Upper Limb Practice Questions

Q: Which of the following muscles of the scapula does NOT function as a retractor?

Levator scapulae. The movement of **scapular retraction** (adduction) involves pulling the medial border of the scapula toward the vertebral column. This action is primarily performed by muscles with horizontally oriented fibers that originate from the spine and insert into the medial border or acromion of the scapula. **Why Levator Scapulae is the Correct Answer:** The **Levator scapulae** originates from the transverse processes of C1-C4 and inserts into the superior angle of the scapula. Its primary function is to **elevate** the scapula and assist in downward rotation of the glenoid cavity. Because its fibers run vertically, it does not contribute to retraction. **Analysis of Incorrect Options:** * **Trapezius:** The middle fibers of the trapezius run horizontally from the spinous processes to the acromion and spine of the scapula. It is the **primary retractor** of the scapula. * **Rhomboid Major & Minor:** These muscles originate from the nuchal ligament/spinous processes (C7-T5) and insert into the medial border of the scapula. Their oblique-horizontal orientation allows them to powerfully **retract** and rotate the scapula. **High-Yield NEET-PG Pearls:** * **Nerve Supply:** Trapezius is supplied by the **Spinal Accessory Nerve (CN XI)**, while the Rhomboids and Levator scapulae are supplied by the **Dorsal Scapular Nerve (C5)**. * **Winged Scapula:** True winging (medial) is due to **Serratus anterior** palsy (Long thoracic nerve). "Pseudo-winging" or lateral displacement occurs with Trapezius palsy. * **Scapular Protractor:** The **Serratus anterior** is the chief protractor (boxer’s muscle), acting as the functional antagonist to the retractors listed above.

Q: All of the following arteries participate in the formation of the anastomosis around the scapula except?

Lateral thoracic artery. The **scapular anastomosis** is a vital collateral circulation network that allows blood to reach the upper limb if the first or second parts of the axillary artery are obstructed. It occurs primarily between branches of the **subclavian artery** and the **third part of the axillary artery**. ### Why Lateral Thoracic Artery is the Correct Answer: The **Lateral thoracic artery** (Option C) is a branch of the *second part* of the axillary artery. It travels along the lateral border of the pectoralis minor to supply the serratus anterior and mammary glands [1]. It does **not** travel to the dorsal or costal surfaces of the scapula and therefore does not participate in this specific anastomosis. ### Analysis of Other Options: * **Deep branch of transverse cervical artery (Dorsal Scapular Artery):** Arises from the thyrocervical trunk (subclavian). It runs along the medial border of the scapula. * **Suprascapular artery:** Arises from the thyrocervical trunk (subclavian). It passes over the superior transverse scapular ligament to reach the supraspinous and infraspinous fossae. * **Circumflex scapular artery:** A branch of the subscapular artery (from the 3rd part of the axillary artery). It curves around the lateral border of the scapula to enter the infraspinous fossa. ### NEET-PG High-Yield Pearls: * **The Connection:** The anastomosis connects the **1st part of the subclavian artery** (via the thyrocervical trunk) to the **3rd part of the axillary artery** (via the subscapular artery). * **Direction of Flow:** If the axillary artery is ligated between the 1st and 3rd parts, blood flow **reverses** in the circumflex scapular artery to reach the distal axillary artery. * **Location:** The anastomosis occurs in three main areas: the supraspinous fossa, the infraspinous fossa, and along the medial border of the scapula.

Q: A penetrating wound to the axilla that severs the posterior cord of the brachial plexus would denervate which muscle?

Deltoid. The **posterior cord** of the brachial plexus is formed by the union of the posterior divisions of all three trunks (C5-T1). It gives rise to five major branches, easily remembered by the mnemonic **ULTRA**: **U**pper subscapular, **L**ower subscapular, **T**horacodorsal, **R**adial, and **A**xillary nerves. 1. **Why Deltoid is Correct:** The **Axillary nerve** (C5, C6) is a terminal branch of the posterior cord. It supplies the **deltoid** and teres minor muscles. Therefore, severing the posterior cord results in the denervation of the deltoid, leading to loss of shoulder abduction (beyond 15 degrees) and atrophy of the shoulder contour. 2. **Why Other Options are Incorrect:** * **Serratus anterior:** Supplied by the **Long Thoracic nerve**, which arises directly from the **roots** (C5, C6, C7) of the brachial plexus, not the cords. * **Pronator teres:** Supplied by the **Median nerve**, which is formed by the contribution of the **lateral and medial cords**, not the posterior cord. * **Biceps brachii:** Supplied by the **Musculocutaneous nerve**, which is a branch of the **lateral cord** (C5-C7). **High-Yield Clinical Pearls for NEET-PG:** * **Radial Nerve:** The largest branch of the posterior cord; injury leads to **wrist drop**. * **Quadrangular Space:** The axillary nerve passes through this space along with the posterior circumflex humeral artery. * **Thoracodorsal Nerve:** Also from the posterior cord; supplies the **Latissimus dorsi** ("Climber's muscle") [1]. * **Posterior Cord Injury:** Typically results in "Crutch Palsy" or "Saturday Night Palsy," primarily affecting the extensors of the arm and forearm.

Q: The Pen Test is primarily used to assess the function of which nerve?

Median Nerve. The **Pen Test** is a clinical assessment used to evaluate the motor function of the **Median Nerve**, specifically the integrity of the **Abductor Pollicis Brevis (APB)** muscle. [1] ### 1. Why the Median Nerve is Correct The Median nerve supplies the muscles of the **thenar eminence** (LOAF: Lumbricals 1 & 2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis). The APB is responsible for **palmar abduction**—moving the thumb perpendicular to the plane of the palm. [1] * **The Test:** The patient’s hand is placed flat on a table (supine). They are asked to touch a pen held horizontally above the thumb. If the Median nerve is injured (as in Carpal Tunnel Syndrome or Ape Thumb Deformity), the patient cannot abduct the thumb to touch the pen. ### 2. Why Other Options are Incorrect * **Ulnar Nerve:** Assessed via **Froment’s Sign** (testing Adductor Pollicis) or the **Card Test** (testing Palmar Interossei for adduction). [1] Ulnar nerve injury leads to "Claw Hand." * **Radial Nerve:** Assessed by checking for **Wrist Drop** or the ability to extend the wrist and metacarpophalangeal joints. [1] * **Posterior Interosseous Nerve (PIN):** A motor branch of the Radial nerve. Injury results in "Finger Drop" (loss of extension at MCP joints) without wrist drop, as the Extensor Carpi Radialis Longus is spared. ### 3. Clinical Pearls for NEET-PG * **Ape Thumb Deformity:** Caused by Median nerve palsy; characterized by the thumb falling into the same plane as the fingers due to loss of thenar muscle action. * **Ochsner’s Clasping Test:** Another test for Median nerve (specifically FDP of index/middle fingers); the index finger remains straight when clasping hands. * **Point of Injury:** High Median nerve lesions (at the elbow) affect the long flexors, while low lesions (at the wrist) primarily affect the thenar muscles. [1]

Q: All of the following structures pass through the intermediate compartment of the extensor retinaculum except?

Anterior interosseous vein. The extensor retinaculum of the wrist is divided into **six fibro-osseous compartments** by septa passing from the retinaculum to the radius and ulna [1]. ### **Explanation of the Correct Answer** The **4th compartment** (often referred to as the intermediate compartment) contains the Extensor Digitorum (ED), Extensor Indicis (EI), the Posterior Interosseous Nerve (PIN), and the **Anterior Interosseous Artery (AIA)** [1]. The **Anterior Interosseous Vein (AIV)** is the correct answer (the "except") because, while the AIA pierces the interosseous membrane to enter the posterior compartment, the AIV typically drains into the deep venous system of the forearm before reaching the extensor retinaculum. In some anatomical contexts, the **Posterior Interosseous Artery** is also associated with this space, but the AIV is not a standard constituent of the 4th compartment. ### **Analysis of Incorrect Options** * **A & B (Extensor Digitorum & Extensor Indicis):** These are the primary tendons passing through the 4th compartment [1]. They share a common synovial sheath. * **C (Posterior Interosseous Nerve):** This nerve (a branch of the radial nerve) passes deep to the tendons in the 4th compartment to provide sensory innervation to the wrist joint capsule. ### **High-Yield Facts for NEET-PG** To master the extensor retinaculum, remember the contents of all six compartments (Lateral to Medial): 1. **1st:** Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB) — *Site of De Quervain’s Tenosynovitis* [1]. 2. **2nd:** Extensor Carpi Radialis Longus (ECRL), Extensor Carpi Radialis Brevis (ECRB) [1]. 3. **3rd:** Extensor Pollicis Longus (EPL) — *Hooks around Lister’s Tubercle* [1]. 4. **4th:** ED, EI, PIN, and AIA [1]. 5. **5th:** Extensor Digiti Minimi (EDM) [1]. 6. **6th:** Extensor Carpi Ulnaris (ECU) [1]. **Mnemonic:** **2-2-1-2-1-1** (Number of tendons in each compartment).

Q: Which movements of the thumb are not affected in a radial nerve injury?

Opposition. **Explanation:** The **Radial Nerve** is primarily responsible for the motor innervation of the posterior compartment of the arm and forearm [1]. In the hand, it supplies no intrinsic muscles; its contribution to thumb movement is limited to the **Extensor Pollicis Longus (EPL)**, **Extensor Pollicis Brevis (EPB)**, and **Abductor Pollicis Longus (APL)** via its deep branch (Posterior Interosseous Nerve) [1]. **1. Why Opposition is the correct answer:** Opposition is a complex movement involving flexion, abduction, and medial rotation of the thumb. It is primarily mediated by the **Opponens Pollicis** muscle, which is located in the thenar eminence. This muscle is innervated by the **Recurrent branch of the Median Nerve** [1]. Since the Median nerve remains intact in a pure radial nerve injury, opposition is preserved. **2. Why the other options are incorrect:** * **Extension (Option C):** Thumb extension at the CMC, MCP, and IP joints is performed by the EPL and EPB [1]. These are supplied by the Posterior Interosseous Nerve (PIN), a branch of the radial nerve. Thus, extension is lost. * **Abduction (Option B):** While the Abductor Pollicis Brevis (Median nerve) helps, the **Abductor Pollicis Longus (APL)** is a major abductor of the thumb and is supplied by the radial nerve (PIN) [1]. Therefore, abduction is significantly weakened/affected. **High-Yield Clinical Pearls for NEET-PG:** * **Wrist Drop:** The hallmark of high radial nerve injury (e.g., Saturday Night Palsy or Mid-shaft humerus fracture). * **Rule of Thumb:** The **Median Nerve** is the "Nerve of Precision" (controls thenar muscles for opposition), while the **Ulnar Nerve** is the "Nerve of Power" (adduction via Adductor Pollicis) [1]. * **Sensory Loss:** In radial nerve injury, sensory loss is typically minimal, localized to the small area of the **dorsal first web space**.

Q: The circumflex scapular artery is a branch of which structure?

Subscapular artery. **Explanation:** The **circumflex scapular artery** is the larger of the two terminal branches of the **subscapular artery**. The subscapular artery itself is the largest branch of the **third part of the axillary artery**. The circumflex scapular artery curves around the lateral border of the scapula, passing through the **upper triangular space** (bounded by Teres minor, Teres major, and the long head of triceps). It plays a vital role in the **scapular anastomosis**, which ensures collateral circulation to the upper limb if the axillary artery is obstructed. **Analysis of Options:** * **Option A (Thyrocervical trunk):** This is a branch of the first part of the subclavian artery. It gives off the suprascapular and transverse cervical arteries, which contribute to the scapular anastomosis but do not give rise to the circumflex scapular artery. * **Option C (Subclavian artery):** While the subclavian artery eventually becomes the axillary artery, it does not directly give off the circumflex scapular artery. * **Option D (Aorta):** The aorta gives rise to the brachiocephalic trunk (on the right) and the subclavian artery (on the left), making it too proximal to be the direct source. **High-Yield Clinical Pearls for NEET-PG:** * **Scapular Anastomosis:** Involves the Suprascapular artery (from Thyrocervical trunk), Deep branch of Transverse cervical artery (from Thyrocervical trunk), and Circumflex scapular artery (from Subscapular artery). * **Upper Triangular Space:** Contains the circumflex scapular artery. * **Quadrangular Space:** Contains the axillary nerve and posterior circumflex humeral artery. * **Lower Triangular Space:** Contains the radial nerve and profunda brachii artery.

Q: Erb's palsy occurs due to involvement of which part of the brachial plexus?

Upper trunk. **Explanation:** **Erb’s Palsy** (Waiters’s tip deformity) is a clinical condition resulting from an injury to the **Upper Trunk** of the brachial plexus, specifically at the junction of C5 and C6 nerve roots, known as **Erb’s Point** [2]. 1. **Why the Upper Trunk is Correct:** Erb’s point is the site where six nerves meet (C5, C6 roots, suprascapular nerve, nerve to subclavius, and the anterior/posterior divisions of the upper trunk). Injury here—often due to birth trauma such as shoulder dystocia or a fall on the shoulder—paralyzes muscles supplied by C5 and C6, including the deltoid, biceps brachii, brachialis, and supraspinatus [1][2]. This results in the characteristic "policeman’s tip" position: arm adducted, medially rotated, and forearm extended and pronated. 2. **Why other options are incorrect:** * **Middle Trunk (C7):** Isolated middle trunk injuries are rare. Involvement would primarily affect the radial nerve distribution (extensors), not the classic Erb's presentation. * **Medial Cord:** Injury here typically involves C8-T1 fibers, leading to **Klumpke’s Paralysis**, characterized by a "claw hand" due to the loss of intrinsic hand muscles. * **Lateral Trunk:** This is a distractor; the brachial plexus consists of roots, trunks, divisions, cords, and branches. There is no "lateral trunk," only a lateral cord. **High-Yield Clinical Pearls for NEET-PG:** * **Nerves involved:** Suprascapular, Axillary, and Musculocutaneous nerves. * **Deformity components:** Adduction (loss of deltoid/supraspinatus), Medial rotation (loss of infraspinatus/teres minor), and Extension/Pronation (loss of biceps/brachialis). * **Reflexes:** The Biceps and Supinator reflexes are lost. * **Sensory loss:** Small area over the lower part of the deltoid (regimental badge area).

Question 1

Which of the following muscles of the scapula does NOT function as a retractor?

Accepted Answer

Levator scapulae

Answer

Trapezius

Answer

Rhomboid major

Answer

Rhomboid minor

Question 2

A stab wound injury to the shoulder results in a patient being unable to form a fist, presenting with a 'pointing index' appearance. Which nerve is most likely injured?

Accepted Answer

Median nerve

Answer

Radial nerve

Answer

Ulnar nerve

Answer

Axillary nerve

Question 3

All of the following arteries participate in the formation of the anastomosis around the scapula except?

Accepted Answer

Lateral thoracic artery

Answer

Deep branch of transverse cervical artery

Answer

Suprascapular artery

Answer

Circumflex scapular artery

Question 4

A penetrating wound to the axilla that severs the posterior cord of the brachial plexus would denervate which muscle?

Accepted Answer

Deltoid

Answer

Serratus anterior

Answer

Pronator teres

Answer

Biceps brachii

Question 5

The Pen Test is primarily used to assess the function of which nerve?

Accepted Answer

Median Nerve

Answer

Ulnar Nerve

Answer

Radial Nerve

Answer

Posterior Interosseous Nerve

Question 6

All of the following structures pass through the intermediate compartment of the extensor retinaculum except?

Accepted Answer

Anterior interosseous vein

Answer

Extensor Digitorum

Answer

Extensor Indicis

Answer

Posterior interosseous nerve

Question 7

Which movements of the thumb are not affected in a radial nerve injury?

Accepted Answer

Opposition

Answer

Abduction

Answer

Extension

Answer

All of the above

Question 8

The circumflex scapular artery is a branch of which structure?

Accepted Answer

Subscapular artery

Answer

Thyrocervical trunk

Answer

Subclavian artery

Answer

Aorta

Question 9

A 23-year-old male soldier accidentally punctured the ventral side of the fifth digit at the base of the distal phalanx while sharpening his knife. The wound became infected and spread into the palm, within the sheath of the flexor digitorum profundus tendons. If the infection were left untreated, into which of the following spaces could it most likely spread?

Accepted Answer

Mid-palmar space

Answer

Central compartment

Answer

Hypothenar compartment

Answer

Thenar compartment

Question 10

Erb's palsy occurs due to involvement of which part of the brachial plexus?

Accepted Answer

Upper trunk

Answer

Middle trunk

Answer

Medial cord

Answer

Lateral trunk

Upper Limb — MCQs

Upper Limb — MCQs

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