Upper Limb Practice Questions

Q: Extension at the MCP joint is primarily achieved by which of the following muscles?

Extensor Digitorum. ### Explanation **1. Why Extensor Digitorum is Correct:** The **Extensor Digitorum (ED)** is the primary muscle responsible for extension at the Metacarpophalangeal (MCP) joints of the medial four fingers [2]. It originates from the common extensor origin (lateral epicondyle) and inserts into the extensor expansions. While it can assist in extending the Interphalangeal (IP) joints, its mechanical advantage is greatest at the MCP joint. Isolated contraction of the ED results in hyperextension at the MCP joint. **2. Why the Other Options are Incorrect:** * **Lumbricals:** These are unique muscles that originate from the tendons of Flexor Digitorum Profundus. Their primary action is to **flex the MCP joints** and **extend the IP joints** (the "Z-position") [1]. * **Dorsal Interossei (DAB):** Their primary action is **Abduction** of the fingers at the MCP joints [1]. Like lumbricals, they also assist in MCP flexion and IP extension. * **Palmar Interossei (PAD):** Their primary action is **Adduction** of the fingers at the MCP joints. They also contribute to the "Z-position" (MCP flexion, IP extension) [1]. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **The "Z-Position":** Flexion at MCP + Extension at IP joints is a combined action of the Lumbricals and Interossei (collectively called the intrinsic muscles of the hand) [1]. * **Claw Hand:** Paralysis of the lumbricals and interossei (Ulnar nerve palsy) leads to the opposite of the Z-position: **Hyperextension at MCP** (due to unopposed Extensor Digitorum) and **Flexion at IP joints** (due to unopposed FDP/FDS). * **Nerve Supply:** Extensor Digitorum is supplied by the **Posterior Interosseous Nerve (C7, C8)**, a branch of the Radial nerve [2]. * **Extensor Indicis & Extensor Digiti Minimi:** These provide independent MCP extension for the index and little fingers, respectively [2].

Q: Which muscle produces supination when the elbow is flexed?

Biceps brachii. The **Biceps brachii** is the correct answer because it is the most powerful supinator of the forearm, but its mechanical advantage is highly dependent on the position of the elbow. The muscle inserts into the **radial tuberosity**. When the elbow is flexed to 90°, the biceps tendon is perpendicular to the radius, providing the maximum torque required for powerful supination (e.g., tightening a screw). **Analysis of Options:** * **Biceps brachii (Correct):** It acts as the primary supinator during flexed-elbow activities. When the elbow is extended, its supinatory power significantly diminishes. * **Supinator (Incorrect):** While this muscle supinates the forearm, it is the primary mover during **slow, unresisted supination** or when the elbow is fully extended. It lacks the power of the biceps in a flexed position. * **Coracobrachialis (Incorrect):** This muscle is located in the arm and acts primarily as a flexor and adductor of the glenohumeral (shoulder) joint. It has no attachment to the radius or ulna and thus cannot rotate the forearm. * **Brachialis (Incorrect):** Known as the "workhorse" of elbow flexion, it inserts into the **ulnar tuberosity**. Since the ulna does not rotate during pronation/supination, the brachialis has no role in these movements. **NEET-PG High-Yield Pearls:** * **Nerve Supply:** Biceps and Brachialis are supplied by the **Musculocutaneous nerve (C5-C7)**. * **Screwdriver Muscle:** Biceps brachii is often referred to as the "screwdriver muscle" because of its role in powerful supination at 90° flexion. * **Paralysis:** In a Musculocutaneous nerve injury, supination is still possible (via the Supinator muscle, supplied by the Radial nerve), but it is significantly weakened.

Q: During a strenuous game of tennis, a 55-year-old woman complained of severe shoulder pain that forced her to quit the game. During physical examination, it was found that she could not initiate abduction of her arm, but if her arm was passively elevated to 45 degrees from the vertical (at her side) position, she had no trouble fully abducting it. Injury to which muscle was responsible?

Supraspinatus. ### Explanation The clinical presentation describes a classic case of a **Supraspinatus tear** or injury. **1. Why Supraspinatus is correct:** Abduction of the arm at the shoulder joint is a coordinated effort involving multiple muscles. The **Supraspinatus** is responsible for the **initiation of abduction (0° to 15°)**. It stabilizes the humeral head in the glenoid cavity, allowing the deltoid to gain a mechanical advantage. If the supraspinatus is injured, the patient cannot initiate the movement. However, if the arm is passively lifted beyond 15°–20°, the **Deltoid** takes over the action, explaining why the patient could complete the movement once elevated to 45°. **2. Why the other options are incorrect:** * **Deltoid:** This muscle is the primary abductor from **15° to 90°**. If the deltoid were injured, the patient would be able to initiate the first few degrees of movement but would fail to lift the arm to the horizontal level. * **Infraspinatus:** This is a member of the rotator cuff primarily responsible for **lateral (external) rotation** of the humerus, not abduction. * **Teres major:** This muscle acts to **adduct and medially rotate** the arm; it does not assist in abduction. **3. NEET-PG High-Yield Pearls:** * **Rotator Cuff (SITS):** Supraspinatus (Abduction), Infraspinatus (External rotation), Teres minor (External rotation), Subscapularis (Internal rotation). * **The

Q: A patient presents with inability to flex her hand at the joint indicated by a black arrow. Which of the following muscles appears to be paralyzed upon further examination of her finger?

Flexor digitorum superficialis. ***Flexor digitorum superficialis*** - The **proximal interphalangeal (PIP) joint** is primarily flexed by the flexor digitorum superficialis, making its paralysis the cause of inability to flex at this joint. - FDS inserts at the **middle phalanx** and is responsible for isolated PIP joint flexion when the DIP joint is held in extension. *Palmar interossei* - These muscles primarily **adduct fingers** toward the middle finger and assist in **MCP joint flexion**, not PIP joint flexion. - They also contribute to **IP joint extension** through their connection to the extensor hood, opposite to the described deficit. *Dorsal interossei* - These muscles **abduct fingers** away from the middle finger and primarily flex the **MCP joints**, not the PIP joints. - Like palmar interossei, they assist in **IP joint extension** via the extensor mechanism, not flexion. *Flexor digitorum profundus* - FDP primarily flexes the **distal interphalangeal (DIP) joint** as it inserts on the distal phalanx. - While it can assist PIP flexion, its paralysis would primarily affect **DIP joint flexion**, not isolated PIP joint dysfunction.

Q: Which of the following muscles of the scapula, functioning as retractors, is the exception?

Levator scapulae. ### Explanation The movement of the scapula is governed by the coordinated action of extrinsic shoulder muscles. **Retraction (adduction)** refers to the movement of the scapula toward the vertebral column. **Why Levator Scapulae is the Correct Answer:** The **Levator Scapulae** primarily functions to **elevate** the scapula and assist in its downward rotation. While it originates from the cervical vertebrae and attaches to the superior angle of the scapula, its vector of pull is vertical rather than horizontal. Therefore, it does not contribute to retraction. **Analysis of Incorrect Options:** * **Trapezius (Middle fibers):** The middle fibers of the trapezius run horizontally from the spinous processes to the acromion. They are the **primary retractors** of the scapula. * **Rhomboid Major & Minor:** These muscles run obliquely from the nuchal ligament and spinous processes (C7–T5) to the medial border of the scapula. Their contraction pulls the scapula medially and superiorly, acting as **powerful retractors** and stabilizers. **NEET-PG High-Yield Pearls:** 1. **Nerve Supply:** The Rhomboids and Levator scapulae are both supplied by the **Dorsal Scapular Nerve (C5)**. The Trapezius is supplied by the **Spinal Accessory Nerve (CN XI)**. 2. **Antagonist Movement:** The primary **protractor** of the scapula is the **Serratus Anterior** (supplied by the Long Thoracic Nerve). Paralysis of this muscle leads to "Winged Scapula." 3. **Upward Rotation:** To abduct the arm above 90°, the scapula must rotate upward; this is a synergistic action of the **Trapezius (upper and lower fibers)** and the **Serratus Anterior**.

Q: Which of the following muscles is NOT supplied by the radial nerve below the spiral groove?

Anconeus. The radial nerve’s distribution in the arm is a high-yield topic for NEET-PG, specifically regarding the **level** at which branches arise relative to the spiral (radial) groove. ### **Explanation of the Correct Answer** The **Anconeus** is supplied by the radial nerve via a long branch that arises **within the spiral groove** (specifically, the branch to the medial head of the triceps). Because this nerve branch originates high in the arm and descends through the substance of the triceps to reach the anconeus, it is considered a branch given off **at or above** the spiral groove, not below it. ### **Analysis of Incorrect Options** After the radial nerve pierces the lateral intermuscular septum to enter the anterior compartment of the lower arm (distal to the spiral groove), it supplies: * **Brachialis (Option A):** Receives a small proprioceptive/motor branch from the radial nerve (though its main supply is Musculocutaneous). * **Brachioradialis (Option B):** Supplied by the radial nerve in the lower third of the arm, below the groove. * **Extensor Carpi Radialis Longus (Option C):** Supplied by the radial nerve in the arm before it divides into superficial and deep branches at the lateral epicondyle. ### **High-Yield Clinical Pearls** * **The "Saturday Night Palsy" Rule:** In a mid-shaft humerus fracture (spiral groove injury), the **Triceps** is usually spared (branches arise high), but the **Anconeus** and all distal extensors are affected, leading to **Wrist Drop**. * **Brachialis Dual Supply:** It is a hybrid/composite muscle supplied by the Musculocutaneous (medial part) and Radial nerve (lateral part). * **Order of Supply:** Below the spiral groove, the sequence of innervation is: Brachialis → Brachioradialis → ECRL. ECRB is usually supplied by the Deep Branch of the Radial Nerve (or PIN).

Q: Which of the following statements about radial nerve palsy is NOT true?

Loss of nerve supply to brachioradialis. This question tests your knowledge of the **topographical anatomy** of the radial nerve and the level at which its branches arise. ### **Explanation of the Correct Answer (A)** The statement "Loss of nerve supply to brachioradialis" is considered **NOT true** in the context of a typical radial nerve injury occurring at the **spiral groove** (the most common site of palsy, e.g., Saturday Night Palsy). * **The Concept:** The radial nerve gives off branches to the **Triceps (long and medial heads)** in the axilla and to the **Brachioradialis** and **Extensor Carpi Radialis Longus (ECRL)** in the arm, *proximal* to the lateral epicondyle. * In many clinical scenarios of radial nerve palsy (like mid-shaft humerus fractures), the nerve is injured after these branches have already been given off, sparing the brachioradialis. ### **Analysis of Incorrect Options** * **B & C (ECRB and EPB):** These muscles are supplied by the **Deep Branch of the Radial Nerve** (or the Posterior Interosseous Nerve). Since these branches arise distal to the spiral groove/lateral epicondyle, they are invariably paralyzed in a radial nerve palsy, leading to "Wrist Drop" and "Thumb Drop." * **D (First dorsal web space):** This is the "autonomous zone" supplied by the **Superficial Radial Nerve**. Sensory loss here is a classic hallmark of radial nerve injury above the elbow. ### **NEET-PG High-Yield Pearls** * **Wrist Drop:** Caused by paralysis of wrist extensors. * **Finger Drop:** Specifically refers to PIN (Posterior Interosseous Nerve) palsy; notably, in PIN palsy, **wrist extension is preserved** (due to ECRL being supplied by the main radial nerve) but deviates radially. * **The "Rule of 3":** The radial nerve supplies 3 muscles before dividing: Brachioradialis, ECRL, and Anconeus. * **Most common site of injury:** Spiral groove (Humerus shaft fracture).

Q: The dorsal scapular nerve supplies all of the following muscles except?

Supraspinatus. ### Explanation The **Dorsal Scapular Nerve** arises from the **ventral ramus of the C5 nerve root** (the root stage of the brachial plexus). It travels posteriorly, piercing the middle scalene muscle to reach the medial border of the scapula. **1. Why Supraspinatus is the correct answer:** The **Supraspinatus** is supplied by the **Suprascapular Nerve** (C5, C6), which arises from the **Upper Trunk** of the brachial plexus. It does not receive any innervation from the dorsal scapular nerve. Therefore, it is the "except" in this list. **2. Analysis of incorrect options:** * **Rhomboid Major & Minor:** These are the primary muscles supplied by the dorsal scapular nerve. It enters their deep surface to provide motor innervation, facilitating scapular retraction and elevation. * **Levator Scapulae:** This muscle has a dual nerve supply. It is supplied by the **Dorsal Scapular Nerve (C5)** and direct branches from the **C3 and C4 cervical nerves**. Since it is partially supplied by the dorsal scapular nerve, it is an incorrect choice for this "except" question. **3. NEET-PG High-Yield Pearls:** * **Nerve Root:** Remember "Dorsal Scapular = C5 root." * **Clinical Sign:** Injury to the dorsal scapular nerve results in a lateral shift of the scapula (the rhomboids can no longer retract it) and difficulty "squaring" the shoulders. * **Suprascapular Nerve:** Supplies both the **Supraspinatus** and **Infraspinatus**. It passes through the suprascapular notch (under the superior transverse scapular ligament). * **Dual Supply:** Always remember Levator Scapulae (C3, C4 + C5) and Pectoralis Major (Medial + Lateral Pectoral nerves) as common "dual supply" questions in Anatomy.

Question 1

Extension at the MCP joint is primarily achieved by which of the following muscles?

Accepted Answer

Extensor Digitorum

Answer

Dorsal Interossei

Answer

Palmar Interossei

Answer

Lumbricals

Question 2

Which muscle produces supination when the elbow is flexed?

Accepted Answer

Biceps brachii

Answer

Supinator

Answer

Coracobrachialis

Answer

Brachialis

Question 3

All of the following muscles elevate the scapula, EXCEPT:

Accepted Answer

Latissimus dorsi

Answer

Trapezius

Answer

Levator scapulae

Answer

Rhomboid major

Question 4

During a strenuous game of tennis, a 55-year-old woman complained of severe shoulder pain that forced her to quit the game. During physical examination, it was found that she could not initiate abduction of her arm, but if her arm was passively elevated to 45 degrees from the vertical (at her side) position, she had no trouble fully abducting it. Injury to which muscle was responsible?

Accepted Answer

Supraspinatus

Answer

Deltoid

Answer

Infraspinatus

Answer

Teres major

Question 5

A patient presents with inability to flex her hand at the joint indicated by a black arrow. Which of the following muscles appears to be paralyzed upon further examination of her finger?

Accepted Answer

Flexor digitorum superficialis

Answer

Palmar interossei

Answer

Dorsal interossei

Answer

Flexor digitorum profundus

Question 6

Which of the following muscles of the scapula, functioning as retractors, is the exception?

Accepted Answer

Levator scapulae

Answer

Trapezius

Answer

Rhomboid major

Answer

Rhomboid minor

Question 7

Which of the following muscles is NOT supplied by the radial nerve below the spiral groove?

Accepted Answer

Anconeus

Answer

Brachialis

Answer

Brachioradialis

Answer

Extensor carpi radialis longus

Question 8

Which of the following statements about radial nerve palsy is NOT true?

Accepted Answer

Loss of nerve supply to brachioradialis

Answer

Loss of nerve supply to extensor carpi radialis brevis

Answer

Loss of nerve supply to extensor pollicis brevis

Answer

Loss of sensation over first dorsal web space

Question 9

The dorsal scapular nerve supplies all of the following muscles except?

Accepted Answer

Supraspinatus

Answer

Rhomboid major

Answer

Rhomboid minor

Answer

Levator scapulae

Question 10

Regarding the anatomical snuffbox, which of the following statements is true?

Accepted Answer

Abductor pollicis longus and Extensor pollicis brevis form the anterior wall.

Answer

Abductor pollicis longus forms the posterior wall.

Answer

Basilic vein forms the roof.

Answer

The floor is formed by Extensor carpi radialis longus and brevis.

Upper Limb — MCQs

Upper Limb — MCQs

On this page

Practice by Chapter

Want unlimited practice?