Upper Limb — MCQs

A person riding a mountain bike on a rustic trail hits a rut, the fork of the bike breaks and the person is thrown into a tree, severely fracturing the upper end of his humerus. During the repair, the surgeon ties off the artery traveling through the quadrangular space to stop the hemorrhage. Which artery did he ligate?

Q39Easy

At what age is the ossification center of the upper end of the ulna united?

Q40Easy

Which of the following deformities is evident in Erb's palsy?

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 31: Which of the following bones has an epiphysis at its base?

A. Distal phalanx
B. Middle phalanx
C. Thumb metacarpal (Correct Answer)
D. Third metacarpal

Explanation: ### Explanation The location of the epiphysis in the tubular bones of the hand follows a specific pattern based on the bone type. This is a high-yield concept for NEET-PG regarding osteology and ossification. During fetal development, most bones are modeled in cartilage and then transformed into bone by ossification [1]. **1. Why the Thumb Metacarpal is Correct:** In the hand, **metacarpals II through V** have their epiphyses at their **heads** (distal end). However, the **1st metacarpal (thumb)** is an exception; its epiphysis is located at its **base** (proximal end) [1]. Regulated bone growth through puberty occurs through epiphysial plates located near the end of the bone shaft [1]. This makes the thumb metacarpal behave developmentally more like a phalanx than a typical metacarpal. **2. Analysis of Incorrect Options:** * **Distal and Middle Phalanges (Options A & B):** All phalanges (proximal, middle, and distal) follow a uniform rule: the epiphysis is always located at the **base** (proximal end). While these bones do have an epiphysis at the base, the question specifically tests the unique "reversal" seen in the metacarpals. * **Third Metacarpal (Option D):** As mentioned, the 2nd, 3rd, 4th, and 5th metacarpals have their epiphyses at the **head** (distal end), not the base. **3. Clinical Pearls & High-Yield Facts:** * **The "Rule of the Base":** All phalanges and the **1st metacarpal** have epiphyses at the base. * **The "Rule of the Head":** Metacarpals **2–5** have epiphyses at the head. * **Pseudo-epiphysis:** Occasionally, an extra epiphysis may appear at the distal end of the 1st metacarpal or the proximal end of the 2nd metacarpal; this is a normal variant and should not be mistaken for a fracture. * **Clavicle Fact:** The clavicle is the first bone to ossify in the body (membranous ossification) but has a secondary epiphysis at its **medial (sternal) end**, which is the last to fuse (around age 25) [1].

Question 32: Which of the following is NOT a part of the proximal row of carpal bones?

A. Scaphoid
B. Lunate
C. Triquetral
D. Hamate (Correct Answer)

Explanation: The carpal bones are arranged in two rows, each containing four bones. To identify the correct answer, one must distinguish between the **proximal row** (closer to the forearm) and the **distal row** (closer to the metacarpals). [1] ### **Explanation of the Correct Answer** **D. Hamate:** This is the correct answer because the Hamate belongs to the **distal row** of carpal bones. It is characterized by a hook-like process (the hook of the hamate) on its palmar surface [1] and articulates with the 4th and 5th metacarpals. ### **Analysis of Incorrect Options** The proximal row consists of four bones (lateral to medial): * **A. Scaphoid:** The most lateral bone of the proximal row; it articulates with the radius [1] and is the most commonly fractured carpal bone [2]. * **B. Lunate:** Located between the scaphoid and triquetral; it is the most commonly dislocated carpal bone. * **C. Triquetral:** A pyramidal bone located on the medial side of the proximal row, situated proximal to the hamate. *(Note: The **Pisiform**, a sesamoid bone in the tendon of flexor carpi ulnaris, completes the proximal row). ### **High-Yield Clinical Pearls for NEET-PG** * **Mnemonic:** "She Looks Too Pretty, Try To Catch Her" (Scaphoid, Lunate, Triquetral, Pisiform / Trapezium, Trapezoid, Capitate, Hamate). * **Guyon’s Canal:** Formed between the hook of the hamate and the pisiform; it transmits the ulnar nerve and artery [1]. * **Carpal Tunnel:** The scaphoid and trapezium form the lateral wall, while the pisiform and hook of hamate form the medial wall [1]. * **Avascular Necrosis (AVN):** The scaphoid is prone to AVN due to its retrograde blood supply [2].

Question 33: Which of the following nerves is also known as the 'labourer's nerve'?

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

Explanation: ### Explanation The **Median nerve** is known as the **'Labourer’s nerve'** because it is the primary nerve responsible for the coarse movements of the hand [1]. It supplies most of the long flexors of the forearm and the muscles of the thenar eminence, which are essential for a strong **power grip** and **precision handling** required in manual labor. #### Analysis of Options: * **Median Nerve (Correct):** Beyond being the 'Labourer's nerve,' it is also called the **'Musician’s nerve'** (though this title is more commonly shared with or attributed to the Ulnar nerve in some texts, the Median nerve is vital for fine motor control of the thumb) [1]. * **Ulnar Nerve (Incorrect):** Known as the **'Musician’s nerve'**, it controls the fine, intricate movements of the fingers (via the interossei and lumbricals) required for playing instruments like the piano or violin [1]. * **Anterior Interosseous Nerve (Incorrect):** A pure motor branch of the median nerve. Damage to this nerve results in the inability to make the "OK" sign (paralysis of Flexor Pollicis Longus and Flexor Digitorum Profundus to the index finger). * **Radial Nerve (Incorrect):** Known as the nerve of **extension**. Injury typically leads to 'Wrist Drop.' #### High-Yield Clinical Pearls for NEET-PG: * **Ape Thumb Deformity:** Caused by a proximal median nerve injury leading to wasting of the thenar eminence and loss of thumb opposition. * **Pointing Index (Benediction Gesture):** Occurs when attempting to make a fist in a high median nerve palsy. * **Carpal Tunnel Syndrome:** The most common entrapment neuropathy involving the median nerve at the wrist [1]. * **Supracondylar Fracture of Humerus:** The most common site for a proximal median nerve injury in children.

Question 34: A 37-year-old man suffers a traumatic injury to the axilla that damages the thoracodorsal nerve. Which of the following movements of the arm or scapula could be affected in this patient?

A. Abduction
B. Adduction (Correct Answer)
C. Flexion
D. Lateral rotation

Explanation: ### Explanation The **thoracodorsal nerve** (C6, C7, C8), a branch of the posterior cord of the brachial plexus, innervates the **Latissimus Dorsi** muscle. To identify the affected movement, one must recall the primary actions of this muscle. **1. Why Adduction is Correct:** The Latissimus Dorsi is a powerful muscle of the posterior axillary wall. Its primary actions on the humerus are **Adduction**, **Extension**, and **Medial (Internal) Rotation**. A lesion to the thoracodorsal nerve results in paralysis of this muscle, significantly weakening the patient's ability to pull the trunk upward (as in climbing) or adduct the arm against resistance. **2. Analysis of Incorrect Options:** * **Abduction (A):** Primarily performed by the Deltoid (axillary nerve) and Supraspinatus (suprascapular nerve). * **Flexion (C):** Primarily performed by the Pectoralis major (clavicular head), Coracobrachialis, and anterior fibers of the Deltoid. Latissimus dorsi is actually an *extensor*. * **Lateral rotation (D):** Performed by the Infraspinatus and Teres minor. Latissimus dorsi is a *medial* rotator. **3. Clinical Pearls for NEET-PG:** * **"Climber’s Muscle":** Latissimus dorsi is essential for climbing and using crutches because it adducts and extends the humerus to lift the body. * **Surgical Significance:** The thoracodorsal nerve is at high risk during **axillary lymph node dissection** (e.g., for breast cancer surgery) or surgeries involving the posterior axillary wall [1]. * **The "Cough" Muscle:** It also aids in forced expiration and coughing. * **Nerve Origin:** Remember the mnemonic "C6, 7, 8—keep the Latissimus straight."

Question 35: Axillary artery occlusion affects all EXCEPT:

A. Posterior circumflex humeral artery
B. Suprascapular artery (Correct Answer)
C. Subscapular artery
D. Superior thoracic artery

Explanation: **Explanation:** The **axillary artery** is a direct continuation of the subclavian artery, beginning at the outer border of the first rib and ending at the lower border of the teres major muscle [1]. To answer this question, one must distinguish between the branches of the subclavian artery and the axillary artery. **1. Why Suprascapular Artery is the correct answer:** The **suprascapular artery** is a branch of the **thyrocervical trunk**, which arises from the **first part of the subclavian artery**. Since it originates proximal to the axillary artery, an occlusion of the axillary artery will not affect the flow within the suprascapular artery. In fact, the suprascapular artery plays a vital role in the collateral circulation (scapular anastomosis) to bypass such occlusions. **2. Why the other options are incorrect:** All other options are direct branches of the axillary artery and would be affected by its occlusion [1]: * **Superior thoracic artery:** Arises from the **1st part** of the axillary artery. * **Subscapular artery:** The largest branch, arising from the **3rd part** of the axillary artery. * **Posterior circumflex humeral artery:** Arises from the **3rd part** of the axillary artery (travels through the quadrangular space). **NEET-PG High-Yield Pearls:** * **Scapular Anastomosis:** This vital bypass connects the 1st part of the subclavian artery (via suprascapular and deep branch of transverse cervical arteries) with the 3rd part of the axillary artery (via circumflex scapular branch of the subscapular artery). * **Mnemonics for Axillary branches:** "Save The Lions And Pity Mammals" (Superior thoracic, Thoracoacromial, Lateral thoracic, Alar thoracic/Subscapular, Posterior circumflex, Anterior circumflex). * **Clinical Correlation:** If the axillary artery is ligated between the thyrocervical trunk and the subscapular artery, the scapular anastomosis maintains blood supply to the upper limb [1].

Question 36: Hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints is caused by injury to which nerve?

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

Explanation: The clinical presentation described—**hyperextension at the metacarpophalangeal (MCP) joints and flexion at the interphalangeal (IP) joints**—is the classic definition of **Claw Hand (Main en Griffe)**. ### 1. Why Ulnar Nerve is Correct The ulnar nerve innervates the **lumbricals (3rd and 4th)** and all **interossei** [1]. These muscles normally perform a specific dual action: flexing the MCP joints and extending the IP joints (the "Z-position"). When the ulnar nerve is injured, these muscles are paralyzed [1]. The **extensor digitorum** (radial nerve) acts unopposed at the MCP joints, causing hyperextension [2]. Simultaneously, the **flexor digitorum profundus** (ulnar/median nerve) acts unopposed at the IP joints, causing flexion [1]. This imbalance results in the characteristic claw deformity, most prominent in the ring and little fingers. ### 2. Why Other Options are Incorrect * **Radial Nerve:** Injury leads to **Wrist Drop**. The radial nerve supplies the extensors of the wrist and MCP joints; its injury would result in an inability to extend these joints, not hyperextension [1]. * **Median Nerve:** Injury typically causes **Ape Thumb deformity** (loss of opposition) or "Hand of Benediction" (when attempting to make a fist) [1]. While it supplies the 1st and 2nd lumbricals, a pure median nerve injury does not cause a generalized claw hand. * **Musculocutaneous Nerve:** Supplies the coracobrachialis, biceps brachii, and brachialis. Injury results in loss of forearm flexion and supination, with no direct effect on the intrinsic hand muscles. ### 3. Clinical Pearls for NEET-PG * **Ulnar Paradox:** A distal ulnar nerve lesion (at the wrist) causes a *more severe* clawing than a proximal lesion (at the elbow) because, in proximal lesions, the medial half of the Flexor Digitorum Profundus is also paralyzed, reducing the flexion force at the IP joints [1]. * **Froment’s Sign:** Used to test for ulnar nerve palsy (paralysis of Adductor Pollicis) [1]. * **Total Claw Hand:** Occurs in **Klumpke’s Paralysis** (C8-T1 injury), affecting both ulnar and median intrinsic muscles.

Question 37: Which intrinsic muscle of the hand is not supplied by the median nerve?

A. Abductor pollicis brevis
B. Opponens pollicis
C. First lumbrical
D. Adductor pollicis brevis (Correct Answer)

Explanation: ### 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**. These five are commonly remembered by the mnemonic **"LOAF"** (Lumbricals 1 & 2, Opponens pollicis, Abductor pollicis brevis, and Flexor pollicis brevis). [1] **Why Option D is Correct:** **Adductor pollicis** is the only muscle of the thenar eminence (the ball of the thumb) that is **not** supplied by the median nerve. It is supplied by the **deep branch of the ulnar nerve (C8, T1)**. It functions to adduct the thumb, bringing it toward the palm. **Why the Other Options are Incorrect:** * **A & B (Abductor pollicis brevis & Opponens pollicis):** These are part of the thenar muscle group supplied by the **recurrent branch of the median nerve**. * **C (First lumbrical):** The first and second (lateral) lumbricals are supplied by the **median nerve**, whereas the third and fourth (medial) lumbricals are supplied by the ulnar nerve. [1] **High-Yield Clinical Pearls for NEET-PG:** 1. **Ape Thumb Deformity:** Caused by median nerve injury at the wrist (e.g., Carpal Tunnel Syndrome), leading to atrophy of the thenar eminence and loss of thumb opposition. [1] 2. **Froment’s Sign:** Tests for ulnar nerve palsy. Since the **Adductor pollicis** is paralyzed, the patient compensates by using the Flexor Pollicis Longus (Median nerve) to grip paper, resulting in flexion of the thumb IP joint. 3. **Flexor pollicis brevis (FPB):** This muscle often has a **dual nerve supply** (superficial head by median nerve, deep head by ulnar nerve). [1]

Question 38: A person riding a mountain bike on a rustic trail hits a rut, the fork of the bike breaks and the person is thrown into a tree, severely fracturing the upper end of his humerus. During the repair, the surgeon ties off the artery traveling through the quadrangular space to stop the hemorrhage. Which artery did he ligate?

A. Dorsal scapular
B. Posterior circumflex humeral (Correct Answer)
C. Scapular circumflex
D. Subscapular

Explanation: The correct answer is **Posterior circumflex humeral artery**. This question tests your knowledge of the surgical anatomy of the axillary spaces and their contents. **1. Why the Correct Answer is Right:** The **Quadrangular Space** is a vital anatomical gateway in the posterior shoulder. Its boundaries are: * **Superior:** Teres minor muscle * **Inferior:** Teres major muscle * **Medial:** Long head of the triceps brachii * **Lateral:** Surgical neck of the humerus The two structures passing through this space are the **Axillary nerve** and the **Posterior circumflex humeral artery**. In fractures of the surgical neck of the humerus, these structures are at high risk of injury. Ligation of this artery [1] is often necessary during surgical repair to control hemorrhage. **2. Why Other Options are Wrong:** * **Dorsal scapular artery (A):** Arises from the subclavian artery and travels along the medial border of the scapula, deep to the levator scapulae and rhomboids. * **Scapular circumflex artery (C):** This is a branch of the subscapular artery that passes through the **Triangular Space** (bounded by Teres minor, Teres major, and Long head of triceps). * **Subscapular artery (D):** The largest branch of the axillary artery (3rd part); it stays on the anterior surface of the subscapularis muscle before dividing into the circumflex scapular and thoracodorsal arteries. **3. Clinical Pearls for NEET-PG:** * **Surgical Neck Fracture:** Always look for damage to the **Axillary Nerve** (loss of deltoid contour/abduction) and **Posterior Circumflex Humeral Artery** [1]. * **Triangular Space:** Contains only the Scapular circumflex artery. * **Triangular Interval:** Contains the **Radial Nerve** and **Profunda Brachii Artery**. * **Anastomosis:** The posterior circumflex humeral artery anastomoses with the anterior circumflex humeral artery around the surgical neck.

Question 39: At what age is the ossification center of the upper end of the ulna united?

A. 9 years
B. 11 years
C. 14 years
D. 16 years (Correct Answer)

Explanation: The ossification of the long bones of the upper limb is a high-yield topic for NEET-PG, specifically regarding the timeline of appearance and fusion of epiphyses. [1] ### **Explanation of the Correct Answer** The upper end of the ulna (the olecranon process) typically develops from one or two secondary ossification centers. These centers appear around the age of **8–10 years**. The fusion of this epiphysis with the shaft (diaphysis) occurs during puberty, specifically around **14–16 years** in males and slightly earlier in females. Therefore, **16 years** represents the completion of the union process. ### **Analysis of Incorrect Options** * **A (9 years):** This is the age when the ossification center for the olecranon typically **appears**, not when it unites. * **B (11 years):** At this age, the ossification center is active and growing, but the growth plate (epiphyseal plate) remains open. * **C (14 years):** While fusion can begin at 14, standard anatomical texts (like Gray’s Anatomy and Chaurasia) cite 16 years as the definitive age of union for the upper end of the ulna. ### **Clinical Pearls & High-Yield Facts** * **Direction of Nutrient Foramen:** Remember the rule: *"To the elbow I go, from the knee I flee."* In the ulna, the nutrient foramen is directed upwards (towards the elbow), meaning the **upper end is the growing end**. * **Exception to the Rule:** Paradoxically, even though the upper end is the "growing end," it fuses **earlier** (16 years) than the lower end (18–20 years). * **Medico-legal Importance:** Determining the fusion of the olecranon and the fusion of the lower end of the radius/ulna is a primary method used in forensic radiology to estimate the age of adolescents between 14 and 20 years.

Question 40: Which of the following deformities is evident in Erb's palsy?

A. Policeman tip deformity (Correct Answer)
B. Winging of scapula
C. Claw hand
D. Wrist drop

Explanation: **Explanation:** **Erb’s Palsy** (Duchenne-Erb paralysis) results from an injury to the **upper trunk of the brachial plexus (C5-C6 roots)** [1], most commonly due to birth trauma or a fall on the shoulder. **1. Why "Policeman’s Tip Deformity" is correct:** The paralysis affects the deltoid, biceps brachii, brachialis, and supinator muscles. This leads to a characteristic limb position: * **Arm:** Adducted and medially rotated (loss of abductors and external rotators). * **Forearm:** Extended and pronated (loss of flexors and supinator). This specific posture is classically described as the **"Policeman’s tip," "Waiter’s tip," or "Porter’s tip" deformity.** **2. Why other options are incorrect:** * **Winging of Scapula:** Caused by injury to the **Long Thoracic Nerve (C5-C7)**, paralyzing the Serratus Anterior muscle [2]. * **Claw Hand:** Typically results from **Klumpke’s Palsy** (Lower trunk injury, C8-T1) or isolated Ulnar nerve palsy, affecting the intrinsic muscles of the hand. * **Wrist Drop:** Caused by **Radial nerve injury** [3] (often due to mid-shaft humerus fractures [3]), leading to paralysis of the wrist extensors. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Injury:** **Erb’s Point** (the junction of 6 nerves: C5, C6 roots, suprascapular n., n. to subclavius, and the anterior/posterior divisions of the upper trunk). * **Sensory Loss:** Usually occurs over a small area on the lateral aspect of the arm (Regimental badge area/deltoid region). * **Reflexes:** The **Biceps and Supinator reflexes** are lost. * **Mnemonic:** Erb's = **U**pper trunk (**U**pward traction/fall), Klumpke's = **L**ower trunk (**L**ower limb/grabbing a branch).

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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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Muscles and Their Actions

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Upper Limb — MCQs

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