Upper Limb Practice Questions

Q: Guyon's canal is associated with which of the following structures?

Ulnar nerve. **Explanation:** **Guyon’s Canal (Ulnar Canal)** is a fibro-osseous tunnel located on the medial side of the wrist. It serves as a conduit for the **ulnar nerve** and the **ulnar artery** as they pass from the forearm into the hand. * **Why Option B is Correct:** The canal is bounded medially by the pisiform bone and laterally by the hook of the hamate [1]. The roof is formed by the palmar carpal ligament and the palmaris brevis muscle. The ulnar nerve enters the canal and divides into superficial and deep branches within it. Compression here leads to **Guyon’s canal syndrome**. **Why the other options are incorrect:** * **A. Anterior Interosseous Nerve:** This is a branch of the median nerve that travels deep in the forearm (between the flexor digitorum profundus and flexor pollicis longus) and does not pass through the wrist. * **C. Median Nerve:** This nerve passes through the **carpal tunnel**, which lies lateral and deep to Guyon’s canal [1]. * **D. Radial Artery:** This artery passes through the **anatomical snuffbox** on the lateral (radial) aspect of the wrist to reach the dorsum of the hand [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Handlebar Palsy:** Common in long-distance cyclists due to direct pressure on Guyon’s canal, leading to sensory loss in the medial 1.5 fingers and weakness of intrinsic hand muscles. * **Zone of Compression:** Unlike carpal tunnel syndrome, Guyon’s canal syndrome often spares the palmar cutaneous branch (which arises proximal to the wrist), meaning sensation over the hypothenar eminence may remain intact. * **Contents:** Remember that both the **ulnar nerve** and **ulnar artery** are contents; the nerve is typically medial to the artery.

Q: All of the following muscles form the rotator cuff EXCEPT?

Deltoid. The **Rotator Cuff** (also known as the musculotendinous cuff) is a functional unit formed by the tendons of four specific muscles that blend with the fibrous capsule of the shoulder joint. Its primary role is to stabilize the humeral head within the glenoid cavity during movements. ### Why Deltoid is the Correct Answer: The **Deltoid (Option C)** is a large, superficial muscle that forms the rounded contour of the shoulder. While it is the primary abductor of the arm (beyond 15 degrees), it is **not** part of the rotator cuff. It does not insert into the joint capsule and acts as a "shunt muscle" rather than a stabilizer of the glenoid labrum. ### Explanation of Incorrect Options (Rotator Cuff Muscles): The rotator cuff is easily remembered by the mnemonic **SITS**: * **Supraspinatus (Option D):** Originates from the supraspinous fossa and inserts on the greater tubercle. It initiates the first 0–15° of abduction. * **Infraspinatus:** Originates from the infraspinous fossa and inserts on the greater tubercle. It is a lateral rotator. * **Teres minor (Option A):** Originates from the lateral border of the scapula and inserts on the greater tubercle. It also assists in lateral rotation. * **Subscapularis (Option B):** The only member that inserts on the **lesser tubercle**. It is a powerful medial rotator. ### High-Yield Clinical Pearls for NEET-PG: * **Most commonly injured muscle:** Supraspinatus (due to its location beneath the acromion process, making it prone to impingement). * **Nerve Supply:** Supraspinatus and Infraspinatus are supplied by the **Suprascapular nerve**; Teres minor by the **Axillary nerve**; Subscapularis by the **Upper and Lower Subscapular nerves**. * **The "Gatekeeper":** The rotator cuff is deficient **inferiorly**, which explains why anterior-inferior shoulder dislocations are the most common.

Q: Which muscle is primarily responsible for overhead abduction at the shoulder joint?

Serratus anterior. Abduction at the shoulder joint is a complex, coordinated movement involving multiple muscles acting at different stages. To achieve **overhead abduction** (above 90°), the scapula must rotate upward to reposition the glenoid cavity. **Why Serratus Anterior is correct:** The **Serratus anterior** (supplied by the Long Thoracic Nerve) is the primary muscle responsible for the **upward rotation of the scapula**. Along with the Trapezius, it rotates the scapula so that the glenoid fossa faces upwards, allowing the humerus to move beyond the horizontal plane (90° to 180°). Without this scapular rotation, the humerus would hit the acromion process, halting abduction. **Analysis of Incorrect Options:** * **Supraspinatus:** Responsible for the **initiation** of abduction (first 0–15°). It stabilizes the humeral head in the glenoid cavity. * **Deltoid:** The primary abductor from **15° to 90°**. While essential, it cannot lift the arm above the head without the synergistic upward rotation of the scapula. * **Pectoralis major:** This is primarily an **adductor** and medial rotator of the arm; it opposes abduction. **High-Yield Clinical Pearls for NEET-PG:** * **Winged Scapula:** Damage to the Long Thoracic Nerve (C5-C7) paralyzes the Serratus anterior, leading to an inability to perform overhead abduction and a protruding medial border of the scapula. * **Scapulohumeral Rhythm:** The ratio of glenohumeral movement to scapulothoracic movement is generally **2:1**. * **The

Q: Injury to the long thoracic nerve can be tested by asking the patient to perform which action?

Push against a wall. **Explanation:** The **long thoracic nerve (Nerve of Bell)** arises from the roots of the brachial plexus (**C5, C6, C7**) and supplies the **Serratus Anterior** muscle. The primary function of this muscle is to protract the scapula and keep its medial border firmly opposed to the thoracic wall. **Why Option A is Correct:** When a patient is asked to **push against a wall** with outstretched hands, the Serratus Anterior must contract to stabilize the scapula against the rib cage. If the long thoracic nerve is injured, the muscle fails, and the medial border of the scapula protrudes posteriorly. This clinical sign is known as **"Winging of the Scapula."** **Why Other Options are Incorrect:** * **Option B:** While the Serratus Anterior (along with the Trapezius) helps in rotating the scapula for abduction above 90°, "pushing against a wall" is the specific provocative test used to elicit winging. * **Option C:** Touching the opposite shoulder primarily involves the Pectoralis Major and Deltoid (adduction and internal rotation). * **Option D:** Lifting a heavy object primarily tests the Trapezius (elevation) and the muscles of the arm/forearm (biceps/brachialis). **NEET-PG High-Yield Pearls:** * **Mechanism of Injury:** The nerve is superficial; it is commonly injured during **mastectomy** (axillary lymph node dissection), chest tube insertion, or heavy carrying on the shoulder. * **Mnemonic for Roots:** "C5, 6, 7 raise your wings to heaven." * **Clinical Presentation:** Patients often complain of difficulty in overhead lifting or combing hair due to impaired upward rotation of the scapula.

Q: The coracohumeral ligament is a degenerated part of which muscle?

Pectoralis minor. The **coracohumeral ligament** is a broad, functional band that strengthens the upper part of the shoulder joint capsule. From an embryological and comparative anatomy perspective, it is considered the **degenerated (vestigial) tendon of the Pectoralis minor muscle**. In many lower mammals, the Pectoralis minor inserts directly into the humerus. However, in humans, the insertion has shifted proximally to the coracoid process. The distal portion of the original tendon has persisted as a ligamentous band stretching from the lateral border of the coracoid process to the greater tubercle of the humerus. **Analysis of Options:** * **Pectoralis minor (Correct):** Its ancestral insertion was the humerus; the coracohumeral ligament represents the remnant of this primitive insertion. * **Biceps brachii:** The long head is intracapsular but extrasynovial; it does not form this ligament. * **Coracobrachialis:** This muscle shares the coracoid origin but remains a distinct muscular entity inserting into the humeral shaft. * **Latissimus dorsi:** This muscle inserts into the floor of the bicipital groove and is unrelated to the superior joint capsule. **High-Yield NEET-PG Pearls:** * **Function:** The coracohumeral ligament is the primary restraint against **inferior subluxation** of the humeral head when the arm is adducted (at rest). * **Morphology:** It blends with the tendon of the supraspinatus and the capsule of the shoulder joint. * **Clinical Correlation:** Thickening and contracture of this ligament are key pathological findings in **Adhesive Capsulitis (Frozen Shoulder)**, significantly restricting external rotation.

Q: A patient who sustained an injury cannot abduct their right arm and cannot lift it. Examination reveals tenderness near the right upper arm, and an X-ray shows a fracture of the surgical neck of the humerus. Which muscle was paralyzed?

Supraspinatus. ### Explanation **1. Why Supraspinatus is the Correct Answer:** The patient presents with an inability to **abduct** the arm. Abduction of the shoulder is a coordinated movement involving specific muscles at different ranges: * **0–15°:** Initiated by the **Supraspinatus** (Suprascapular nerve). * **15–90°:** Performed by the **Deltoid** (Axillary nerve). * **>90°:** Performed by the Serratus Anterior and Trapezius (scapular rotation). In a fracture of the **surgical neck of the humerus**, the **Axillary nerve** is the most commonly injured structure. While the Deltoid is paralyzed in such cases, the question specifies the patient "cannot abduct" at all. If the Supraspinatus is also compromised (often due to associated rotator cuff tears or secondary inhibition from pain/trauma at the insertion site), the initiation of abduction is lost. Among the options provided, the Supraspinatus is the only muscle listed that is a primary abductor. **2. Analysis of Incorrect Options:** * **A. Subscapularis:** Responsible for **internal rotation** and adduction. * **C. Infraspinatus:** Responsible for **external rotation**. * **D. Teres major:** Responsible for **adduction** and internal rotation ("The little helper of Latissimus dorsi"). **3. NEET-PG High-Yield Clinical Pearls:** * **Nerve at Risk:** Surgical neck fracture = **Axillary Nerve** (supplies Deltoid and Teres Minor). * **Mid-shaft fracture:** Radial Nerve (results in Wrist Drop) [1]. * **Supracondylar fracture:** Median Nerve. * **Medial Epicondyle fracture:** Ulnar Nerve. * **Rotator Cuff (SITS):** Supraspinatus (Abduction), Infraspinatus (External rotation), Teres minor (External rotation), Subscapularis (Internal rotation). The Supraspinatus is the most commonly injured muscle in rotator cuff tears.

Q: All of the following nerves arise from the posterior cord of the brachial plexus, EXCEPT?

Musculocutaneous nerve. The Brachial Plexus is a high-yield topic for NEET-PG. To answer this question, one must recall the specific branches arising from the cords. ### **Explanation** The **Musculocutaneous nerve** is the correct answer because it arises from the **Lateral Cord** (C5, C6, C7), not the posterior cord. It pierces the coracobrachialis muscle and supplies the muscles of the anterior compartment of the arm. The **Posterior Cord** (formed by the posterior divisions of all three trunks) gives off five branches, easily remembered by the mnemonic **ULTRA**: 1. **U**pper subscapular nerve (C5, C6) 2. **L**ower subscapular nerve (C5, C6) 3. **T**horacodorsal nerve (Nerve to Latissimus Dorsi) (C6, C7, C8) [1] 4. **R**adial nerve (C5–T1) – The largest branch. 5. **A**xillary nerve (C5, C6) ### **Analysis of Incorrect Options** * **Option A & B (Upper & Lower Subscapular nerves):** These are direct branches of the posterior cord. They supply the subscapularis muscle (Lower also supplies Teres major). * **Option C (Thoracodorsal nerve):** This is a branch of the posterior cord that supplies the Latissimus dorsi ("Climber’s muscle") [1]. ### **High-Yield Clinical Pearls for NEET-PG** * **Erb’s Palsy:** Involves the "Upper Trunk" (C5-C6), leading to a "Waiter’s tip" deformity. * **Klumpke’s Palsy:** Involves the "Lower Trunk" (C8-T1), leading to a "Claw hand." * **Winged Scapula:** Caused by injury to the **Long Thoracic Nerve** (arises from Roots C5, C6, C7), not the cords. * **Radial Nerve:** The most common nerve injured in mid-shaft humerus fractures (Spiral groove).

Q: Which of the following groups of axillary lymph nodes is considered a terminal group?

Apical. The axillary lymph nodes are organized into five main groups based on their anatomical location within the axilla. Understanding the flow of lymph is crucial for NEET-PG, as it follows a hierarchical pattern from peripheral to central groups. **Why Apical is Correct:** The **Apical (Subclavicular) group** is considered the **terminal group** because it represents the final common pathway for all lymph draining from the upper limb and the breast. These nodes are situated at the apex of the axilla, medial to the axillary vein and above the pectoralis minor. They receive efferents from all other axillary node groups (Pectoral, Subscapular, Lateral, and Central). The efferents from the apical nodes unite to form the **subclavian lymph trunk**, which drains into the thoracic duct or the right lymphatic duct. **Why Other Options are Incorrect:** * **Pectoral (Anterior):** These are primary nodes located along the lower border of the pectoralis minor. They primarily drain the major portion of the breast and the anterior thoracic wall. * **Subscapular (Posterior):** Located along the subscapular vessels, these drain the posterior thoracic wall and the scapular region. * **Central:** These nodes lie deep in the axillary fat. While they receive lymph from the pectoral, subscapular, and lateral groups, they are an intermediate station that ultimately drains into the apical nodes. **High-Yield Clinical Pearls:** * **Sentinel Node Biopsy:** Usually involves the pectoral group, as it is the first station for breast cancer metastasis. * **Rotter’s Nodes:** These are interpectoral nodes located between the pectoralis major and minor; they drain directly into the apical group. * **Level Classification:** In surgery (Berg’s levels), Level I is lateral to pectoralis minor, Level II is behind it, and **Level III (Apical)** is medial/superior to it [1].

Question 1

Guyon's canal is associated with which of the following structures?

Accepted Answer

Ulnar nerve

Answer

Anterior interosseus nerve

Answer

Median nerve

Answer

Radial artery

Question 2

All of the following muscles form the rotator cuff EXCEPT?

Accepted Answer

Deltoid

Answer

Teres minor

Answer

Subscapularis

Answer

Supraspinatus

Question 3

Which muscle is primarily responsible for overhead abduction at the shoulder joint?

Accepted Answer

Serratus anterior

Answer

Deltoid

Answer

Supraspinatus

Answer

Pectoralis major

Question 4

Injury to the long thoracic nerve can be tested by asking the patient to perform which action?

Accepted Answer

Push against a wall

Answer

Raise the arm above the head

Answer

Touch the opposite shoulder

Answer

Lift a heavy object

Question 5

The coracohumeral ligament is a degenerated part of which muscle?

Accepted Answer

Pectoralis minor

Answer

Biceps brachii

Answer

Coracobrachialis

Answer

Latissimus dorsi

Question 6

A patient who sustained an injury cannot abduct their right arm and cannot lift it. Examination reveals tenderness near the right upper arm, and an X-ray shows a fracture of the surgical neck of the humerus. Which muscle was paralyzed?

Accepted Answer

Supraspinatus

Answer

Subscapularis

Answer

Infraspinatus

Answer

Teres major

Question 7

A patient complains of pain with repeated movements of his thumb, often referred to as thumb claudication. The physician performs the Allen test and notes an insufficiency of the radial artery. Which of the following conditions would result from radial artery stenosis?

Accepted Answer

A marked decrease in blood flow in the princeps pollicis artery

Answer

A marked decrease in blood flow in the superficial palmar arterial arch

Answer

Decreased pulsation in the artery passing superficial to the flexor retinaculum

Answer

Ischemia of the entire extensor muscles of the forearm

Question 8

A patient presented with numbness of the little and ring finger and atrophy of the hypothenar muscles. Which nerve is damaged?

Accepted Answer

Ulnar nerve before its division into superficial and deep branches

Answer

Palmar cutaneous branch of the ulnar nerve

Answer

Deep branch of the ulnar nerve

Answer

Posterior cord of the brachial plexus

Question 9

All of the following nerves arise from the posterior cord of the brachial plexus, EXCEPT?

Accepted Answer

Musculocutaneous nerve

Answer

Upper subscapular nerve

Answer

Lower subscapular nerve

Answer

Thoracodorsal nerve

Question 10

Which of the following groups of axillary lymph nodes is considered a terminal group?

Accepted Answer

Apical

Answer

Pectoral

Answer

Central

Answer

Subscapular

Upper Limb — MCQs

Upper Limb — MCQs

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