Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 341: Which is a branch of the ulnar nerve in the arm?

A. To Flexor Carpi Ulnaris (FCU)
B. To Flexor Digitorum Profundus (FDP)
C. To Flexor Carpi Radialis (FCR)
D. No branch (Correct Answer)

Explanation: ### Explanation **1. Why "No branch" is the correct answer:** The ulnar nerve (C8, T1) originates from the medial cord of the brachial plexus. In the arm, it descends medial to the brachial artery, pierces the medial intermuscular septum at the midpoint of the humerus, and passes behind the medial epicondyle. **Crucially, the ulnar nerve gives off no motor or cutaneous branches in the arm.** Its first branches arise only after it enters the forearm, distal to the elbow joint. **2. Analysis of Incorrect Options:** * **Option A (To Flexor Carpi Ulnaris):** This is the first muscular branch of the ulnar nerve, but it arises in the **forearm**, just after the nerve passes between the two heads of the FCU [1]. * **Option B (To Flexor Digitorum Profundus):** The ulnar nerve supplies the medial half (ulnar half) of the FDP. Like the branch to the FCU, this branch arises in the **upper part of the forearm**, not the arm. * **Option C (To Flexor Carpi Radialis):** This is incorrect because the FCR is supplied by the **median nerve** [1]. **3. NEET-PG High-Yield Pearls:** * **The "No Branch" Rule:** Both the **Ulnar nerve** and the **Median nerve** give off no branches in the arm (axilla to elbow). The only major nerve of the terminal brachial plexus that branches extensively in the arm is the **Radial nerve**. * **Clinical Correlation:** Because the ulnar nerve has no branches in the arm, a mid-shaft humerus fracture or a high humeral injury will typically spare the forearm muscles but will manifest symptoms once the nerve reaches the hand (e.g., claw hand). * **The "Funny Bone":** The ulnar nerve is most vulnerable to compression at the **retrocondylar groove** (behind the medial epicondyle), where it is superficial and rests directly against the bone.

Question 342: What are the root values of the axillary nerve?

A. C5, C6 (Correct Answer)
B. C7, C8
C. C8, T1
D. C5, T1

Explanation: The **axillary nerve** (also known as the circumflex nerve) is a major terminal branch of the **posterior cord** of the brachial plexus. ### 1. Why C5, C6 is Correct The axillary nerve originates from the posterior cord, which receives contributions from all three trunks of the brachial plexus. However, the specific fibers that form the axillary nerve are derived solely from the **ventral rami of C5 and C6**. These roots provide the motor supply to the deltoid and teres minor muscles and sensory innervation to the "regimental badge" area of the shoulder. ### 2. Analysis of Incorrect Options * **C7, C8 (Option B):** These roots contribute to the radial nerve (C5-T1) and the ulnar nerve (C8-T1), but do not form the axillary nerve. * **C8, T1 (Option C):** These are the root values for the **medial cord** derivatives, such as the ulnar nerve and the medial cutaneous nerves of the arm and forearm. * **D. C5, T1 (Option D):** This represents the entire span of the brachial plexus. While the **radial nerve** carries fibers from C5 to T1, the axillary nerve is restricted to the upper roots. ### 3. Clinical Pearls for NEET-PG * **Course:** It passes through the **quadrangular space** alongside the posterior circumflex humeral artery. [1] * **Injury Site:** Most commonly injured during **anterior dislocation of the shoulder joint** or **fracture of the surgical neck of the humerus**. * **Clinical Presentation:** * **Motor:** Loss of abduction of the arm (15–90 degrees) due to deltoid paralysis. * **Sensory:** Loss of sensation over the lower half of the deltoid (**Regimental Badge area**). * **Deformity:** Flattening of the shoulder contour due to deltoid atrophy.

Question 343: Modified Allen's test is used to check the patency of the arteries supplying which part of the upper limb?

A. Wrist (Correct Answer)
B. Arm
C. Elbow
D. Forearm

Explanation: **Explanation:** The **Modified Allen’s Test** is a clinical bedside procedure used to assess the **collateral circulation** of the hand, specifically the patency of the **radial and ulnar arteries** at the level of the **wrist** [1]. **Why Option A is Correct:** The test is performed before procedures like arterial blood gas (ABG) sampling or radial artery cannulation. The clinician compresses both the radial and ulnar arteries at the wrist while the patient makes a tight fist to blanch the palm. Upon releasing pressure from the ulnar artery (while keeping the radial artery compressed), the palm should return to its normal pink color within 5–15 seconds [1]. This confirms that the ulnar artery provides sufficient collateral flow to the superficial palmar arch, ensuring the hand remains perfused even if the radial artery is damaged [1]. **Why Other Options are Incorrect:** * **B & C (Arm and Elbow):** These regions are supplied primarily by the brachial artery and its proximal branches (profunda brachii). Patency here is typically assessed via the brachial pulse or Doppler studies, not Allen’s test. * **D (Forearm):** While the radial and ulnar arteries travel through the forearm, the test specifically evaluates their terminal adequacy at the wrist to supply the hand [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Normal Result:** Reperfusion within **<7 seconds**. * **Equivocal:** 7–15 seconds. * **Abnormal (Positive):** >15 seconds (indicates inadequate collateral circulation; radial artery cannulation is contraindicated). * **Anatomy:** The test primarily evaluates the integrity of the **superficial palmar arch**, which is mainly formed by the ulnar artery [1].

Question 344: The musculocutaneous nerve supplies all of the following muscles, EXCEPT?

A. Brachialis
B. Brachioradialis (Correct Answer)
C. Biceps brachii
D. Coracobrachialis

Explanation: **Explanation:** The **musculocutaneous nerve (C5–C7)** is the continuation of the lateral cord of the brachial plexus. It is the primary motor nerve for the muscles in the **anterior compartment of the arm** (flexors of the elbow and supinators). **Why Brachioradialis is the correct answer:** The **Brachioradialis** is located in the lateral aspect of the forearm. Despite being a flexor of the elbow, it belongs morphologically to the posterior compartment of the forearm and is supplied by the **Radial Nerve (C5–C6)**. This is a classic "trap" in anatomy exams because the muscle crosses the elbow joint anteriorly. **Analysis of Incorrect Options:** * **Coracobrachialis:** This muscle is pierced by the musculocutaneous nerve and is the first muscle it supplies. * **Biceps Brachii:** Both the long and short heads are supplied by the musculocutaneous nerve. It is the chief supinator of the forearm when the elbow is flexed. * **Brachialis:** This muscle has a **dual nerve supply**. The medial (larger) part is supplied by the **musculocutaneous nerve**, while the lateral part is supplied by the **radial nerve**. Since it receives its primary innervation from the musculocutaneous nerve, it is not the "except" option. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Musculocutaneous supply:** **BBC** (Biceps, Brachialis, Coracobrachialis). * **Sensory supply:** After supplying the arm muscles, the nerve continues as the **Lateral Cutaneous Nerve of the Forearm**, supplying the skin of the lateral forearm up to the base of the thumb. * **Injury:** Damage to this nerve results in weak elbow flexion and weak supination, along with sensory loss on the lateral forearm.

Question 345: A patient presents with a history of trauma to the right upper limb. The patient has lost the ability to extend the metacarpophalangeal joints, but has no wrist drop and normal extension of the interphalangeal joints. Which nerve is most likely involved?

A. Ulnar nerve
B. Median nerve
C. Radial nerve
D. Posterior interosseous nerve (Correct Answer)

Explanation: ### Explanation The key to solving this question lies in understanding the functional anatomy of the radial nerve and its branches. **1. Why Posterior Interosseous Nerve (PIN) is correct:** The PIN is the deep branch of the radial nerve that arises near the elbow (after the radial nerve has already supplied the ECRL and ECRB). It supplies the **Extensor Digitorum**, which is the primary extensor of the **metacarpophalangeal (MCP) joints**. [1] * **No Wrist Drop:** Because the Extensor Carpi Radialis Longus (ECRL) is supplied by the main radial nerve *before* it bifurcates, wrist extension is preserved (though it may deviate radially). * **IP Joint Extension:** Extension of the interphalangeal (IP) joints is primarily performed by the **lumbricals and interossei** (supplied by the ulnar and median nerves), not the PIN. [1] Therefore, IP extension remains intact. **2. Why other options are incorrect:** * **Radial Nerve:** A lesion of the main radial nerve (e.g., in the spiral groove) would result in **wrist drop** because the ECRL, ECRB, and Brachioradialis would be paralyzed along with the finger extensors. [1] * **Ulnar Nerve:** Injury leads to "claw hand" (hyperextension of MCP and flexion of IP joints) due to lumbrical paralysis, but it does not cause a loss of active MCP extension. [1] * **Median Nerve:** Primarily involves thumb opposition and finger flexion (lateral two digits); it does not control MCP extension. **3. High-Yield Clinical Pearls for NEET-PG:** * **PIN Syndrome (Frohse’s Arcade):** The PIN can be compressed as it passes between the two heads of the **supinator muscle**. * **Finger Drop vs. Wrist Drop:** PIN palsy causes "finger drop" (loss of MCP extension) without "wrist drop." * **Sensory Note:** The PIN is a purely motor nerve to muscles, but it carries sensory fibers to the **carpal ligaments/joint capsule**. It does not supply any cutaneous sensation.

Question 346: A patient presents with a laceration of the wrist but with no vascular injury. On examination, a structure lateral to the flexor digitorum superficialis is found to be injured. What action can the patient most likely not perform?

A. Abduction of the 2nd digit
B. Adduction of the 2nd digit
C. Opposition of the thumb (Correct Answer)
D. Flexion of the thumb

Explanation: ### Explanation **1. Analysis of the Correct Answer (C):** The key to this question lies in the anatomical relationship at the wrist. The structure located **lateral to the flexor digitorum superficialis (FDS)** and medial to the flexor carpi radialis (FCR) is the **Median Nerve** [1]. A laceration at the wrist (e.g., "suicide cut") frequently damages the median nerve before it enters the carpal tunnel. This leads to paralysis of the **thenar muscles** (Abductor pollicis brevis, Flexor pollicis brevis, and Opponens pollicis) [2]. The **Opponens pollicis** is specifically responsible for **opposition of the thumb**, a hallmark function of the median nerve [2]. Loss of this action results in "Ape thumb deformity." **2. Analysis of Incorrect Options:** * **A & B (Abduction/Adduction of the 2nd digit):** These actions are performed by the **Dorsal and Palmar Interossei**, respectively. All interossei are innervated by the **Deep branch of the Ulnar Nerve** [2]. * **D (Flexion of the thumb):** While the median nerve supplies the Flexor Pollicis Brevis (FPB), the primary flexor of the thumb is the **Flexor Pollicis Longus (FPL)**. The FPL muscle belly is in the forearm and its nerve supply (Anterior Interosseous Nerve) occurs much higher than the wrist; therefore, thumb flexion is often partially preserved or less affected than opposition [2]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Median Nerve at Wrist:** "Meat Loaf" – The nerve is **M**edial to the **L**ateral-most structures (FCR/Radial artery) and **L**ateral to the **O**thers (FDS/Palmaris Longus) [1]. * **LOAF Muscles:** The Median nerve supplies the **L**umbricals (1st & 2nd), **O**pponens pollicis, **A**bductor pollicis brevis, and **F**lexor pollicis brevis [2]. * **Point of Injury:** If the injury is at the wrist (low median nerve palsy), sensation is lost over the lateral 3.5 digits, but the **palmar cutaneous branch** (sparing the proximal palm) may be spared if the cut is distal to its origin [1].

Question 347: A 22-year-old male is thrown through a plate glass wall in a fight. Radiologic examination reveals that the lateral border of his right scapula is shattered. Physical examination reveals difficulty laterally rotating his arm. Which of the following muscles is most probably injured?

A. Teres major
B. Infraspinatus (Correct Answer)
C. Latissimus dorsi
D. Trapezius

Explanation: ### **Explanation** **1. Why Infraspinatus is Correct:** The clinical scenario describes a fracture of the **lateral border of the scapula** and a functional deficit in **lateral (external) rotation** of the arm. The **Infraspinatus** muscle originates from the infraspinous fossa of the scapula and inserts onto the middle impression of the greater tubercle of the humerus. Along with the **Teres minor**, it is a primary lateral rotator of the glenohumeral joint. Since the lateral border of the scapula serves as the attachment site for these muscles, a shattered lateral border directly compromises their function, leading to the inability to rotate the arm laterally. **2. Why the Other Options are Incorrect:** * **A. Teres major:** While it originates from the lower third of the lateral border of the scapula, its action is **medial rotation**, adduction, and extension of the arm (the "handcuff" muscle). * **C. Latissimus dorsi:** This muscle originates from the spinous processes of T7-L5, thoracolumbar fascia, and iliac crest. It acts as a **medial rotator**, adductor, and extensor. It does not originate from the lateral border of the scapula. * **D. Trapezius:** This is a superficial muscle of the back that inserts onto the spine of the scapula, acromion, and lateral clavicle. Its primary functions involve scapular movements (elevation, retraction, rotation), not lateral rotation of the humerus. **3. Clinical Pearls for NEET-PG:** * **Rotator Cuff (SITS):** Supraspinatus (Abduction 0-15°), Infraspinatus (Lateral rotation), Teres minor (Lateral rotation), and Subscapularis (Medial rotation). * **Innervation:** Infraspinatus is supplied by the **Suprascapular nerve (C5, C6)**. * **Lateral Rotators:** Only two muscles primarily perform lateral rotation—Infraspinatus and Teres minor. If lateral rotation is lost, look for these two. * **Medial Rotators:** Subscapularis, Pectoralis major, Latissimus dorsi, and Teres major.

Question 348: A 54-year-old woman presents with a wrist dislocation after falling onto an outstretched hand. Which of the following carpal bones are most likely involved?

A. Scaphoid-lunate (Correct Answer)
B. Trapezoid-trapezium
C. Hamate-lunate
D. Pisiform-triquetrum

Explanation: **Explanation:** The correct answer is **A. Scaphoid-lunate**. **Underlying Medical Concept:** The most common type of carpal instability and wrist dislocation occurs at the **scapholunate joint**. The scaphoid and lunate are the most critical bones in the proximal carpal row for maintaining wrist stability. A fall on an outstretched hand (FOOSH) with the wrist in extension and ulnar deviation puts maximum stress on the **scapholunate interosseous ligament**. Rupture of this ligament leads to "scapholunate dissociation," the most frequent precursor to perilunate and lunate dislocations. **Analysis of Incorrect Options:** * **B. Trapezoid-trapezium:** These are distal row carpal bones. They are tightly bound by strong interosseous ligaments and are rarely the primary site of dislocation in FOOSH injuries. * **C. Hamate-lunate:** While the lunate articulates with the hamate, the primary axis of instability in wrist trauma is longitudinal between the scaphoid and lunate. A "lunate-hamate" dissociation is not a standard clinical entity in common wrist dislocations. * **D. Pisiform-triquetrum:** The pisiform is a sesamoid bone within the flexor carpi ulnaris tendon. While it can be fractured, it does not play a structural role in the carpal stability required to prevent major wrist dislocations. **NEET-PG High-Yield Pearls:** * **Terry Thomas Sign:** A gap of >3mm between the scaphoid and lunate on an AP X-ray, indicating scapholunate dissociation. * **Lunate Dislocation:** On a lateral X-ray, the lunate looks like a **"spilled teacup."** * **Perilunate Dislocation:** The lunate remains in contact with the radius, but the capitate is displaced posteriorly. * **Most common carpal fracture:** Scaphoid (risk of avascular necrosis) [1]. * **Most common carpal dislocation:** Lunate.

Question 349: A 24-year-old college student presented with 'winged scapula' after a fall. Winging of the scapula is due to injury to which of the following?

A. The nerve supplying the serratus anterior (Correct Answer)
B. Pectoral nerve
C. Subscapular nerve
D. Ulnar nerve

Explanation: **Explanation:** **Winging of the scapula** is a classic clinical sign characterized by the medial border of the scapula protruding posteriorly, resembling a wing. This occurs due to paralysis of the **Serratus Anterior** muscle. 1. **Why the Correct Answer is Right:** The Serratus Anterior is supplied by the **Long Thoracic Nerve (Nerve of Bell)**, which arises from the roots of the brachial plexus (C5, C6, C7). The primary function of this muscle is to protract the scapula and keep its medial border firmly applied against the thoracic wall. When the long thoracic nerve is injured (commonly via trauma, surgery, or heavy lifting), the muscle loses its ability to anchor the scapula, causing it to "wing" outward, especially when the patient attempts to push against a wall. 2. **Why Other Options are Incorrect:** * **Pectoral Nerve:** Supplies the Pectoralis Major and Minor [1]. Injury leads to weakness in adduction and medial rotation of the arm, not winging. * **Subscapular Nerve:** Supplies the Subscapularis and Teres Major. Injury affects internal rotation of the humerus. * **Ulnar Nerve:** Supplies most intrinsic muscles of the hand [2]. Injury leads to "Claw Hand" deformity and sensory loss in the medial 1.5 fingers. 3. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve Root:** Remember the mnemonic *"C5, 6, 7 raise your arms to heaven"* (Long Thoracic Nerve). * **Overhead Abduction:** The Serratus Anterior (along with the Trapezius) is essential for rotating the scapula to allow abduction of the arm beyond 90 degrees. * **Differential Diagnosis:** If winging occurs when the patient *pulls* (rather than pushes), or if the scapula moves laterally, consider injury to the **Spinal Accessory Nerve** (supplying the Trapezius).

Question 350: A 34-year-old female skier presents after striking a tree on the ski slope, with imaging evidence of a shoulder separation. Which of the following is typically associated with this type of injury?

A. Displacement of the head of the humerus from the glenoid cavity
B. Partial or complete tearing of the coracoclavicular ligament (Correct Answer)
C. Partial or complete tearing of the coracoacromial ligament
D. Rupture of the transverse scapular ligament

Explanation: **1. Why Option B is Correct:** "Shoulder separation" is the clinical term for **Acromioclavicular (AC) joint dislocation**. This injury typically results from a direct blow to the shoulder or a fall on an outstretched hand. The stability of the AC joint depends on two sets of ligaments: the acromioclavicular ligament (intrinsic) and the **coracoclavicular (CC) ligament** (extrinsic). The CC ligament, composed of the **conoid and trapezoid** parts, is the primary stabilizer that anchors the clavicle to the coracoid process. In significant shoulder separations (Grade II and III), the CC ligament is partially or completely torn, allowing the scapula to fall away from the clavicle due to the weight of the upper limb. **2. Why Other Options are Incorrect:** * **Option A:** Displacement of the humeral head from the glenoid cavity describes a **shoulder dislocation** (Glenohumeral joint), not a shoulder separation. * **Option B:** The **coracoacromial ligament** forms the coracoacromial arch, preventing superior displacement of the humerus. While it is in the vicinity, it does not stabilize the AC joint and is rarely torn in this mechanism. * **Option D:** The **transverse scapular ligament** bridges the suprascapular notch. Its rupture is not associated with joint stability; however, its ossification can lead to suprascapular nerve entrapment. **3. NEET-PG High-Yield Pearls:** * **Step-off Deformity:** A visible gap or "step" between the acromion and the distal clavicle is a classic physical finding in AC separation. * **Piano Key Sign:** Downward pressure on the elevated distal clavicle causes it to depress and then spring back, indicating a complete CC ligament tear. * **Ligament Strength:** The coracoclavicular ligament is much stronger than the acromioclavicular ligament; therefore, a "separation" usually implies the CC ligament has been compromised.

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Pectoral Region and Axilla

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Arm and Cubital Fossa

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Forearm and Hand

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Joints of Upper Limb

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Nerves of Upper Limb

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Arterial Supply and Venous Drainage

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Lymphatic Drainage

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Muscles and Their Actions

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Applied Anatomy and Clinical Correlations

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Surface Anatomy and Landmarks

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Upper Limb — MCQs

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