Upper Limb Practice Questions

Q: An X-ray of the wrist and hand is shown below. If there is damage to structure E, which of the following muscle weaknesses does it cause?

Flexor carpi ulnaris. ***Flexor carpi ulnaris*** - The **pisiform bone** (structure E) serves as the primary insertion point for the **flexor carpi ulnaris (FCU)**, which is innervated by the **ulnar nerve**. - Damage to the pisiform disrupts FCU function, causing weakness in **wrist flexion** and **ulnar deviation**, as FCU also inserts on the **hook of hamate** and **5th metacarpal base**. *Flexor carpi radialis* - Innervated by the **median nerve** and inserts on the base of the **2nd metacarpal**, not the pisiform bone. - Pisiform damage would not affect FCR function as it has no anatomical relationship with structure E. *Palmaris longus* - Innervated by the **median nerve** and inserts into the **palmar aponeurosis**, completely bypassing the pisiform bone. - This muscle's function remains intact with pisiform damage as it has no connection to structure E. *Brachioradialis* - Innervated by the **radial nerve** and inserts on the **distal radius**, not involving any carpal bones. - Pisiform bone damage has no impact on brachioradialis function due to its separate anatomical pathway and innervation.

Q: What is the nerve supply of the trapezius muscle?

Spinal accessory nerve. **Explanation:** The **Trapezius** is a large, superficial muscle of the back and neck. It has a unique dual nerve supply that is a frequent high-yield topic in anatomy: 1. **Motor Supply:** The **Spinal Accessory Nerve (CN XI)** provides the motor fibers responsible for muscle contraction. 2. **Sensory Supply:** Branches from the **C3 and C4 spinal nerves** provide proprioceptive fibers. **Analysis of Options:** * **Option D (Correct):** The Spinal Accessory Nerve enters the posterior triangle of the neck and passes deep to the trapezius to supply it. Damage to this nerve results in "drooping of the shoulder" and an inability to shrug. * **Option A (Incorrect):** The **Axillary nerve** (C5-C6) supplies the deltoid and teres minor muscles. * **Option B (Incorrect):** The **Musculocutaneous nerve** (C5-C7) supplies the anterior compartment of the arm (Biceps brachii, Coracobrachialis, and Brachialis). * **Option C (Incorrect):** The **Median nerve** (C5-T1) supplies most of the flexor muscles of the forearm and the thenar muscles of the hand. **High-Yield Clinical Pearls for NEET-PG:** * **Testing:** The trapezius is tested by asking the patient to **shrug their shoulders** against resistance. * **Iatrogenic Injury:** The Spinal Accessory nerve is the most commonly injured nerve during **lymph node biopsies** in the posterior triangle of the neck. * **Action:** It is the primary muscle for **overhead abduction** (above 90 degrees) by rotating the scapula, acting alongside the Serratus Anterior. * **Origin:** It is a "branchiomeric" muscle, meaning it is derived from the pharyngeal arches (specifically the 6th arch), which explains its cranial nerve supply.

Q: What is the nerve supply of the opponens pollicis muscle?

Median nerve. **Explanation:** The **opponens pollicis** is one of the three muscles forming the thenar eminence of the hand. The correct answer is the **Median nerve** [1], specifically its **recurrent branch** (C8, T1). This nerve supplies the "LOAF" muscles: the lateral two Lumbricals, Opponens pollicis, Abductor pollicis brevis, and Flexor pollicis brevis [3]. **Analysis of Options:** * **Median Nerve (Correct):** It provides motor innervation to the thenar muscles. The recurrent branch is often called the "million-dollar nerve" because its injury results in the loss of thumb opposition, severely disabling hand function [1]. * **Deep branch of the ulnar nerve:** This nerve supplies most of the intrinsic muscles of the hand, including the hypothenar muscles, all interossei, and the Adductor pollicis [3]. It does *not* supply the opponens pollicis. * **Superficial branch of the ulnar nerve:** This is primarily sensory to the medial 1.5 fingers and provides motor supply only to the Palmaris brevis [3]. * **Posterior interosseous nerve:** This is a branch of the radial nerve that supplies the extensor compartment of the forearm; it does not innervate any intrinsic hand muscles [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Ape Thumb Deformity:** Caused by a proximal median nerve injury, leading to atrophy of the thenar eminence and loss of opposition. * **Opponens Digiti Minimi:** Unlike the opponens pollicis, this muscle is supplied by the **deep branch of the ulnar nerve** [3]. * **Mnemonic:** Remember **"Meat LOAF"**—**Me**dian nerve supplies **L**umbricals (1&2), **O**pponens pollicis, **A**bductor pollicis brevis, and **F**lexor pollicis brevis.

Q: Which muscle of the hand is NOT supplied by the median nerve?

Opponens pollicis. ### Explanation The intrinsic muscles of the hand are primarily supplied by the **Ulnar nerve**, with the exception of five muscles supplied by the **Median nerve** (specifically its recurrent branch and digital branches). These five are remembered by the mnemonic **LOAF**: **L**umbricals (1st and 2nd), **O**pponens pollicis, **A**bductor pollicis brevis, and **F**lexor pollicis brevis. [3] **Why the Question/Options are unique:** There appears to be a technical error in the provided key. **Opponens pollicis (A)**, **Abductor pollicis brevis (B)**, and the **First lumbrical (D)** are all classic examples of muscles **supplied** by the Median nerve. The correct answer to "Which is NOT supplied by the median nerve?" is **C. Extensor pollicis brevis**. This is because all **Extensor** muscles of the thumb and wrist are located in the posterior compartment of the forearm and are supplied by the **Posterior Interosseous Nerve (a branch of the Radial nerve)**. [2] **Analysis of Options:** * **Opponens pollicis & Abductor pollicis brevis:** These are Thenar muscles supplied by the recurrent branch of the median nerve (C8, T1). * **First lumbrical:** Supplied by the digital branches of the median nerve. * **Extensor pollicis brevis:** Supplied by the Radial nerve; it is an extrinsic muscle of the hand. [2] **High-Yield Clinical Pearls for NEET-PG:** * **Ape Thumb Deformity:** Caused by Median nerve injury at the wrist (e.g., Carpal Tunnel Syndrome), leading to paralysis of the thenar muscles. [1] * **Million Dollar Nerve:** The recurrent branch of the median nerve is so named because its injury during carpal tunnel surgery leads to loss of thumb opposition, a major disability. * **Ulnar Paradox:** All interossei and the medial two lumbricals are ulnar-supplied. If the median nerve is spared, the index and middle fingers will not show "clawing."

Q: Following anterior dislocation of the shoulder, a patient develops weakness of flexion at the elbow and lack of sensation over the lateral aspect of the forearm. Which nerve is injured?

Musculocutaneous nerve. ### Explanation The correct answer is **Musculocutaneous nerve**. **1. Why it is correct:** The musculocutaneous nerve (C5–C7) arises from the lateral cord of the brachial plexus. It is responsible for: * **Motor supply:** It innervates the muscles of the anterior compartment of the arm—**Coracobrachialis, Biceps brachii, and Brachialis**. Loss of these muscles leads to significant weakness in **elbow flexion** and forearm supination. * **Sensory supply:** After passing through the arm, it continues as the **Lateral cutaneous nerve of the forearm**, providing sensation to the lateral aspect of the forearm. In anterior shoulder dislocations, the humeral head can compress or stretch the cords of the brachial plexus, with the musculocutaneous nerve being a classic, though less common, target than the axillary nerve. **2. Why the other options are incorrect:** * **Radial nerve:** Injury (e.g., mid-shaft humerus fracture) leads to "wrist drop" and loss of extension at the elbow/wrist, not flexion weakness. * **Axillary nerve:** This is the *most common* nerve injured in shoulder dislocations. However, it results in deltoid paralysis (loss of abduction) and sensory loss over the "regimental badge" area (lateral shoulder), not the forearm. * **Ulnar nerve:** Injury causes "claw hand" and sensory loss over the medial 1.5 fingers; it does not affect elbow flexion. **3. NEET-PG High-Yield Pearls:** * **Mnemonic for Musculocutaneous muscles:** **BBC** (Biceps, Brachialis, Coracobrachialis). * **Piercing Nerve:** The musculocutaneous nerve is unique because it **pierces the Coracobrachialis muscle**. * **Dislocation Association:** While the **Axillary nerve** is the most frequently injured in shoulder dislocations, the **Musculocutaneous nerve** is the correct clinical fit when forearm sensory loss and flexion weakness are specified.

Q: Which ligament prevents the displacement of the humerus?

Glenohumeral. **Explanation:** The **Glenohumeral ligaments** (Superior, Middle, and Inferior) are the primary static stabilizers of the shoulder joint. They are thickenings of the anterior joint capsule that reinforce the joint and prevent the **anterior and inferior displacement** of the humeral head. Among these, the **Inferior Glenohumeral Ligament (IGHL)** is the most important stabilizer when the arm is abducted and externally rotated, acting as a "hammock" to prevent dislocation. **Analysis of Incorrect Options:** * **A. Coracoclavicular:** This ligament (composed of the conoid and trapezoid parts) connects the coracoid process to the clavicle. Its primary function is to stabilize the **acromioclavicular joint** and transmit the weight of the upper limb to the clavicle; it does not directly stabilize the humerus. * **B. Coracohumeral:** While this ligament strengthens the upper part of the capsule, its primary role is to prevent **inferior displacement** of the humerus specifically when the arm is hanging at the side (adducted). It is secondary to the glenohumeral ligaments in overall stability. * **C. Coracoacromial:** This ligament connects two parts of the same bone (scapula). Along with the acromion and coracoid process, it forms the **coracoacromial arch**, which prevents **superior displacement** of the humerus but is not a capsular stabilizer. **NEET-PG High-Yield Pearls:** * The **Inferior Glenohumeral Ligament** is the most frequently injured structure in anterior shoulder dislocations (Bankart lesion). * The shoulder joint is the most commonly dislocated joint in the body due to the disproportionate size between the large humeral head and the shallow glenoid cavity (often compared to a "golf ball on a tee"). * The **Rotator Cuff muscles** (SITS) provide dynamic stability, while the **Glenoid Labrum** deepens the socket to increase static stability.

Question 1

An X-ray of the wrist and hand is shown below. If there is damage to structure E, which of the following muscle weaknesses does it cause?

Accepted Answer

Flexor carpi ulnaris

Answer

Flexor carpi radialis

Answer

Palmaris longus

Answer

Brachioradialis

Question 2

Which nerve is involved in the Arcade of Frohse?

Accepted Answer

Posterior interosseous nerve (PIN)

Answer

Median nerve

Answer

Ulnar nerve

Answer

Radial nerve

Question 3

What is the nerve supply of the trapezius muscle?

Accepted Answer

Spinal accessory nerve

Answer

Axillary nerve

Answer

Musculocutaneous nerve

Answer

Median nerve

Question 4

What is the nerve supply of the opponens pollicis muscle?

Accepted Answer

Median nerve

Answer

Superficial branch of the ulnar nerve

Answer

Deep branch of the ulnar nerve

Answer

Posterior interosseous nerve

Question 5

Which of the following statements about the scapula is false?

Accepted Answer

The medial border of the scapula indicates a horizontal fissure.

Answer

The root of the spine of the scapula is at the level of T3.

Answer

The inferior angle of the scapula is at the level of T7.

Answer

The lateral angle of the scapula bears the glenoid cavity.

Question 6

Pointing index in a supracondylar fracture is due to which nerve injury?

Accepted Answer

Anterior interosseous nerve

Answer

Radial nerve

Answer

Ulnar nerve

Answer

Musculocutaneous nerve

Question 7

Which muscles produce flexion of the metacarpophalangeal joint?

Accepted Answer

All of the above

Answer

Lumbricals

Answer

Dorsal interossei

Answer

Palmar interossei

Question 8

Which muscle of the hand is NOT supplied by the median nerve?

Accepted Answer

Opponens pollicis

Answer

Abductor pollicis brevis

Answer

Extensor pollicis brevis

Answer

First lumbrical

Question 9

Following anterior dislocation of the shoulder, a patient develops weakness of flexion at the elbow and lack of sensation over the lateral aspect of the forearm. Which nerve is injured?

Accepted Answer

Musculocutaneous nerve

Answer

Radial nerve

Answer

Axillary nerve

Answer

Ulnar nerve

Question 10

Which ligament prevents the displacement of the humerus?

Accepted Answer

Glenohumeral

Answer

Coracoclavicular

Answer

Coracohumeral

Answer

Coracoacromial

Upper Limb — MCQs

Upper Limb — MCQs

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