Upper Limb Practice Questions

Q: Identify the marked muscle in the diagram.

Extensor carpi radialis brevis. ***Extensor carpi radialis brevis*** - This muscle originates from the **lateral epicondyle of the humerus** and inserts onto the base of the **3rd metacarpal**. - It is a primary extensor and abductor of the wrist, located on the **posterior forearm**. *Brachialis* - The **brachialis** muscle is located in the **anterior compartment of the upper arm**, deep to the biceps brachii. - Its primary function is **flexion of the elbow joint**, entirely different from the marked forearm muscle. *Flexor carpi ulnaris* - The **flexor carpi ulnaris** is located in the **anterior compartment of the forearm** and is a primary flexor and adductor of the wrist. - It originates from the **medial epicondyle** and inserts into the pisiform, hook of hamate, and base of the 5th metacarpal, clearly distinct from the posterior lateral location shown. *Extensor digitorum* - The **extensor digitorum** primarily extends the medial four fingers, originating from the lateral epicondyle and inserting into the extensor expansions of the digits. - While also in the posterior forearm, its more medial position and distal tendinous divisions distinguish it from the muscle marked, which mainly acts on the wrist.

Q: What is the nerve supply of the structure marked in the image?

Median nerve. ***Median nerve*** - The image points to the **lateral two lumbricals**. The **median nerve** innervates the first and second (lateral two) lumbrical muscles. - These muscles contribute to **flexion of the metacarpophalangeal joints** and **extension of the interphalangeal joints** of the index and middle fingers. *Anterior interosseous nerve* - The anterior interosseous nerve is a branch of the **median nerve** and primarily supplies deep muscles of the forearm, such as the **flexor pollicis longus**, **flexor digitorum profundus (lateral half),** and **pronator quadratus**. - It does not directly innervate the lumbricals in the hand. *Posterior interosseous nerve* - The posterior interosseous nerve is a branch of the **radial nerve**. - It primarily innervates the **extensor muscles of the forearm** and wrist, not the lumbrical muscles. *Ulnar nerve* - The **ulnar nerve** innervates the **medial two lumbricals** (third and fourth), as well as most of the other intrinsic hand muscles, including the interossei. - The nerve supply of the lumbricals is split between the median and ulnar nerves, with the lateral two supplied by the median nerve.

Q: Which nerve supplies the rhomboid major and minor muscles?

Dorsal scapular nerve. Dorsal scapular nerve - The **dorsal scapular nerve** directly innervates the **rhomboid major** and **rhomboid minor** muscles, as well as the **levator scapulae** muscle. - This nerve originates from the C5 root of the brachial plexus. *Thoracodorsal nerve* - The **thoracodorsal nerve** primarily innervates the **latissimus dorsi** muscle, which is involved in adduction, extension, and internal rotation of the humerus [1]. - This nerve arises from the posterior cord of the brachial plexus. *Spinal accessory nerve* - The **spinal accessory nerve (CN XI)** is responsible for innervating the **sternocleidomastoid** and **trapezius** muscles. - It plays a crucial role in neck movement and shoulder elevation. *Suprascapular nerve* - The **suprascapular nerve** supplies the **supraspinatus** and **infraspinatus** muscles, which are part of the rotator cuff. - Damage to this nerve can impair shoulder abduction and external rotation.

Q: Identify the anatomical structures visible in the image.

Styloid process of the ulna. ***Styloid process of the ulna*** - The styloid process of the ulna is a **pointed projection** of bone located on the **medial side of the distal ulna**. - It serves as an **attachment point** for the ulnar collateral ligament and stabilizes the **distal radioulnar joint**. *Extensor pollicis longus and Abductor pollicis longus* - The **extensor pollicis longus** forms the **ulnar border of the anatomical snuffbox**, while the **abductor pollicis longus** forms the **radial border**. - While these **tendons are located in the vicinity**, the image specifically highlights the **bony landmark** of the ulnar styloid. *Styloid process of the radius* - The **styloid process of the radius** is located on the **lateral aspect of the distal radius**. - It is **larger and more prominent** than the ulnar styloid process, and the image clearly points to the **medial distal forearm**. *Scaphoid bone* - The **scaphoid bone** is one of the **carpal bones** located in the proximal row of the wrist. - It lies **distal to the radius** and is a common site for fractures, but the pointer in the image is clearly indicating a **distal forearm bony projection**, not a carpal bone.

Q: What is the role of the anconeus muscle in elbow movement?

Assists in elbow extension. ***Assists in elbow extension*** - The **anconeus muscle** is a small muscle located on the posterior aspect of the **elbow joint**. - Its primary role is to assist the **triceps brachii** in **elbow extension** and to stabilize the elbow joint during pronation. - It acts as an **accessory extensor** and also tenses the capsule of the elbow joint to prevent it from being pinched during extension. *Wrist extension* - **Wrist extension** is primarily performed by muscles originating from the lateral epicondyle of the humerus, such as the **extensor carpi radialis longus and brevis** and **extensor carpi ulnaris** [1]. - The anconeus muscle is not involved in wrist movements. *Thumb abduction* - **Thumb abduction** is the movement of the thumb away from the palm, controlled by muscles like the **abductor pollicis longus** and **abductor pollicis brevis** [1]. - The anconeus muscle has no role in thumb movements. *Elbow flexion* - **Elbow flexion** is performed by anterior compartment muscles including the **biceps brachii**, **brachialis**, and **brachioradialis**. - The anconeus is located in the **posterior compartment** and produces the opposite action (extension), not flexion.

Q: Which of the following arteries contributes MOST to the deep palmar arch?

Radial artery. ***Radial artery*** - The **radial artery** is the primary contributor to the **deep palmar arch**, giving off the **princeps pollicis artery** and the **radialis indicis artery** before continuing as the main part of the arch. - It anastomoses with the deep branch of the ulnar artery to complete the arch. *Ulnar artery* - The **deep branch of the ulnar artery** contributes to the deep palmar arch, but it is a smaller, anastomotic component rather than the primary contributor itself. - The ulnar artery is the primary contributor to the **superficial palmar arch**. *Posterior interosseous artery* - The **posterior interosseous artery** supplies muscles in the posterior compartment of the forearm and does not directly contribute to the deep palmar arch. - It arises from the common interosseous artery and terminates in the wrist region, supplying the dorsal carpal network. *Anterior interosseous artery* - The **anterior interosseous artery** supplies muscles of the deep anterior forearm compartment and gives off branches to the wrist but does not directly form the deep palmar arch. - It also contributes to the **palmar carpal arch** but not the deep palmar arch.

Q: Which of the following is a sensory region of the ulnar nerve?

Tip of little finger. ***Tip of little finger*** - The **ulnar nerve** innervates the medial side of the hand, including the **little finger** and the medial half of the ring finger, both dorsally and palmarly [1]. - Sensation to the **tip of the little finger** is exclusively supplied by the ulnar nerve, making it a reliable indicator of its sensory function. *Tip of index finger* - The **tip of the index finger** receives its sensory innervation from the **median nerve**, specifically via its digital branches [1]. - Testing sensation here assesses the function of the median nerve, not the ulnar nerve. *1st web space* - The sensory innervation of the **1st web space** (between the thumb and index finger) is primarily by the **radial nerve**, via its superficial branch. - This area is crucial for assessing radial nerve function. *Lateral upper aspect of arm* - The sensation of the **lateral upper aspect of the arm** is primarily supplied by the **axillary nerve** (via the superior lateral cutaneous nerve of the arm) and partially by the **radial nerve**. - This region is distant from the hand and not innervated by the ulnar nerve.

Q: Low radial nerve palsy (just after the spiral groove) does not produce which of the following?

Loss of elbow extension. ***Loss of elbow extension*** - A low radial nerve palsy, occurring **distal to the spiral groove**, affects branches supplying the forearm and hand. - The nerves to the **triceps brachii**, responsible for elbow extension, branch off **proximal to the spiral groove**. *Loss of wrist extension* - The muscles responsible for **wrist extension** (e.g., extensor carpi radialis longus, brevis, and extensor carpi ulnaris) are innervated by the radial nerve or its deep branch **distal to the spiral groove**. - Therefore, a low radial nerve palsy would cause **loss of wrist extension**, leading to **wrist drop**. *Loss of finger extension* - The **extensor digitorum**, **extensor indicis**, and **extensor digiti minimi** muscles, which extend the fingers, are innervated by the posterior interosseous nerve (a continuation of the deep radial nerve) also **distal to the spiral groove**. - A low radial nerve palsy would result in the inability to **extend the fingers**. *Loss of thumb extension* - The muscles involved in **thumb extension** (e.g., abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) are also supplied by the posterior interosseous nerve, originating **distal to the spiral groove**. - Consequently, **loss of thumb extension** would be a feature of a low radial nerve palsy.

Q: Which muscle protects the brachial plexus in case of clavicle fractures?

Subclavius. ***Subclavius*** - The **subclavius muscle** lies inferior to the clavicle, between the clavicle and the first rib, acting as a **cushion** during trauma. - Its strategic position provides a **protective barrier** for the underlying neurovascular structures, including the **brachial plexus** and subclavian vessels, against clavicular fragments. *Supraspinatus* - The **supraspinatus muscle** is located in the **supraspinous fossa** of the scapula, superior to the spine of the scapula. - Its primary role is in **shoulder abduction** and stabilization of the glenohumeral joint, not providing direct protection to the brachial plexus during clavicle fractures. *Subscapularis* - The **subscapularis muscle** is situated in the **subscapular fossa** on the anterior surface of the scapula. - It functions in **internal rotation** of the humerus and stabilization of the shoulder joint, and does not lie in a position to protect the brachial plexus from clavicular trauma. *Teres Minor* - The **teres minor muscle** is one of the rotator cuff muscles, located on the **posterior aspect of the scapula**, inferior to the infraspinatus. - Its main actions are **external rotation** and adduction of the humerus, and it is anatomically distant from the clavicle and brachial plexus in this context.

Q: Infraspinous fossa of scapula contains which of the following muscles?

Infraspinatus. ***Infraspinatus*** - The **infraspinous fossa** is a large depression on the posterior surface of the scapula, inferior to the spine. - As its name suggests, it is the origin for the **infraspinatus muscle**, which is a key component of the rotator cuff. - This muscle is responsible for **external rotation** of the humerus at the shoulder joint. *Subscapularis* - The **subscapularis muscle** originates from the **subscapular fossa**, which is on the anterior (costal) surface of the scapula. - This muscle is responsible for internal rotation of the humerus. *Teres major* - The **teres major muscle** originates from the inferior angle and lower part of the lateral border of the scapula. - It works to extend, adduct, and internally rotate the humerus, acting synergistically with the latissimus dorsi. *Supraspinatus* - The **supraspinatus muscle** originates from the **supraspinous fossa**, which is located above the spine of the scapula. - This muscle is primarily responsible for the initiation of abduction of the arm.

Question 1

Identify the marked muscle in the diagram.

Accepted Answer

Extensor carpi radialis brevis

Answer

Brachialis

Answer

Flexor carpi ulnaris

Answer

Extensor digitorum

Question 2

What is the nerve supply of the structure marked in the image?

Accepted Answer

Median nerve

Answer

Anterior interosseous nerve

Answer

Posterior interosseous nerve

Answer

Ulnar nerve

Question 3

Which nerve supplies the rhomboid major and minor muscles?

Accepted Answer

Dorsal scapular nerve

Answer

Thoracodorsal nerve

Answer

Spinal accessory nerve

Answer

Suprascapular nerve

Question 4

Identify the anatomical structures visible in the image.

Accepted Answer

Styloid process of the ulna

Answer

Scaphoid bone

Answer

Styloid process of the radius

Answer

Extensor pollicis longus and Abductor pollicis longus

Question 5

What is the role of the anconeus muscle in elbow movement?

Accepted Answer

Assists in elbow extension

Answer

Wrist extension

Answer

Thumb abduction

Answer

Elbow flexion

Question 6

Which of the following arteries contributes MOST to the deep palmar arch?

Accepted Answer

Radial artery

Answer

Ulnar artery

Answer

Posterior interosseous artery

Answer

Anterior interosseous artery

Question 7

Which of the following is a sensory region of the ulnar nerve?

Accepted Answer

Tip of little finger

Answer

Tip of index finger

Answer

1st web space

Answer

Lateral upper aspect of arm

Question 8

Low radial nerve palsy (just after the spiral groove) does not produce which of the following?

Accepted Answer

Loss of elbow extension

Answer

Loss of finger extension

Answer

Loss of wrist extension

Answer

Loss of thumb extension

Question 9

Which muscle protects the brachial plexus in case of clavicle fractures?

Accepted Answer

Subclavius

Answer

Supraspinatus

Answer

Subscapularis

Answer

Teres Minor

Question 10

Infraspinous fossa of scapula contains which of the following muscles?

Accepted Answer

Infraspinatus

Answer

Subscapularis

Answer

Teres major

Answer

Supraspinatus

Upper Limb — MCQs

Upper Limb — MCQs

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