Upper Limb Practice Questions

Q: Fracture of the surgical neck of the humerus leads to loss of abduction movement of the corresponding shoulder joint due to injury of which nerve?

Axillary nerve. ### Explanation **Correct Option: C. Axillary nerve** The **axillary nerve (C5, C6)**, a branch of the posterior cord of the brachial plexus, travels through the quadrangular space and winds around the **surgical neck of the humerus**. It supplies the **deltoid** and **teres minor** muscles. * **Mechanism:** A fracture at the surgical neck directly compresses or lacerates the axillary nerve. * **Functional Loss:** The deltoid is the primary abductor of the arm from 15° to 90°. Injury leads to paralysis of the deltoid, resulting in the loss of abduction and characteristic flattening of the shoulder contour. **Analysis of Incorrect Options:** * **A. Radial nerve:** This nerve runs in the **radial (spiral) groove** at the mid-shaft of the humerus. Injury here leads to "wrist drop" due to paralysis of the extensors of the wrist and fingers. * **B. Musculocutaneous nerve:** This nerve pierces the coracobrachialis and supplies the anterior compartment of the arm (Biceps, Brachialis). It is rarely injured in humeral fractures but would affect elbow flexion if damaged. * **D. Median nerve:** This nerve travels medially and is most commonly injured in **supracondylar fractures** of the humerus, leading to the "Ape thumb" deformity or "Hand of Benediction." **High-Yield Clinical Pearls for NEET-PG:** * **Sensory Loss:** Axillary nerve injury also causes loss of sensation over the lower half of the deltoid, known as the **"Regimental Badge Area."** * **Humerus Fracture Sites & Nerve Injuries:** 1. Surgical Neck → **Axillary Nerve** 2. Mid-shaft (Spiral groove) → **Radial Nerve** 3. Supracondylar → **Median Nerve** 4. Medial Epicondyle → **Ulnar Nerve** * **Abduction Sequence:** 0–15° (Supraspinatus), 15–90° (Deltoid), >90° (Serratus anterior & Trapezius).

Q: Intramuscular injections are typically administered in which part of the deltoid muscle?

The middle part of the deltoid muscle. **Explanation:** The deltoid muscle is a common site for intramuscular (IM) injections, particularly for vaccines. The **middle (central) part** of the muscle is the preferred site because it offers the greatest muscle mass and provides the safest distance from vital neurovascular structures. **Why the middle part is correct:** The target zone is the thickest portion of the deltoid, located approximately 2–3 fingerbreadths (3–5 cm) below the **acromion process**. Injecting here ensures the medication is deposited into well-vascularized muscle tissue, facilitating optimal absorption while avoiding bone and nerve injury. **Why other options are incorrect:** * **Upper part:** Injecting too high (near the acromion) risks hitting the subacromial bursa or the shoulder joint capsule, leading to "Shoulder Injury Related to Vaccine Administration" (SIRVA) or chronic bursitis. * **Lower part:** The lower third of the deltoid is thin and tapers toward its insertion on the humerus. Injecting here increases the risk of hitting the **radial nerve** as it winds around the spiral groove or the deep brachial artery. * **Anywhere:** This is incorrect due to the specific anatomical hazards mentioned above. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve at Risk:** The **Axillary Nerve** (C5-C6) runs horizontally across the deep surface of the deltoid, roughly 5 cm below the acromion. Injections must be placed below the acromion but above this nerve level. * **Anatomical Landmark:** Always palpate the lower edge of the acromion process to define the upper boundary of the "safe triangle." * **Muscle Action:** The multipennate middle fibers of the deltoid are the primary abductors of the arm (from 15° to 90°).

Q: An 11-year-old boy falls down the stairs. A physician examines a radiograph of the boy's shoulder region. If the structure indicated by the letter A is calcified, which of the following muscles is most likely paralyzed?

Infraspinatus. ***Infraspinatus*** - Structure A represents the **suprascapular ligament** at the **suprascapular notch**, and its calcification compresses the **suprascapular nerve**. - The **suprascapular nerve** specifically innervates the **infraspinatus muscle** (along with supraspinatus), making it the only option affected by this compression. *Deltoid* - Innervated by the **axillary nerve** (C5-C6), which passes through the **quadrangular space** below the shoulder joint. - Calcification of the **suprascapular ligament** does not affect the **axillary nerve** pathway or the deltoid muscle function. *Teres major* - Supplied by the **lower subscapular nerve** (C6-C7), a branch of the **posterior cord** of the brachial plexus. - The **suprascapular nerve** compression has no impact on the **subscapular nerves** or teres major function. *Teres minor* - Innervated by the **axillary nerve** (C5-C6), similar to the deltoid muscle. - Calcification at the **suprascapular notch** does not involve the **quadrangular space** where the axillary nerve travels.

Q: What is the action of the anterior fibers of the deltoid muscle?

Flexion and medial rotation. The deltoid is a multipennate muscle with three distinct functional sets of fibers. Understanding its action requires looking at the orientation of these fibers relative to the glenohumeral joint axis. **Explanation of the Correct Answer (C):** The **anterior (clavicular) fibers** originate from the lateral third of the clavicle. Because they pass anterior to the center of the humeral head, their contraction pulls the humerus forward and rotates it inward. Therefore, the primary actions of the anterior fibers are **flexion and medial rotation** of the arm at the shoulder. **Analysis of Incorrect Options:** * **A. Flexion:** While correct, it is incomplete. The anterior fibers are also powerful medial rotators. * **B. Lateral rotation:** This is incorrect for the anterior fibers. Lateral rotation is performed by the **posterior fibers** and the infraspinatus/teres minor. * **D. Extension and lateral rotation:** These are the primary actions of the **posterior (spinous) fibers** of the deltoid, which originate from the spine of the scapula and pass behind the joint axis. **NEET-PG High-Yield Pearls:** * **The Multipennate Nature:** The **middle (acromial) fibers** are multipennate, making them the strongest part of the muscle, responsible for **abduction** from 15° to 90°. * **Axillary Nerve (C5, C6):** The deltoid is supplied by the axillary nerve. Damage (e.g., surgical neck fracture or shoulder dislocation) leads to loss of shoulder contour ("square shoulder") and inability to abduct the arm. * **Intramuscular Injections:** Usually given in the middle of the deltoid to avoid the axillary nerve, which winds around the surgical neck of the humerus.

Q: A 27-year-old patient presents with an inability to draw the scapula forward and downward because of paralysis of the pectoralis minor. Which of the following would most likely be a cause of his condition?

Fracture of the coracoid process. Explanation: The **Pectoralis minor** muscle originates from the 3rd, 4th, and 5th ribs and inserts into the **medial border and upper surface of the coracoid process** of the scapula. Its primary actions include pulling the scapula forward (protraction) and downward (depression). A fracture of the coracoid process can lead to an avulsion or functional loss of the pectoralis minor insertion, resulting in the inability to perform these specific movements. **Analysis of Options:** * **Fracture of the coracoid process (Correct):** As the site of insertion for the pectoralis minor, any structural disruption here directly affects the muscle's ability to act on the scapula. * **Fracture of the clavicle:** The pectoralis minor has no attachment to the clavicle. While a clavicular fracture might affect the pectoralis major or subclavius, it would not cause isolated paralysis of the pectoralis minor. * **Injury to the posterior cord:** The pectoralis minor is supplied by the **medial pectoral nerve** (C8, T1), which arises from the **medial cord** of the brachial plexus. The posterior cord gives rise to nerves like the axillary and radial nerves. * **Axillary nerve injury:** This nerve supplies the deltoid and teres minor muscles. Injury would result in loss of shoulder abduction and sensation over the "regimental badge" area, not pectoralis minor dysfunction. **NEET-PG High-Yield Pearls:** * **Coracoid Process Attachments:** Remember the mnemonic **"Short Head of Biceps, Coracobrachialis, and Pectoralis Minor"** (The "Triple C" or "B-C-P" attachments). * **Nerve Supply:** The **Medial Pectoral Nerve** pierces the pectoralis minor to reach the pectoralis major, supplying both. The **Lateral Pectoral Nerve** supplies only the pectoralis major. * **Clinical Significance:** The pectoralis minor serves as a key anatomical landmark, dividing the **axillary artery** into three parts.

Q: Which of the following statements about the supraspinatus is FALSE?

Abducts the arm to the horizontal level.. **Explanation:** The **supraspinatus** is a critical muscle of the rotator cuff, but its primary role in abduction is limited to the **initial 0–15 degrees**. **Why Option C is FALSE:** While the supraspinatus initiates abduction, the **deltoid** muscle is the primary abductor responsible for taking the arm from 15 degrees up to the horizontal level (90 degrees). Beyond 90 degrees, the serratus anterior and trapezius facilitate upward rotation of the scapula to achieve full overhead abduction. Therefore, stating that the supraspinatus abducts the arm to the horizontal level is anatomically incorrect. **Analysis of Other Options:** * **Option A:** Despite being part of the "rotator" cuff, the supraspinatus is the only member that **does not rotate** the humerus; its vector is purely for initiation of abduction and stabilization of the humeral head. * **Option B:** The muscle belly and tendon lie in the supraspinatus fossa and pass **deep to the coracoacromial arch** (formed by the coracoid process, acromion, and coracoacromial ligament). * **Option D:** Due to its position between the humeral head and the acromion, it is the **most common muscle injured** in rotator cuff tears and impingement syndrome. **High-Yield NEET-PG Pearls:** * **Nerve Supply:** Suprascapular nerve (C5, C6). * **Painful Arc Syndrome:** Pain during abduction between **60°–120°** usually indicates supraspinatus tendinitis or subacromial bursitis. * **Empty Can Test (Jobe’s Test):** Used clinically to assess supraspinatus integrity. * **Blood Supply:** Suprascapular and posterior circumflex humeral arteries.

Q: The cords of the brachial plexus are named relative to the axillary artery. Which muscle lies behind the axillary artery in relation to these cords?

Pectoralis minor. The **Pectoralis minor** muscle is the key anatomical landmark used to divide the axillary artery into three parts [1]. More importantly, it defines the position and naming of the **cords of the brachial plexus**: 1. **First part** (proximal to muscle): Cords are not yet formed (divisions are present). 2. **Second part** (behind the muscle): The cords are named **Lateral, Medial, and Posterior** based on their specific orientation to the axillary artery at this exact location [1]. 3. **Third part** (distal to muscle): The cords begin to branch into terminal nerves. Therefore, the Pectoralis minor is the muscle that physically overlies the second part of the axillary artery and the surrounding cords [1]. **Analysis of Incorrect Options:** * **Deltoid (A):** A superficial muscle of the shoulder; it does not serve as a landmark for the divisions of the axillary artery or the cords. * **Subclavius (B):** Located superiorly, it protects the neurovascular bundle as it passes under the clavicle but does not define the relationship of the cords to the artery. * **Teres major (C):** Marks the **inferior boundary** where the axillary artery becomes the brachial artery. It lies distal to the cords. **High-Yield NEET-PG Pearls:** * **The "Rule of 3s":** Pectoralis minor divides the axillary artery into **3 parts**; the 1st part has **1 branch**, the 2nd part has **2 branches**, and the 3rd part has **3 branches**. * **Clavipectoral Fascia:** Pierced by four structures: Lateral pectoral nerve, Thoraco-acromial artery, Cephalic vein, and Lymphatics. * **Safe Zone:** For axillary nerve blocks, the relationship of the cords to the artery behind the Pectoralis minor is crucial for successful anesthesia.

Q: The anterior interosseous nerve is a branch of which of the following?

Median nerve. ### Explanation **Correct Answer: C. Median nerve** The **Anterior Interosseous Nerve (AIN)** is the largest branch of the **median nerve** in the forearm. It arises in the cubital fossa between the two heads of the pronator teres [1]. It descends on the anterior surface of the interosseous membrane alongside the anterior interosseous artery [1]. **Why it is correct:** The AIN is a purely motor nerve (with sensory fibers only for joint capsules). It supplies the **"Deep Group"** of muscles in the anterior compartment of the forearm: 1. **Flexor pollicis longus (FPL)** 2. **Pronator quadratus (PQ)** 3. **Lateral half of Flexor digitorum profundus (FDP)** (supplying the index and middle fingers). **Why incorrect options are wrong:** * **Options A & B (Radial Nerve):** The radial nerve and its deep branch (Posterior Interosseous Nerve) supply the **posterior (extensor)** compartment of the forearm. * **Option D (Ulnar Nerve):** The ulnar nerve supplies the Flexor Carpi Ulnaris and the medial half of the FDP [1]. It does not give off the AIN. --- ### High-Yield Clinical Pearls for NEET-PG * **AIN Syndrome (Kiloh-Nevin Syndrome):** This is an isolated palsy of the AIN (often due to compression). * **The "OK Sign" Test:** Patients with AIN palsy cannot flex the distal phalanges of the thumb and index finger. When asked to make an "OK" sign, they produce a **"pinch"** (flat finger-to-finger contact) instead of a circle, due to paralysis of the FPL and the lateral half of the FDP. * **Sensory Note:** Unlike the main median nerve, the AIN has **no cutaneous distribution**. It only provides sensory innervation to the wrist and distal radio-ulnar joints.

Q: A 41-year-old male presents with weakness of the flexor pollicis longus and flexor digitorum profundus of the index finger. Which nerve is most likely involved?

Median nerve. ### Explanation The clinical presentation describes a classic **Anterior Interosseous Nerve (AIN) Syndrome**. **1. Why the Median Nerve is Correct:** The **Anterior Interosseous Nerve** is a purely motor branch of the **Median Nerve**. It arises in the proximal forearm and supplies three deep muscles: [1] * **Flexor Pollicis Longus (FPL):** Responsible for flexion of the thumb IP joint. * **Flexor Digitorum Profundus (FDP) of the index and middle fingers:** Responsible for flexion of the DIP joints. * **Pronator Quadratus:** Responsible for forearm pronation. Weakness in the FPL and the radial half of the FDP directly points to an injury of the AIN or the parent Median nerve. [1] **2. Why the Other Options are Incorrect:** * **Ulnar Nerve:** Supplies the medial half (ring and small fingers) of the FDP and most intrinsic hand muscles. Ulnar nerve injury would cause "claw hand" and weakness in finger abduction/adduction. * **Posterior Interosseous Nerve (PIN):** This is a branch of the **Radial Nerve**. It supplies the extensors of the wrist and fingers. Injury leads to "finger drop" without sensory loss, not flexor weakness. * **Radial Nerve:** Injury typically occurs at the axilla or radial groove, leading to "wrist drop" and loss of extension at the MCP joints. **3. Clinical Pearls for NEET-PG:** * **The "OK" Sign Test:** Patients with AIN syndrome cannot make a circle with their thumb and index finger (pulp-to-pulp contact instead of tip-to-tip) due to FPL and FDP weakness. * **Sensory Note:** The AIN has **no cutaneous sensory distribution**. If the patient also has numbness in the lateral 3.5 fingers, the lesion is in the main Median nerve (e.g., Carpal Tunnel or Pronator Syndrome), not the isolated AIN. [1] * **Kiloh-Nevin Syndrome:** Another name for isolated Anterior Interosseous Nerve palsy.

Question 1

Fracture of the surgical neck of the humerus leads to loss of abduction movement of the corresponding shoulder joint due to injury of which nerve?

Accepted Answer

Axillary nerve

Answer

Radial nerve

Answer

Musculocutaneous nerve

Answer

Median nerve

Question 2

Intramuscular injections are typically administered in which part of the deltoid muscle?

Accepted Answer

The middle part of the deltoid muscle

Answer

Anywhere in the deltoid muscle

Answer

The upper part of the deltoid muscle

Answer

The lower part of the deltoid muscle

Question 3

An 11-year-old boy falls down the stairs. A physician examines a radiograph of the boy's shoulder region. If the structure indicated by the letter A is calcified, which of the following muscles is most likely paralyzed?

Accepted Answer

Infraspinatus

Answer

Deltoid

Answer

Teres major

Answer

Teres minor

Question 4

What is the action of the anterior fibers of the deltoid muscle?

Accepted Answer

Flexion and medial rotation

Answer

Flexion

Answer

Lateral rotation

Answer

Extension and lateral rotation

Question 5

A 27-year-old patient presents with an inability to draw the scapula forward and downward because of paralysis of the pectoralis minor. Which of the following would most likely be a cause of his condition?

Accepted Answer

Fracture of the coracoid process

Answer

Fracture of the clavicle

Answer

Injury to the posterior cord of the brachial plexus

Answer

Axillary nerve injury

Question 6

Which of the following statements about the supraspinatus is FALSE?

Accepted Answer

Abducts the arm to the horizontal level.

Answer

A rotator cuff muscle that does not rotate the humerus.

Answer

Located deep to the coracoacromial arch.

Answer

The most commonly involved muscle in rotator cuff injuries.

Question 7

The cords of the brachial plexus are named relative to the axillary artery. Which muscle lies behind the axillary artery in relation to these cords?

Accepted Answer

Pectoralis minor

Answer

Deltoid

Answer

Subclavius

Answer

Teres major

Question 8

The anterior interosseous nerve is a branch of which of the following?

Accepted Answer

Median nerve

Answer

Superficial branch of the radial nerve

Answer

Deep branch of the radial nerve

Answer

Ulnar nerve

Question 9

A 41-year-old male presents with weakness of the flexor pollicis longus and flexor digitorum profundus of the index finger. Which nerve is most likely involved?

Accepted Answer

Median nerve

Answer

Ulnar nerve

Answer

Posterior interosseous nerve

Answer

Radial nerve

Question 10

A patient presents with inability to extend the wrist following an accident. The patient reports no sensory loss. At what anatomical location is the affected nerve most likely injured?

Accepted Answer

Spiral groove of the humerus

Answer

Head of the radius

Answer

Near the medial epicondyle

Answer

Surgical neck of the humerus

Upper Limb — MCQs

Upper Limb — MCQs

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