Upper Limb Practice Questions

Q: A 32-year-old woman presents with multiple humerus fractures following an automobile collision. She exhibits severely weakened forearm flexion and supination, along with loss of sensation on the lateral forearm. Which nerve is most likely injured?

Musculocutaneous. ### Explanation The clinical presentation points to an injury of the **Musculocutaneous nerve (C5–C7)**. **1. Why Musculocutaneous is Correct:** The musculocutaneous nerve originates from the lateral cord of the brachial plexus. It supplies the muscles of the anterior compartment of the arm: **Coracobrachialis, Biceps Brachii, and Brachialis**. * **Motor Loss:** Paralysis of the Biceps brachii and Brachialis leads to severely weakened **forearm flexion**. Since the Biceps is the most powerful supinator of the flexed forearm, **supination** is also significantly impaired. * **Sensory Loss:** After passing through the arm, the nerve continues as the **Lateral Cutaneous Nerve of the Forearm**, supplying sensation to the lateral aspect of the forearm. **2. Why Other Options are Incorrect:** * **Radial Nerve:** Injury (commonly in the spiral groove) would cause "Wrist Drop" due to loss of extensors and sensory loss on the posterior arm/forearm and dorsal web space [1]. * **Median Nerve:** Injury would affect forearm pronation, wrist flexion, and thumb opposition (Ape thumb deformity), with sensory loss on the palmar aspect of the lateral 3.5 digits [2]. * **Lateral Cord:** While the musculocutaneous nerve arises from the lateral cord, a cord-level injury would also involve the lateral root of the **Median nerve**, leading to additional deficits in the hand and forearm that are not described here. **3. High-Yield Clinical Pearls for NEET-PG:** * **Nerve Course:** It pierces the **Coracobrachialis** muscle (a classic identification point in anatomy). * **Reflex:** It is the afferent and efferent limb for the **Biceps Reflex (C5-C6)**. * **Fracture Association:** While Radial nerve injury is most common with mid-shaft humerus fractures [1], Musculocutaneous injury can occur in severe proximal trauma or heavy compression.

Q: Which nerve supplies the serratus anterior muscle?

Long thoracic nerve. The **Long thoracic nerve** (also known as the Nerve of Bell) is the correct answer. It arises from the ventral rami of the **C5, C6, and C7** nerve roots. It descends posterior to the brachial plexus and the first part of the axillary artery, running along the lateral surface of the serratus anterior muscle, which it supplies. The serratus anterior is crucial for protracting the scapula and rotating it upwards to allow for overhead abduction of the arm. **Analysis of Incorrect Options:** * **A. Thoracodorsal nerve (C6-C8):** Supplies the **Latissimus dorsi** muscle [1]. It is a branch of the posterior cord of the brachial plexus. * **B. Axillary nerve (C5-C6):** Supplies the **Deltoid** and **Teres minor** muscles. It passes through the quadrangular space. * **C. Musculocutaneous nerve (C5-C7):** Supplies the muscles of the **anterior compartment of the arm** (Biceps brachii, Coracobrachialis, and Brachialis). **Clinical Pearls for NEET-PG:** 1. **Winging of Scapula:** Damage to the long thoracic nerve (often during axillary lymph node dissection or radical mastectomy) leads to paralysis of the serratus anterior. This causes the medial border of the scapula to become prominent ("winging") when the patient pushes against a wall. 2. **Vulnerability:** Because the nerve runs superficially on the external surface of the muscle, it is highly susceptible to trauma or surgical injury. 3. **Mnemonic:** *"C5, 6, 7 raise your arms to heaven"* (referring to the nerve roots and the muscle's role in overhead abduction).

Q: Which of the following muscles arises from the infraglenoid tubercle?

Long head of triceps. The scapula features two important tubercles related to the glenoid cavity that serve as origin points for the long heads of the arm muscles. The **infraglenoid tubercle**, located just below the glenoid labrum, provides the origin for the **long head of the triceps brachii**. This muscle then travels distally to insert on the olecranon process of the ulna, acting as a powerful extensor of the elbow and a weak adductor of the shoulder. **Analysis of Options:** * **Long head of biceps (A):** Arises from the **supraglenoid tubercle** of the scapula. It is intracapsular but extrasynovial as it traverses the shoulder joint. * **Short head of biceps (C):** Arises from the tip of the **coracoid process** of the scapula, sharing a common origin with the coracobrachialis. * **Coracobrachialis (D):** Also arises from the tip of the **coracoid process**. It is a key landmark in the axilla and is pierced by the musculocutaneous nerve. **High-Yield NEET-PG Pearls:** 1. **Mnemonic:** **S**upraglenoid = **B**iceps (SB), **I**nfraglenoid = **T**riceps (IT). Think "Sit" (S-I-T) to remember Superior/Biceps and Inferior/Triceps. 2. **Nerve Supply:** The triceps is supplied by the **radial nerve** (C6-C8). A mid-shaft humerus fracture (radial groove) may paralyze the medial and lateral heads, but the long head often remains functional as its nerve branch arises high in the axilla. 3. **Space Boundaries:** The long head of the triceps is a crucial boundary for the **quadrangular and triangular spaces** of the axilla, separating the axillary nerve and circumflex humeral vessels.

Q: A 21-year-old male with a fracture of the surgical neck of the humerus presents with a regimental badge sign and difficulty in abduction. What is the most likely nerve injury?

Axillary nerve injury. ### **Explanation** The correct answer is **Axillary nerve injury**. **1. Why Axillary Nerve Injury is Correct:** The axillary nerve (C5, C6) winds around the **surgical neck of the humerus** within the quadrangular space. Fractures at this site or anterior dislocations of the shoulder commonly result in its injury. * **Regimental Badge Sign:** The axillary nerve provides sensory innervation to the skin over the lower half of the deltoid muscle via the upper lateral cutaneous nerve of the arm. Loss of sensation in this specific area is known as the "Regimental Badge Sign." * **Difficulty in Abduction:** The nerve supplies the **deltoid** (the primary abductor of the arm after 15°) and the teres minor. Paralysis of the deltoid leads to significant weakness in abduction. **2. Why Other Options are Incorrect:** * **Ulnar Nerve Injury:** Typically occurs with fractures of the medial epicondyle of the humerus. It presents with "claw hand" and sensory loss in the medial 1.5 fingers, not abduction deficits. * **Klumpke's Paralysis:** This is a lower brachial plexus injury (C8-T1) usually caused by hyper-abduction of the arm. It results in a total claw hand and sensory loss along the ulnar aspect of the forearm and hand. * **Supraclavicular Nerve Injury:** These are cutaneous nerves from the cervical plexus (C3, C4) supplying the skin over the shoulder and clavicle. Injury would not cause motor weakness in abduction. **3. NEET-PG High-Yield Pearls:** * **Most common nerve injured in shoulder dislocation:** Axillary nerve. * **Most common nerve injured in mid-shaft humerus fracture:** Radial nerve (presents with wrist drop). * **Deltoid Atrophy:** Chronic axillary nerve palsy leads to the loss of the rounded contour of the shoulder, making it appear "flat." * **Abduction sequence:** 0–15° (Supraspinatus), 15–90° (Deltoid), >90° (Serratus anterior and Trapezius).

Q: Which muscle performs flexion, adduction, and medial rotation of the arm?

Pectoralis major. **Explanation:** The **Pectoralis Major** is a large, fan-shaped muscle of the anterior chest wall. Its primary actions are determined by its insertion into the **lateral lip of the bicipital groove** of the humerus. Because it crosses the shoulder joint anteriorly and laterally, its contraction pulls the humerus toward the midline (**adduction**), rotates it inward (**medial rotation**), and the clavicular fibers specifically assist in drawing the arm forward (**flexion**). **Analysis of Options:** * **Pectoralis Major (Correct):** It is the "climbing muscle" (along with Latissimus dorsi). Its dual nerve supply (Medial and Lateral pectoral nerves) and broad origin allow it to perform the triad of flexion, adduction, and medial rotation [1]. * **Serratus Anterior:** Known as the "boxer’s muscle," it originates from the ribs and inserts into the medial border of the scapula. Its primary role is **protraction** of the scapula and keeping it closely applied to the thoracic wall; it does not act directly on the humerus to cause rotation or flexion. * **Pectoralis Minor:** This muscle lies deep to the pectoralis major and inserts into the **coracoid process** of the scapula [1]. It stabilizes the scapula by pulling it anteriorly and inferiorly; it does not move the arm. * **Subclavius:** A small muscle that anchors and depresses the clavicle. It plays no role in the movements of the humerus. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve Supply:** Pectoralis major is supplied by **both** medial (C8, T1) and lateral (C5-C7) pectoral nerves [1]. * **Surgical Significance:** It forms the anterior wall of the axilla. * **Testing:** To test the muscle, the patient is asked to press their hands against their hips or adduct the arm against resistance. * **Poland Syndrome:** A congenital condition characterized by the unilateral absence of the Pectoralis major, often associated with syndactyly.

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: 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: Several weeks after surgical dissection of her left axilla for the removal of lymph nodes for staging and treatment of her breast cancer, a 32-year-old woman presented with "winging" of her left scapula when pushed against resistance. She also reported difficulty raising her right arm above her head. A nerve was accidentally injured during the surgical procedure, causing the scapular abnormality and inability to raise her arm normally. What was the origin of this injured nerve?

Roots of the brachial plexus. **Explanation:** The clinical presentation of **"winging of the scapula"** following axillary surgery is a classic sign of injury to the **Long Thoracic Nerve**. This nerve innervates the **Serratus Anterior** muscle, which is responsible for protracting the scapula and holding its medial border against the thoracic wall. It also assists the Trapezius in rotating the scapula upward to allow for abduction of the arm above 90 degrees. **1. Why the Correct Answer is Right:** The Long Thoracic Nerve (Nerve of Bell) originates directly from the **Roots (ventral rami) of the brachial plexus**, specifically **C5, C6, and C7**. Because it arises so proximally and descends along the lateral thoracic wall, it is vulnerable during axillary lymph node dissection (ALND) or radical mastectomies [1]. **2. Why Incorrect Options are Wrong:** * **Option A (Upper Trunk):** The Suprascapular nerve and Nerve to Subclavius arise from the upper trunk, not the long thoracic nerve. * **Option B (Posterior Division):** Divisions of the plexus do not give off any branches; they merely redistribute fibers to the cords. * **Option D (Posterior Cord):** The posterior cord gives rise to the Axillary, Radial, Upper/Lower Subscapular, and Thoracodorsal nerves [1]. Injury to the Thoracodorsal nerve would cause weakness in extension and adduction (Latissimus dorsi), not winging. **Clinical Pearls for NEET-PG:** * **Mnemonic for Long Thoracic Nerve:** "C5, 6, 7 raise your arms to heaven." * **Winging Test:** Ask the patient to push against a wall; the medial border of the scapula becomes prominent (wings). * **Nerve at Risk:** During axillary surgery, two nerves are at high risk: the **Long Thoracic** (leading to winging) and the **Thoracodorsal** [1] (leading to "climbing" weakness/Latissimus dorsi palsy).

Q: Which ligament transfers weight from the peripheral to the axial skeleton?

Coracoclavicular ligament. **Explanation:** The **Coracoclavicular ligament** is the primary structure responsible for transferring the weight of the upper limb (peripheral skeleton) to the clavicle and subsequently to the axial skeleton. It consists of two parts: the **conoid** and **trapezoid** ligaments. While the upper limb is suspended from the scapula, the scapula itself is attached to the clavicle via this ligament. Therefore, the weight of the arm is transmitted from the scapula to the clavicle through the coracoclavicular ligament, and then to the sternum via the sternoclavicular joint. **Analysis of Incorrect Options:** * **Acromioclavicular ligament:** This ligament strengthens the capsule of the acromioclavicular joint but is relatively weak and does not play a major role in weight transmission. * **Ligament of Bigelow (Iliofemoral ligament):** This is a Y-shaped ligament of the hip joint. It is the strongest ligament in the body and prevents hyperextension of the hip, but it is located in the lower limb. * **Sternoclavicular ligament:** While the sternoclavicular joint is the only bony attachment of the upper limb to the axial skeleton, the *ligament* itself primarily stabilizes the joint rather than acting as the primary weight-transferring bridge from the limb. **High-Yield NEET-PG Pearls:** * The **Conoid** part is medially placed and fan-shaped; the **Trapezoid** part is laterally placed and quadrilateral. * In **Acromioclavicular joint dislocation** (Shoulder separation), the tearing of the coracoclavicular ligament is the clinical hallmark of a severe (Grade II/III) injury. * The clavicle is the first bone to ossify (intramembranous) and is the most commonly fractured bone in the body, typically at the junction of its medial 2/3 and lateral 1/3 [1].

Question 1

A 32-year-old woman presents with multiple humerus fractures following an automobile collision. She exhibits severely weakened forearm flexion and supination, along with loss of sensation on the lateral forearm. Which nerve is most likely injured?

Accepted Answer

Musculocutaneous

Answer

Radial

Answer

Median

Answer

Lateral cord of brachial plexus

Question 2

Which nerve supplies the serratus anterior muscle?

Accepted Answer

Long thoracic nerve

Answer

Thoracodorsal nerve

Answer

Axillary nerve

Answer

Musculocutaneous nerve

Question 3

Which of the following muscles arises from the infraglenoid tubercle?

Accepted Answer

Long head of triceps

Answer

Long head of biceps

Answer

Short head of biceps

Answer

Coracobrachialis

Question 4

A 21-year-old male with a fracture of the surgical neck of the humerus presents with a regimental badge sign and difficulty in abduction. What is the most likely nerve injury?

Accepted Answer

Axillary nerve injury

Answer

Ulnar nerve injury

Answer

Klumpke's paralysis

Answer

Supraclavicular nerve injury

Question 5

Which muscle performs flexion, adduction, and medial rotation of the arm?

Accepted Answer

Pectoralis major

Answer

Serratus Anterior

Answer

Pectoralis minor

Answer

Subclavius

Question 6

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 7

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 8

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

Accepted Answer

C8

Answer

C6

Answer

C7

Answer

T1

Question 9

Several weeks after surgical dissection of her left axilla for the removal of lymph nodes for staging and treatment of her breast cancer, a 32-year-old woman presented with "winging" of her left scapula when pushed against resistance. She also reported difficulty raising her right arm above her head. A nerve was accidentally injured during the surgical procedure, causing the scapular abnormality and inability to raise her arm normally. What was the origin of this injured nerve?

Accepted Answer

Roots of the brachial plexus

Answer

The upper trunk of the brachial plexus

Answer

The posterior division of the middle trunk

Answer

The posterior cord of the brachial plexus

Question 10

Which ligament transfers weight from the peripheral to the axial skeleton?

Accepted Answer

Coracoclavicular ligament

Answer

Acromioclavicular ligament

Answer

Ligament of Bigelow

Answer

Sternoclavicular ligament

Upper Limb — MCQs

Upper Limb — MCQs

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