Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 571: A 31-year-old roofer presents with tenosynovitis resulting from a deep penetrating wound in the palm caused by a large nail. On examination, he has an infection in the ulnar bursa. This infection most likely resulted in necrosis of which of the following tendons?

A. Tendon of flexor carpi ulnaris
B. Tendon of flexor pollicis longus
C. Tendon of flexor digitorum profundus (Correct Answer)
D. Tendon of palmaris longus

Explanation: ### Explanation **1. Why the Correct Answer is Right:** The **ulnar bursa** is a large synovial sheath that envelops the tendons of both the **flexor digitorum superficialis (FDS)** and the **flexor digitorum profundus (FDP)** as they pass through the carpal tunnel. It typically begins proximal to the flexor retinaculum and extends into the palm. Crucially, while it ends blindly for the index, middle, and ring fingers, it is usually continuous with the digital synovial sheath of the **little finger**. Therefore, a penetrating wound in the palm leading to ulnar bursa tenosynovitis directly involves the FDP tendons, potentially leading to ischemia and necrosis due to increased pressure within the sheath [1]. **2. Why the Incorrect Options are Wrong:** * **Tendon of flexor carpi ulnaris (A):** This muscle inserts onto the pisiform, hamate, and 5th metacarpal. It is an extrinsic muscle of the wrist and does **not** pass through the carpal tunnel or the ulnar bursa. * **Tendon of flexor pollicis longus (B):** This tendon is contained within its own separate synovial sheath known as the **radial bursa**. While the radial and ulnar bursae may communicate in some individuals, the FPL is primarily associated with the radial bursa. * **Tendon of palmaris longus (D):** This tendon passes **superficial** to the flexor retinaculum and inserts into the palmar aponeurosis. It is not enclosed within any synovial bursa. **3. Clinical Pearls for NEET-PG:** * **Ulnar Bursa:** Contains 8 tendons (4 FDS + 4 FDP). It communicates with the digital sheath of the **5th digit**. * **Radial Bursa:** Contains 1 tendon (**FPL**). It communicates with the digital sheath of the **thumb**. * **Kanavel’s Signs:** Used to diagnose infectious tenosynovitis (Finger held in flexion, fusiform swelling, tenderness over the sheath, pain on passive extension). * **Horseshoe Abscess:** Because the radial and ulnar bursae communicate in ~80% of people, an infection can spread from the thumb to the little finger (or vice versa), forming a "horseshoe" shaped infection [1].

Question 572: If the musculocutaneous nerve is injured at the lateral cord of the brachial plexus, which clinical finding would be positive?

A. Loss of flexion at the elbow
B. Sensory loss on the lateral aspect of the forearm (Correct Answer)
C. Loss of extension of the forearm
D. Loss of extension of the wrist

Explanation: The **musculocutaneous nerve** (C5–C7) is a terminal branch of the **lateral cord** of the brachial plexus. It pierces the coracobrachialis muscle and descends between the biceps brachii and brachialis, supplying all three muscles in the anterior compartment of the arm. ### Why the correct answer is right: After supplying the flexors of the arm, the musculocutaneous nerve continues distal to the elbow as the **lateral cutaneous nerve of the forearm**. This nerve provides sensory innervation to the skin of the lateral (radial) aspect of the forearm from the elbow to the base of the thumb. Therefore, an injury to the musculocutaneous nerve results in sensory loss in this specific distribution. ### Why the other options are wrong: * **A. Loss of flexion at the elbow:** While the musculocutaneous nerve supplies the primary flexors (biceps and brachialis), elbow flexion is not completely lost because the **brachioradialis** (supplied by the radial nerve) and **pronator teres** (supplied by the median nerve) also contribute to flexion. * **C & D. Loss of extension of the forearm/wrist:** Extension of the forearm (triceps) and wrist (extensors) is the primary function of the **radial nerve**. ### NEET-PG High-Yield Pearls: * **The "Piercing" Nerve:** The musculocutaneous nerve is famous for piercing the **coracobrachialis** muscle. * **Biceps Reflex:** This nerve carries the afferent and efferent limbs of the **C5-C6** deep tendon reflex. * **Clinical Presentation:** Injury (often from trauma or heavy backpacks) leads to weak forearm flexion, weak supination (biceps is the chief supinator), and sensory loss on the lateral forearm.

Question 573: All of the following are posterior relations of the 3rd part of the axillary artery, except?

A. Radial Nerve
B. Axillary Nerve
C. Ulnar Nerve (Correct Answer)
D. Teres Major and Subscapularis muscles

Explanation: To master the relations of the axillary artery, one must understand its division into three parts by the **Pectoralis minor muscle**. The 3rd part extends from the lower border of the Pectoralis minor to the lower border of the Teres major. [1] ### **Why Ulnar Nerve is the Correct Answer** The **Ulnar nerve** is a branch of the medial cord. In the 3rd part of the axillary artery, it is located **medially** (between the artery and the axillary vein), not posteriorly. Therefore, it is the "except" in this question. ### **Analysis of Incorrect Options (Posterior Relations)** The posterior relations of the 3rd part of the axillary artery include: * **Radial Nerve (Option A):** This is the largest branch of the posterior cord and lies directly behind the artery before entering the radial groove. * **Axillary Nerve (Option B):** It lies posterior to the artery in the upper portion of the 3rd part before passing through the quadrangular space. * **Teres Major and Subscapularis (Option D):** These muscles, along with the Latissimus dorsi tendon, form the posterior wall of the axilla upon which the 3rd part of the artery rests. [1] ### **High-Yield NEET-PG Pearls** * **Rule of Cord Relations:** The names of the cords (Lateral, Medial, Posterior) describe their relationship to the **2nd part** of the axillary artery. * **3rd Part Relations Mnemonic:** * **Lateral:** Coracobrachialis, Musculocutaneous nerve, Lateral root of Median nerve. * **Medial:** Axillary vein, Ulnar nerve, Medial cutaneous nerve of forearm. * **Posterior:** Radial nerve, Axillary nerve, Subscapularis, Latissimus dorsi, Teres major. * **Clinical Fact:** The 3rd part of the axillary artery is the preferred site for ligation, provided it is done distal to the subscapular artery to maintain collateral circulation via the scapular anastomosis.

Question 574: At what vertebral level is the inferior angle of the scapula typically located?

A. 5th rib
B. 6th rib
C. 7th rib (Correct Answer)
D. 8th rib

Explanation: ### Explanation The scapula is a flat, triangular bone that serves as a vital landmark for surface anatomy of the posterior thorax. Its position varies slightly with posture, but in the neutral anatomical position, its landmarks correspond to specific vertebral and costal levels. **Why the Correct Answer is Right:** The **inferior angle of the scapula** is the lowest point of the bone where the medial and lateral borders meet. In a resting position, it typically lies at the level of the **7th rib** or the **T7 spinous process**. This is a high-yield landmark used by clinicians to count ribs and intercostal spaces from the posterior aspect, especially during procedures like thoracocentesis. **Analysis of Incorrect Options:** * **5th Rib:** This level corresponds roughly to the **middle of the medial border** of the scapula, above the inferior angle. * **6th Rib:** This is situated between the scapular spine and the inferior angle. While the scapula covers the 2nd through 7th ribs, the 6th rib is not the terminal landmark for the inferior angle. * **8th Rib:** This lies just below the scapula. The inferior angle may reach this level during full abduction of the arm (due to upward rotation of the scapula), but it is not the standard anatomical position. **High-Yield Clinical Pearls for NEET-PG:** * **Superior Angle:** Located at the level of the **T2** vertebra. * **Root of Scapular Spine:** Located at the level of the **T3** vertebra. * **Triangle of Auscultation:** The inferior angle forms the lateral boundary of this space (along with the Trapezius and Latissimus Dorsi), where breath sounds are most clearly heard. * **Serratus Anterior:** This muscle inserts into the costal surface of the medial border, including the inferior angle; its paralysis leads to **"Winging of Scapula."**

Question 575: The axillary artery is divided into 3 parts by which of the following muscles?

A. Teres major
B. Teres minor
C. Pectoralis major
D. Pectoralis minor (Correct Answer)

Explanation: The **axillary artery** is the direct continuation of the subclavian artery, beginning at the outer border of the first rib and ending at the lower border of the teres major muscle. ### Why Pectoralis Minor is Correct The **pectoralis minor muscle** crosses the axillary artery anteriorly, serving as the key anatomical landmark to divide it into three distinct parts: * **First part:** Proximal to the muscle (between the 1st rib and the medial border of the muscle). It has **one** branch (Superior thoracic artery). * **Second part:** Posterior to the muscle. It has **two** branches (Thoracoacromial and Lateral thoracic arteries). * **Third part:** Distal to the muscle (between the lateral border of the muscle and the lower border of teres major). It has **three** branches (Subscapular, Anterior circumflex humeral, and Posterior circumflex humeral arteries). ### Why Other Options are Incorrect * **Teres major (A):** This muscle marks the **termination** of the axillary artery, where it becomes the brachial artery. * **Teres minor (B):** This muscle forms the superior boundary of the quadrangular space but does not divide the axillary artery. * **Pectoralis major (C):** While it forms the anterior wall of the axilla, it is a superficial muscle and is not used as the landmark for surgical or anatomical division of the artery. ### High-Yield Clinical Pearls for NEET-PG * **Mnemonic for Branches:** "Save The Lions And Stars Proclaim" (Superior thoracic, Thoracoacromial, Lateral thoracic, Subscapular, Anterior circumflex, Posterior circumflex). * **Relation to Brachial Plexus:** The cords of the brachial plexus are named (Lateral, Medial, Posterior) based on their relationship to the **second part** of the axillary artery. * **Aneurysms:** Axillary artery aneurysms can compress the trunks of the brachial plexus, leading to neurological deficits in the upper limb.

Question 576: Which of the following statements regarding anterior axillary lymph nodes is FALSE?

A. They are located on the anterior wall of the axilla on the pectoral muscle.
B. They are situated along the lateral thoracic vein.
C. They drain into the central axillary lymph nodes.
D. They drain the medial aspect of the mammary gland. (Correct Answer)

Explanation: ### Explanation The axillary lymph nodes are divided into five main groups: anterior (pectoral), posterior (subscapular), lateral (humeral), central, and apical. Understanding their drainage patterns is high-yield for NEET-PG. **Why Option D is the Correct (False) Statement:** The **anterior (pectoral) group** of lymph nodes primarily drains the **lateral quadrants** of the mammary gland and the anterolateral aspect of the body wall above the level of the umbilicus [3]. The **medial aspect** of the mammary gland drains primarily into the **internal mammary (parasternal) lymph nodes**, which are located along the internal thoracic artery. **Analysis of Other Options:** * **Option A:** This is **true**. The anterior nodes lie along the lower border of the pectoralis minor muscle, deep to the pectoralis major, forming the anterior wall of the axilla [1]. * **Option B:** This is **true**. They are anatomically situated along the course of the **lateral thoracic vein**. * **Option C:** This is **true**. Lymph from the anterior, posterior, and lateral groups drains into the **central group**, which then drains into the apical group [1]. **Clinical Pearls for NEET-PG:** * **Breast Cancer Metastasis:** Approximately **75%** of lymph from the breast drains into the axillary nodes, specifically the anterior (pectoral) group first [1]. * **Sentinel Node:** The anterior group often contains the sentinel lymph node in breast cancer staging. * **Order of Drainage:** Anterior/Posterior/Lateral → Central → Apical → Supraclavicular nodes/Subclavian lymph trunk. * **Nerve at Risk:** During axillary lymph node dissection, the **long thoracic nerve** (supplying serratus anterior) and **thoracodorsal nerve** (supplying latissimus dorsi) are at risk of injury [2].

Question 577: Which of the following statements about the clavicle is false?

A. Ossifies partly in membrane and partly in cartilage
B. Transmits part of the weight of the upper limb to the axial skeleton
C. It is subcutaneous throughout its length
D. Fractures typically occur at the junction of the medial third and lateral two-thirds (Correct Answer)

Explanation: ### Explanation The correct answer is **D** because it is a factually incorrect statement. Fractures of the clavicle typically occur at the **junction of the medial two-thirds and the lateral one-third**. This is the weakest point of the bone because it is where the curvature changes (from convex forward to concave forward) and where the cross-section changes from cylindrical to flattened. **Analysis of Options:** * **Option A (True):** The clavicle is unique as it is the first bone to start ossifying (5th–6th week of intrauterine life). It undergoes **membranous ossification** for the shaft, while the ends ossify in **cartilage** [1]. * **Option B (True):** It acts as a "strut" that holds the arm away from the trunk. It transmits forces from the upper limb to the axial skeleton via the **coracoclavicular ligament** and the sternoclavicular joint. * **Option C (True):** The clavicle is located just beneath the skin throughout its entire length, making it easily palpable and its fractures easily visible. **High-Yield NEET-PG Pearls:** * **First bone to ossify:** Clavicle. * **Only long bone** that lies horizontally and has no medullary cavity. * **Primary Centers:** Two primary centers (medial and lateral) appear in membrane [1]. * **Secondary Center:** One secondary center appears in the sternal end (cartilaginous) around age 18–20 and fuses by 25. * **Clinical Sign:** In a fracture, the medial fragment is displaced upward by the **sternocleidomastoid** muscle, while the lateral fragment drops due to the weight of the limb.

Question 578: What is the root value of the radial nerve?

A. C3, 4, 5, 6, 7
B. C4, 5, 6, 7, 8
C. C5, 6, 7, 8; T1 (Correct Answer)
D. C6, 7, 8; T1, 2

Explanation: **Explanation:** The **Radial Nerve** is the largest branch of the brachial plexus and is the direct continuation of the **posterior cord**. It receives fibers from all five roots of the brachial plexus: **C5, C6, C7, C8, and T1**. This comprehensive root value is essential because the radial nerve supplies the entire extensor compartment of the upper limb (arm and forearm), requiring a wide range of motor and sensory inputs. **Analysis of Options:** * **Option C (Correct):** Reflects the complete contribution from the posterior cord. C5-C6 fibers primarily supply the brachioradialis and supinator, C7 supplies the triceps, and C8-T1 contribute to the long extensors of the wrist and fingers. * **Option A & B:** These include C3 or C4 roots. These roots contribute to the cervical plexus (e.g., Phrenic nerve), not the brachial plexus. * **Option D:** This excludes C5 and includes T2. While T2 may contribute via the intercostobrachial nerve, it is not a standard component of the radial nerve's functional root value. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Injury:** The radial nerve is most commonly injured in the **spiral groove** (mid-shaft humerus fracture), leading to **Wrist Drop** due to paralysis of the extensors. * **Triceps Sparing:** In a spiral groove injury, the long head of the triceps is spared because its nerve branch arises in the axilla, proximal to the groove. * **Finger Drop:** Injury to the **Posterior Interosseous Nerve (PIN)**, a deep branch of the radial nerve, causes "Finger Drop" but spares the wrist extensors (no wrist drop). * **Saturday Night Palsy:** Compression of the nerve in the axilla (e.g., crutch palsy) affects all muscles, including the triceps.

Question 579: Which muscle does NOT contribute to the dorsal digital expansion?

A. Interossei
B. Lumbricals
C. Extensor digitorum
D. Adductor pollicis (Correct Answer)

Explanation: ### Explanation The **Dorsal Digital Expansion (Extensor Expansion)** is a specialized aponeurosis located on the dorsum of the fingers that coordinates complex movements of the hand. It serves as a common insertion point for several muscles to allow for the simultaneous extension of interphalangeal (IP) joints and flexion of metacarpophalangeal (MCP) joints [2]. **Why Adductor Pollicis is the Correct Answer:** The **Adductor pollicis** is a muscle of the thenar eminence (specifically the deep palmar compartment) that acts on the thumb. The thumb does not possess a formal dorsal digital expansion similar to the four fingers. Furthermore, the Adductor pollicis inserts into the ulnar side of the base of the proximal phalanx of the thumb and the sesamoid bone, not into an extensor hood. **Analysis of Incorrect Options:** * **Extensor Digitorum:** This is the primary contributor. Its tendons flatten out over the MCP joints to form the central "hood" or backbone of the expansion [2]. * **Lumbricals:** These originate from the tendons of the Flexor Digitorum Profundus and insert into the **radial side** of the extensor expansion [1]. They are crucial for the "Z-movement" (MCP flexion + IP extension) [1]. * **Interossei:** Both Palmar and Dorsal interossei insert into the extensor expansion [1]. They assist the lumbricals in IP extension and MCP flexion while performing adduction/abduction. **High-Yield NEET-PG Pearls:** * **The "Z-position":** The combination of Lumbricals and Interossei acting through the expansion results in MCP flexion and IP extension [1]. * **Nerve Supply:** Lumbricals 1 & 2 (Median nerve); Lumbricals 3 & 4 and all Interossei (Ulnar nerve). * **Clinical Correlation:** Damage to the extensor expansion can lead to deformities like **Boutonnière deformity** (central slip tear) or **Swan-neck deformity**.

Question 580: Ossification is typically seen at two months for which of the following carpal bones?

A. Lunate
B. Capitate (Correct Answer)
C. Scaphoid
D. Hamate

Explanation: The ossification of carpal bones follows a predictable chronological sequence, typically occurring in a clockwise or counter-clockwise direction starting from the largest bone. **Why Capitate is Correct:** The **Capitate** is the first carpal bone to begin ossification. It typically appears at **1–2 months** of age. It is followed closely by the Hamate. Identifying these centers on a pediatric X-ray is a standard method for assessing "bone age" and general skeletal development. During fetal development, most bones are modeled in cartilage and then transformed into bone by ossification [1]. **Analysis of Incorrect Options:** * **Hamate:** This is the second bone to ossify, appearing shortly after the capitate, usually at **3 months**. While close, the capitate is the definitive answer for the 2-month mark. * **Lunate:** This bone ossifies much later, typically around **4–5 years** of age. * **Scaphoid:** This is one of the last carpal bones to ossify, usually appearing between **5–6 years** of age. **High-Yield NEET-PG Pearls:** * **Mnemonic for Order of Ossification:** **C**apitate, **H**amate, **T**riquetral, **L**unate, **S**caphoid, **T**rapezium, **T**rapezoid, **P**isiform (**C**ome **H**ome **T**o **L**et **S**ay **T**hank **T**o **P**apa). * **Chronology Simplified:** * 1st year: Capitate (1-2m), Hamate (3m) * 3rd year: Triquetral * 4th year: Lunate * 5th year: Scaphoid, Trapezium, Trapezoid (approximate) * 12th year: **Pisiform** (Last to ossify; sesamoid bone). * **Clinical Fact:** At birth, no carpal bones are ossified; the wrist appears as a wide radiolucent gap on X-ray.

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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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