Upper Limb Practice Questions

Q: Damage to the coracobrachialis muscle and to the nerve passing through it could reasonably be expected to produce all of the following, EXCEPT?

Diminished cutaneous sensation over the lateral palm. ### Explanation The muscle described is the **coracobrachialis**, and the nerve passing through it is the **musculocutaneous nerve (C5–C7)**. This nerve is a branch of the lateral cord of the brachial plexus and supplies the muscles of the anterior compartment of the arm. **Why Option D is the Correct Answer (The "Except"):** The musculocutaneous nerve terminates as the **lateral cutaneous nerve of the forearm**, providing sensation to the lateral aspect of the forearm down to the wrist. It does **not** supply the palm. Cutaneous sensation over the lateral palm is primarily supplied by the **median nerve** (palmar cutaneous branch). Therefore, damage to the musculocutaneous nerve will not affect the lateral palm. **Analysis of Incorrect Options:** * **A. Weakened flexion at the elbow:** The musculocutaneous nerve supplies the **brachialis** and **biceps brachii**, the primary flexors of the elbow. * **B. Weakened flexion at the shoulder:** Both the **coracobrachialis** and the long head of the **biceps brachii** assist in shoulder flexion. * **C. Weakened supination of the forearm:** The **biceps brachii** is the most powerful supinator of the forearm when the elbow is flexed. Loss of its innervation significantly weakens this movement. **High-Yield NEET-PG Pearls:** * **The "BBC" Muscles:** The musculocutaneous nerve supplies the **B**iceps brachii, **B**rachialis, and **C**oracobrachialis. * **Piercing Nerve:** The musculocutaneous nerve is unique because it **pierces** the coracobrachialis muscle. * **Sensory Loss:** Injury results in anesthesia over the **lateral (radial) border of the forearm** (Pre-axial border). * **Reflex:** Damage to this nerve leads to a lost or diminished **biceps tendon reflex**.

Q: Neglected whitlow may lead to necrosis of which part of the distal phalanx?

Distal 4/5th of terminal phalanx. The distal phalanx of the finger is unique due to its blood supply and anatomical compartments. A **whitlow (felon)** is an abscess in the pulp space of the finger. This space is divided into several tight, non-compliant compartments by fibrous septa that run from the skin to the periosteum. **1. Why Option A is correct:** The blood supply to the **distal four-fifths** of the terminal phalanx is provided by small branches of the digital arteries that run through these tight pulp compartments. When pus accumulates (whitlow), the pressure within these compartments rises rapidly, compressing the vessels and causing **ischemic necrosis** of the bone. [1] **2. Why Options B and C are incorrect:** The **proximal one-fifth (base)** of the distal phalanx is spared from necrosis. This is because the epiphysis (base) of the bone receives its blood supply from a separate branch of the digital artery that arises proximal to the pulp space. Therefore, the whole tip is not involved, and the necrosis is specifically limited to the diaphysis (distal 4/5th). **Clinical Pearls for NEET-PG:** * **Pulp Space Anatomy:** The fibrous septa create a "closed-box" system; hence, even a small amount of inflammation causes exquisite pain. [1] * **Osteomyelitis:** Neglected whitlow is a common cause of terminal phalanx osteomyelitis. [1] * **Surgical Management:** Treatment requires a lateral incision to divide the fibrous septa and decompress the space, avoiding the tactile part of the finger pad. * **Nerve Supply:** The pulp is richly supplied by sensory receptors (Meissner’s and Pacinian corpuscles), explaining the high intensity of pain.

Q: A 22-year-old male football player suffered a wrist injury while falling with force on his outstretched hand. When the anatomic snuffbox is exposed in surgery, an artery is visualized crossing the fractured bone that provides a floor for this space. What artery was visualized?

Radial. The clinical scenario describes a classic injury to the **scaphoid bone**, which forms the floor of the **anatomic snuffbox**. The patient fell on an outstretched hand (FOOSH), the most common mechanism for scaphoid fractures [1]. **Why the Radial Artery is Correct:** The **radial artery** is the key vascular structure passing through the anatomic snuffbox. After giving off the superficial palmar branch, the radial artery winds dorsally around the lateral aspect of the wrist, passing deep to the tendons of the abductor pollicis longus and extensor pollicis brevis. It then crosses the floor of the snuffbox (specifically over the scaphoid and trapezium) before piercing the two heads of the first dorsal interosseous muscle to enter the palm. **Why the Incorrect Options are Wrong:** * **Ulnar Artery:** This artery enters the hand via Guyon’s canal, medial to the flexor carpi ulnaris [3]. It is located on the medial (ulnar) side of the wrist, far from the snuffbox. * **Anterior/Posterior Interosseous Arteries:** These are branches of the common interosseous artery (from the ulnar artery) that supply the forearm compartments. While the posterior interosseous artery terminates by joining the dorsal carpal arch, it does not cross the floor of the snuffbox. **High-Yield Clinical Pearls for NEET-PG:** * **Boundaries of Snuffbox:** Lateral (Abductor pollicis longus, Extensor pollicis brevis); Medial (Extensor pollicis longus); Floor (Scaphoid and Trapezium). * **Contents:** Radial artery (deep), Cephalic vein (superficial), and Superficial branch of the radial nerve. * **Scaphoid Fracture Risk:** The scaphoid has a **retrograde blood supply** from the radial artery. A fracture at the waist can lead to **avascular necrosis (AVN)** of the proximal pole [2]. * **Tenderness:** Point tenderness in the anatomic snuffbox is pathognomonic for a scaphoid fracture.

Q: Which of the following statements about the brachial plexus is FALSE?

The long thoracic nerve arises from the posterior cord.. ### Explanation The **brachial plexus** is a complex network of nerves (C5–T1) that provides motor and sensory innervation to the upper limb. To identify the false statement, one must distinguish between the branches arising from the **roots, trunks, and cords**. **1. Why Option C is the Correct (False) Statement:** The **long thoracic nerve** (Nerve to Serratus Anterior) does not arise from the posterior cord. Instead, it arises directly from the **roots of C5, C6, and C7**. This is a high-yield distinction because it originates more proximally than the cords. **2. Analysis of Other Options:** * **Option A (True):** The **radial nerve** is the largest branch of the **posterior cord** (C5–T1). It provides the main supply for the extensor compartments of the arm and forearm. * **Option B (True):** The **axillary nerve** (C5, C6) is a major branch of the **posterior cord**. It supplies the deltoid and teres minor muscles. * **Option D (True):** The brachial plexus begins with five roots (C5–T1). The **C5 and C6 roots** unite to form the **upper (superior) trunk**. **Clinical Pearls for NEET-PG:** * **Erb’s Palsy:** Involves injury to the **upper trunk** (C5, C6), resulting in the "waiter’s tip" deformity. * **Klumpke’s Palsy:** Involves injury to the "lower trunk" (C8, T1), leading to a "claw hand." * **Winged Scapula:** Caused by damage to the **long thoracic nerve**, paralyzing the serratus anterior. * **Mnemonic for Posterior Cord Branches (STAR):** **S**ubscapular (upper/lower), **T**horacodorsal [1], **A**xillary, and **R**adial nerves. [1] Townsend. Sabiston Textbook Of Surgery. 20E ed. Head and Neck, pp. 843-844.

Q: Guyon's canal is associated with which of the following structures?

Ulnar nerve. **Explanation:** **Guyon’s Canal (Ulnar Canal)** is a fibro-osseous tunnel located on the medial side of the wrist. It serves as a conduit for the **ulnar nerve** and the **ulnar artery** as they pass from the forearm into the hand. * **Why Option B is Correct:** The canal is bounded medially by the pisiform bone and laterally by the hook of the hamate [1]. The roof is formed by the palmar carpal ligament and the palmaris brevis muscle. The ulnar nerve enters the canal and divides into superficial and deep branches within it. Compression here leads to **Guyon’s canal syndrome**. **Why the other options are incorrect:** * **A. Anterior Interosseous Nerve:** This is a branch of the median nerve that travels deep in the forearm (between the flexor digitorum profundus and flexor pollicis longus) and does not pass through the wrist. * **C. Median Nerve:** This nerve passes through the **carpal tunnel**, which lies lateral and deep to Guyon’s canal [1]. * **D. Radial Artery:** This artery passes through the **anatomical snuffbox** on the lateral (radial) aspect of the wrist to reach the dorsum of the hand [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Handlebar Palsy:** Common in long-distance cyclists due to direct pressure on Guyon’s canal, leading to sensory loss in the medial 1.5 fingers and weakness of intrinsic hand muscles. * **Zone of Compression:** Unlike carpal tunnel syndrome, Guyon’s canal syndrome often spares the palmar cutaneous branch (which arises proximal to the wrist), meaning sensation over the hypothenar eminence may remain intact. * **Contents:** Remember that both the **ulnar nerve** and **ulnar artery** are contents; the nerve is typically medial to the artery.

Q: All of the following muscles form the rotator cuff EXCEPT?

Deltoid. The **Rotator Cuff** (also known as the musculotendinous cuff) is a functional unit formed by the tendons of four specific muscles that blend with the fibrous capsule of the shoulder joint. Its primary role is to stabilize the humeral head within the glenoid cavity during movements. ### Why Deltoid is the Correct Answer: The **Deltoid (Option C)** is a large, superficial muscle that forms the rounded contour of the shoulder. While it is the primary abductor of the arm (beyond 15 degrees), it is **not** part of the rotator cuff. It does not insert into the joint capsule and acts as a "shunt muscle" rather than a stabilizer of the glenoid labrum. ### Explanation of Incorrect Options (Rotator Cuff Muscles): The rotator cuff is easily remembered by the mnemonic **SITS**: * **Supraspinatus (Option D):** Originates from the supraspinous fossa and inserts on the greater tubercle. It initiates the first 0–15° of abduction. * **Infraspinatus:** Originates from the infraspinous fossa and inserts on the greater tubercle. It is a lateral rotator. * **Teres minor (Option A):** Originates from the lateral border of the scapula and inserts on the greater tubercle. It also assists in lateral rotation. * **Subscapularis (Option B):** The only member that inserts on the **lesser tubercle**. It is a powerful medial rotator. ### High-Yield Clinical Pearls for NEET-PG: * **Most commonly injured muscle:** Supraspinatus (due to its location beneath the acromion process, making it prone to impingement). * **Nerve Supply:** Supraspinatus and Infraspinatus are supplied by the **Suprascapular nerve**; Teres minor by the **Axillary nerve**; Subscapularis by the **Upper and Lower Subscapular nerves**. * **The "Gatekeeper":** The rotator cuff is deficient **inferiorly**, which explains why anterior-inferior shoulder dislocations are the most common.

Q: Which muscle is primarily responsible for overhead abduction at the shoulder joint?

Serratus anterior. Abduction at the shoulder joint is a complex, coordinated movement involving multiple muscles acting at different stages. To achieve **overhead abduction** (above 90°), the scapula must rotate upward to reposition the glenoid cavity. **Why Serratus Anterior is correct:** The **Serratus anterior** (supplied by the Long Thoracic Nerve) is the primary muscle responsible for the **upward rotation of the scapula**. Along with the Trapezius, it rotates the scapula so that the glenoid fossa faces upwards, allowing the humerus to move beyond the horizontal plane (90° to 180°). Without this scapular rotation, the humerus would hit the acromion process, halting abduction. **Analysis of Incorrect Options:** * **Supraspinatus:** Responsible for the **initiation** of abduction (first 0–15°). It stabilizes the humeral head in the glenoid cavity. * **Deltoid:** The primary abductor from **15° to 90°**. While essential, it cannot lift the arm above the head without the synergistic upward rotation of the scapula. * **Pectoralis major:** This is primarily an **adductor** and medial rotator of the arm; it opposes abduction. **High-Yield Clinical Pearls for NEET-PG:** * **Winged Scapula:** Damage to the Long Thoracic Nerve (C5-C7) paralyzes the Serratus anterior, leading to an inability to perform overhead abduction and a protruding medial border of the scapula. * **Scapulohumeral Rhythm:** The ratio of glenohumeral movement to scapulothoracic movement is generally **2:1**. * **The

Q: Injury to the long thoracic nerve can be tested by asking the patient to perform which action?

Push against a wall. **Explanation:** The **long thoracic nerve (Nerve of Bell)** arises from the roots of the brachial plexus (**C5, C6, C7**) and supplies the **Serratus Anterior** muscle. The primary function of this muscle is to protract the scapula and keep its medial border firmly opposed to the thoracic wall. **Why Option A is Correct:** When a patient is asked to **push against a wall** with outstretched hands, the Serratus Anterior must contract to stabilize the scapula against the rib cage. If the long thoracic nerve is injured, the muscle fails, and the medial border of the scapula protrudes posteriorly. This clinical sign is known as **"Winging of the Scapula."** **Why Other Options are Incorrect:** * **Option B:** While the Serratus Anterior (along with the Trapezius) helps in rotating the scapula for abduction above 90°, "pushing against a wall" is the specific provocative test used to elicit winging. * **Option C:** Touching the opposite shoulder primarily involves the Pectoralis Major and Deltoid (adduction and internal rotation). * **Option D:** Lifting a heavy object primarily tests the Trapezius (elevation) and the muscles of the arm/forearm (biceps/brachialis). **NEET-PG High-Yield Pearls:** * **Mechanism of Injury:** The nerve is superficial; it is commonly injured during **mastectomy** (axillary lymph node dissection), chest tube insertion, or heavy carrying on the shoulder. * **Mnemonic for Roots:** "C5, 6, 7 raise your wings to heaven." * **Clinical Presentation:** Patients often complain of difficulty in overhead lifting or combing hair due to impaired upward rotation of the scapula.

Question 1

Damage to the coracobrachialis muscle and to the nerve passing through it could reasonably be expected to produce all of the following, EXCEPT?

Accepted Answer

Diminished cutaneous sensation over the lateral palm

Answer

Weakened flexion at the elbow

Answer

Weakened flexion at the shoulder

Answer

Weakened supination of the forearm

Question 2

Neglected whitlow may lead to necrosis of which part of the distal phalanx?

Accepted Answer

Distal 4/5th of terminal phalanx

Answer

Whole of tip of terminal phalanx

Answer

Only the tip of terminal phalanx

Answer

None of the above

Question 3

In a subclavian artery block at the outer border of the 1st rib, all of the following arteries help in maintaining circulation to the upper limb except?

Accepted Answer

Superior thoracic artery

Answer

Subscapular artery

Answer

Thyrocervical trunk

Answer

Suprascapular artery

Question 4

A 22-year-old male football player suffered a wrist injury while falling with force on his outstretched hand. When the anatomic snuffbox is exposed in surgery, an artery is visualized crossing the fractured bone that provides a floor for this space. What artery was visualized?

Accepted Answer

Radial

Answer

Ulnar

Answer

Anterior interosseous

Answer

Posterior interosseous

Question 5

Content of the star marked triangle?

Accepted Answer

Radial artery only

Answer

Basilic vein and superficial branch of radial nerve

Answer

Radial artery and Posterior interosseous nerve(PIN)

Answer

Cephalic vein and Posterior interosseous nerve(PIN)

Question 6

Which of the following statements about the brachial plexus is FALSE?

Accepted Answer

The long thoracic nerve arises from the posterior cord.

Answer

The posterior cord gives the main supply to the radial nerve.

Answer

The axillary nerve arises from the posterior cord.

Answer

The C5 and C6 roots join to form the upper trunk.

Question 7

Guyon's canal is associated with which of the following structures?

Accepted Answer

Ulnar nerve

Answer

Anterior interosseus nerve

Answer

Median nerve

Answer

Radial artery

Question 8

All of the following muscles form the rotator cuff EXCEPT?

Accepted Answer

Deltoid

Answer

Teres minor

Answer

Subscapularis

Answer

Supraspinatus

Question 9

Which muscle is primarily responsible for overhead abduction at the shoulder joint?

Accepted Answer

Serratus anterior

Answer

Deltoid

Answer

Supraspinatus

Answer

Pectoralis major

Question 10

Injury to the long thoracic nerve can be tested by asking the patient to perform which action?

Accepted Answer

Push against a wall

Answer

Raise the arm above the head

Answer

Touch the opposite shoulder

Answer

Lift a heavy object

Upper Limb — MCQs

Upper Limb — MCQs

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