Upper Limb Practice Questions

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.

Q: A 43-year-old man presents with a whiplash injury after his car was struck from behind. An MRI reveals cervical disk herniation. Physical examination shows loss of elbow extension, absence of the triceps reflex, and loss of extension of the metacarpophalangeal joints on the ipsilateral side. Which spinal nerve is most likely affected?

C7. ### Explanation The patient presents with a classic constellation of symptoms pointing toward a **C7 spinal nerve** injury. In the cervical spine, a herniated disc typically compresses the nerve root exiting at that level (e.g., a C6-C7 disc herniation affects the C7 nerve) [1]. **Why C7 is the Correct Answer:** The C7 nerve root provides the primary motor innervation for: 1. **Elbow Extension:** The **Triceps brachii** is predominantly supplied by C7 (via the radial nerve). Loss of elbow extension is a hallmark of C7 palsy. 2. **Triceps Reflex:** This is the specific deep tendon reflex used to test the C7 cord level. 3. **Finger Extension:** Extension of the metacarpophalangeal (MCP) joints is performed by the **extensor digitorum**, which is primarily innervated by C7. **Why Other Options are Incorrect:** * **C5:** Injury leads to weakness in shoulder abduction (Deltoid) and elbow flexion (Biceps), with loss of the Biceps reflex. * **C6:** Injury affects elbow flexion (Brachialis/Biceps) and wrist extension (Extensor carpi radialis). It is associated with the Brachioradialis reflex. * **C8:** Injury primarily affects **finger flexion** (making a fist) and thumb movements, not elbow extension. **NEET-PG High-Yield Pearls:** * **Cervical Rule:** In the cervical spine, there are 8 nerves but only 7 vertebrae. Nerve C1-C7 exit **above** their corresponding vertebrae; C8 exits below C7. * **Reflex Map:** C5/C6 = Biceps/Brachioradialis; **C7 = Triceps**; L3/L4 = Patellar; S1 = Achilles. * **Sensory C7:** Sensory loss typically occurs in the **middle finger** ("C7 points to heaven").

Q: Which structure is intracapsular but extrasynovial?

Long head of biceps. The **Long Head of the Biceps Brachii (LHBB)** is a unique anatomical structure in the shoulder joint. It originates from the supraglenoid tubercle of the scapula, which is located inside the fibrous capsule of the glenohumeral joint. However, as the tendon passes through the joint, the synovial membrane reflects around it, forming a tubular sheath. This means the tendon is physically located within the joint capsule (**intracapsular**) but is excluded from the synovial cavity by this membrane (**extrasynovial**). **Analysis of Options:** * **Long head of biceps (Correct):** It remains extrasynovial to prevent friction and maintain a sterile environment within the synovial fluid while traversing the joint to reach the bicipital groove. * **Long head of triceps:** This originates from the infraglenoid tubercle of the scapula. It is entirely **extracapsular** and does not enter the shoulder joint. * **Short head of biceps:** This originates from the tip of the coracoid process. It is an **extracapsular** structure. * **Medial head of biceps:** This is a **distractor**; the biceps brachii only has two heads (long and short). The triceps has a medial head, but it originates from the posterior surface of the humerus, far from the joint capsule. **High-Yield Clinical Pearls for NEET-PG:** * **Other Intracapsular, Extrasynovial structures:** The **Popliteus tendon** in the knee joint and the **Ligamentum teres** in the hip joint follow the same principle. * **Bicipital Groove:** The LHBB is held in the intertubercular sulcus by the transverse humeral ligament. * **SLAP Lesion:** Injuries to the superior labrum where the LHBB attaches are high-yield clinical correlations.

Q: A knife wound to the neck damages the posterior cord of the brachial plexus. Which of the following muscles would be most likely to be paralyzed?

Deltoid. The brachial plexus is a high-yield topic for NEET-PG. To solve this question, one must trace the terminal branches of the **Posterior Cord**. **1. Why Deltoid is Correct:** The posterior cord (formed by the posterior divisions of all three trunks, C5-T1) gives rise to five terminal branches, remembered by the mnemonic **ULTRA**: **U**pper subscapular, **L**ower subscapular, **T**horacodorsal, **R**adial, and **A**xillary nerves. The **Axillary nerve (C5, C6)** specifically innervates the **Deltoid** and Teres minor muscles. Therefore, damage to the posterior cord will result in paralysis of the deltoid, leading to loss of shoulder abduction (beyond 15 degrees). **2. Why the Other Options are Incorrect:** * **Flexor carpi ulnaris (B):** This muscle is innervated by the **Ulnar nerve**, which is a terminal branch of the **Medial cord**. * **Flexor digitorum superficialis (C):** This muscle is innervated by the **Median nerve**, which is formed by contributions from both the **Medial and Lateral cords**. * **Flexor pollicis brevis (D):** The superficial head is innervated by the **Median nerve** (Recurrent branch) and the deep head by the **Ulnar nerve**. Neither originates from the posterior cord. **Clinical Pearls for NEET-PG:** * **Posterior Cord mnemonic (ULTRA):** Upper subscapular (Subscapularis), Lower subscapular (Subscapularis/Teres major), Thoracodorsal (Latissimus dorsi), Radial (Extensors of arm/forearm), Axillary (Deltoid). * **Crutch Palsy/Saturday Night Palsy:** These typically involve compression of the posterior cord or the radial nerve. * **Quadrangular Space:** The Axillary nerve passes through this space along with the posterior circumflex humeral artery; a fracture of the surgical neck of the humerus is a common site of injury.

Q: All of the following bones form the proximal row of carpal bones except?

Trapezium. The carpal bones are organized into two rows: **Proximal** and **Distal**. Understanding this arrangement is fundamental for solving upper limb anatomy questions in NEET-PG. ### **Explanation of the Correct Answer** **C. Trapezium:** This is the correct answer because the Trapezium belongs to the **distal row** of carpal bones, not the proximal row. It is the most lateral bone of the distal row and articulates with the first metacarpal to form the thumb's saddle joint. ### **Analysis of Incorrect Options** The proximal row consists of four bones (lateral to medial): * **D. Scaphoid:** The most lateral bone of the proximal row; it is the most commonly fractured carpal bone. * **A. Lunate:** Located between the scaphoid and triquetrum; it is the most commonly dislocated carpal bone. * **Triquetrum:** A pyramidal bone located medially. * **B. Pisiform:** A sesamoid bone (within the Flexor Carpi Ulnaris tendon) that sits on the anterior surface of the triquetrum. Note: The option "Piriformis" in the question is likely a distractor or typo for "Pisiform," as Piriformis is a muscle of the gluteal region. ### **High-Yield Clinical Pearls for NEET-PG** * **Mnemonic:** "She Looks Too Pretty, Try To Catch Her" (Scaphoid, Lunate, Triquetrum, Pisiform / Trapezium, Trapezoid, Capitate, Hamate). * **Scaphoid Fracture:** Characterized by tenderness in the **Anatomical Snuffbox**. Risk of avascular necrosis due to retrograde blood supply. * **Lunate Dislocation:** May compress the **Median Nerve** within the carpal tunnel. * **Capitate:** The largest carpal bone and the first to begin ossification. * **Pisiform:** The last carpal bone to ossify.

Q: Which nerve is involved in Guyon's canal syndrome?

Ulnar nerve. **Explanation:** **Guyon’s Canal Syndrome** (also known as Ulnar Tunnel Syndrome) is a compression neuropathy caused by the entrapment of the **ulnar nerve** as it passes through Guyon’s canal at the wrist. **1. Why the Ulnar Nerve is Correct:** Guyon’s canal is an anatomical fibro-osseous tunnel located on the medial (ulnar) side of the wrist [1]. Its boundaries include the **pisiform bone** medially, the **hook of the hamate** laterally, and the **volar carpal ligament** forming the roof. The ulnar nerve and ulnar artery pass through this space [1]. Compression here typically results from repetitive trauma (e.g., "handlebar palsy" in cyclists) or ganglion cysts, leading to sensory loss in the medial 1.5 fingers and weakness of the intrinsic hand muscles. **2. Why Other Options are Incorrect:** * **Median Nerve:** This nerve passes through the **carpal tunnel** [1]. Compression here leads to Carpal Tunnel Syndrome, affecting the lateral 3.5 fingers and the thenar muscles [1]. * **Radial Nerve:** This nerve primarily supplies the posterior compartment of the arm and forearm. Compression of its superficial branch at the wrist is known as **Wartenberg’s Syndrome**, causing sensory loss on the dorsal-lateral hand. * **Axillary Nerve:** This nerve arises from the posterior cord of the brachial plexus and winds around the surgical neck of the humerus. It is not related to the wrist or hand anatomy. **Clinical Pearls for NEET-PG:** * **Handlebar Palsy:** A classic clinical scenario for Guyon’s canal syndrome in long-distance cyclists. * **Sparing of Sensation:** Unlike ulnar nerve lesions at the elbow (Cubital Tunnel), sensation to the **dorsal** medial 1.5 fingers is often **preserved** in Guyon's canal syndrome because the dorsal cutaneous branch of the ulnar nerve arises proximal to the wrist. * **Froment’s Sign:** Positive in ulnar nerve palsy due to adductor pollicis paralysis.

Q: The palmar interossei are supplied by which nerve branch?

Deep branch of the ulnar nerve. ### Explanation **1. Why the Correct Answer is Right:** The **deep branch of the ulnar nerve** is the primary motor nerve of the hand. After passing through Guyon’s canal, it pierces the muscles of the hypothenar eminence and curves across the palm, following the deep palmar arch. It supplies all the **interossei** (both 3-4 palmar and 4 dorsal), the two medial lumbricals, the hypothenar muscles, and the adductor pollicis [2]. The palmar interossei are responsible for **adducting** the fingers (PAD) toward the midline of the hand [2]. **2. Why the Incorrect Options are Wrong:** * **Superficial branch of the ulnar nerve:** This branch is primarily sensory, supplying the skin of the medial 1.5 fingers. Its only motor contribution is to the **Palmaris brevis** muscle [2]. * **Superficial branch of the median nerve:** This is a purely sensory branch (Palmar cutaneous branch) that supplies the skin over the lateral aspect of the palm [1]. The median nerve's motor supply in the hand is limited to the **LOAF** muscles (Lateral two lumbricals, Opponens pollicis, Abductor pollicis brevis, and Flexor pollicis brevis) [2]. * **Radial nerve:** The radial nerve (via the posterior interosseous nerve) supplies the extensors in the forearm [3]. It provides **no motor supply** to the intrinsic muscles of the hand. **3. High-Yield Clinical Pearls for NEET-PG:** * **PAD & DAB:** Remember **P**almar **AD**duct (3 muscles) and **D**orsal **AB**duct (4 muscles). * **Ulnar Paradox:** The higher the lesion of the ulnar nerve, the less prominent the clawing (because the long flexors are also paralyzed). * **Froment’s Sign:** Tests for **Adductor pollicis** palsy (ulnar nerve). If weak, the patient compensates by flexing the thumb at the IP joint using the median nerve (Flexor pollicis longus). * **Egawa’s Test:** Tests the **Dorsal interossei** by asking the patient to side-to-side (abduct) the middle finger.

Question 1

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 2

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 3

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

Question 4

A 43-year-old man presents with a whiplash injury after his car was struck from behind. An MRI reveals cervical disk herniation. Physical examination shows loss of elbow extension, absence of the triceps reflex, and loss of extension of the metacarpophalangeal joints on the ipsilateral side. Which spinal nerve is most likely affected?

Accepted Answer

C7

Answer

C5

Answer

C6

Answer

C8

Question 5

All of the following are associated with pronator syndrome, except?

Accepted Answer

Pronator quadratus

Answer

Struthers ligament

Answer

Bicipital aponeurosis

Answer

Flexor digitorum superficialis (FDS)

Question 6

Which structure is intracapsular but extrasynovial?

Accepted Answer

Long head of biceps

Answer

Long head of triceps

Answer

Short head of biceps

Answer

Medial head of biceps

Question 7

A knife wound to the neck damages the posterior cord of the brachial plexus. Which of the following muscles would be most likely to be paralyzed?

Accepted Answer

Deltoid

Answer

Flexor carpi ulnaris

Answer

Flexor digitorum superficialis

Answer

Flexor pollicis brevis

Question 8

All of the following bones form the proximal row of carpal bones except?

Accepted Answer

Trapezium

Answer

Lunate

Answer

Piriformis

Answer

Scaphoid

Question 9

Which nerve is involved in Guyon's canal syndrome?

Accepted Answer

Ulnar nerve

Answer

Axillary nerve

Answer

Median nerve

Answer

Radial nerve

Question 10

The palmar interossei are supplied by which nerve branch?

Accepted Answer

Deep branch of the ulnar nerve

Answer

Superficial branch of the ulnar nerve

Answer

Superficial branch of the median nerve

Answer

Radial nerve

Upper Limb — MCQs

Upper Limb — MCQs

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