Upper Limb Practice Questions

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

Wrist. **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 ** 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].

Q: 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?

Posterior interosseous nerve. ### 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.

Q: 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?

Infraspinatus. ### **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.

Q: 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?

The nerve supplying the serratus anterior. **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).

Q: Fracture of the shaft of the humerus commonly damages which nerve?

Radial nerve. The **radial nerve** is the most frequently injured nerve in fractures of the humeral shaft, particularly those involving the **middle third**. This is due to the close anatomical relationship where the nerve winds around the posterior aspect of the humerus in the **spiral (radial) groove**, lying directly against the periosteum. **Why the other options are incorrect:** * **Axillary nerve:** This nerve is most commonly injured in fractures of the **surgical neck** of the humerus or during anterior dislocations of the shoulder joint. * **Median nerve:** It is typically injured in **supracondylar fractures** of the humerus (along with the brachial artery), rather than shaft fractures. * **Ulnar nerve:** This nerve is most vulnerable at the **medial epicondyle** (where it sits in the retrocondylar groove) or in fractures of the medial epicondyle itself. **Clinical Pearls for NEET-PG:** 1. **Clinical Presentation:** Injury to the radial nerve at the humeral shaft results in **Wrist Drop** due to paralysis of the extensors of the wrist and digits. 2. **Holstein-Lewis Fracture:** A spiral fracture of the distal one-third of the humerus that is specifically associated with radial nerve neuropraxia [1]. 3. **Sensory Loss:** Patients typically exhibit anesthesia over the **dorsal aspect of the first web space**. 4. **Rule of Thumb:** Remember the "S-A-R-U" mnemonic for humerus fractures: **S**urgical neck = **A**xillary nerve; **R**adial groove = **R**adial nerve; **U**lnar groove = **U**lnar nerve.

Q: Contents of the anatomical snuff box include:

Radial Artery. The **Anatomical Snuffbox** is a triangular depression on the lateral aspect of the wrist, visible during thumb extension. Understanding its boundaries versus its contents is a frequent high-yield topic for NEET-PG [1]. ### **Why Radial Artery is the Correct Answer** The **Radial Artery** is the primary structure passing through the **floor** of the anatomical snuffbox. After giving off the superficial palmar branch, the artery winds dorsally around the lateral side of the carpus, deep to the tendons of the abductor pollicis longus and extensor pollicis brevis, to lie in the snuffbox before passing between the two heads of the first dorsal interosseous muscle. ### **Analysis of Incorrect Options** * **B & C (Tendon of APL and EPB):** These structures form the **lateral (anterior) boundary** of the snuffbox [1]. They are part of the "walls" rather than the "contents." * **D (Scaphoid bone):** Along with the trapezium, the scaphoid forms the **floor** of the snuffbox. While it is a landmark within the area, in standard anatomical nomenclature, "contents" typically refers to neurovascular structures or tendons passing *through* the space, whereas the scaphoid is a structural boundary. ### **High-Yield Clinical Pearls for NEET-PG** * **Boundaries:** * **Medial (Posterior):** Tendon of Extensor Pollicis Longus (EPL) [1]. * **Lateral (Anterior):** Tendons of Abductor Pollicis Longus (APL) and Extensor Pollicis Brevis (EPB) [1]. * **Floor:** Scaphoid and Trapezium bones. * **Contents:** Radial artery, Cephalic vein (starts here), and the superficial branch of the Radial nerve. * **Clinical Significance:** Tenderness in the snuffbox is a classic sign of a **Scaphoid fracture**. The radial pulse can also be palpated here.

Q: At which anatomical level does the radial nerve divide?

Anterior aspect of the lateral epicondyle. ### Explanation The radial nerve is the largest branch of the brachial plexus (C5-T1). Its division into terminal branches is a high-yield anatomical landmark for the elbow region. **Why Option B is Correct:** As the radial nerve descends the arm, it pierces the lateral intermuscular septum to enter the anterior compartment. It then passes **anterior to the lateral epicondyle** of the humerus, lying in a deep groove between the Brachialis and Brachioradialis muscles. At this specific level (the joint line), it divides into its two terminal branches: 1. **Superficial branch:** A purely sensory nerve. 2. **Deep branch (Posterior Interosseous Nerve - PIN):** A motor nerve that enters the supinator muscle through the Arcade of Frohse. **Why the Other Options are Incorrect:** * **Options A & C (Medial Epicondyle):** The **Ulnar nerve** is the primary nerve associated with the medial epicondyle. It passes *posterior* to it (the "funny bone" location). The Median nerve passes anterior to the medial epicondyle but does not divide there. * **Option D (Posterior Lateral Epicondyle):** While the radial nerve is posterior to the *humerus* (in the spiral groove), it must move anteriorly before reaching the elbow to divide. **NEET-PG High-Yield Pearls:** * **Injury Site:** Fracture of the **mid-shaft humerus** (spiral groove) typically spares the triceps but causes **wrist drop**. * **PIN Syndrome:** Compression of the deep branch at the **Arcade of Frohse** (supinator) causes motor loss of finger extensors but **no sensory loss**, distinguishing it from more proximal radial nerve injuries. * **The "BEAST" Muscles:** The radial nerve supplies the **B**rachioradialis, **E**xtensors, **A**nconeus, **S**upinator, and **T**riceps.

Q: All of the following take part in the formation of the wrist joint, except?

Distal end of ulna. The **wrist joint (Radiocarpal joint)** is a synovial joint of the ellipsoid variety. The core concept to remember for NEET-PG is that the **ulna is excluded** from this joint by a fibrocartilaginous structure. ### Why the Distal End of Ulna is the Correct Answer: The distal end of the ulna does not articulate directly with the carpal bones. It is separated from the carpal bones (specifically the triquetrum and lunate) by the **Triangular Fibrocartilage Complex (TFCC)** or the articular disc of the inferior radioulnar joint. Therefore, the ulna does not participate in the formation of the wrist joint proper. ### Why the Other Options are Incorrect: * **Distal end of Radius:** This forms the proximal articular surface of the wrist joint. It has two facets: a lateral triangular facet for the scaphoid and a medial quadrangular facet for the lunate. * **Scaphoid:** This is a lateral carpal bone of the proximal row that articulates directly with the radial facet during all movements of the wrist. * **Triquetrum:** While the scaphoid and lunate are the primary articulators, the triquetrum comes into contact with the articular disc (TFCC) during **adduction (ulnar deviation)** of the hand, making it a functional part of the radiocarpal unit. ### High-Yield Clinical Pearls: 1. **Articular Surfaces:** Proximal surface = Distal radius + Articular disc. Distal surface = Scaphoid + Lunate + Triquetrum. 2. **Colles’ Fracture:** A fracture of the distal end of the radius (dinner fork deformity) often involves the wrist joint, whereas ulnar styloid fractures are secondary. 3. **Most Commonly Fractured Carpal Bone:** Scaphoid (risk of avascular necrosis). 4. **Most Commonly Dislocated Carpal Bone:** Lunate.

Question 1

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

Accepted Answer

Wrist

Answer

Arm

Answer

Elbow

Answer

Forearm

Question 2

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?

Accepted Answer

Posterior interosseous nerve

Answer

Ulnar nerve

Answer

Median nerve

Answer

Radial nerve

Question 3

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?

Accepted Answer

Opposition of the thumb

Answer

Abduction of the 2nd digit

Answer

Adduction of the 2nd digit

Answer

Flexion of the thumb

Question 4

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?

Accepted Answer

Infraspinatus

Answer

Teres major

Answer

Latissimus dorsi

Answer

Trapezius

Question 5

Which of the following arteries supply the pectoralis major muscle?

Accepted Answer

All of the above

Answer

Pectoral branches of the thoracoacromial artery

Answer

Intercostal arteries

Answer

Lateral thoracic artery

Question 6

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?

Accepted Answer

The nerve supplying the serratus anterior

Answer

Pectoral nerve

Answer

Subscapular nerve

Answer

Ulnar nerve

Question 7

Fracture of the shaft of the humerus commonly damages which nerve?

Accepted Answer

Radial nerve

Answer

Median nerve

Answer

Axillary nerve

Answer

Ulnar nerve

Question 8

Contents of the anatomical snuff box include:

Accepted Answer

Radial Artery

Answer

Tendon of Abductor Pollicis longus

Answer

Tendon of Extensor Pollicis brevis

Answer

Scaphoid bone

Question 9

At which anatomical level does the radial nerve divide?

Accepted Answer

Anterior aspect of the lateral epicondyle

Answer

Anterior aspect of the medial epicondyle

Answer

Posterior aspect of the medial epicondyle

Answer

Posterior aspect of the lateral epicondyle

Question 10

All of the following take part in the formation of the wrist joint, except?

Accepted Answer

Distal end of ulna

Answer

Scaphoid

Answer

Triquetrum

Answer

Distal end of radius

Upper Limb — MCQs

Upper Limb — MCQs

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