Upper Limb Practice Questions

Q: Which muscle of the hand contains a sesamoid bone?

Adductor pollicis. **Explanation:** The correct answer is **Adductor pollicis**. Sesamoid bones are small, rounded bones embedded within tendons or joint capsules, primarily functioning to reduce friction and modify pressure. In the hand, the most constant sesamoid bones are found at the **metacarpophalangeal (MCP) joint of the thumb**. The **Adductor pollicis** muscle inserts into the ulnar side of the base of the proximal phalanx of the thumb. Its tendon contains a sesamoid bone that glides over the ulnar aspect of the head of the first metacarpal. This bone provides a mechanical advantage and protects the tendon during the powerful "pinch" grip. **Analysis of Options:** * **Flexor pollicis brevis (FPB):** While the radial sesamoid of the thumb is associated with the insertion of the FPB, the question specifically targets the muscle most classically associated with the ulnar sesamoid in standard anatomical texts, which is the Adductor pollicis. * **Flexor pollicis longus (FPL):** This is an extrinsic muscle. Its tendon passes between the two sesamoid bones of the thumb but does not contain one within its substance. * **Opponens pollicis:** This muscle inserts into the lateral border of the first metacarpal shaft, not the joint capsule or phalanx, and therefore does not contain a sesamoid bone. **High-Yield Facts for NEET-PG:** * **Constant Sesamoids:** The thumb MCP joint consistently has two sesamoids (Radial in FPB/Abductor pollicis brevis and Ulnar in Adductor pollicis). * **Stieda’s Process:** Occasionally, a sesamoid is found in the Adductor pollicis that may be mistaken for a fracture on X-ray. * **Palmar Plate:** These sesamoids are actually embedded within the palmar ligament (palmar plate) of the MCP joint. * **Other sites:** Sesamoids are also frequently found in the tendons of the Flexor Hallucis Brevis (Great toe) and the Gastrocnemius (Fabella).

Q: Which flexor muscle attaches to the hook of the hamate?

Flexor digiti minimi. ### Explanation The **hook of the hamate** is a crucial bony landmark on the medial side of the carpal tunnel [1]. It serves as an attachment point for the **flexor retinaculum** and several muscles of the hypothenar eminence [1]. **Why Option C is Correct:** The **Flexor digiti minimi brevis** originates from the hook of the hamate and the adjacent flexor retinaculum [2]. It inserts into the ulnar side of the base of the proximal phalanx of the little finger. Along with the *Opponens digiti minimi* (which also attaches to the hook), it forms the hypothenar muscle group responsible for moving the fifth digit [2]. **Analysis of Incorrect Options:** * **A. Flexor pollicis brevis:** This is a thenar muscle [2]. Its superficial head originates from the flexor retinaculum and the **trapezium**, not the hamate. * **B. Flexor pollicis longus:** This is a deep muscle of the anterior forearm. It originates from the anterior surface of the **radius** and the interosseous membrane, passing through the carpal tunnel to insert on the distal phalanx of the thumb [2]. * **C. Flexor carpi ulnaris:** This muscle inserts primarily onto the **pisiform bone**. Its tension is then transmitted via the pisohamate and pisometacarpal ligaments. It does not directly "attach" to the hook of the hamate as its primary insertion. **High-Yield Clinical Pearls for NEET-PG:** * **Guyon’s Canal:** The hook of the hamate forms the lateral boundary of the ulnar canal (Guyon’s canal). Fractures of the hook of the hamate (common in golfers or baseball players) can result in **ulnar nerve compression**, leading to sensory loss in the medial 1.5 fingers and motor weakness of intrinsic hand muscles [1]. * **Hypothenar Muscles:** Remember the mnemonic **"OAF"** for both thenar and hypothenar groups (Opponens, Abductor, Flexor). For the hypothenar group, both the Opponens and Flexor digiti minimi attach to the hook of the hamate.

Q: A patient attempts to make a fist, but the index and middle fingers remain partially extended. Which nerve is most likely involved?

Median nerve. The clinical presentation described is known as the **"Hand of Benediction"** (or Preacher’s Hand). This occurs due to a high lesion of the **Median nerve** (typically at the elbow or supracondylar region). [1] **1. Why the Median Nerve is Correct:** To make a fist, one must flex the Interphalangeal (IP) and Metacarpophalangeal (MCP) joints. The Median nerve innervates the **Flexor Digitorum Superficialis (FDS)** and the radial half of the **Flexor Digitorum Profundus (FDP)**. [1] When the Median nerve is damaged, the patient cannot flex the index and middle fingers at the IP joints. Consequently, when asked to make a fist, these two fingers remain extended, while the ring and little fingers flex normally (as their portion of the FDP is supplied by the Ulnar nerve). [1] **2. Why Other Options are Incorrect:** * **Musculocutaneous nerve:** Supplies the coracobrachialis, biceps brachii, and brachialis. Injury results in loss of forearm flexion and supination, not finger extension issues. * **Radial nerve:** Supplies the extensors. Injury typically leads to **Wrist Drop**. If the radial nerve were injured, the patient would have trouble extending fingers, not flexing them. * **Ulnar nerve:** Injury causes **Ulnar Claw Hand** (seen at rest). While it affects the ring and little fingers, it does not prevent the index and middle fingers from flexing. [1] **Clinical Pearls for NEET-PG:** * **Hand of Benediction:** Seen only when the patient **attempts to make a fist** (Active sign). * **Ulnar Claw Hand:** Seen when the hand is **at rest** (Passive sign). * **Point to remember:** The "Pointing Index" (Ochsner’s Clasping Test) is also a diagnostic sign for Median nerve palsy. * **Million Dollar Nerve:** The recurrent branch of the Median nerve (supplies thenar muscles); injury leads to "Ape Thumb" deformity.

Q: The little finger of the hand corresponds to which of the following dermatomes?

C8. **Explanation:** The sensory innervation of the upper limb is organized segmentally according to the spinal cord levels. The dermatomes of the hand follow a specific radial-to-ulnar sequence that is high-yield for clinical examinations. **Why C8 is Correct:** The **C8 dermatome** provides sensory innervation to the medial (ulnar) side of the hand, specifically including the **little finger** and the medial half of the ring finger. This corresponds to the distribution of the ulnar nerve, though it is important to distinguish that a dermatome refers to the spinal nerve root level, while a peripheral nerve may carry fibers from multiple roots [1]. **Analysis of Incorrect Options:** * **A. C6:** Supplies the lateral aspect of the forearm and the **thumb** (radial side). A common mnemonic is making a "6" shape with your thumb and index finger. * **B. C7:** Supplies the **middle finger** and the center of the palm/back of the hand. * **D. T1:** Supplies the **medial aspect of the forearm** and the upper arm, proximal to the wrist. It does not typically extend into the fingers. **Clinical Pearls for NEET-PG:** * **The "Hand Rule":** C6 = Thumb; C7 = Middle finger; C8 = Little finger. * **C5:** Supplies the lateral aspect of the upper arm (over the deltoid). * **Klumpke’s Palsy:** Injury to the C8-T1 nerve roots often presents with sensory loss along the ulnar border of the hand (C8) and medial forearm (T1), along with a "claw hand" deformity. * **Testing Point:** The most distal point for testing the C8 dermatome is the dorsal surface of the proximal phalanx of the little finger.

Q: Which of the following structures passes through the triangular interval of the arm?

Radial nerve. The **triangular interval** (also known as the lower triangular space) is a critical anatomical gateway located in the posterior region of the arm. ### **Anatomical Basis** The boundaries of the triangular interval are: * **Superior:** Lower border of the Teres major muscle. * **Medial:** Long head of the Triceps brachii. * **Lateral:** Lateral head of the Triceps or the shaft of the humerus. The **Radial nerve** and the **Profunda brachii artery** pass through this space to reach the spiral groove of the humerus. Therefore, Option A is correct. ### **Analysis of Incorrect Options** * **B. Axillary nerve:** This nerve passes through the **quadrangular space** (along with the posterior circumflex humeral artery), which is located superior to the triangular interval. * **C. Median nerve:** This nerve travels in the anterior compartment of the arm within the medial bicipital groove; it does not pass through any posterior scapular spaces. * **D. Ulnar nerve:** Initially located in the anterior compartment, it pierces the medial intermuscular septum to enter the posterior compartment but does not traverse the triangular interval. ### **High-Yield Clinical Pearls for NEET-PG** * **Radial Nerve Injury:** Because the radial nerve lies directly against the humerus after exiting the triangular interval, it is highly susceptible to injury in **mid-shaft fractures of the humerus**, leading to "wrist drop." * **Space Differentiation:** * *Quadrangular Space:* Axillary nerve. * *Upper Triangular Space:* Circumflex scapular artery. * *Lower Triangular Space (Interval):* Radial nerve. * **Mnemonic:** Remember **"T-R-P"** for the Triangular Interval: **T**riceps, **R**adial nerve, **P**rofunda brachii.

Q: Boundaries of the anatomical snuff box are all except?

Extensor carpi ulnaris (ECU). The **Anatomical Snuffbox** is a triangular depression located on the radial (lateral) aspect of the dorsum of the hand at the level of the carpal bones [1]. ### **Explanation of the Correct Answer** **D. Extensor carpi ulnaris (ECU):** This is the correct answer because the ECU is located on the **medial (ulnar) side** of the forearm and wrist [1]. It inserts into the base of the 5th metacarpal and does not contribute to the boundaries of the snuffbox, which is strictly a lateral (radial) structure. ### **Why the Other Options are Incorrect** The boundaries of the snuffbox are formed by three specific tendons of the thumb: * **Anterior (Lateral) Boundary:** Formed by the tendons of the **Abductor pollicis longus (APL)** and **Extensor pollicis brevis (EPB)** [1]. These two tendons travel together in the first dorsal compartment of the wrist. * **Posterior (Medial) Boundary:** Formed by the tendon of the **Extensor pollicis longus (EPL)** [1]. This tendon hooks around Lister’s tubercle on the radius before reaching the thumb. ### **High-Yield Clinical Pearls for NEET-PG** * **Floor:** Formed by the **Scaphoid** and **Trapezium** bones [1]. Tenderness in the snuffbox is the classic clinical sign of a **Scaphoid fracture**. * **Contents:** The **Radial Artery** passes through the floor of the snuffbox. The **Cephalic vein** and the superficial branch of the **Radial nerve** lie in the roof (skin/fascia). * **Mnemonic:** To remember the lateral boundary, think **"Brevis Sandwich"**—the EPB is between the APL (lateral) and the EPL (medial).

Q: A patient presents with loss of sensation in the lateral three and a half fingers. Which of the following will be an additional finding in this patient?

Opponens paralysis. ### Explanation **1. Understanding the Core Concept** The patient presents with loss of sensation in the **lateral three and a half fingers**, which is the classic sensory distribution of the **Median Nerve** [1]. This indicates a lesion of the median nerve, most likely at the level of the wrist (e.g., Carpal Tunnel Syndrome). **2. Why "Opponens paralysis" is correct** The median nerve enters the hand and gives off a **recurrent branch** (the "million-dollar nerve") which supplies the **Thenar muscles**: * **A**bductor pollicis brevis * **F**lexor pollicis brevis (superficial head) * **O**pponens pollicis Paralysis of the **Opponens pollicis** leads to the inability to oppose the thumb to the other fingertips, a hallmark sign of median nerve injury at the wrist. **3. Why other options are incorrect** * **Loss of sensation on hypothenar eminence:** This area is supplied by the **Ulnar nerve**. Median nerve injury affects the thenar eminence and the radial palm [1]. * **Atrophy of adductor pollicis:** The Adductor pollicis is the only thenar-region muscle supplied by the **Deep branch of the Ulnar nerve**. In median nerve palsy, this muscle remains intact (often leading to "Froment’s sign" if the ulnar nerve were the one injured instead). **4. Clinical Pearls for NEET-PG** * **Ape Thumb Deformity:** Caused by median nerve injury at the wrist, resulting in thenar atrophy and the thumb falling into the same plane as the fingers. * **Hand of Benediction:** Seen when the patient attempts to make a fist in a **high** median nerve lesion (at or above the elbow). * **LOAF Muscles:** A mnemonic for muscles supplied by the Median nerve in the hand: **L**aterals two lumbricals, **O**pponens pollicis, **A**bductor pollicis brevis, **F**lexor pollicis brevis.

Q: The superficial palmar arch is related to which anatomical landmark?

The distal end of the fully extended thumb. The superficial palmar arch is a critical arterial network in the hand, primarily formed by the terminal part of the ulnar artery, usually completed by the superficial palmar branch of the radial artery. [1] **1. Why Option A is Correct:** In surface anatomy, the convexity of the superficial palmar arch lies at the level of a transverse line drawn across the palm from the distal border of the fully extended thumb. This landmark is essential for surgeons to avoid accidental injury to the arch during palmar incisions. **2. Why the Other Options are Incorrect:** * **Options B & C:** The "flexed thumb" positions move the thumb's tip toward the center or base of the palm. These landmarks are inconsistent and do not align with the anatomical projection of the arch. * **Option D:** The proximal end (base) of the extended thumb corresponds more closely to the **deep palmar arch**, which lies approximately one finger-breadth (1–1.5 cm) proximal to the superficial arch. **3. High-Yield NEET-PG Clinical Pearls:** * **Formation:** The superficial arch is mainly ulnar; the deep arch is mainly radial. * **Location:** The superficial arch lies deep to the palmar aponeurosis but **superficial** to the long flexor tendons. * **Deep Palmar Arch Landmark:** It lies at the level of the proximal border of the extended thumb (or the bases of the metacarpal bones). * **Allen’s Test:** Used clinically to assess the patency of the radial and ulnar arteries before performing arterial blood gas (ABG) sampling, ensuring the palmar arches are intact. * **Nerve Relation:** The superficial arch is closely related to the common palmar digital branches of the **median nerve**. [1]

Q: What is the primary action of the highlighted muscle?

Protraction of the scapula forward around the thorax. ***Protraction of the scapula forward around the thorax*** - The highlighted muscle is the **serratus anterior**, which originates from the first 8-9 ribs and inserts on the medial border of the scapula. - Its primary function is **scapular protraction** (pulling the scapula forward around the thorax) and is innervated by the **long thoracic nerve**. *Supination of the forearm and flexion of the elbow* - This describes the action of the **biceps brachii** muscle, which acts on the forearm and elbow joint. - The serratus anterior has no involvement in **forearm supination** or **elbow flexion** as it acts specifically on the scapula. *Flexion and adduction of the shoulder joint* - These actions are primarily performed by muscles like the **pectoralis major** and **anterior deltoid**. - The serratus anterior does not directly act on the **glenohumeral joint** but rather stabilizes and moves the scapula. *None of the above* - This option is incorrect as the serratus anterior does indeed perform **scapular protraction**. - The muscle is also known as the **"boxer's muscle"** due to its role in pushing movements and scapular stabilization.

Q: Which nerve is injured in a fracture of the medial epicondyle of the humerus?

Ulnar nerve. **Explanation:** The **ulnar nerve** is the correct answer because of its specific anatomical course in the elbow. It descends along the medial side of the arm, pierces the medial intermuscular septum, and passes posteriorly through the **retrocondylar groove** (ulnar groove) located directly behind the **medial epicondyle** of the humerus. Due to this close proximity, any fracture or trauma involving the medial epicondyle frequently results in ulnar nerve compression or laceration. **Analysis of Incorrect Options:** * **Median Nerve:** This nerve passes anterior to the elbow joint, medial to the brachial artery. It is most commonly injured in **supracondylar fractures** of the humerus, not medial epicondyle fractures. * **Anterior Interosseous Nerve (AIN):** A motor branch of the median nerve, the AIN is typically injured in supracondylar fractures (Gartland Type II/III). Injury results in the inability to make the "OK" sign. * **Radial Nerve:** This nerve runs in the spiral groove of the humerus and passes anterior to the **lateral epicondyle**. It is most commonly injured in **mid-shaft humeral fractures**. **Clinical Pearls for NEET-PG:** * **Ulnar Nerve (C8-T1):** Injury at the medial epicondyle leads to "Claw Hand" (main en griffe) due to paralysis of the medial half of the flexor digitorum profundus and intrinsic hand muscles. * **Tardy Ulnar Palsy:** A delayed ulnar nerve palsy that occurs years after a lateral condyle fracture due to resultant cubitus valgus deformity. * **High-Yield Sites:** * Mid-shaft fracture → Radial nerve. * Surgical neck fracture → Axillary nerve. * Supracondylar fracture → Median nerve.

Question 1

Which muscle of the hand contains a sesamoid bone?

Accepted Answer

Adductor pollicis

Answer

Flexor pollicis brevis

Answer

Flexor pollicis longus

Answer

Opponens pollicis

Question 2

Which flexor muscle attaches to the hook of the hamate?

Accepted Answer

Flexor digiti minimi

Answer

Flexor pollicis brevis

Answer

Flexor pollicis longus

Answer

Flexor carpi ulnaris

Question 3

A patient attempts to make a fist, but the index and middle fingers remain partially extended. Which nerve is most likely involved?

Accepted Answer

Median nerve

Answer

Musculocutaneous nerve

Answer

Radial nerve

Answer

Ulnar nerve

Question 4

The little finger of the hand corresponds to which of the following dermatomes?

Accepted Answer

C8

Answer

C6

Answer

C7

Answer

T1

Question 5

Which of the following structures passes through the triangular interval of the arm?

Accepted Answer

Radial nerve

Answer

Axillary nerve

Answer

Median nerve

Answer

Ulnar nerve

Question 6

Boundaries of the anatomical snuff box are all except?

Accepted Answer

Extensor carpi ulnaris (ECU)

Answer

Abductor pollicis longus (APL)

Answer

Extensor pollicis longus (EPL)

Answer

Extensor pollicis brevis (EPB)

Question 7

A patient presents with loss of sensation in the lateral three and a half fingers. Which of the following will be an additional finding in this patient?

Accepted Answer

Opponens paralysis

Answer

Loss of sensation on hypothenar eminence

Answer

Atrophy of adductor pollicis

Answer

None of the above

Question 8

The superficial palmar arch is related to which anatomical landmark?

Accepted Answer

The distal end of the fully extended thumb

Answer

The distal end of the fully flexed thumb

Answer

The proximal end of the fully flexed thumb

Answer

The proximal end of the fully extended thumb

Question 9

What is the primary action of the highlighted muscle?

Accepted Answer

Protraction of the scapula forward around the thorax

Answer

Supination of the forearm and flexion of the elbow

Answer

Flexion and adduction of the shoulder joint

Answer

None of the above

Question 10

Which nerve is injured in a fracture of the medial epicondyle of the humerus?

Accepted Answer

Ulnar nerve

Answer

Anterior interosseous nerve

Answer

Median nerve

Answer

Radial nerve

Upper Limb — MCQs

Upper Limb — MCQs

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