Upper Limb Practice Questions

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

No branch. ### 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.

Q: What are the root values of the axillary nerve?

C5, C6. 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.

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

Brachioradialis. **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.

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 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?

Scaphoid-lunate. **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.

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).

Question 1

Which is a branch of the ulnar nerve in the arm?

Accepted Answer

No branch

Answer

To Flexor Carpi Ulnaris (FCU)

Answer

To Flexor Digitorum Profundus (FDP)

Answer

To Flexor Carpi Radialis (FCR)

Question 2

What are the root values of the axillary nerve?

Accepted Answer

C5, C6

Answer

C7, C8

Answer

C8, T1

Answer

C5, T1

Question 3

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 4

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

Accepted Answer

Brachioradialis

Answer

Brachialis

Answer

Biceps brachii

Answer

Coracobrachialis

Question 5

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 6

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 7

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 8

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?

Accepted Answer

Scaphoid-lunate

Answer

Trapezoid-trapezium

Answer

Hamate-lunate

Answer

Pisiform-triquetrum

Question 9

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 10

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?

Accepted Answer

Partial or complete tearing of the coracoclavicular ligament

Answer

Displacement of the head of the humerus from the glenoid cavity

Answer

Partial or complete tearing of the coracoacromial ligament

Answer

Rupture of the transverse scapular ligament

Upper Limb — MCQs

Upper Limb — MCQs

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