve (C5).** 4. **The "Scapular Clock":** Remember that retraction is the opposite of protraction; if a muscle pulls the scapula toward the spine, it is a retractor.

Question 362: During a strenuous game of tennis, a 55-year-old woman complained of severe shoulder pain that forced her to quit the game. During physical examination, it was found that she could not initiate abduction of her arm, but if her arm was passively elevated to 45 degrees from the vertical (at her side) position, she had no trouble fully abducting it. Injury to which muscle was responsible?

A. Deltoid
B. Infraspinatus
C. Supraspinatus (Correct Answer)
D. Teres major

Explanation: ### Explanation The clinical presentation describes a classic case of a **Supraspinatus tear** or injury. **1. Why Supraspinatus is correct:** Abduction of the arm at the shoulder joint is a coordinated effort involving multiple muscles. The **Supraspinatus** is responsible for the **initiation of abduction (0° to 15°)**. It stabilizes the humeral head in the glenoid cavity, allowing the deltoid to gain a mechanical advantage. If the supraspinatus is injured, the patient cannot initiate the movement. However, if the arm is passively lifted beyond 15°–20°, the **Deltoid** takes over the action, explaining why the patient could complete the movement once elevated to 45°. **2. Why the other options are incorrect:** * **Deltoid:** This muscle is the primary abductor from **15° to 90°**. If the deltoid were injured, the patient would be able to initiate the first few degrees of movement but would fail to lift the arm to the horizontal level. * **Infraspinatus:** This is a member of the rotator cuff primarily responsible for **lateral (external) rotation** of the humerus, not abduction. * **Teres major:** This muscle acts to **adduct and medially rotate** the arm; it does not assist in abduction. **3. NEET-PG High-Yield Pearls:** * **Rotator Cuff (SITS):** Supraspinatus (Abduction), Infraspinatus (External rotation), Teres minor (External rotation), Subscapularis (Internal rotation). * **The

Question 363: A patient presents with inability to flex her hand at the joint indicated by a black arrow. Which of the following muscles appears to be paralyzed upon further examination of her finger?

A. Palmar interossei
B. Dorsal interossei
C. Flexor digitorum profundus
D. Flexor digitorum superficialis (Correct Answer)

Explanation: ***Flexor digitorum superficialis*** - The **proximal interphalangeal (PIP) joint** is primarily flexed by the flexor digitorum superficialis, making its paralysis the cause of inability to flex at this joint. - FDS inserts at the **middle phalanx** and is responsible for isolated PIP joint flexion when the DIP joint is held in extension. *Palmar interossei* - These muscles primarily **adduct fingers** toward the middle finger and assist in **MCP joint flexion**, not PIP joint flexion. - They also contribute to **IP joint extension** through their connection to the extensor hood, opposite to the described deficit. *Dorsal interossei* - These muscles **abduct fingers** away from the middle finger and primarily flex the **MCP joints**, not the PIP joints. - Like palmar interossei, they assist in **IP joint extension** via the extensor mechanism, not flexion. *Flexor digitorum profundus* - FDP primarily flexes the **distal interphalangeal (DIP) joint** as it inserts on the distal phalanx. - While it can assist PIP flexion, its paralysis would primarily affect **DIP joint flexion**, not isolated PIP joint dysfunction.

Question 364: Which of the following muscles of the scapula, functioning as retractors, is the exception?

A. Trapezius
B. Rhomboid major
C. Rhomboid minor
D. Levator scapulae (Correct Answer)

Explanation: ### Explanation The movement of the scapula is governed by the coordinated action of extrinsic shoulder muscles. **Retraction (adduction)** refers to the movement of the scapula toward the vertebral column. **Why Levator Scapulae is the Correct Answer:** The **Levator Scapulae** primarily functions to **elevate** the scapula and assist in its downward rotation. While it originates from the cervical vertebrae and attaches to the superior angle of the scapula, its vector of pull is vertical rather than horizontal. Therefore, it does not contribute to retraction. **Analysis of Incorrect Options:** * **Trapezius (Middle fibers):** The middle fibers of the trapezius run horizontally from the spinous processes to the acromion. They are the **primary retractors** of the scapula. * **Rhomboid Major & Minor:** These muscles run obliquely from the nuchal ligament and spinous processes (C7–T5) to the medial border of the scapula. Their contraction pulls the scapula medially and superiorly, acting as **powerful retractors** and stabilizers. **NEET-PG High-Yield Pearls:** 1. **Nerve Supply:** The Rhomboids and Levator scapulae are both supplied by the **Dorsal Scapular Nerve (C5)**. The Trapezius is supplied by the **Spinal Accessory Nerve (CN XI)**. 2. **Antagonist Movement:** The primary **protractor** of the scapula is the **Serratus Anterior** (supplied by the Long Thoracic Nerve). Paralysis of this muscle leads to "Winged Scapula." 3. **Upward Rotation:** To abduct the arm above 90°, the scapula must rotate upward; this is a synergistic action of the **Trapezius (upper and lower fibers)** and the **Serratus Anterior**.

Question 365: Which of the following muscles is NOT supplied by the radial nerve below the spiral groove?

A. Brachialis
B. Brachioradialis
C. Extensor carpi radialis longus
D. Anconeus (Correct Answer)

Explanation: The radial nerve’s distribution in the arm is a high-yield topic for NEET-PG, specifically regarding the **level** at which branches arise relative to the spiral (radial) groove. ### **Explanation of the Correct Answer** The **Anconeus** is supplied by the radial nerve via a long branch that arises **within the spiral groove** (specifically, the branch to the medial head of the triceps). Because this nerve branch originates high in the arm and descends through the substance of the triceps to reach the anconeus, it is considered a branch given off **at or above** the spiral groove, not below it. ### **Analysis of Incorrect Options** After the radial nerve pierces the lateral intermuscular septum to enter the anterior compartment of the lower arm (distal to the spiral groove), it supplies: * **Brachialis (Option A):** Receives a small proprioceptive/motor branch from the radial nerve (though its main supply is Musculocutaneous). * **Brachioradialis (Option B):** Supplied by the radial nerve in the lower third of the arm, below the groove. * **Extensor Carpi Radialis Longus (Option C):** Supplied by the radial nerve in the arm before it divides into superficial and deep branches at the lateral epicondyle. ### **High-Yield Clinical Pearls** * **The "Saturday Night Palsy" Rule:** In a mid-shaft humerus fracture (spiral groove injury), the **Triceps** is usually spared (branches arise high), but the **Anconeus** and all distal extensors are affected, leading to **Wrist Drop**. * **Brachialis Dual Supply:** It is a hybrid/composite muscle supplied by the Musculocutaneous (medial part) and Radial nerve (lateral part). * **Order of Supply:** Below the spiral groove, the sequence of innervation is: Brachialis → Brachioradialis → ECRL. ECRB is usually supplied by the Deep Branch of the Radial Nerve (or PIN).

Question 366: Which of the following statements about radial nerve palsy is NOT true?

A. Loss of nerve supply to brachioradialis (Correct Answer)
B. Loss of nerve supply to extensor carpi radialis brevis
C. Loss of nerve supply to extensor pollicis brevis
D. Loss of sensation over first dorsal web space

Explanation: This question tests your knowledge of the **topographical anatomy** of the radial nerve and the level at which its branches arise. ### **Explanation of the Correct Answer (A)** The statement "Loss of nerve supply to brachioradialis" is considered **NOT true** in the context of a typical radial nerve injury occurring at the **spiral groove** (the most common site of palsy, e.g., Saturday Night Palsy). * **The Concept:** The radial nerve gives off branches to the **Triceps (long and medial heads)** in the axilla and to the **Brachioradialis** and **Extensor Carpi Radialis Longus (ECRL)** in the arm, *proximal* to the lateral epicondyle. * In many clinical scenarios of radial nerve palsy (like mid-shaft humerus fractures), the nerve is injured after these branches have already been given off, sparing the brachioradialis. ### **Analysis of Incorrect Options** * **B & C (ECRB and EPB):** These muscles are supplied by the **Deep Branch of the Radial Nerve** (or the Posterior Interosseous Nerve). Since these branches arise distal to the spiral groove/lateral epicondyle, they are invariably paralyzed in a radial nerve palsy, leading to "Wrist Drop" and "Thumb Drop." * **D (First dorsal web space):** This is the "autonomous zone" supplied by the **Superficial Radial Nerve**. Sensory loss here is a classic hallmark of radial nerve injury above the elbow. ### **NEET-PG High-Yield Pearls** * **Wrist Drop:** Caused by paralysis of wrist extensors. * **Finger Drop:** Specifically refers to PIN (Posterior Interosseous Nerve) palsy; notably, in PIN palsy, **wrist extension is preserved** (due to ECRL being supplied by the main radial nerve) but deviates radially. * **The "Rule of 3":** The radial nerve supplies 3 muscles before dividing: Brachioradialis, ECRL, and Anconeus. * **Most common site of injury:** Spiral groove (Humerus shaft fracture).

Question 367: The dorsal scapular nerve supplies all of the following muscles except?

A. Rhomboid major
B. Rhomboid minor
C. Supraspinatus (Correct Answer)
D. Levator scapulae

Explanation: ### Explanation The **Dorsal Scapular Nerve** arises from the **ventral ramus of the C5 nerve root** (the root stage of the brachial plexus). It travels posteriorly, piercing the middle scalene muscle to reach the medial border of the scapula. **1. Why Supraspinatus is the correct answer:** The **Supraspinatus** is supplied by the **Suprascapular Nerve** (C5, C6), which arises from the **Upper Trunk** of the brachial plexus. It does not receive any innervation from the dorsal scapular nerve. Therefore, it is the "except" in this list. **2. Analysis of incorrect options:** * **Rhomboid Major & Minor:** These are the primary muscles supplied by the dorsal scapular nerve. It enters their deep surface to provide motor innervation, facilitating scapular retraction and elevation. * **Levator Scapulae:** This muscle has a dual nerve supply. It is supplied by the **Dorsal Scapular Nerve (C5)** and direct branches from the **C3 and C4 cervical nerves**. Since it is partially supplied by the dorsal scapular nerve, it is an incorrect choice for this "except" question. **3. NEET-PG High-Yield Pearls:** * **Nerve Root:** Remember "Dorsal Scapular = C5 root." * **Clinical Sign:** Injury to the dorsal scapular nerve results in a lateral shift of the scapula (the rhomboids can no longer retract it) and difficulty "squaring" the shoulders. * **Suprascapular Nerve:** Supplies both the **Supraspinatus** and **Infraspinatus**. It passes through the suprascapular notch (under the superior transverse scapular ligament). * **Dual Supply:** Always remember Levator Scapulae (C3, C4 + C5) and Pectoralis Major (Medial + Lateral Pectoral nerves) as common "dual supply" questions in Anatomy.

Question 368: Regarding the anatomical snuffbox, which of the following statements is true?

A. Abductor pollicis longus forms the posterior wall.
B. Abductor pollicis longus and Extensor pollicis brevis form the anterior wall. (Correct Answer)
C. Basilic vein forms the roof.
D. The floor is formed by Extensor carpi radialis longus and brevis.

Explanation: ### Explanation The **anatomical snuffbox** is a triangular depression on the radial aspect of the dorsum of the hand, visible when the thumb is fully extended. **1. Why Option B is Correct:** The boundaries of the snuffbox are defined by the tendons of the extrinsic thumb muscles. The **anterior (lateral) border** is formed by the tendons of the **Abductor Pollicis Longus (APL)** and **Extensor Pollicis Brevis (EPB)** [1]. These two tendons travel together in the first dorsal compartment of the extensor retinaculum [1]. **2. Analysis of Incorrect Options:** * **Option A:** The **posterior (medial) border** is formed by the tendon of the **Extensor Pollicis Longus (EPL)**, which hooks around Lister’s tubercle [1]. * **Option C:** The **roof** is formed by skin, superficial fascia, the **Cephalic vein** (not Basilic), and the superficial branch of the radial nerve. * **Option D:** The **floor** is composed of the **Scaphoid** and **Trapezium** bones [1]. The Extensor Carpi Radialis Longus (ECRL) and Brevis (ECRB) tendons actually pass *under* the floor of the snuffbox. **3. NEET-PG High-Yield Clinical Pearls:** * **Scaphoid Fracture:** Tenderness in the anatomical snuffbox is the classic clinical sign of a scaphoid fracture. Due to retrograde blood supply, this carries a high risk of **avascular necrosis (AVN)**. * **Radial Artery:** The radial artery pulses can be felt deep within the floor of the snuffbox as it passes from the anterior to the posterior aspect of the hand. * **De Quervain’s Tenosynovitis:** Inflammation of the tendons forming the anterior wall (APL and EPB) leads to pain over the radial styloid (positive Finkelstein’s test).

Question 369: What is the 'ulnar paradox'?

A. High ulnar nerve lesion (Correct Answer)
B. Low ulnar nerve lesion
C. Triple nerve disease
D. All of the above

Explanation: The **Ulnar Paradox** refers to the clinical observation that a **higher** (more proximal) lesion of the ulnar nerve results in a **less severe** physical deformity (claw hand) than a lower (more distal) lesion. [1] ### 1. Why High Ulnar Nerve Lesion is Correct In a **low ulnar nerve lesion** (at the wrist), the medial half of the **Flexor Digitorum Profundus (FDP)** remains intact. This muscle continues to flex the distal interphalangeal (DIP) joints of the ring and little fingers. Combined with the paralysis of the lumbricals, this leads to a "pronounced" clawing effect. In a **high ulnar nerve lesion** (at or above the elbow), the nerve supply to the medial half of the **FDP is lost**. Since the FDP can no longer flex the DIP joints, the fingers appear straighter and the clawing is **less prominent**. Paradoxically, the more proximal the injury, the better the hand looks. [1] ### 2. Why Other Options are Incorrect * **Low ulnar nerve lesion:** This produces a more severe claw hand because the FDP is spared, pulling the fingers into deeper flexion. * **Triple nerve disease:** This involves the ulnar, radial, and median nerves simultaneously, leading to total claw hand and extensive sensory loss, which does not follow the specific "paradox" mechanism. ### 3. NEET-PG High-Yield Pearls * **Claw Hand (Main-en-griffe):** Characterized by hyperextension at the MCP joints and flexion at the IP joints. [1] * **Froment’s Sign:** Tests for adductor pollicis paralysis (ulnar nerve); the patient compensates by flexing the thumb (FPL - median nerve). * **Rule of Thumb:** Proximal lesion = less clawing; Distal lesion = more clawing. * **Nerve Roots:** Ulnar nerve arises from C8 and T1.

Question 370: What is the major nerve that innervates the intrinsic muscles of the hand?

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

Explanation: The **Ulnar Nerve (C8-T1)** is known as the **"Musician’s Nerve"** because it controls the fine, intricate movements of the hand. It is the primary motor supply to the intrinsic hand muscles, innervating 15 out of the 20 muscles. These include all interossei (palmar and dorsal), the adductor pollicis, the hypothenar eminence, and the medial two lumbricals. [1] ### Why the other options are incorrect: * **Median Nerve:** Often called the "Laborer’s Nerve," it supplies only five intrinsic muscles (the **LOAF** muscles): the lateral two **L**umbricals, **O**pponens pollicis, **A**bductor pollicis brevis, and **F**lexor pollicis brevis. [1] * **Radial Nerve:** This nerve primarily supplies the extensor compartment of the arm and forearm. It provides **no motor innervation** to any intrinsic muscles of the hand; its contribution to the hand is purely sensory (via the superficial branch). * **Musculocutaneous Nerve:** This nerve terminates after supplying the coracobrachialis, biceps brachii, and brachialis, continuing only as the lateral cutaneous nerve of the forearm. It has no motor role in the hand. ### High-Yield Clinical Pearls for NEET-PG: * **Froment’s Sign:** Tests for ulnar nerve palsy; specifically assesses the paralysis of the **Adductor Pollicis**, leading to compensatory flexion of the thumb IP joint by the FPL (Median nerve). * **Ulnar Paradox:** The higher the lesion (at the elbow), the less prominent the clawing of the fingers, because the long flexors (FDP) are also paralyzed. * **Klumpke’s Paralysis:** Injury to the lower trunk (C8-T1) results in "Total Claw Hand" because both Ulnar and Median contributions to the hand are affected.

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Arm and Cubital Fossa

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Arterial Supply and Venous Drainage

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Upper Limb — MCQs

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