Upper Limb — MCQs

A 52-year-old male conductor experienced excruciating pain in the posterior aspect of his right forearm after several days of 12-hour daily rehearsals. Palpation 2 cm distal to and posteromedial to the lateral epicondyle caused him to weep due to intense pain. Injections of steroids and rest were recommended. Which of the following injuries is most likely?

Q607Medium

A 32-year-old woman presents with multiple humerus fractures following an automobile collision. She exhibits severely weakened forearm flexion and supination, along with loss of sensation on the lateral forearm. Which nerve is most likely injured?

Q608Easy

Which of the following muscles arises from the infraglenoid tubercle?

Q609Easy

What forms the arterial anastomosis around the surgical neck of the humerus?

Q610Easy

Which muscle performs flexion, adduction, and medial rotation of the arm?

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 601: Which of the following is NOT true about the ulnar nerve?

A. Its root value includes C8 and T1.
B. It passes through the cubital tunnel.
C. It supplies the flexor digitorum superficialis muscle. (Correct Answer)
D. It supplies the flexor carpi ulnaris muscle.

Explanation: The ulnar nerve, often called the "musician’s nerve," is a major branch of the medial cord of the brachial plexus. **Why Option C is the correct answer (The False Statement):** The **Flexor Digitorum Superficialis (FDS)** is supplied entirely by the **Median Nerve**. The ulnar nerve only supplies one and a half muscles in the forearm: the Flexor Carpi Ulnaris (FCU) and the medial half (ulnar half) of the Flexor Digitorum Profundus (FDP) [1]. **Analysis of Incorrect Options:** * **Option A:** The root value of the ulnar nerve is **C8 and T1**. In many individuals, it also receives fibers from **C7** via a communication from the lateral cord (high-yield for identifying variations). * **Option B:** The ulnar nerve passes behind the medial epicondyle of the humerus and enters the forearm through the **cubital tunnel** (formed by the humeral and ulnar heads of the FCU). This is a common site for entrapment. * **Option D:** The **Flexor Carpi Ulnaris** is the primary muscle supplied by the ulnar nerve in the forearm, responsible for wrist flexion and adduction [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Guyon’s Canal:** The ulnar nerve passes superficial to the flexor retinaculum through this canal at the wrist [1]. * **Ulnar Paradox:** A lesion at the wrist causes a more prominent "claw hand" than a lesion at the elbow because the FDP remains intact, increasing the flexion deformity of the IP joints. * **Froment’s Sign:** Tests for adductor pollicis paralysis (ulnar nerve) where the patient compensates by flexing the thumb IP joint (median nerve/FPL) [1].

Question 602: Benedict's hand is due to injury to which nerve?

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

Explanation: **Explanation:** **Hand of Benediction** (or Benedict’s hand) is a clinical sign that occurs due to a **high median nerve injury** (at or above the elbow). **Why Median Nerve is Correct:** When a patient with a high median nerve lesion is asked to **make a fist**, they are unable to flex the thumb, index, and middle fingers. This happens because of the paralysis of the **Flexor Digitorum Superficialis (FDS)** and the lateral half of the **Flexor Digitorum Profundus (FDP)** [2]. The ring and little fingers can still flex because their portion of the FDP is supplied by the ulnar nerve [3]. The resulting position—with the index and middle fingers extended and the others flexed—resembles a hand giving a blessing. **Why Other Options are Incorrect:** * **Ulnar Nerve:** Injury leads to **"Ulnar Claw Hand."** This is characterized by hyperextension at the MCP joints and flexion at the IP joints of the ring and little fingers, visible at **rest**. * **Radial Nerve:** Injury leads to **Wrist Drop** due to paralysis of the extensors of the wrist and fingers [3]. * **Axillary Nerve:** Injury leads to paralysis of the deltoid muscle, resulting in loss of shoulder abduction and "flat shoulder" appearance. **High-Yield Clinical Pearls for NEET-PG:** 1. **Active vs. Passive:** Benedict’s hand is an **active** sign (seen only when attempting to clench the fist), whereas Ulnar Clawing is a **passive** sign (seen at rest). 2. **Point of Injury:** A low median nerve injury (at the wrist/Carpal Tunnel) causes "Ape Thumb" deformity (loss of opposition) but does not typically cause Benedict's hand because the FDP/FDS supply is preserved [1]. 3. **Ochsner’s Clasping Test:** Used to diagnose high median nerve palsy; the index finger fails to flex when the hands are clasped.

Question 603: For every 3 degrees of arm abduction at the shoulder, what is the corresponding scapular rotation?

A. 1 degree (Correct Answer)
B. 2 degrees
C. 3 degrees
D. 0.5 degrees

Explanation: ### Explanation **1. The Correct Answer: A (1 degree)** The movement of the shoulder involves a coordinated rhythm between the humerus and the scapula, known as the **Scapulohumeral Rhythm**. * The overall ratio of glenohumeral (GH) movement to scapulothoracic (ST) movement is **2:1**. * This means that for every 3 degrees of total abduction, **2 degrees** occur at the GH joint and **1 degree** occurs due to the rotation of the scapula. * Therefore, for the 180 degrees of total abduction: 120 degrees is GH motion and 60 degrees is ST motion. **2. Why Other Options are Incorrect:** * **B (2 degrees):** This represents the amount of **glenohumeral** movement for every 3 degrees of total abduction, not the scapular rotation. * **C (3 degrees):** This would imply a 1:1 ratio, which does not occur. If the scapula rotated 3 degrees for every 3 degrees of abduction, the humerus would remain static relative to the glenoid. * **D (0.5 degrees):** This ratio (6:1) is incorrect and does not align with the physiological mechanics required to maintain the length-tension relationship of the deltoid. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Setting Phase:** In the first 30 degrees of abduction, the movement is primarily glenohumeral; the scapula seeks a position of stability (the "setting phase"). The 2:1 ratio becomes consistent after 30 degrees. * **Muscles Involved:** Scapular rotation is primarily achieved by the **Serratus Anterior** and the **Trapezius** (upper and lower fibers acting as a force couple). * **Clinical Correlation:** A reversal or disturbance of this rhythm is often seen in **Frozen Shoulder (Adhesive Capsulitis)** or **Rotator Cuff tears**, where the patient compensates for lack of GH motion by "shrugging" the scapula prematurely. * **Deltoid Efficiency:** The scapulohumeral rhythm prevents the deltoid from undergoing active insufficiency by maintaining optimal muscle fiber length.

Question 604: The subclavian artery is divided by which muscle?

A. Pectoralis minor
B. Teres minor
C. Scaleneus anterior (Correct Answer)
D. Trapezius

Explanation: The **subclavian artery** is divided into three parts based on its anatomical relationship with the **scalenus anterior** muscle. This muscle passes anterior to the artery, acting as a landmark for its division: 1. **First Part:** From the origin of the artery to the medial border of the scalenus anterior. 2. **Second Part:** Lies directly posterior (behind) the scalenus anterior. 3. **Third Part:** From the lateral border of the scalenus anterior to the outer border of the first rib (where it becomes the axillary artery). ### Explanation of Incorrect Options: * **Pectoralis minor:** This muscle divides the **axillary artery** (not the subclavian) into three parts. * **Teres minor:** This muscle forms the superior boundary of the quadrangular and triangular spaces in the axilla but does not divide the subclavian artery. * **Trapezius:** This is a superficial muscle of the back and neck; it does not have a direct topographical relationship with the division of the subclavian artery. ### High-Yield Clinical Pearls for NEET-PG: * **Branches:** Remember the mnemonic **VIT C & D** for the branches of the subclavian artery: **V**ertebral, **I**nternal thoracic, **T**hyrocervical trunk (from 1st part); **C**ostocervical trunk (from 2nd part); **D**orsal scapular (from 3rd part). * **Scalene Triangle:** The subclavian artery and the trunks of the brachial plexus pass through the scalene triangle (between scalenus anterior and medius), whereas the **subclavian vein** passes anterior to the scalenus anterior. * **Phrenic Nerve:** This nerve descends vertically on the anterior surface of the scalenus anterior muscle, separating it from the subclavian vein.

Question 605: Injury to which nerve originating from the C5 nerve root of the brachial plexus leads to a specific deficit?

A. Loss of abduction of the arm
B. Loss of external rotation of the arm
C. Loss of shoulder shrugging
D. Winging of the scapula (Correct Answer)

Explanation: The correct answer is **Winging of the Scapula** because it is caused by paralysis of the **Serratus Anterior** muscle, which is supplied by the **Long Thoracic Nerve**. This nerve originates directly from the ventral rami of **C5, C6, and C7**. Since C5 is a primary root of origin, an injury to this root (or the nerve itself) results in the inability of the muscle to hold the medial border of the scapula against the posterior chest wall, leading to its protrusion (winging). **Analysis of Options:** * **A & B (Loss of abduction/external rotation):** These are characteristic of **Erb’s Palsy**, which involves the **upper trunk** (C5-C6) rather than just a specific nerve originating from the C5 root. Abduction is lost due to Suprascapular (Supraspinatus) and Axillary (Deltoid) nerve involvement. External rotation is lost due to Suprascapular (Infraspinatus) and Axillary (Teres minor) involvement. * **C (Loss of shoulder shrugging):** This is mediated by the **Trapezius** muscle, which is supplied by the **Spinal Accessory Nerve (CN XI)**, not the brachial plexus. **Clinical Pearls for NEET-PG:** * **Long Thoracic Nerve (Nerve of Bell):** It is unique because it arises from the **roots** (C5-C7) and runs along the lateral thoracic wall. It is commonly injured during radical mastectomy or chest tube insertion. * **Dorsal Scapular Nerve:** Another nerve arising solely from the **C5 root**; it supplies the Rhomboids. Paralysis leads to a lateral shift of the scapula. * **Dynamic Winging:** Winging is accentuated when the patient is asked to push against a wall.

Question 606: A 52-year-old male conductor experienced excruciating pain in the posterior aspect of his right forearm after several days of 12-hour daily rehearsals. Palpation 2 cm distal to and posteromedial to the lateral epicondyle caused him to weep due to intense pain. Injections of steroids and rest were recommended. Which of the following injuries is most likely?

A. Compression of the median nerve by the pronator teres
B. Compression of the median nerve by the flexor digitorum superficialis
C. Compression of the superficial radial nerve by the brachioradialis
D. Compression of the deep radial nerve by the supinator (Correct Answer)

Explanation: ### **Explanation** The clinical presentation describes **Radial Tunnel Syndrome** (or Posterior Interosseous Nerve Syndrome), specifically involving compression of the **Deep Radial Nerve** as it passes through the **Arcade of Frohse** (the fibrous arch of the supinator muscle). **1. Why Option D is Correct:** The deep branch of the radial nerve enters the supinator muscle and emerges as the **Posterior Interosseous Nerve (PIN)**. Repetitive forearm movements (like conducting an orchestra or manual labor) lead to hypertrophy or inflammation of the supinator. The point of maximal tenderness—**2 cm distal and posteromedial to the lateral epicondyle**—corresponds precisely to the entry point into the supinator. Unlike "Tennis Elbow," which involves the common extensor origin, this pain is neurogenic and localized over the muscle belly. **2. Why Other Options are Incorrect:** * **Options A & B:** The **Median Nerve** supplies the anterior (flexor) compartment. Compression by the pronator teres (Pronator Syndrome) or FDS would cause pain in the **anterior forearm** and sensory loss in the lateral 3.5 digits, not posterior forearm pain [1]. * **Option C:** The **Superficial Radial Nerve** is purely sensory. Compression (Wartenberg’s Syndrome) typically occurs at the wrist near the brachioradialis tendon, causing paresthesia over the dorsal web space, not deep muscular pain in the proximal posterior forearm. **3. NEET-PG High-Yield Pearls:** * **Arcade of Frohse:** The most common site of PIN compression. * **PIN vs. Radial Nerve:** The PIN is a **purely motor nerve** (after the supinator). Compression causes motor weakness of finger/thumb extensors but **no sensory loss** [1]. * **Differential Diagnosis:** Always distinguish from **Lateral Epicondylitis** (Tennis Elbow); in Tennis Elbow, tenderness is directly on the lateral epicondyle, whereas in Radial Tunnel Syndrome, it is ~4 cm distal. * **Finger Drop:** Severe PIN compression leads to "finger drop" (inability to extend MCP joints) but **not** "wrist drop," as the ECRL is supplied by the radial nerve proximal to the supinator.

Question 607: A 32-year-old woman presents with multiple humerus fractures following an automobile collision. She exhibits severely weakened forearm flexion and supination, along with loss of sensation on the lateral forearm. Which nerve is most likely injured?

A. Radial
B. Musculocutaneous (Correct Answer)
C. Median
D. Lateral cord of brachial plexus

Explanation: ### Explanation The clinical presentation points to an injury of the **Musculocutaneous nerve (C5–C7)**. **1. Why Musculocutaneous is Correct:** The musculocutaneous nerve originates from the lateral cord of the brachial plexus. It supplies the muscles of the anterior compartment of the arm: **Coracobrachialis, Biceps Brachii, and Brachialis**. * **Motor Loss:** Paralysis of the Biceps brachii and Brachialis leads to severely weakened **forearm flexion**. Since the Biceps is the most powerful supinator of the flexed forearm, **supination** is also significantly impaired. * **Sensory Loss:** After passing through the arm, the nerve continues as the **Lateral Cutaneous Nerve of the Forearm**, supplying sensation to the lateral aspect of the forearm. **2. Why Other Options are Incorrect:** * **Radial Nerve:** Injury (commonly in the spiral groove) would cause "Wrist Drop" due to loss of extensors and sensory loss on the posterior arm/forearm and dorsal web space [1]. * **Median Nerve:** Injury would affect forearm pronation, wrist flexion, and thumb opposition (Ape thumb deformity), with sensory loss on the palmar aspect of the lateral 3.5 digits [2]. * **Lateral Cord:** While the musculocutaneous nerve arises from the lateral cord, a cord-level injury would also involve the lateral root of the **Median nerve**, leading to additional deficits in the hand and forearm that are not described here. **3. High-Yield Clinical Pearls for NEET-PG:** * **Nerve Course:** It pierces the **Coracobrachialis** muscle (a classic identification point in anatomy). * **Reflex:** It is the afferent and efferent limb for the **Biceps Reflex (C5-C6)**. * **Fracture Association:** While Radial nerve injury is most common with mid-shaft humerus fractures [1], Musculocutaneous injury can occur in severe proximal trauma or heavy compression.

Question 608: Which of the following muscles arises from the infraglenoid tubercle?

A. Long head of biceps
B. Long head of triceps (Correct Answer)
C. Short head of biceps
D. Coracobrachialis

Explanation: The scapula features two important tubercles related to the glenoid cavity that serve as origin points for the long heads of the arm muscles. The **infraglenoid tubercle**, located just below the glenoid labrum, provides the origin for the **long head of the triceps brachii**. This muscle then travels distally to insert on the olecranon process of the ulna, acting as a powerful extensor of the elbow and a weak adductor of the shoulder. **Analysis of Options:** * **Long head of biceps (A):** Arises from the **supraglenoid tubercle** of the scapula. It is intracapsular but extrasynovial as it traverses the shoulder joint. * **Short head of biceps (C):** Arises from the tip of the **coracoid process** of the scapula, sharing a common origin with the coracobrachialis. * **Coracobrachialis (D):** Also arises from the tip of the **coracoid process**. It is a key landmark in the axilla and is pierced by the musculocutaneous nerve. **High-Yield NEET-PG Pearls:** 1. **Mnemonic:** **S**upraglenoid = **B**iceps (SB), **I**nfraglenoid = **T**riceps (IT). Think "Sit" (S-I-T) to remember Superior/Biceps and Inferior/Triceps. 2. **Nerve Supply:** The triceps is supplied by the **radial nerve** (C6-C8). A mid-shaft humerus fracture (radial groove) may paralyze the medial and lateral heads, but the long head often remains functional as its nerve branch arises high in the axilla. 3. **Space Boundaries:** The long head of the triceps is a crucial boundary for the **quadrangular and triangular spaces** of the axilla, separating the axillary nerve and circumflex humeral vessels.

Question 609: What forms the arterial anastomosis around the surgical neck of the humerus?

A. 1st part of the axillary artery
B. 2nd part of the axillary artery
C. 3rd part of the axillary artery (Correct Answer)
D. Subclavian artery

Explanation: The surgical neck of the humerus is a critical anatomical landmark where the axillary nerve and the **circumflex humeral arteries** are located. The arterial anastomosis in this region is formed by the **Anterior and Posterior Circumflex Humeral Arteries**. **1. Why Option C is Correct:** The axillary artery is divided into three parts by the pectoralis minor muscle. The **3rd part** (extending from the lower border of pectoralis minor to the lower border of teres major) gives off three branches: the Subscapular artery, the Anterior Circumflex Humeral artery, and the Posterior Circumflex Humeral artery. These last two encircle the surgical neck of the humerus and anastomose with each other, providing blood supply to the shoulder joint and the deltoid muscle. **2. Why Other Options are Incorrect:** * **Option A (1st part):** Gives off only one branch—the Superior Thoracic artery—which supplies the upper thoracic wall. * **Option B (2nd part):** Gives off two branches—the Thoracoacromial and Lateral Thoracic arteries—which supply the pectoral and mammary regions. * **Option D (Subclavian artery):** Ends at the outer border of the first rib, where it becomes the axillary artery. While it contributes to the anastomosis around the *scapula*, it does not directly form the circle around the *humeral neck*. **Clinical Pearls for NEET-PG:** * **Fracture Risk:** A fracture of the surgical neck of the humerus can damage the **Axillary Nerve** and the **Posterior Circumflex Humeral Artery**. * **Avascular Necrosis (AVN):** Although there is an anastomosis, the anterior circumflex humeral artery (specifically the *arcuate branch*) provides the major blood supply to the head of the humerus. * **Mnemonics:** Remember the number of branches for each part of the axillary artery: 1st part = 1 branch; 2nd part = 2 branches; 3rd part = 3 branches.

Question 610: Which muscle performs flexion, adduction, and medial rotation of the arm?

A. Serratus Anterior
B. Pectoralis major (Correct Answer)
C. Pectoralis minor
D. Subclavius

Explanation: **Explanation:** The **Pectoralis Major** is a large, fan-shaped muscle of the anterior chest wall. Its primary actions are determined by its insertion into the **lateral lip of the bicipital groove** of the humerus. Because it crosses the shoulder joint anteriorly and laterally, its contraction pulls the humerus toward the midline (**adduction**), rotates it inward (**medial rotation**), and the clavicular fibers specifically assist in drawing the arm forward (**flexion**). **Analysis of Options:** * **Pectoralis Major (Correct):** It is the "climbing muscle" (along with Latissimus dorsi). Its dual nerve supply (Medial and Lateral pectoral nerves) and broad origin allow it to perform the triad of flexion, adduction, and medial rotation [1]. * **Serratus Anterior:** Known as the "boxer’s muscle," it originates from the ribs and inserts into the medial border of the scapula. Its primary role is **protraction** of the scapula and keeping it closely applied to the thoracic wall; it does not act directly on the humerus to cause rotation or flexion. * **Pectoralis Minor:** This muscle lies deep to the pectoralis major and inserts into the **coracoid process** of the scapula [1]. It stabilizes the scapula by pulling it anteriorly and inferiorly; it does not move the arm. * **Subclavius:** A small muscle that anchors and depresses the clavicle. It plays no role in the movements of the humerus. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve Supply:** Pectoralis major is supplied by **both** medial (C8, T1) and lateral (C5-C7) pectoral nerves [1]. * **Surgical Significance:** It forms the anterior wall of the axilla. * **Testing:** To test the muscle, the patient is asked to press their hands against their hips or adduct the arm against resistance. * **Poland Syndrome:** A congenital condition characterized by the unilateral absence of the Pectoralis major, often associated with syndactyly.

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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

Upper Limb — MCQs

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