Upper Limb Practice Questions

Q: All are true about the pisiform bone, except?

It can be seen on a newborn X-ray.. ### Explanation The **pisiform** is a unique carpal bone located in the proximal row of the wrist. Understanding its developmental and anatomical characteristics is crucial for NEET-PG. **1. Why Option C is correct (The "Except" statement):** Carpal bones are cartilaginous at birth and ossify in a specific chronological order [1]. The pisiform is the **last carpal bone to ossify**, typically appearing between the ages of **9 and 12 years**. Therefore, it is radiologically invisible on a newborn X-ray, making this statement false. **2. Analysis of other options:** * **Option A:** True. As mentioned, it is the final carpal bone to undergo ossification. (Mnemonic for order: **S**o **L**ong **T**ill **P**inkie, **H**ere **C**omes **T**he **T**humb — Scaphoid, Lunate, Triquetrum, **Pisiform**, Hamate, Capitate, Trapezoid, Trapezium. *Note: Capitate is the first to ossify at 1-3 months.*) * **Option B:** True. The pisiform serves as the insertion point for the **Flexor Carpi Ulnaris (FCU)** muscle. * **Option D:** True. It is anatomically classified as a **sesamoid bone** because it develops within the tendon of the Flexor Carpi Ulnaris. **3. Clinical Pearls & High-Yield Facts:** * **Articulations:** Unlike other carpals, it only has one articular facet (for the triquetrum) and does not participate in the radiocarpal (wrist) joint. * **Guyon’s Canal:** The pisiform forms the medial boundary of the ulnar canal (Guyon’s canal), which transmits the ulnar nerve and artery. * **Attachments:** Apart from the FCU, it provides attachment to the **pisohamate ligament**, **pisotriquetral ligament**, and the **abductor digiti minimi**. * **Palpation:** It is the most prominent bone on the ulnar side of the distal wrist crease.

Q: What is the primary action of the anconeus muscle?

Screwing movements of the elbow. **Explanation:** The **Anconeus** is a small, triangular muscle located on the posterior aspect of the elbow. While it is often described as a weak extensor of the elbow, its primary functional role is the **"screwing movement"** of the elbow. 1. **Why Option A is Correct:** During the final stages of elbow extension, the anconeus contracts to pull the ulna laterally. This lateral abduction of the ulna allows the olecranon to lock into the olecranon fossa of the humerus, effectively "screwing" or stabilizing the joint in full extension. It also serves to pull the capsule of the elbow joint posteriorly to prevent it from being pinched during extension. 2. **Why Other Options are Incorrect:** * **B. Elbow flexion:** This is performed by the Brachialis (prime mover), Biceps Brachii, and Brachioradialis. The anconeus is an extensor. * **C. Forearm supination:** This is primarily the function of the Supinator muscle and the Biceps Brachii. * **D. Adduction of the arm:** This involves muscles acting on the glenohumeral joint, such as the Pectoralis major and Latissimus dorsi. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve Supply:** Radial Nerve (C7, C8, T1). Specifically, it is supplied by the nerve to the medial head of the triceps. * **Origin/Insertion:** Originates from the posterior surface of the lateral epicondyle of the humerus and inserts into the lateral surface of the olecranon process. * **Clinical Significance:** It is considered a continuation of the triceps brachii and helps in stabilizing the elbow joint during pronation and supination.

Q: A 23-year-old woman sustains a deep cut to her ring finger by a kitchen knife and is unable to move the metacarpophalangeal joint. Which of the following pairs of nerves was most likely damaged?

Ulnar and radial. The movement of the metacarpophalangeal (MCP) joints involves both **extension** and **flexion/adduction/abduction**. To lose all movement at the MCP joint of the ring finger, both the nerve supplying the extensors and the nerve supplying the intrinsic muscles must be compromised. [1] 1. **Radial Nerve:** It supplies the **Extensor Digitorum** and **Extensor Digiti Miimi** (via the Posterior Interosseous Nerve) [1]. These muscles are the primary extensors of the MCP joints. Damage leads to an inability to extend the finger at the MCP level. 2. **Ulnar Nerve:** It supplies the **Palmar and Dorsal Interossei** and the **medial two Lumbricals**. These muscles are responsible for flexion at the MCP joints and abduction/adduction of the fingers [1]. Specifically, the ring finger's intrinsic motor supply is entirely ulnar-derived. **Analysis of Incorrect Options:** * **Median Nerve:** Supplies the lateral two lumbricals (index and middle fingers). It does not significantly contribute to the motor function of the ring finger's MCP joint [1]. * **Musculocutaneous Nerve:** Supplies the anterior compartment of the arm (Biceps, Brachialis, Coracobrachialis) and provides sensation to the lateral forearm. it has no motor role in finger movement. **High-Yield Clinical Pearls for NEET-PG:** * **MCP Joint Rule:** Extension is purely **Radial nerve**; Flexion/Abduction/Adduction is primarily **Ulnar nerve** (except for the index/middle lumbricals which are Median) [1]. * **Lumbricals:** "Flex the MCP and extend the IP joints." * **Interossei:** "DAB" (Dorsal Abduct) and "PAD" (Palmar Adduct). All are supplied by the Deep branch of the Ulnar nerve (C8, T1) [1]. * **Ring Finger:** Often considered the "border" finger, but for intrinsic muscle testing in exams, it is classically associated with the Ulnar nerve.

Q: 'Dropped shoulder' occurs due to paralysis of which muscle?

Trapezius. Explanation: The **Trapezius** muscle is primarily responsible for the elevation and stabilization of the scapula. It is innervated by the **Spinal Accessory Nerve (CN XI)**. When this nerve is damaged (often due to posterior triangle neck surgeries or trauma), the trapezius loses its tone and ability to support the shoulder girdle against gravity. Consequently, the scapula moves downwards and outwards (lateral displacement), leading to the clinical presentation known as **'Dropped Shoulder.'** Patients also experience difficulty in shrugging their shoulders and performing overhead abduction (above 90°). **Analysis of Incorrect Options:** * **Deltoid:** Innervated by the Axillary nerve. Paralysis leads to loss of shoulder contour (flattening) and inability to abduct the arm from 15° to 90°, but not a "dropped" shoulder. * **Teres Major:** Acts as an adductor and medial rotator of the humerus. Its paralysis does not significantly alter the resting position of the shoulder. * **Serratus Anterior:** Innervated by the Long Thoracic Nerve. Paralysis results in **'Winging of Scapula'** (medial border of scapula becomes prominent), particularly when pushing against a wall. **Clinical Pearls for NEET-PG:** * **Trapezius vs. Serratus Anterior:** Both are required for overhead abduction (>90°). Trapezius rotates the scapula such that the glenoid cavity faces upwards. * **Nerve Injury:** The Spinal Accessory Nerve is the most common nerve injured during cervical lymph node biopsies. * **Testing:** Trapezius strength is tested by asking the patient to shrug their shoulders against resistance.

Q: What is true about the deep palmar arch?

It gives three perforating branches.. The **Deep Palmar Arch** is a vital arterial network in the hand, primarily responsible for supplying the deep structures of the palm and the metacarpal area. ### **Explanation of the Correct Option** * **Option C is correct:** The deep palmar arch gives off **three perforating branches**. These branches pass through the proximal ends of the 2nd, 3rd, and 4th interosseous spaces to anastomose with the dorsal metacarpal arteries, providing collateral circulation between the palmar and dorsal aspects of the hand. ### **Analysis of Incorrect Options** * **Option A:** The deep palmar arch is formed primarily by the **terminal part of the radial artery**, supplemented by the deep branch of the ulnar artery. (The superficial arch is primarily formed by the ulnar artery). * **Option B:** It lies **deep to the lumbricals** and the flexor tendons. It rests directly on the proximal ends of the metacarpal shafts and the interossei muscles. * **Option D:** It gives off **three palmar metacarpal arteries** (not four), which run distally in the 2nd, 3rd, and 4th interosseous spaces to join the common palmar digital arteries from the superficial arch. ### **High-Yield Facts for NEET-PG** * **Location:** It lies approximately 1 cm proximal to the superficial palmar arch. * **Nerve Relation:** It is closely associated with the **deep branch of the ulnar nerve**, which lies in its concavity [1]. * **Allen’s Test:** Used clinically to assess the patency of the radial and ulnar arteries before arterial blood sampling, ensuring the palmar arches are intact. * **Branches Summary:** 3 Palmar metacarpal arteries, 3 Perforating branches, and Recurrent branches (to the carpus).

Q: Which of the following is NOT true about the ulnar nerve?

It supplies the flexor digitorum superficialis muscle.. The ulnar nerve, often called the "musician’s nerve," is a major branch of the medial cord of the brachial plexus. **Why Option C is the correct answer (The False Statement):** The **Flexor Digitorum Superficialis (FDS)** is supplied entirely by the **Median Nerve**. The ulnar nerve only supplies one and a half muscles in the forearm: the Flexor Carpi Ulnaris (FCU) and the medial half (ulnar half) of the Flexor Digitorum Profundus (FDP) [1]. **Analysis of Incorrect Options:** * **Option A:** The root value of the ulnar nerve is **C8 and T1**. In many individuals, it also receives fibers from **C7** via a communication from the lateral cord (high-yield for identifying variations). * **Option B:** The ulnar nerve passes behind the medial epicondyle of the humerus and enters the forearm through the **cubital tunnel** (formed by the humeral and ulnar heads of the FCU). This is a common site for entrapment. * **Option D:** The **Flexor Carpi Ulnaris** is the primary muscle supplied by the ulnar nerve in the forearm, responsible for wrist flexion and adduction [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Guyon’s Canal:** The ulnar nerve passes superficial to the flexor retinaculum through this canal at the wrist [1]. * **Ulnar Paradox:** A lesion at the wrist causes a more prominent "claw hand" than a lesion at the elbow because the FDP remains intact, increasing the flexion deformity of the IP joints. * **Froment’s Sign:** Tests for adductor pollicis paralysis (ulnar nerve) where the patient compensates by flexing the thumb IP joint (median nerve/FPL) [1].

Q: For every 3 degrees of arm abduction at the shoulder, what is the corresponding scapular rotation?

1 degree. ### Explanation **1. The Correct Answer: A (1 degree)** The movement of the shoulder involves a coordinated rhythm between the humerus and the scapula, known as the **Scapulohumeral Rhythm**. * The overall ratio of glenohumeral (GH) movement to scapulothoracic (ST) movement is **2:1**. * This means that for every 3 degrees of total abduction, **2 degrees** occur at the GH joint and **1 degree** occurs due to the rotation of the scapula. * Therefore, for the 180 degrees of total abduction: 120 degrees is GH motion and 60 degrees is ST motion. **2. Why Other Options are Incorrect:** * **B (2 degrees):** This represents the amount of **glenohumeral** movement for every 3 degrees of total abduction, not the scapular rotation. * **C (3 degrees):** This would imply a 1:1 ratio, which does not occur. If the scapula rotated 3 degrees for every 3 degrees of abduction, the humerus would remain static relative to the glenoid. * **D (0.5 degrees):** This ratio (6:1) is incorrect and does not align with the physiological mechanics required to maintain the length-tension relationship of the deltoid. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Setting Phase:** In the first 30 degrees of abduction, the movement is primarily glenohumeral; the scapula seeks a position of stability (the "setting phase"). The 2:1 ratio becomes consistent after 30 degrees. * **Muscles Involved:** Scapular rotation is primarily achieved by the **Serratus Anterior** and the **Trapezius** (upper and lower fibers acting as a force couple). * **Clinical Correlation:** A reversal or disturbance of this rhythm is often seen in **Frozen Shoulder (Adhesive Capsulitis)** or **Rotator Cuff tears**, where the patient compensates for lack of GH motion by "shrugging" the scapula prematurely. * **Deltoid Efficiency:** The scapulohumeral rhythm prevents the deltoid from undergoing active insufficiency by maintaining optimal muscle fiber length.

Q: Injury to which nerve originating from the C5 nerve root of the brachial plexus leads to a specific deficit?

Winging of the scapula. The correct answer is **Winging of the Scapula** because it is caused by paralysis of the **Serratus Anterior** muscle, which is supplied by the **Long Thoracic Nerve**. This nerve originates directly from the ventral rami of **C5, C6, and C7**. Since C5 is a primary root of origin, an injury to this root (or the nerve itself) results in the inability of the muscle to hold the medial border of the scapula against the posterior chest wall, leading to its protrusion (winging). **Analysis of Options:** * **A & B (Loss of abduction/external rotation):** These are characteristic of **Erb’s Palsy**, which involves the **upper trunk** (C5-C6) rather than just a specific nerve originating from the C5 root. Abduction is lost due to Suprascapular (Supraspinatus) and Axillary (Deltoid) nerve involvement. External rotation is lost due to Suprascapular (Infraspinatus) and Axillary (Teres minor) involvement. * **C (Loss of shoulder shrugging):** This is mediated by the **Trapezius** muscle, which is supplied by the **Spinal Accessory Nerve (CN XI)**, not the brachial plexus. **Clinical Pearls for NEET-PG:** * **Long Thoracic Nerve (Nerve of Bell):** It is unique because it arises from the **roots** (C5-C7) and runs along the lateral thoracic wall. It is commonly injured during radical mastectomy or chest tube insertion. * **Dorsal Scapular Nerve:** Another nerve arising solely from the **C5 root**; it supplies the Rhomboids. Paralysis leads to a lateral shift of the scapula. * **Dynamic Winging:** Winging is accentuated when the patient is asked to push against a wall.

Question 1

All are true about the pisiform bone, except?

Accepted Answer

It can be seen on a newborn X-ray.

Answer

It is the last carpal bone to ossify.

Answer

It is attached to the flexor carpi ulnaris.

Answer

It is a sesamoid bone.

Question 2

What is the primary action of the anconeus muscle?

Accepted Answer

Screwing movements of the elbow

Answer

Elbow flexion

Answer

Forearm supination

Answer

Adduction of the arm

Question 3

A 23-year-old woman sustains a deep cut to her ring finger by a kitchen knife and is unable to move the metacarpophalangeal joint. Which of the following pairs of nerves was most likely damaged?

Accepted Answer

Ulnar and radial

Answer

Median and ulnar

Answer

Radial and median

Answer

Musculocutaneous and ulnar

Question 4

'Dropped shoulder' occurs due to paralysis of which muscle?

Accepted Answer

Trapezius

Answer

Deltoid

Answer

Teres major

Answer

Serratus anterior

Question 5

What is true about the deep palmar arch?

Accepted Answer

It gives three perforating branches.

Answer

Its main contribution is by the ulnar artery.

Answer

It lies superficial to the lumbricals.

Answer

It gives four palmar metacarpal arteries.

Question 6

The distal end of the humerus develops from how many ossification centers?

Accepted Answer

4

Answer

2

Answer

5

Answer

3

Question 7

Which of the following is NOT true about the ulnar nerve?

Accepted Answer

It supplies the flexor digitorum superficialis muscle.

Answer

Its root value includes C8 and T1.

Answer

It passes through the cubital tunnel.

Answer

It supplies the flexor carpi ulnaris muscle.

Question 8

For every 3 degrees of arm abduction at the shoulder, what is the corresponding scapular rotation?

Accepted Answer

1 degree

Answer

2 degrees

Answer

3 degrees

Answer

0.5 degrees

Question 9

Injury to which nerve originating from the C5 nerve root of the brachial plexus leads to a specific deficit?

Accepted Answer

Winging of the scapula

Answer

Loss of abduction of the arm

Answer

Loss of external rotation of the arm

Answer

Loss of shoulder shrugging

Question 10

A 52-year-old male conductor experienced excruciating pain in the posterior aspect of his right forearm after several days of 12-hour daily rehearsals. Palpation 2 cm distal to and posteromedial to the lateral epicondyle caused him to weep due to intense pain. Injections of steroids and rest were recommended. Which of the following injuries is most likely?

Accepted Answer

Compression of the deep radial nerve by the supinator

Answer

Compression of the median nerve by the pronator teres

Answer

Compression of the median nerve by the flexor digitorum superficialis

Answer

Compression of the superficial radial nerve by the brachioradialis

Upper Limb — MCQs

Upper Limb — MCQs

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