Upper Limb Practice Questions

Q: Where is the extensor carpi ulnaris inserted?

Base of the 5th metacarpal. ### Explanation **Correct Answer: C. Base of the 5th metacarpal** The **Extensor Carpi Ulnaris (ECU)** is a muscle located in the superficial layer of the posterior compartment of the forearm. It originates from the lateral epicondyle of the humerus (via the common extensor origin) and the posterior border of the ulna. Its primary function is to extend and adduct (ulnar deviate) the wrist. To perform these actions effectively, it inserts onto the **medial side of the base of the 5th metacarpal bone**. [1] #### Analysis of Incorrect Options: * **Option A & B:** The base of the proximal and distal phalanges of the thumb are insertion sites for the **Extensor Pollicis Brevis** and **Extensor Pollicis Longus**, respectively. These muscles belong to the deep group of the posterior compartment and act specifically on the thumb. [1] * **Option D:** The **Scaphoid** is a carpal bone. While several ligaments attach here, no major forearm extensor muscle inserts directly onto the scaphoid. Most wrist extensors bypass the carpal bones to insert onto the bases of the metacarpals to provide a better mechanical advantage for wrist movement. [1] #### High-Yield Clinical Pearls for NEET-PG: * **Nerve Supply:** Like most muscles in the posterior compartment, the ECU is supplied by the **Posterior Interosseous Nerve (C7, C8)**, which is a continuation of the deep branch of the radial nerve. [1] * **Synergistic Action:** During ulnar deviation, the ECU works synergistically with the **Flexor Carpi Ulnaris (FCU)**. * **Anatomical Compartment:** The ECU tendon passes through the **6th dorsal compartment** of the extensor retinaculum (the most medial compartment). [1] * **Comparison:** Remember that the Extensor Carpi Radialis Longus (ECRL) inserts at the base of the **2nd metacarpal**, while the Extensor Carpi Radialis Brevis (ECRB) inserts at the base of the **3rd metacarpal**. [1]

Q: What is the root value of the long thoracic nerve?

C-5, 6, 7. ### Explanation **Correct Option: B (C-5, 6, 7)** The **Long Thoracic Nerve** (also known as the Nerve of Bell) arises directly from the **ventral rami of C5, C6, and C7** roots of the brachial plexus. It descends posterior to the brachial plexus and the first part of the axillary artery to reach the medial wall of the axilla, where it supplies the **Serratus Anterior** muscle. **Analysis of Incorrect Options:** * **A (C-3, 4, 5):** This is the root value of the **Phrenic Nerve**, which supplies the diaphragm. * **C (C-7, 8, T-1):** These roots contribute to the formation of the medial cord and nerves like the Ulnar nerve (though Ulnar is typically C8-T1, sometimes receiving a C7 contribution). * **D (C-2, 3, 4):** These roots form part of the **Cervical Plexus**, supplying the skin and muscles of the neck (e.g., Lesser Occipital, Great Auricular nerves). **High-Yield Clinical Pearls for NEET-PG:** 1. **Clinical Presentation:** Injury to this nerve leads to **"Winging of Scapula"** due to paralysis of the Serratus Anterior. The patient will be unable to perform overhead abduction (beyond 90°) and will have difficulty with "pushing" movements. 2. **Mechanism of Injury:** It is most commonly injured during surgical procedures like **Radical Mastectomy** (axillary lymph node dissection) or due to direct trauma/pressure in the axilla. 3. **Mnemonic:** *"C5, 6, 7 raise your arms to heaven"* (referring to its role in overhead abduction via the Serratus Anterior). 4. **Unique Feature:** Unlike most branches of the brachial plexus, it arises directly from the **roots**, not from the trunks, divisions, or cords.

Q: The posterior cord of the brachial plexus is formed by which divisions?

The dorsal divisions of the upper, middle, and lower trunks. ### Explanation The brachial plexus is organized into Roots, Trunks, Divisions, Cords, and Branches. The formation of the **Posterior Cord** is a high-yield concept based on the embryological division of muscles into anterior (flexor) and posterior (extensor) compartments. **1. Why the Correct Answer is Right:** The **Posterior Cord** is formed by the union of the **dorsal (posterior) divisions of all three trunks** (Upper, Middle, and Lower). These divisions carry fibers from all spinal levels of the plexus (C5-T1). Because it is formed by dorsal divisions, the posterior cord and its terminal branches (Radial and Axillary nerves) primarily supply the extensor compartments of the upper limb. **2. Analysis of Incorrect Options:** * **Option A & B:** A single division from one trunk cannot form a cord. The upper trunk's ventral division contributes to the Lateral Cord, while its dorsal division is only one-third of the Posterior Cord. * **Option C:** The ventral divisions of the upper and middle trunks join to form the **Lateral Cord**. The ventral division of the lower trunk continues alone as the **Medial Cord**. Ventral divisions generally supply the flexor compartments (via Musculocutaneous, Median, and Ulnar nerves). **3. NEET-PG High-Yield Clinical Pearls:** * **Mnemonic for Cords:** **L**ateral (from **L**ateral and **M**iddle trunks), **P**osterior (from **A**ll three), **M**edial (from **M**edial trunk only). * **Positional Landmark:** Cords are named based on their relationship to the **second part of the Axillary Artery**. * **Posterior Cord Branches (Mnemonic: STAR):** **S**ubscapular (Upper & Lower), **T**horacodorsal, **A**xillary, and **R**adial nerves [1]. * **Clinical Correlation:** A lesion to the posterior cord results in "Wrist Drop" (Radial nerve) and loss of shoulder abduction (Axillary nerve).

Q: An elderly patient complains of shoulder pain and has difficulty abducting his arm. Arthroscopy is performed with dye injection into the shoulder joint followed by an X-ray. The radiologist notes that the dye has leaked from the shoulder joint into the subacromial bursa. Which tendon rupture would allow for this dye leakage?

Supraspinatus. **Explanation:** The correct answer is **Supraspinatus**. This question tests your understanding of the anatomical relationship between the glenohumeral joint and the surrounding bursae. **1. Why Supraspinatus is correct:** The **Supraspinatus tendon** forms the superior part of the rotator cuff and lies directly beneath the **subacromial bursa**. Crucially, the subacromial bursa and the glenohumeral joint cavity are normally separated by the rotator cuff tendons. If the Supraspinatus tendon ruptures (a common injury in elderly patients due to chronic impingement), a communication is created between the joint cavity and the bursa. Therefore, dye injected into the joint space will leak into the subacromial bursa, confirming a full-thickness tear. **2. Why other options are incorrect:** * **Deltoid:** This is a superficial muscle. While it overlies the subacromial bursa, it does not form the wall between the joint cavity and the bursa. * **Infraspinatus:** While part of the rotator cuff, the Supraspinatus is the most frequently ruptured tendon and is the primary structure separating the joint from the subacromial bursa. * **Latissimus dorsi:** This muscle inserts into the floor of the bicipital groove and is not involved in the superior boundary of the shoulder joint capsule. **Clinical Pearls for NEET-PG:** * **Rotator Cuff Muscles (SITS):** Supraspinatus (Abduction 0-15°), Infraspinatus (External rotation), Teres minor (External rotation), Subscapularis (Internal rotation). * **Most Common Site of Tear:** The "Critical Zone" of the Supraspinatus tendon (near its insertion on the greater tubercle) due to poor vascularity. * **Painful Arc Syndrome:** Pain during abduction between 60° and 120° often indicates Supraspinatus tendinitis or subacromial bursitis.

Q: What is the medial boundary of the cubital fossa?

Pronator teres. The **cubital fossa** is a triangular depression located on the anterior aspect of the elbow. Understanding its boundaries is high-yield for NEET-PG, as it serves as a transition zone for neurovascular structures entering the forearm. ### **Explanation of Boundaries** The cubital fossa is shaped like an inverted triangle: * **Medial Boundary (Correct Answer):** Formed by the **lateral border of the Pronator teres**. It is important to note that the medial border of the fossa is the lateral edge of this muscle. * **Lateral Boundary:** Formed by the **medial border of the Brachioradialis**. * **Superior Boundary (Base):** An imaginary horizontal line connecting the medial and lateral epicondyles of the humerus. * **Apex:** Directed downwards, where the Brachioradialis crosses the Pronator teres. * **Floor:** Formed by the Brachialis (medially) and the Supinator (laterally). * **Roof:** Formed by skin, superficial fascia (containing the median cubital vein), and the bicipital aponeurosis. ### **Why Other Options are Incorrect** * **Brachioradialis:** This muscle forms the **lateral** boundary of the fossa. * **Supinator:** This muscle forms part of the **floor** of the fossa, not its boundaries. ### **High-Yield Clinical Pearls** 1. **Contents (Medial to Lateral - "MBBR"):** **M**edian nerve, **B**rachial artery, **B**iceps brachii tendon, and **R**adial nerve. 2. **Median Cubital Vein:** Located in the roof; it is the preferred site for venipuncture. It is separated from the underlying brachial artery by the **bicipital aponeurosis** (the "grace de Dieu" fascia). 3. **Supracondylar Fracture:** The most common fracture involving this area in children, which can lead to **Volkmann’s Ischemic Contracture** due to brachial artery injury.

Q: If the C5 and C6 nerve roots are injured, sensation loss in which part of the upper limb will occur?

Thumb and index finger. This question tests your knowledge of **dermatomes** and the clinical presentation of **Erb’s Palsy**. ### **Explanation of the Correct Answer** The **C5 and C6 nerve roots** form the upper trunk of the brachial plexus. In the upper limb, the C6 dermatome specifically supplies the skin over the **lateral aspect of the forearm, the thumb, and the radial side of the index finger**. Therefore, an injury to these roots (most commonly seen in Erb’s Palsy) results in sensory loss along the pre-axial border of the limb, specifically the thumb and index finger [1]. ### **Analysis of Incorrect Options** * **B. Little finger:** Sensation to the little finger and the medial side of the hand is provided by the **C8 nerve root** (via the ulnar nerve). * **C. Upper medial part of the arm:** This area is supplied by the **T2 nerve root** (Intercostobrachial nerve) and the **T1 nerve root** (Medial cutaneous nerve of the arm). * **D. Upper medial side of the forearm:** This area is supplied by the **C8 and T1 nerve roots** via the Medial cutaneous nerve of the forearm. ### **High-Yield Clinical Pearls for NEET-PG** * **Erb’s Palsy (C5-C6):** Caused by an increase in the angle between the neck and shoulder. The classic deformity is the **"Policeman’s tip" or "Waiter’s tip" hand** (Adducted shoulder, internally rotated arm, and extended elbow). * **Klumpke’s Palsy (C8-T1):** Caused by hyperabduction of the arm. It results in a **"Claw hand"** deformity and sensory loss on the ulnar side of the forearm and hand. * **Dermatome Mnemonics:** * **C6:** "Six" looks like a **G** (for thumb/radial side). * **C8:** Little finger. * **T1:** Medial elbow/forearm.

Q: A patient presents with winging of the scapula, noticed when pushing against a wall. The nerve responsible for this condition arises from which part of the brachial plexus?

Root. ***Root*** - **Winging of the scapula** is caused by **long thoracic nerve palsy**, which paralyzes the **serratus anterior muscle**. - The **long thoracic nerve** arises directly from the **roots C5, C6, and C7** of the brachial plexus, making this the correct answer. *Trunk* - Nerves arising from trunks include the **suprascapular nerve** and **nerve to subclavius**. - These nerves do not innervate the **serratus anterior muscle** responsible for preventing scapular winging. *Division* - The **divisions** of the brachial plexus are primarily organizational structures that separate into **anterior and posterior** components. - No major nerves arise directly from the divisions that would cause scapular winging when damaged. *Cord* - Nerves from cords include the **median nerve** (lateral and medial cords), **ulnar nerve** (medial cord), and **radial nerve** (posterior cord). - These nerves primarily innervate **forearm and hand muscles**, not the serratus anterior muscle.

Q: Which muscle causes adduction of the wrist joint?

Flexor carpi ulnaris. **Explanation:** The movement of the wrist joint (radiocarpal joint) occurs along two axes: flexion/extension and abduction/adduction. **Adduction (ulnar deviation)** is primarily performed by the simultaneous contraction of muscles on the medial (ulnar) aspect of the forearm. **Why Flexor Carpi Ulnaris (FCU) is correct:** The FCU is the most medial muscle of the superficial flexor compartment. It inserts into the pisiform, hook of hamate, and the base of the 5th metacarpal [1]. Due to its medial position relative to the axis of the wrist, its contraction pulls the hand toward the midline (ulnar side). It works in synergy with the **Extensor Carpi Ulnaris (ECU)** to produce pure adduction. **Analysis of Incorrect Options:** * **A. Flexor carpi radialis:** This muscle is located on the lateral side of the forearm. Its contraction results in **abduction (radial deviation)** and flexion of the wrist. * **C. Flexor pollicis longus:** This is a deep muscle primarily responsible for flexing the interphalangeal joint of the thumb [1]. While it may weakly assist in wrist flexion, it does not contribute to adduction. * **D. Flexor digitorum profundus:** This muscle primarily flexes the distal interphalangeal (DIP) joints of the fingers and the wrist as a whole, but it does not have a specific vector for ulnar deviation [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Synergy:** Pure adduction requires the co-contraction of FCU (flexor) and ECU (extensor) to cancel out their respective flexion/extension components. * **Nerve Supply:** FCU is a notable exception in the flexor compartment as it is supplied by the **Ulnar Nerve (C8, T1)**, not the Median Nerve. * **Range of Motion:** Adduction (approx. 45°) has a greater range than abduction (approx. 15°) because the radial styloid process extends further distally than the ulnar styloid, limiting lateral movement.

Q: Which of the following muscles is enclosed within the clavipectoral fascia?

Subclavius. **Explanation:** The **clavipectoral fascia** is a strong fascial sheet situated deep to the pectoralis major muscle. It extends vertically from the clavicle above to the axillary fascia below. Its anatomical arrangement is a high-yield topic for NEET-PG due to the specific structures it encloses and those that pierce it. **1. Why Subclavius is Correct:** As the clavipectoral fascia descends from the clavicle, it splits into two layers to enclose the **subclavius** muscle. These layers then fuse to form a single sheet (the costocoracoid membrane) before splitting again to enclose the **pectoralis minor** muscle. Therefore, both the subclavius and pectoralis minor are the only two muscles contained within this fascia. **2. Why Other Options are Incorrect:** * **Pectoralis major:** This muscle lies superficial to the clavipectoral fascia [1]. It is enclosed by its own dedicated pectoral fascia. * **Serratus anterior:** This muscle forms the medial wall of the axilla and is covered by the serratus fascia, not the clavipectoral fascia. * **Coracobrachialis:** This muscle is located in the arm (originating from the coracoid process) and is not enclosed by this fascia, though the fascia attaches to the coracoid process nearby. **3. High-Yield Clinical Pearls:** * **Structures piercing the fascia:** Remember the mnemonic **"CALL"** or **"LACS"**: 1. **L**ateral pectoral nerve 2. **A**cro-thoracic artery (Thoracoacromial artery) 3. **C**ephalic vein 4. **L**ymphatics (from the breast to apical axillary nodes) * **Suspensory ligament of axilla:** The part of the fascia extending from the pectoralis minor to the axillary fascia is called the suspensory ligament; it maintains the characteristic concavity of the armpit.

Question 1

A patient underwent sentinel node biopsy for treatment of breast carcinoma. Which of the following nerves is likely to be injured during this procedure?

Accepted Answer

Intercostobrachial nerve

Answer

Nerve to latissimus dorsi

Answer

Nerve to serratus anterior

Answer

Lateral pectoral nerve

Question 2

Where is the extensor carpi ulnaris inserted?

Accepted Answer

Base of the 5th metacarpal

Answer

Base of proximal phalanx of the thumb

Answer

Base of distal phalanx of the thumb

Answer

Base of the scaphoid

Question 3

What is the root value of the long thoracic nerve?

Accepted Answer

C-5, 6, 7

Answer

C-3, 4, 5

Answer

C-7, 8 T-1

Answer

C-2, 3, 4

Question 4

The posterior cord of the brachial plexus is formed by which divisions?

Accepted Answer

The dorsal divisions of the upper, middle, and lower trunks

Answer

The ventral division of the upper trunk

Answer

The dorsal division of the upper trunk

Answer

The ventral divisions of the upper, middle, and lower trunks

Question 5

An elderly patient complains of shoulder pain and has difficulty abducting his arm. Arthroscopy is performed with dye injection into the shoulder joint followed by an X-ray. The radiologist notes that the dye has leaked from the shoulder joint into the subacromial bursa. Which tendon rupture would allow for this dye leakage?

Accepted Answer

Supraspinatus

Answer

Deltoid

Answer

Infraspinatus

Answer

Latissimus dorsi

Question 6

What is the medial boundary of the cubital fossa?

Accepted Answer

Pronator teres

Answer

Brachioradialis

Answer

Supinator

Answer

None of the above

Question 7

If the C5 and C6 nerve roots are injured, sensation loss in which part of the upper limb will occur?

Accepted Answer

Thumb and index finger

Answer

Little finger

Answer

Upper medial part of the arm

Answer

Upper medial side of the forearm

Question 8

A patient presents with winging of the scapula, noticed when pushing against a wall. The nerve responsible for this condition arises from which part of the brachial plexus?

Accepted Answer

Root

Answer

Trunk

Answer

Division

Answer

Cord

Question 9

Which muscle causes adduction of the wrist joint?

Accepted Answer

Flexor carpi ulnaris

Answer

Flexor carpi radialis

Answer

Flexor pollicis longus

Answer

Flexor digitorum profundus

Question 10

Which of the following muscles is enclosed within the clavipectoral fascia?

Accepted Answer

Subclavius

Answer

Pectoralis major

Answer

Serratus anterior

Answer

Coracobrachialis

Upper Limb — MCQs

Upper Limb — MCQs

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