Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 271: A female presented with loss of extension of the little and ring finger, hypothenar atrophy, and metacarpophalangeal joint hyperextension. Which nerve is injured?

A. Posterior interosseous nerve
B. Radial trunk
C. Ulnar nerve (Correct Answer)
D. Median nerve

Explanation: ### 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.

Question 272: The carpometacarpal joint of the thumb is a type of joint?

A. Ellipsoid
B. Saddle (Correct Answer)
C. Condylar
D. Ball and socket

Explanation: **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.

Question 273: Erb's Point is located at the junction of which cervical vertebrae?

A. C5 and C6 (Correct Answer)
B. C6 and C7
C. C7 and C8
D. C8 and T1

Explanation: ### Explanation **1. Why C5 and C6 is Correct:** Erb’s point is a specific anatomical location in the **Upper Trunk** of the brachial plexus. It is formed by the union of the **C5 and C6 nerve roots**. This point is clinically significant because six different nerves meet here: the C5 root, C6 root, suprascapular nerve, nerve to subclavius, and the anterior and posterior divisions of the upper trunk. Damage to this junction results in **Erb-Duchenne Paralysis**. **2. Why the Other Options are Incorrect:** * **C6 and C7 (Option B):** There is no major anatomical junction or "point" named at this specific intersection in the brachial plexus. The C7 root continues independently as the Middle Trunk. * **C7 and C8 (Option C):** These roots do not join; C7 forms the middle trunk, while C8 joins T1. * **C8 and T1 (Option D):** The union of these roots forms the **Lower Trunk** of the brachial plexus. Injury here leads to **Klumpke’s Paralysis**, characterized by a "claw hand" deformity, rather than Erb's palsy. **3. Clinical Pearls for NEET-PG:** * **Mechanism of Injury:** Erb’s palsy is typically caused by an increase in the angle between the head and shoulder (e.g., birth trauma or falling on the shoulder). * **Deformity:** Known as **"Policeman’s Tip Hand"** or **"Waiter’s Tip Hand."** The arm is adducted, medially rotated, and the forearm is extended and pronated. * **Muscle Involvement:** Primarily affects the deltoid, biceps brachii, brachialis, and brachioradialis. * **Sensory Loss:** Usually occurs over a small area on the lateral aspect of the arm (over the deltoid).

Question 274: All of the following muscles constitute the rotator cuff muscles, EXCEPT:

A. Supraspinatus
B. Infraspinatus
C. Teres major (Correct Answer)
D. Subscapularis

Explanation: The **Rotator Cuff** (also known as the musculotendinous cuff) is a functional unit formed by the tendons of four muscles that blend with the fibrous capsule of the shoulder joint. These muscles provide dynamic stability to the glenohumeral joint by "seating" the humeral head into the shallow glenoid cavity. **Why Teres Major is the Correct Answer:** While the **Teres major** is anatomically close to the rotator cuff, it is **not** part of it. It originates from the lower third of the lateral border of the scapula and inserts into the medial lip of the bicipital groove of the humerus. Crucially, its tendon does **not** blend with the joint capsule, and it acts as an adductor and internal rotator (often called "Lat's little helper") rather than a stabilizer. **Analysis of Incorrect Options:** The rotator cuff is easily remembered by the mnemonic **SITS**: * **Supraspinatus (A):** Initiates abduction (0-15°). It is the most commonly injured rotator cuff muscle. * **Infraspinatus (B):** Facilitates lateral (external) rotation. * **Subscapularis (D):** The only member located anteriorly; it facilitates medial (internal) rotation. * *(Note: Teres minor is the fourth member, not listed in the options).* **High-Yield Clinical Pearls for NEET-PG:** * **The "Gap":** The rotator cuff is deficient **inferiorly**, making this the most common site for shoulder dislocations. * **Innervation:** Supraspinatus and Infraspinatus are supplied by the **Suprascapular nerve** (C5, C6). * **Clinical Test:** The **"Drop Arm Test"** is used to assess Supraspinatus tears. * **Insertion:** Supraspinatus, Infraspinatus, and Teres minor insert on the **Greater Tubercle**, while Subscapularis inserts on the **Lesser Tubercle**.

Question 275: The upper lateral cutaneous nerve of the arm is a branch of which nerve?

A. Musculocutaneous nerve
B. Radial nerve
C. Ulnar nerve
D. Axillary nerve (Correct Answer)

Explanation: ### 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.

Question 276: Saturday night palsy affects which nerve?

A. Radial (Correct Answer)
B. Median
C. Ulnar
D. Anterior interosseous

Explanation: **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 277: 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?

A. Axillary nerve (Correct Answer)
B. Radial nerve
C. Long thoracic nerve
D. Median nerve

Explanation: 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).

Question 278: Which part of the scapula is more prominent in winging of the scapula?

A. Superior angle and medial border
B. Inferior angle and lateral border
C. Superior angle and lateral border
D. Inferior angle and medial border (Correct Answer)

Explanation: ### Explanation **Winging of the scapula** is a clinical sign characterized by the abnormal protrusion of the scapula from the posterior thoracic wall. #### 1. Why the Correct Answer is Right The primary muscle responsible for keeping the scapula closely applied to the chest wall is the **Serratus Anterior**. It originates from the upper eight ribs and inserts into the **ventral aspect of the medial border** of the scapula, with the largest portion of the muscle inserting at the **inferior angle**. When the **Long Thoracic Nerve (of Bell)** is paralyzed, the Serratus Anterior fails to protract and stabilize the scapula. Consequently, the antagonistic muscles (Trapezius and Rhomboids) and the weight of the arm cause the scapula to rotate. This results in the **medial border and the inferior angle** projecting backward and becoming prominently visible, especially when the patient attempts to push against a wall. #### 2. Why Other Options are Wrong * **A & C (Superior Angle):** The superior angle is anchored by the Levator Scapulae and is less affected by the loss of the Serratus Anterior. It does not protrude significantly in classic winging. * **B & C (Lateral Border):** The lateral border is pulled forward by the Pectoralis Minor and stabilized by the Deltoid and Rotator Cuff muscles. It does not wing outward; rather, the entire scapula shifts medially and backward. #### 3. Clinical Pearls for NEET-PG * **Nerve Involved:** Long Thoracic Nerve (Roots: **C5, C6, C7** – "C5, 6, 7 move to heaven"). * **Common Causes:** Radical mastectomy (axillary lymph node dissection), carrying heavy loads on the shoulder, or blunt trauma to the neck. * **Functional Deficit:** The patient will have difficulty with **overhead abduction** of the arm (above 90°) because the Serratus Anterior is required to rotate the scapula upward. * **Pseudo-winging:** Can occur in Spinal Accessory Nerve (CN XI) palsy, but this typically involves lateral displacement and drooping of the shoulder.

Question 279: What is the nerve supply of the latissimus dorsi muscle?

A. Radial nerve
B. Long thoracic nerve
C. Thoracodorsal nerve (Correct Answer)
D. Axillary nerve

Explanation: ### Explanation **Correct Option: C. Thoracodorsal nerve** The **Latissimus dorsi** is a large, fan-shaped muscle of the back. It is supplied by the **thoracodorsal nerve** (also known as the nerve to latissimus dorsi) [1]. This nerve arises from the **posterior cord** of the brachial plexus and carries fibers from the **C6, C7, and C8** spinal segments. It travels along the posterior axillary wall to reach the deep surface of the muscle [1]. **Analysis of Incorrect Options:** * **A. Radial nerve:** While also a branch of the posterior cord, it primarily supplies the triceps brachii and the extensor compartment of the forearm. * **B. Long thoracic nerve (C5, C6, C7):** This nerve supplies the **Serratus anterior** muscle. Injury to this nerve leads to "winging of the scapula." * **C. Axillary nerve (C5, C6):** This nerve supplies the **Deltoid** and **Teres minor** muscles. It is commonly injured in surgical neck of humerus fractures. **High-Yield Clinical Pearls for NEET-PG:** * **Action:** The Latissimus dorsi is known as the **"Climber’s muscle"** because it performs adduction, extension, and internal rotation of the humerus (pulling the trunk upward). * **Surgical Importance:** The thoracodorsal nerve is at risk during **axillary lymph node dissection** (e.g., for breast cancer surgery) [1]. Damage results in difficulty using crutches or performing activities like rowing or climbing. * **Reconstruction:** The Latissimus dorsi flap is a common choice for **breast reconstruction** surgery due to its reliable vascular supply (thoracodorsal artery).

Question 280: Winging of the scapula is due to paralysis of which nerve?

A. Long thoracic nerve (Correct Answer)
B. Axillary nerve
C. Radial nerve
D. Median nerve

Explanation: **Explanation:** **Winging of the scapula** occurs due to the paralysis of the **Serratus Anterior muscle**, which is exclusively supplied by the **Long Thoracic Nerve (Nerve of Bell)**. 1. **Why the Long Thoracic Nerve is correct:** The Serratus Anterior originates from the upper eight ribs and inserts into the medial border of the scapula. Its primary function is to protract the scapula and keep its medial border closely applied to the thoracic wall. When the Long Thoracic Nerve (C5, C6, C7) is damaged—often due to trauma, surgery (like radical mastectomy), or heavy lifting—the muscle fails to anchor the scapula. Consequently, the medial border of the scapula protrudes posteriorly like a "wing," especially when the patient attempts to push against a wall. 2. **Why the other options are incorrect:** * **Axillary Nerve:** Supplies the Deltoid and Teres Minor. Injury leads to loss of shoulder abduction (15–90°) and sensory loss over the "regimental badge" area. * **Radial Nerve:** Supplies the extensors of the arm and forearm. Injury typically results in "Wrist Drop." * **Median Nerve:** Supplies most flexors of the forearm and thenar muscles [2]. Injury leads to "Ape Thumb" deformity or "Hand of Benediction." **Clinical Pearls for NEET-PG:** * **Nerve Roots:** Remember **C5, C6, C7** (C5, 6, 7 reach the heaven—Long Thoracic Nerve). * **Surgical Risk:** This nerve is classically injured during **axillary lymph node dissection** or chest tube insertion [1]. * **Overhead Abduction:** The Serratus Anterior (along with the Trapezius) is essential for rotating the scapula to allow abduction of the arm above 90°. * **Pseudo-winging:** Paralysis of the Trapezius (Spinal Accessory Nerve) can also cause scapular displacement, but true "winging" on pushing is specific to the Serratus Anterior.

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Pectoral Region and Axilla

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Arm and Cubital Fossa

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Forearm and Hand

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Joints of Upper Limb

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Nerves of Upper Limb

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Arterial Supply and Venous Drainage

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Lymphatic Drainage

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Muscles and Their Actions

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Applied Anatomy and Clinical Correlations

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Upper Limb — MCQs

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