Upper Limb Practice Questions

Q: If the musculocutaneous nerve is injured at the lateral cord of the brachial plexus, which clinical finding would be positive?

Sensory loss on the lateral aspect of the forearm. The **musculocutaneous nerve** (C5–C7) is a terminal branch of the **lateral cord** of the brachial plexus. It pierces the coracobrachialis muscle and descends between the biceps brachii and brachialis, supplying all three muscles in the anterior compartment of the arm. ### Why the correct answer is right: After supplying the flexors of the arm, the musculocutaneous nerve continues distal to the elbow as the **lateral cutaneous nerve of the forearm**. This nerve provides sensory innervation to the skin of the lateral (radial) aspect of the forearm from the elbow to the base of the thumb. Therefore, an injury to the musculocutaneous nerve results in sensory loss in this specific distribution. ### Why the other options are wrong: * **A. Loss of flexion at the elbow:** While the musculocutaneous nerve supplies the primary flexors (biceps and brachialis), elbow flexion is not completely lost because the **brachioradialis** (supplied by the radial nerve) and **pronator teres** (supplied by the median nerve) also contribute to flexion. * **C & D. Loss of extension of the forearm/wrist:** Extension of the forearm (triceps) and wrist (extensors) is the primary function of the **radial nerve**. ### NEET-PG High-Yield Pearls: * **The "Piercing" Nerve:** The musculocutaneous nerve is famous for piercing the **coracobrachialis** muscle. * **Biceps Reflex:** This nerve carries the afferent and efferent limbs of the **C5-C6** deep tendon reflex. * **Clinical Presentation:** Injury (often from trauma or heavy backpacks) leads to weak forearm flexion, weak supination (biceps is the chief supinator), and sensory loss on the lateral forearm.

Q: All of the following are posterior relations of the 3rd part of the axillary artery, except?

Ulnar Nerve. To master the relations of the axillary artery, one must understand its division into three parts by the **Pectoralis minor muscle**. The 3rd part extends from the lower border of the Pectoralis minor to the lower border of the Teres major. [1] ### **Why Ulnar Nerve is the Correct Answer** The **Ulnar nerve** is a branch of the medial cord. In the 3rd part of the axillary artery, it is located **medially** (between the artery and the axillary vein), not posteriorly. Therefore, it is the "except" in this question. ### **Analysis of Incorrect Options (Posterior Relations)** The posterior relations of the 3rd part of the axillary artery include: * **Radial Nerve (Option A):** This is the largest branch of the posterior cord and lies directly behind the artery before entering the radial groove. * **Axillary Nerve (Option B):** It lies posterior to the artery in the upper portion of the 3rd part before passing through the quadrangular space. * **Teres Major and Subscapularis (Option D):** These muscles, along with the Latissimus dorsi tendon, form the posterior wall of the axilla upon which the 3rd part of the artery rests. [1] ### **High-Yield NEET-PG Pearls** * **Rule of Cord Relations:** The names of the cords (Lateral, Medial, Posterior) describe their relationship to the **2nd part** of the axillary artery. * **3rd Part Relations Mnemonic:** * **Lateral:** Coracobrachialis, Musculocutaneous nerve, Lateral root of Median nerve. * **Medial:** Axillary vein, Ulnar nerve, Medial cutaneous nerve of forearm. * **Posterior:** Radial nerve, Axillary nerve, Subscapularis, Latissimus dorsi, Teres major. * **Clinical Fact:** The 3rd part of the axillary artery is the preferred site for ligation, provided it is done distal to the subscapular artery to maintain collateral circulation via the scapular anastomosis.

Q: Which of the following statements regarding anterior axillary lymph nodes is FALSE?

They drain the medial aspect of the mammary gland.. ### Explanation The axillary lymph nodes are divided into five main groups: anterior (pectoral), posterior (subscapular), lateral (humeral), central, and apical. Understanding their drainage patterns is high-yield for NEET-PG. **Why Option D is the Correct (False) Statement:** The **anterior (pectoral) group** of lymph nodes primarily drains the **lateral quadrants** of the mammary gland and the anterolateral aspect of the body wall above the level of the umbilicus [3]. The **medial aspect** of the mammary gland drains primarily into the **internal mammary (parasternal) lymph nodes**, which are located along the internal thoracic artery. **Analysis of Other Options:** * **Option A:** This is **true**. The anterior nodes lie along the lower border of the pectoralis minor muscle, deep to the pectoralis major, forming the anterior wall of the axilla [1]. * **Option B:** This is **true**. They are anatomically situated along the course of the **lateral thoracic vein**. * **Option C:** This is **true**. Lymph from the anterior, posterior, and lateral groups drains into the **central group**, which then drains into the apical group [1]. **Clinical Pearls for NEET-PG:** * **Breast Cancer Metastasis:** Approximately **75%** of lymph from the breast drains into the axillary nodes, specifically the anterior (pectoral) group first [1]. * **Sentinel Node:** The anterior group often contains the sentinel lymph node in breast cancer staging. * **Order of Drainage:** Anterior/Posterior/Lateral → Central → Apical → Supraclavicular nodes/Subclavian lymph trunk. * **Nerve at Risk:** During axillary lymph node dissection, the **long thoracic nerve** (supplying serratus anterior) and **thoracodorsal nerve** (supplying latissimus dorsi) are at risk of injury [2].

Q: What is the root value of the radial nerve?

C5, 6, 7, 8; T1. **Explanation:** The **Radial Nerve** is the largest branch of the brachial plexus and is the direct continuation of the **posterior cord**. It receives fibers from all five roots of the brachial plexus: **C5, C6, C7, C8, and T1**. This comprehensive root value is essential because the radial nerve supplies the entire extensor compartment of the upper limb (arm and forearm), requiring a wide range of motor and sensory inputs. **Analysis of Options:** * **Option C (Correct):** Reflects the complete contribution from the posterior cord. C5-C6 fibers primarily supply the brachioradialis and supinator, C7 supplies the triceps, and C8-T1 contribute to the long extensors of the wrist and fingers. * **Option A & B:** These include C3 or C4 roots. These roots contribute to the cervical plexus (e.g., Phrenic nerve), not the brachial plexus. * **Option D:** This excludes C5 and includes T2. While T2 may contribute via the intercostobrachial nerve, it is not a standard component of the radial nerve's functional root value. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Injury:** The radial nerve is most commonly injured in the **spiral groove** (mid-shaft humerus fracture), leading to **Wrist Drop** due to paralysis of the extensors. * **Triceps Sparing:** In a spiral groove injury, the long head of the triceps is spared because its nerve branch arises in the axilla, proximal to the groove. * **Finger Drop:** Injury to the **Posterior Interosseous Nerve (PIN)**, a deep branch of the radial nerve, causes "Finger Drop" but spares the wrist extensors (no wrist drop). * **Saturday Night Palsy:** Compression of the nerve in the axilla (e.g., crutch palsy) affects all muscles, including the triceps.

Q: Which muscle does NOT contribute to the dorsal digital expansion?

Adductor pollicis. ### Explanation The **Dorsal Digital Expansion (Extensor Expansion)** is a specialized aponeurosis located on the dorsum of the fingers that coordinates complex movements of the hand. It serves as a common insertion point for several muscles to allow for the simultaneous extension of interphalangeal (IP) joints and flexion of metacarpophalangeal (MCP) joints [2]. **Why Adductor Pollicis is the Correct Answer:** The **Adductor pollicis** is a muscle of the thenar eminence (specifically the deep palmar compartment) that acts on the thumb. The thumb does not possess a formal dorsal digital expansion similar to the four fingers. Furthermore, the Adductor pollicis inserts into the ulnar side of the base of the proximal phalanx of the thumb and the sesamoid bone, not into an extensor hood. **Analysis of Incorrect Options:** * **Extensor Digitorum:** This is the primary contributor. Its tendons flatten out over the MCP joints to form the central "hood" or backbone of the expansion [2]. * **Lumbricals:** These originate from the tendons of the Flexor Digitorum Profundus and insert into the **radial side** of the extensor expansion [1]. They are crucial for the "Z-movement" (MCP flexion + IP extension) [1]. * **Interossei:** Both Palmar and Dorsal interossei insert into the extensor expansion [1]. They assist the lumbricals in IP extension and MCP flexion while performing adduction/abduction. **High-Yield NEET-PG Pearls:** * **The "Z-position":** The combination of Lumbricals and Interossei acting through the expansion results in MCP flexion and IP extension [1]. * **Nerve Supply:** Lumbricals 1 & 2 (Median nerve); Lumbricals 3 & 4 and all Interossei (Ulnar nerve). * **Clinical Correlation:** Damage to the extensor expansion can lead to deformities like **Boutonnière deformity** (central slip tear) or **Swan-neck deformity**.

Q: Ossification is typically seen at two months for which of the following carpal bones?

Capitate. The ossification of carpal bones follows a predictable chronological sequence, typically occurring in a clockwise or counter-clockwise direction starting from the largest bone. **Why Capitate is Correct:** The **Capitate** is the first carpal bone to begin ossification. It typically appears at **1–2 months** of age. It is followed closely by the Hamate. Identifying these centers on a pediatric X-ray is a standard method for assessing "bone age" and general skeletal development. During fetal development, most bones are modeled in cartilage and then transformed into bone by ossification [1]. **Analysis of Incorrect Options:** * **Hamate:** This is the second bone to ossify, appearing shortly after the capitate, usually at **3 months**. While close, the capitate is the definitive answer for the 2-month mark. * **Lunate:** This bone ossifies much later, typically around **4–5 years** of age. * **Scaphoid:** This is one of the last carpal bones to ossify, usually appearing between **5–6 years** of age. **High-Yield NEET-PG Pearls:** * **Mnemonic for Order of Ossification:** **C**apitate, **H**amate, **T**riquetral, **L**unate, **S**caphoid, **T**rapezium, **T**rapezoid, **P**isiform (**C**ome **H**ome **T**o **L**et **S**ay **T**hank **T**o **P**apa). * **Chronology Simplified:** * 1st year: Capitate (1-2m), Hamate (3m) * 3rd year: Triquetral * 4th year: Lunate * 5th year: Scaphoid, Trapezium, Trapezoid (approximate) * 12th year: **Pisiform** (Last to ossify; sesamoid bone). * **Clinical Fact:** At birth, no carpal bones are ossified; the wrist appears as a wide radiolucent gap on X-ray.

Q: All of the following features can be observed after injury to the axillary nerve, except?

Loss of overhead abduction. **Explanation:** The **axillary nerve (C5, C6)** is a branch of the posterior cord of the brachial plexus. It supplies the deltoid and teres minor muscles and provides sensory innervation to the skin over the lower half of the deltoid (Regimental badge area). **Why "Loss of overhead abduction" is the correct answer:** Abduction of the arm is a multi-stage process involving different muscles: 1. **0°–15°:** Initiated by the **Suprascapular nerve** (Supraspinatus). 2. **15°–90°:** Carried out by the **Axillary nerve** (Deltoid). 3. **90°–180° (Overhead):** Produced by the rotation of the scapula by the **Long thoracic nerve** (Serratus anterior) and the **Spinal accessory nerve** (Trapezius). Since overhead abduction is primarily the function of the Serratus anterior and Trapezius, it remains intact even if the axillary nerve is damaged. **Analysis of Incorrect Options:** * **Loss of rounded contour:** The deltoid muscle gives the shoulder its rounded shape. Paralysis leads to a "flat shoulder" or "squared-off" appearance. * **Loss of sensation (Lateral upper arm):** The axillary nerve gives off the **upper lateral cutaneous nerve of the arm**, which supplies the "Regimental badge area." * **Atrophy of the deltoid:** Denervation of the deltoid leads to muscle wasting, making the underlying greater tubercle of the humerus prominent. **High-Yield Clinical Pearls for NEET-PG:** * **Common sites of injury:** Surgical neck of the humerus fracture and anterior dislocation of the shoulder joint. * **Regimental Badge Sign:** Sensory loss over the lower deltoid is the most reliable clinical sign of axillary nerve injury. * **Quadrangular Space:** The axillary nerve passes through this space along with the posterior circumflex humeral artery.

Q: A 23-year-old male medical student fell asleep in his chair with an anatomy atlas wedged into his axilla. Upon waking, he was unable to extend the forearm, wrist, or fingers. Movements of the ipsilateral shoulder joint appear to be normal. Which of the following nerves was most likely compressed, producing these symptoms?

Radial nerve. ### Explanation **1. Why the Radial Nerve is Correct:** The clinical presentation describes **"Saturday Night Palsy"** (or in this case, "Anatomy Student Palsy"). Compression of the **Radial nerve** in the axilla—often due to pressure from a chair back or crutches—leads to a loss of function in all muscles supplied by the nerve distal to the site of injury. * **Triceps Brachii:** Loss of forearm extension. * **Extensor Carpi Radialis/Ulnaris:** Loss of wrist extension (Wrist drop). * **Extensor Digitorum:** Loss of finger extension at the MCP joints. Since the compression occurred in the axilla, the long head of the triceps is involved, explaining the inability to extend the forearm. **2. Why the Incorrect Options are Wrong:** * **Lateral Cord:** This gives rise to the Musculocutaneous nerve. Injury would result in weak elbow flexion (Biceps) and sensory loss on the lateral forearm, not loss of extension. * **Medial Cord:** This gives rise to the Ulnar nerve. Injury would cause "Claw hand" and loss of intrinsic hand muscle function, but wrist/finger extension would remain intact. * **Median Nerve:** Injury would affect forearm pronation, wrist flexion, and thumb opposition (Ape thumb deformity), but would not cause wrist drop. **3. High-Yield Clinical Pearls for NEET-PG:** * **Level of Lesion:** If the Radial nerve is injured in the **spiral groove** (e.g., mid-shaft humerus fracture), the Triceps is usually spared (extension of forearm is possible), but wrist drop still occurs. * **Sensory Loss:** In axillary compression, there is sensory loss over the posterior arm, forearm, and the dorsal web space of the thumb. * **Rule of Thumb:** Radial nerve = **Extensors** (Great Extensor Nerve). If you can't "hitchhike" or "extend," think Radial.

Question 1

A 31-year-old roofer presents with tenosynovitis resulting from a deep penetrating wound in the palm caused by a large nail. On examination, he has an infection in the ulnar bursa. This infection most likely resulted in necrosis of which of the following tendons?

Accepted Answer

Tendon of flexor digitorum profundus

Answer

Tendon of flexor carpi ulnaris

Answer

Tendon of flexor pollicis longus

Answer

Tendon of palmaris longus

Question 2

If the musculocutaneous nerve is injured at the lateral cord of the brachial plexus, which clinical finding would be positive?

Accepted Answer

Sensory loss on the lateral aspect of the forearm

Answer

Loss of flexion at the elbow

Answer

Loss of extension of the forearm

Answer

Loss of extension of the wrist

Question 3

All of the following are posterior relations of the 3rd part of the axillary artery, except?

Accepted Answer

Ulnar Nerve

Answer

Radial Nerve

Answer

Axillary Nerve

Answer

Teres Major and Subscapularis muscles

Question 4

Which of the following statements regarding anterior axillary lymph nodes is FALSE?

Accepted Answer

They drain the medial aspect of the mammary gland.

Answer

They are located on the anterior wall of the axilla on the pectoral muscle.

Answer

They are situated along the lateral thoracic vein.

Answer

They drain into the central axillary lymph nodes.

Question 5

Which of the following statements about the clavicle is false?

Accepted Answer

Fractures typically occur at the junction of the medial third and lateral two-thirds

Answer

Ossifies partly in membrane and partly in cartilage

Answer

Transmits part of the weight of the upper limb to the axial skeleton

Answer

It is subcutaneous throughout its length

Question 6

What is the root value of the radial nerve?

Accepted Answer

C5, 6, 7, 8; T1

Answer

C3, 4, 5, 6, 7

Answer

C4, 5, 6, 7, 8

Answer

C6, 7, 8; T1, 2

Question 7

Which muscle does NOT contribute to the dorsal digital expansion?

Accepted Answer

Adductor pollicis

Answer

Interossei

Answer

Lumbricals

Answer

Extensor digitorum

Question 8

Ossification is typically seen at two months for which of the following carpal bones?

Accepted Answer

Capitate

Answer

Lunate

Answer

Scaphoid

Answer

Hamate

Question 9

All of the following features can be observed after injury to the axillary nerve, except?

Accepted Answer

Loss of overhead abduction

Answer

Loss of rounded contour of the shoulder

Answer

Loss of sensation along the lateral side of the upper arm

Answer

Atrophy of the deltoid muscle

Question 10

A 23-year-old male medical student fell asleep in his chair with an anatomy atlas wedged into his axilla. Upon waking, he was unable to extend the forearm, wrist, or fingers. Movements of the ipsilateral shoulder joint appear to be normal. Which of the following nerves was most likely compressed, producing these symptoms?

Accepted Answer

Radial nerve

Answer

Lateral cord of the brachial plexus

Answer

Medial cord of the brachial plexus

Answer

Median nerve

Upper Limb — MCQs

Upper Limb — MCQs

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