Upper Limb Practice Questions

Q: Which nerve arises from a root of the brachial plexus?

Dorsal scapular nerve. To master the brachial plexus for NEET-PG, it is essential to categorize nerves based on their site of origin: Roots, Trunks, Cords, or Terminal Branches. ### **Explanation** The **Dorsal Scapular Nerve** (C5) is one of the two primary nerves that arise directly from the **Roots** of the brachial plexus (the other being the Long Thoracic Nerve, C5-C7). It pierces the scalenus medius muscle and supplies the Rhomboid Major, Rhomboid Minor, and Levator Scapulae muscles. ### **Analysis of Incorrect Options** * **A. Suprascapular nerve:** This nerve arises from the **Upper Trunk** (C5, C6) of the brachial plexus. It is a common site for "Erb’s Palsy" involvement. * **C. Upper subscapular nerve:** This nerve arises from the **Posterior Cord** (C5, C6). It supplies the upper part of the subscapularis muscle. * **D. Lateral pectoral nerve:** As the name suggests, this arises from the **Lateral Cord** (C5-C7) and supplies the pectoralis major [1]. ### **NEET-PG High-Yield Pearls** 1. **Nerves from Roots:** Only two—Dorsal Scapular (C5) and Long Thoracic (C5, C6, C7). 2. **Nerves from Trunks:** Only two arise from the Upper Trunk—Suprascapular and Nerve to Subclavius. No nerves arise from the Middle or Lower trunks. 3. **Clinical Correlation:** Injury to the Long Thoracic Nerve (Root origin) leads to **"Winging of Scapula"** due to paralysis of the Serratus Anterior. 4. **Mnemonic for Cords:** * **Lateral Cord:** **LML** (Lateral pectoral, Musculocutaneous, Lateral root of Median). * **Posterior Cord:** **ULTRA** (Upper subscapular, Lower subscapular, Thoracodorsal, Radial, Axillary) [1]. * **Medial Cord:** **M4U** (Medial pectoral, Medial cutaneous of arm, Medial cutaneous of forearm, Medial root of Median, Ulnar).

Q: The neurovascular bundle in the axilla is surrounded by a sheath derived from which structure?

Prevertebral fascia. ### Explanation The correct answer is **Prevertebral fascia**. **1. Why Prevertebral Fascia is Correct:** The **axillary sheath** is a tubular, fibrous sleeve that encloses the axillary artery, axillary vein, and the cords of the brachial plexus. Anatomically, this sheath is a direct lateral extension of the **prevertebral layer of deep cervical fascia**. As the subclavian vessels and the roots of the brachial plexus emerge from the posterior triangle of the neck and pass over the first rib into the apex of the axilla, they "drag" a layer of the prevertebral fascia with them, creating the sheath. **2. Why the Other Options are Incorrect:** * **Pretracheal fascia:** This layer is limited to the anterior neck, enclosing the thyroid gland, trachea, and esophagus. It does not extend into the axilla. * **Clavipectoral fascia:** This is a strong fascia deep to the pectoralis major. While it forms the anterior wall of the axilla and is pierced by the cephalic vein and lateral pectoral nerve, it does *not* form the axillary sheath [1]. * **Axillary sheath:** This is the *name* of the structure itself, not the *source* from which it is derived. The question asks for the parent structure. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Brachial Plexus Block:** The axillary sheath is clinically significant during regional anesthesia. Local anesthetic injected into the sheath travels proximally and distally, bathing the cords of the brachial plexus. * **Contents of the Sheath:** It contains the axillary artery and the cords of the brachial plexus [1]. Note that the **axillary vein** lies mostly *outside* or in the medial compartment of the sheath, allowing it to distend during increased venous return. * **Boundaries:** The axillary sheath starts at the lateral border of the first rib and ends at the lower border of the teres major muscle.

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 B is fractured, which of the following structures is most likely injured?

Posterior humeral circumflex artery. ***Posterior humeral circumflex artery*** - The **surgical neck of the humerus** (structure B) is closely related to the **posterior humeral circumflex artery** which courses through the **quadrangular space** with the axillary nerve. - Fractures at this location commonly cause **vascular compromise** and **deltoid muscle denervation** due to injury of both the artery and accompanying axillary nerve. *Musculocutaneous nerve* - This nerve pierces the **coracobrachialis muscle** and runs in the **anterior compartment** of the arm, away from the surgical neck. - It supplies the **biceps, brachialis, and coracobrachialis** muscles and provides sensation to the lateral forearm via the lateral antebrachial cutaneous nerve. *Radial nerve* - The radial nerve travels in the **spiral groove** (radial groove) on the **mid-shaft of the humerus**, not at the surgical neck level. - **Mid-shaft humeral fractures** typically injure the radial nerve, causing **wrist drop** and loss of thumb extension. *Deep brachial artery* - This artery accompanies the **radial nerve** in the **spiral groove** of the humeral shaft, distant from the surgical neck. - It is at risk with **mid-shaft humeral fractures** but not with **surgical neck fractures** as described in this pediatric case.

Q: Which border of the scapula is not palpable?

Superior. The scapula is a flat, triangular bone located on the posterolateral aspect of the thoracic cage. Its palpability is determined by the thickness of the overlying musculature. ### **Why the Superior Border is Not Palpable** The **Superior Border** is the shortest and thinnest border of the scapula. It is situated deep to the **Supraspinatus muscle** and is covered by the thick fibers of the **Trapezius muscle**. Due to this deep anatomical positioning and the dense muscular layers overlying it, the superior border cannot be felt through the skin during a physical examination. ### **Analysis of Incorrect Options** * **Medial (Vertebral) Border:** This is the longest border and lies parallel to the vertebral column. It is easily palpable because it is subcutaneous, especially when the arm is positioned behind the back (internal rotation). * **Lateral (Axillary) Border:** This border is thick as it serves as an attachment point for the Teres major and minor muscles. It can be palpated along the posterior wall of the axilla. * **Inferior Angle:** While technically an angle where the medial and lateral borders meet, it is the most mobile and easily palpable part of the scapula, often used as a landmark for the T7 spinous process or the 7th intercostal space. ### **High-Yield NEET-PG Pearls** * **Sprengel’s Deformity:** A congenital condition where the scapula fails to descend, resulting in a high-seated, undescended scapula. * **Winging of Scapula:** Caused by paralysis of the **Serratus Anterior** (Long Thoracic Nerve). The **medial border** becomes abnormally prominent. * **Suprascapular Notch:** Located on the superior border, it transmits the suprascapular nerve (the suprascapular artery passes *above* the superior transverse scapular ligament). * **Ossification:** The scapula develops from **one primary center** (body) and **seven secondary centers**.

Q: A female presented with loss of extension of the little and ring finger, hypothenar atrophy, and metacarpophalangeal joint hyperextension. Which nerve is injured?

Ulnar nerve. ### Explanation The clinical presentation described is a classic case of **Ulnar Claw Hand**, resulting from an injury to the **Ulnar Nerve**. **Why the Ulnar Nerve is correct:** The ulnar nerve (C8-T1) supplies the **medial two lumbricals** and all **interossei** [2]. These muscles normally flex the metacarpophalangeal (MCP) joints and extend the interphalangeal (IP) joints. When paralyzed, the opposing long extensors cause **hyperextension at the MCP joints**, while the long flexors cause **flexion at the IP joints** (loss of extension). This is most prominent in the ring and little fingers. Additionally, the ulnar nerve supplies the **hypothenar muscles**; hence, injury leads to visible hypothenar atrophy. The ulnar nerve travels to the radial side of the pisiform at the wrist [1]. **Why the other options are incorrect:** * **Posterior Interosseous Nerve (PIN):** This is a branch of the radial nerve. Injury leads to "finger drop" (inability to extend MCP joints), but it does not cause MCP hyperextension or hypothenar atrophy. * **Radial Trunk:** Injury high up results in "wrist drop" and loss of extension of all fingers and the thumb, but sensory loss would be on the dorsal aspect of the hand, not localized to the ulnar side [2]. * **Median Nerve:** Injury causes "Ape thumb" deformity and "Hand of Benediction" (when attempting to make a fist), affecting the thenar eminence rather than the hypothenar eminence [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Ulnar Paradox:** A proximal ulnar nerve lesion (at the elbow) results in a *less* prominent claw than a distal lesion (at the wrist) because the Flexor Digitorum Profundus is also paralyzed, reducing IP joint flexion. * **Froment’s Sign:** Tests for Adductor Pollicis (ulnar nerve) palsy; the patient compensates by flexing the thumb IP joint (via the median nerve). * **Guyon’s Canal:** A common site for distal ulnar nerve compression at the wrist.

Q: The carpometacarpal joint of the thumb is a type of joint?

Saddle. **Explanation:** The **1st Carpometacarpal (CMC) joint** of the thumb is a classic example of a **Saddle (Sellar) joint**. It is formed between the distal surface of the **Trapezium** and the base of the **1st Metacarpal** [1]. Both articulating surfaces are concavo-convex (shaped like a rider on a saddle), which allows for a wide range of motion, including flexion, extension, abduction, adduction, and the high-yield movement of **opposition**. **Analysis of Options:** * **A. Ellipsoid:** These joints (e.g., Radiocarpal/Wrist joint) have an oval-shaped surface fitting into an elliptical cavity. They allow movement in two planes but do not allow axial rotation. * **C. Condylar:** These are modified hinge joints (e.g., Knee joint or Temporomandibular joint) where two distinct condyles articulate with concave surfaces. * **D. Ball and Socket:** These (e.g., Shoulder and Hip joints) provide the highest degree of freedom (multiaxial). While the thumb is highly mobile, its bony architecture is sellar, not spherical. **High-Yield Clinical Pearls for NEET-PG:** * **Unique Feature:** The 1st CMC joint is the only saddle joint in the hand. * **Opposition:** This is a complex movement combining flexion, abduction, and medial rotation. * **Clinical Correlation:** The 1st CMC joint is a common site for **Osteoarthritis** [1], often presenting as "basal thumb pain" and a squared appearance of the hand. * **Nerve Supply:** Primarily the Median nerve.

Q: The upper lateral cutaneous nerve of the arm is a branch of which nerve?

Axillary nerve. ### Explanation **Correct Answer: D. Axillary Nerve** The **axillary nerve** (C5, C6) originates from the posterior cord of the brachial plexus. After passing through the quadrangular space, it divides into anterior and posterior branches. The **upper lateral cutaneous nerve of the arm** is the terminal continuation of the **posterior branch** of the axillary nerve. It pierces the deep fascia at the posterior border of the deltoid to supply the skin over the lower half of the deltoid muscle. **Analysis of Incorrect Options:** * **A. Musculocutaneous nerve:** This nerve continues as the **lateral cutaneous nerve of the forearm** (not the arm) after piercing the deep fascia near the cubital fossa. * **B. Radial nerve:** The radial nerve gives off the **lower lateral cutaneous nerve of the arm**, as well as the posterior cutaneous nerves of the arm and forearm. * **C. Ulnar nerve:** The ulnar nerve does not have any cutaneous branches in the arm; its sensory distribution begins in the hand. **High-Yield Clinical Pearls for NEET-PG:** * **Regimental Badge Area:** The area of skin supplied by the upper lateral cutaneous nerve of the arm is clinically significant. Loss of sensation here is a diagnostic sign of **axillary nerve injury** (commonly due to surgical neck of humerus fractures or shoulder dislocations). * **Quadrangular Space:** The axillary nerve travels through this space along with the posterior circumflex humeral artery. * **Motor Supply:** The axillary nerve supplies the deltoid and teres minor muscles. Paralysis leads to loss of shoulder abduction (15–90 degrees) and "flat shoulder" deformity.

Q: Saturday night palsy affects which nerve?

Radial. **Explanation:** **Saturday Night Palsy** refers to a compressive neuropathy of the **Radial nerve**, typically occurring at the **spiral groove** of the humerus. The name originates from individuals falling asleep with an arm draped over a chair after alcohol consumption, leading to prolonged pressure on the nerve. 1. **Why Radial Nerve is Correct:** The radial nerve (C5-T1) winds around the posterior aspect of the humerus in the spiral groove. Compression at this site leads to a motor deficit of the extensors of the wrist and fingers, resulting in **Wrist Drop**. Since the branches to the triceps often arise proximal to this site, elbow extension is usually preserved. 2. **Why Incorrect Options are Wrong:** * **Median Nerve:** Compression (e.g., Honeymoon palsy or Carpal Tunnel) affects thumb opposition and lateral finger flexion, not wrist extension. * **Ulnar Nerve:** Compression (usually at the cubital tunnel) leads to "Claw Hand" and sensory loss in the medial 1.5 fingers. * **Anterior Interosseous Nerve (AIN):** This is a pure motor branch of the median nerve. Damage results in the inability to make the "OK" sign (weakness of Flexor Pollicis Longus and Flexor Digitorum Profundus to the index finger) [1]. **Clinical Pearls for NEET-PG:** * **Site of Lesion:** Spiral groove (Mid-shaft humerus fracture is a common traumatic cause). * **Clinical Sign:** Wrist drop with sensory loss over the first dorsal web space. * **Differential:** If the lesion is in the **axilla** (e.g., "Crutch Palsy"), the **triceps** is also involved (loss of elbow extension). * **Prognosis:** Usually involves **Neuropraxia** (temporary conduction block), and recovery is typically spontaneous within weeks.

Question 1

Which nerve arises from a root of the brachial plexus?

Accepted Answer

Dorsal scapular nerve

Answer

Suprascapular nerve

Answer

Upper subscapular nerve

Answer

Lateral pectoral nerve

Question 2

The neurovascular bundle in the axilla is surrounded by a sheath derived from which structure?

Accepted Answer

Prevertebral fascia

Answer

Pretracheal fascia

Answer

Clavipectoral fascia

Answer

Axillary sheath

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 B is fractured, which of the following structures is most likely injured?

Accepted Answer

Posterior humeral circumflex artery

Answer

Musculocutaneous nerve

Answer

Radial nerve

Answer

Deep brachial artery

Question 4

The forcible separation of the head of the radius from the capitulum of the humerus is mainly prevented by which structure?

Accepted Answer

Annular ligament

Answer

Articular capsule

Answer

Quadrate ligament

Answer

Radial collateral ligament

Question 5

Which border of the scapula is not palpable?

Accepted Answer

Superior

Answer

Medial

Answer

Lateral

Answer

Inferior

Question 6

A female presented with loss of extension of the little and ring finger, hypothenar atrophy, and metacarpophalangeal joint hyperextension. Which nerve is injured?

Accepted Answer

Ulnar nerve

Answer

Posterior interosseous nerve

Answer

Radial trunk

Answer

Median nerve

Question 7

The carpometacarpal joint of the thumb is a type of joint?

Accepted Answer

Saddle

Answer

Ellipsoid

Answer

Condylar

Answer

Ball and socket

Question 8

A 40-year-old male presented to the emergency room after a minor motorcycle accident, complaining of right elbow pain. An X-ray of the region was performed. Which of the following muscles of the hand would be spared in this condition?

Accepted Answer

Muscle D

Answer

Muscle B

Answer

Muscle A

Answer

Muscle C

Question 9

The upper lateral cutaneous nerve of the arm is a branch of which nerve?

Accepted Answer

Axillary nerve

Answer

Musculocutaneous nerve

Answer

Radial nerve

Answer

Ulnar nerve

Question 10

Saturday night palsy affects which nerve?

Accepted Answer

Radial

Answer

Median

Answer

Ulnar

Answer

Anterior interosseous

Upper Limb — MCQs

Upper Limb — MCQs

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