Upper Limb — MCQs
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The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?
What is the function of the Extensor Carpi Radialis Longus?
Which bone does the pisiform articulate with?
What structure passes through the quadrangular space?
What is the medial boundary of the cubital fossa?
Which of the following statements about the lumbrical muscles is correct?
Root value of the thoracodorsal nerve
Teres minor is supplied by
Which artery passes through the anatomical snuffbox?
Which muscle of the arm has additional supinator action?
Upper Limb Indian Medical PG Practice Questions and MCQs
Question 751: The image shows a highlighted region on the dorsal aspect of the hand (anatomical snuffbox). Which of the following anatomical structures form the boundaries or floor of this region?
- A. Abductor pollicis longus muscle.
- B. Styloid process of the radius.
- C. Extensor pollicis longus muscle.
- D. All of the above anatomical structures. (Correct Answer)
Explanation: ***All of the above anatomical structures.*** - The image highlights the **anatomical snuffbox**, a triangular depression on the radial dorsal aspect of the hand. Its boundaries are formed by the tendons of the **extensor pollicis longus muscle** (ulnar side), and the **abductor pollicis longus** and **extensor pollicis brevis muscles** (radial side). - The **styloid process of the radius** forms the floor of the anatomical snuffbox along with the scaphoid and trapezium bones. All the options listed are key anatomical features associated with this region. *Extensor pollicis longus muscle.* - This muscle forms the **ulnar (medial) border** of the anatomical snuffbox. - Its tendon can be palpated during **thumb extension** and contributes to the overall structure of the highlighted area. *Abductor pollicis longus muscle.* - This muscle, along with the extensor pollicis brevis, forms the **radial (lateral) border** of the anatomical snuffbox. - Its tendon is visible and palpable on the radial side of the highlighted region when the thumb is abducted. *Styloid process of the radius.* - This bony prominence is located at the **distal end of the radius** on the radial side of the wrist. - It forms part of the **proximal floor** of the anatomical snuffbox, contributing to its definition.
Question 752: What is the function of the Extensor Carpi Radialis Longus?
- A. Extensor and ulnar deviator of the wrist
- B. Extensor and radial deviator of the wrist (Correct Answer)
- C. Flexor and radial deviator of the wrist
- D. Weak extensor of the wrist
Explanation: ***Extensor and radial deviator of the wrist*** - The **Extensor Carpi Radialis Longus (ECRL)** is one of the primary muscles responsible for wrist **extension** [1]. - It also contributes significantly to **radial deviation** of the wrist [1]. - The ECRL works synergistically with the **Extensor Carpi Radialis Brevis (ECRB)** to produce powerful wrist extension with radial deviation [1]. *Extensor and ulnar deviator of the wrist* - This describes the action of the **Extensor Carpi Ulnaris (ECU)**, not the ECRL [1]. - The ECRL performs **radial deviation**, not ulnar deviation. *Flexor and radial deviator of the wrist* - This describes the action of the **Flexor Carpi Radialis (FCR)**, not the ECRL. - While both muscles cause radial deviation, the ECRL is an **extensor**, not a flexor. *Weak extensor of the wrist* - The **ECRL** is a **powerful primary extensor** of the wrist, especially when combined with the **Extensor Carpi Radialis Brevis (ECRB)** [1]. - It is one of the strongest wrist extensors and is not considered weak.
Question 753: Which bone does the pisiform articulate with?
- A. Triquetral (Correct Answer)
- B. Hamate
- C. Capitate
- D. Trapezium
Explanation: **Correct Answer: Triquetral** - The **pisiform** is a small, pea-shaped sesamoid bone located in the **proximal row** of the wrist. - It lies anterior to the **triquetral bone** and articulates ONLY with the triquetral. - This is the only carpal articulation the pisiform makes. *Incorrect: Hamate* - The **hamate** is in the **distal row** of carpal bones and articulates with the capitate, lunate, triquetral, and metacarpals 4-5. - It does not directly articulate with the pisiform. *Incorrect: Capitate* - The **capitate** is the largest carpal bone, located in the **distal row**. - It articulates with the scaphoid, lunate, trapezoid, hamate, and metacarpals 2-3. - It does not directly articulate with the pisiform. *Incorrect: Trapezium* - The **trapezium** is located in the **distal row** and articulates with the scaphoid, trapezoid, and the first metacarpal. - It is crucial for thumb movement but does not articulate with the pisiform.
Question 754: What structure passes through the quadrangular space?
- A. Axillary nerve (Correct Answer)
- B. Radial nerve
- C. Median nerve
- D. Brachial Artery
Explanation: Axillary nerve - The axillary nerve and the posterior circumflex humeral artery are the primary structures that pass through the quadrangular space. - Compression or injury within this space can lead to deficits in the axillary nerve's distribution, affecting the deltoid and teres minor muscles. *Radial nerve* - The radial nerve passes through the triangular interval, not the quadrangular space. - It supplies the triceps muscle and all muscles in the posterior compartment of the forearm. *Median nerve* - The median nerve travels through the cubital fossa and then down the anterior forearm, supplying most of the forearm flexors and some hand muscles. - It does not pass through any of the posterior axillary spaces. *Brachial Artery* - The brachial artery is the main arterial supply to the arm and runs anteriorly in the arm, deep to the biceps brachii muscle. - It does not pass through the quadrangular space; rather, the posterior circumflex humeral artery (a branch of the axillary artery) traverses this space.
Question 755: What is the medial boundary of the cubital fossa?
- A. Brachioradialis
- B. Pronator teres (Correct Answer)
- C. Supinator
- D. None of the options
Explanation: ***Pronator teres*** - The **pronator teres muscle** forms the **medial boundary** of the cubital fossa, running obliquely from the medial epicondyle to the lateral side of the radius. - This muscle defines the medial aspect of the triangular space at the anterior elbow. *Brachioradialis* - The **brachioradialis** muscle forms the **lateral boundary** of the cubital fossa. - It arises from the humerus and inserts into the distal radius, helping to delineate the region laterally. *Supinator* - The **supinator muscle** is located deep within the forearm and is not a direct boundary of the cubital fossa. - It lies on the posterior aspect of the radius and ulna, deep to some of the cubital fossa contents. *None of the options* - This option is incorrect because the **pronator teres** clearly defines the medial boundary of the cubital fossa.
Question 756: Which of the following statements about the lumbrical muscles is correct?
- A. All lumbricals are supplied by the median nerve
- B. Flex MCP joints and extend IP joints (Correct Answer)
- C. Origin from the tendons of flexor digitorum superficialis
- D. All lumbricals are supplied by the ulnar nerve
Explanation: Flex MCP joints and extend IP joints - The lumbrical muscles are unique in their attachment, originating from tendons and inserting into the extensor hood, allowing them to perform simultaneous metacarpophalangeal (MCP) joint flexion and interphalangeal (IP) joint extension [1]. - This specific action is crucial for fine motor movements of the fingers, particularly in precision grip. All lumbricals are supplied by the median nerve - This statement is incorrect as only the first and second lumbricals (of the index and middle fingers) are typically supplied by the median nerve. - The third and fourth lumbricals are innervated by the ulnar nerve. All lumbricals are supplied by the ulnar nerve - This statement is incorrect because the first and second lumbricals receive innervation from the median nerve. - Only the third and fourth lumbricals are consistently supplied by the deep branch of the ulnar nerve. Origin from the tendons of flexor digitorum superficialis - This statement is incorrect. The lumbricals originate from the tendons of the flexor digitorum profundus, not the superficialis [1]. - They are unique in that they are the only muscles in the human body that originate from a tendon and insert into a tendon (extensor expansion) [1].
Question 757: Root value of the thoracodorsal nerve
- A. C6, C7, C8 (Correct Answer)
- B. T1, T2
- C. C5, C6, C7
- D. C6, T1
Explanation: ***C6, C7, C8*** - The **thoracodorsal nerve**, also known as the middle subscapular nerve, originates from the **posterior cord of the brachial plexus**. - Its specific root values are **C6, C7, and C8**, which supply motor innervation to the **latissimus dorsi muscle** [1]. - This nerve is one of the three subscapular nerves arising from the posterior cord [1]. *C5, C6, C7* - While these roots contribute to the **posterior cord**, the thoracodorsal nerve specifically arises from **C6, C7, C8**. - **C5** primarily contributes to the **upper and middle trunk** and is more associated with nerves like the **suprascapular** and **axillary nerves**. *C6, T1* - These root values contribute to various nerves of the **brachial plexus**, but not specifically the thoracodorsal nerve. - **T1** contributes mainly to the **medial cord** and its branches like the **ulnar nerve**, not the posterior cord from which the thoracodorsal nerve arises. *T1, T2* - These are typical root values for **intercostal nerves** and contribute to the **sympathetic trunk**, not the **brachial plexus** or its branches like the thoracodorsal nerve. - The brachial plexus predominantly arises from **C5 to T1 spinal nerve roots**, and **T2** is not part of the brachial plexus.
Question 758: Teres minor is supplied by
- A. Suprascapular nerve
- B. Lower subscapular nerve
- C. Thoracodorsal nerve
- D. Axillary nerve (Correct Answer)
Explanation: ***Axillary nerve*** - The **axillary nerve** (C5-C6) innervates both the **teres minor** and the **deltoid muscle**. - It arises from the posterior cord of the brachial plexus and traverses the quadrangular space. *Suprascapular nerve* - The **suprascapular nerve** (C5-C6) primarily supplies the **supraspinatus** and **infraspinatus** muscles. - It plays a crucial role in shoulder abduction and external rotation, but not directly in teres minor function. *Lower subscapular nerve* - The **lower subscapular nerve** (C5-C6) innervates the **subscapularis muscle** and **teres major**. - Teres major and teres minor are anatomically adjacent but have different innervations and functions. *Thoracodorsal nerve* - The **thoracodorsal nerve** (C6-C8) innervates the **latissimus dorsi muscle** [1]. - This nerve is distinct from those supplying the rotator cuff muscles, including teres minor.
Question 759: Which artery passes through the anatomical snuffbox?
- A. Radial artery (Correct Answer)
- B. Brachial artery
- C. Ulnar artery
- D. Interosseus artery
Explanation: ***Radial artery*** - The **radial artery** is palpable within the **anatomical snuffbox**, as it courses over the scaphoid and trapezium bones towards the deep palmar arch. - This location is clinically significant for feeling the pulse and is vulnerable to injury, especially during **scaphoid fractures**. *Brachial artery* - The **brachial artery** is found in the **arm**, typically running in the cubital fossa, well proximal to the anatomical snuffbox. - It bifurcates into the radial and ulnar arteries at the level of the elbow, not within the wrist structures. *Ulnar artery* - The **ulnar artery** typically lies on the **medial side of the forearm** and wrist, contributing to the superficial palmar arch. - It does not pass through the anatomical snuffbox, which is located on the lateral aspect of the wrist. *Interosseus artery* - The **interosseus arteries** (anterior and posterior) run between the radius and ulna in the forearm, supplying muscles and bones. - These arteries are deep within the forearm compartments and do not traverse the superficial anatomical snuffbox at the wrist.
Question 760: Which muscle of the arm has additional supinator action?
- A. Brachialis
- B. Biceps (Correct Answer)
- C. Coracobrachialis
- D. Triceps
Explanation: ***Biceps*** - The **biceps brachii** powerfully supinates the forearm, especially when the elbow is flexed, due to its distal attachment on the **radial tuberosity**. - Its two heads originate from the scapula, contributing to both **flexion** at the elbow and supination. *Brachialis* - The **brachialis muscle** is the primary and most powerful flexor of the elbow joint. - It inserts onto the **ulna** and does not have any rotational or supinator action. *Coracobrachialis* - The **coracobrachialis** muscle primarily functions in adduction and flexion of the arm at the shoulder joint. - It has no attachments that allow for supination of the forearm. *Triceps* - The **triceps brachii** is the sole extensor of the elbow joint, located on the posterior aspect of the arm. - It is an antagonist to the biceps and has no supinator action.
Practice by Chapter
Pectoral Region and Axilla
Practice Questions
Arm and Cubital Fossa
Practice Questions
Forearm and Hand
Practice Questions
Joints of Upper Limb
Practice Questions
Nerves of Upper Limb
Practice Questions
Arterial Supply and Venous Drainage
Practice Questions
Lymphatic Drainage
Practice Questions
Muscles and Their Actions
Practice Questions
Applied Anatomy and Clinical Correlations
Practice Questions
Surface Anatomy and Landmarks
Practice Questions
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