Upper Limb Practice Questions

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: 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: Which nerve supplies the area marked as ‘Area B’ in the image?

Radial nerve. ***Radial nerve*** - The radial nerve provides **sensory innervation to the dorsum of the hand**, specifically the radial side including the dorsal aspect of the **thumb, index, middle, and radial half of the ring finger** (excluding the distal phalanges) - This anatomical snuffbox region and dorsal hand area is the characteristic **sensory distribution of the superficial branch of the radial nerve** - The radial nerve also provides **motor innervation to extensor muscles of the forearm** via its posterior interosseous branch *Ulnar nerve* - Supplies sensory innervation to the **ulnar 1.5 digits** (little finger and ulnar half of ring finger) on both palmar and dorsal surfaces - Provides motor innervation to **most intrinsic hand muscles** (hypothenar muscles, interossei, medial lumbricals) - Would not innervate a radial-sided area on the dorsum of the hand *Median nerve* - Provides sensory innervation primarily to the **palmar surface** of the lateral 3.5 digits (thumb, index, middle, and radial half of ring finger) - On the dorsum, only supplies the **distal phalanges (nail beds)** of index and middle fingers - Supplies motor innervation to **thenar muscles** and lateral lumbricals - Does not provide primary sensory innervation to broad dorsal hand areas *Posterior interosseous nerve* - This is the **deep motor branch of the radial nerve** that passes through the supinator muscle - Provides **motor innervation** to extensor muscles in the posterior forearm compartment - Has minimal sensory function, limited to **proprioceptive innervation of wrist joint capsule** - Does not provide cutaneous sensory innervation to skin areas

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 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: Where does the flexor carpi radialis insert?

Base of 2nd and 3rd metacarpal. ***Base of 2nd and 3rd metacarpal*** - The **flexor carpi radialis** muscle, as its name suggests, is a powerful wrist flexor and **radial deviator**. - Its tendon typically inserts onto the **palmar aspect of the base of the second and third metacarpal bones**. *Base of 5th metacarpal* - The **5th metacarpal** is located on the **ulnar side** of the hand, which is not the insertion site for the flexor carpi radialis. - Muscles inserting near the 5th metacarpal include the **flexor carpi ulnaris** and the **extensor carpi ulnaris**. *Scaphoid and trapezium* - The **scaphoid** and **trapezium** are **carpal bones** of the wrist, but they do not serve as the direct insertion point for the flexor carpi radialis [1]. - These bones form part of the **carpal tunnel** and are involved in complex wrist movements [1]. *Capitate and hamate* - The **capitate** and **hamate** are also **carpal bones** located in the distal row of the wrist. - While they are functionally involved in wrist movements, they are not the primary insertion site for the flexor carpi radialis.

Q: What type of muscles are medial two lumbricals?

Bipennate. ***Bipennate*** - The **medial two lumbricals** (third and fourth) are classified as **bipennate muscles** because they originate from two adjacent tendons of the flexor digitorum profundus (FDP). - Each of these lumbricals arises from the **adjacent sides of two FDP tendons**, with muscle fibers converging toward a central insertion, creating a bipennate arrangement. - This dual origin distinguishes them from the lateral two lumbricals, which are unipennate. *Unipennate* - **Unipennate muscles** have fibers that attach obliquely to only one side of a single tendon. - The **lateral two lumbricals** (first and second) are unipennate as they each arise from a single FDP tendon. - This is not the correct classification for the medial two lumbricals. *Multipennate* - **Multipennate muscles** have multiple tendon arrangements with fibers converging at different angles from several directions. - Examples include the **deltoid muscle**, which has a much more complex architecture than lumbricals. *None of the options* - Since **bipennate** accurately describes the structure of the medial two lumbricals based on their dual tendon origins, this option is incorrect. - The architectural classification is well-established in anatomical literature.

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: What movements does the coracoacromial ligament resist?

Upward displacement of humeral head. Upward displacement of humeral head - The **coracoacromial ligament** extends from the coracoid process to the acromion, forming the **coracoacromial arch** which acts as a protective roof over the humeral head. - This anatomical position allows it to act as a **passive restraint against superior migration** or upward displacement of the **humeral head**, especially important when the rotator cuff (particularly supraspinatus) is deficient. - It prevents **superior subluxation** of the humerus and protects the joint from impingement against the acromion. *Abduction of shoulder* - **Abduction** of the shoulder is primarily limited by the **inferior capsule** and **adductor muscles** (latissimus dorsi, pectoralis major, teres major). - The coracoacromial ligament does not play a significant role in limiting the range of abduction movements. *Inferior displacement of humerus* - **Inferior displacement** of the humerus is primarily resisted by the **superior capsule**, the **supraspinatus tendon**, and the **coracohumeral ligament**. - The coracoacromial ligament is positioned superiorly and therefore does not prevent downward movement of the humeral head. *External rotation* - **External rotation** of the shoulder is limited by the **anterior capsule**, **anterior glenohumeral ligaments**, and the **subscapularis muscle**. - The coracoacromial ligament's orientation and function do not contribute to resisting rotational movements of the humerus.

Q: Which muscle acting on the thumb is the only one among the options that has dual nerve supply?

Flexor Pollicis Brevis. ***Flexor Pollicis Brevis (FPB)*** - The **Flexor Pollicis Brevis** is unique among thumb muscles because it commonly has a **dual nerve supply**. [1] - Its superficial head is innervated by the **median nerve**, while its deep head is innervated by the **ulnar nerve**. *Flexor Pollicis Longus (FPL)* - The **Flexor Pollicis Longus** is solely innervated by the **anterior interosseous nerve**, a branch of the **median nerve**. [1] - It does not receive any neural input from the ulnar nerve. *Adductor Pollicis* - The **Adductor Pollicis** muscle is exclusively innervated by the **deep branch of the ulnar nerve**. - It plays a crucial role in **adduction of the thumb** and does not share innervation with the median nerve. *Opponens Pollicis* - The **Opponens Pollicis** is primarily supplied by the **recurrent branch of the median nerve** (also known as the thenar motor branch). - Its function is **opposition of the thumb**, and it does not have dual innervation.

Question 1

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 2

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 3

Which nerve supplies the area marked as ‘Area B’ in the image?

Accepted Answer

Radial nerve

Answer

Ulnar nerve

Answer

Median nerve

Answer

Posterior interosseous nerve

Question 4

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 5

Identify the marked muscle in the diagram.

Accepted Answer

Extensor carpi radialis brevis

Answer

Brachialis

Answer

Flexor carpi ulnaris

Answer

Extensor digitorum

Question 6

Where does the flexor carpi radialis insert?

Accepted Answer

Base of 2nd and 3rd metacarpal

Answer

Base of 5th metacarpal

Answer

Scaphoid and trapezium

Answer

Capitate and hamate

Question 7

What type of muscles are medial two lumbricals?

Accepted Answer

Bipennate

Answer

Multipennate

Answer

None of the options

Answer

Unipennate

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

What movements does the coracoacromial ligament resist?

Accepted Answer

Upward displacement of humeral head

Answer

Abduction of shoulder

Answer

Inferior displacement of humerus

Answer

External rotation

Question 10

Which muscle acting on the thumb is the only one among the options that has dual nerve supply?

Accepted Answer

Flexor Pollicis Brevis

Answer

Flexor Pollicis Longus

Answer

Adductor Pollicis

Answer

Opponens Pollicis

Upper Limb — MCQs

Upper Limb — MCQs

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