Upper Limb Practice Questions

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.

Q: A 24-year-old medical student received a booster dose of hepatitis B vaccination, following which she developed weakness in abduction and lateral rotation of the arm. The lesion is most likely to be in which of the following nerves?

Axillary nerve. The clinical presentation describes a classic injury to the **Axillary nerve** following an intramuscular injection in the deltoid region. **Why Axillary Nerve is Correct:** The axillary nerve (C5, C6) winds around the surgical neck of the humerus, lying deep to the deltoid muscle. It supplies the **deltoid** (primary abductor of the arm from 15° to 90°) and the **teres minor** (a lateral rotator). An improperly placed booster dose in the upper third of the deltoid can cause direct needle trauma or inflammatory neuritis of this nerve, leading to weakness in abduction and lateral rotation, along with sensory loss over the "regimental badge" area. **Why Other Options are Incorrect:** * **Radial Nerve:** Injury typically occurs at the spiral groove (mid-shaft humerus fracture), leading to "wrist drop" and loss of extension at the elbow, wrist, and fingers. * **Long Thoracic Nerve:** Supplies the serratus anterior. Injury leads to "winging of the scapula" and inability to abduct the arm above 90° (overhead abduction), but does not affect lateral rotation. * **Median Nerve:** Primarily involved in forearm pronation, wrist flexion, and thumb opposition. It is not located in the deltoid region. **High-Yield Clinical Pearls for NEET-PG:** * **Safe Zone for Deltoid Injection:** To avoid axillary nerve injury, injections should be given in the **middle or lower third** of the deltoid muscle (approximately 2-3 fingerbreadths below the acromion). * **Quadrangular Space:** The axillary nerve passes through this space along with the posterior circumflex humeral artery. * **Abduction Sequence:** 0-15° (Suprascapular nerve/Supraspinatus); 15-90° (Axillary nerve/Deltoid); >90° (Long thoracic & Spinal accessory nerves/Serratus anterior & Trapezius).

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 notch** bridged by the **superior transverse scapular ligament**; calcification compresses the **suprascapular nerve** that innervates the infraspinatus muscle. - The **suprascapular nerve** (C5-C6) passes through this notch and supplies both **supraspinatus** and **infraspinatus** muscles, making infraspinatus the only option affected by this compression. *Deltoid* - Innervated by the **axillary nerve** (C5-C6), which passes through the **quadrangular space** posterior to the surgical neck of the humerus. - Would not be affected by calcification at the **suprascapular notch** as it follows a completely different anatomical pathway. *Teres major* - Supplied by the **lower subscapular nerve** (C5-C7), which arises from the posterior cord of the brachial plexus. - This nerve pathway does not pass through the **suprascapular notch**, so calcification would not affect teres major function. *Teres minor* - Innervated by the **axillary nerve** (C5-C6), the same nerve that supplies the deltoid muscle. - Like the deltoid, it would remain unaffected by **suprascapular nerve** compression at the suprascapular notch.

Question 1

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 2

Which border of the scapula is not palpable?

Accepted Answer

Superior

Answer

Medial

Answer

Lateral

Answer

Inferior

Question 3

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 4

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

Accepted Answer

Saddle

Answer

Ellipsoid

Answer

Condylar

Answer

Ball and socket

Question 5

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 6

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 7

Saturday night palsy affects which nerve?

Accepted Answer

Radial

Answer

Median

Answer

Ulnar

Answer

Anterior interosseous

Question 8

A 24-year-old medical student received a booster dose of hepatitis B vaccination, following which she developed weakness in abduction and lateral rotation of the arm. The lesion is most likely to be in which of the following nerves?

Accepted Answer

Axillary nerve

Answer

Radial nerve

Answer

Long thoracic nerve

Answer

Median nerve

Question 9

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 10

A 50-year-old electrician reports pain in his left upper extremity and tingling and numbness in the 4th and 5th digits of his left hand. There is mild swelling of the left hand. The patient reports most of his pain and numbness occurs when he is doing electrical work with his arms overhead. X-ray reveals the presence of a cervical rib. Which of the following structures is most likely being compressed?

Accepted Answer

Subclavian artery

Answer

Axillary artery

Answer

Brachial artery

Answer

Brachiocephalic artery

Upper Limb — MCQs

Upper Limb — MCQs

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