Upper Limb Practice Questions

Q: Which muscle of the arm has additional supinator action?

Biceps. ***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.

Q: Which of the following statements about the lumbrical muscles is correct?

Flex MCP joints and extend IP joints. 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].

Q: A patient has a herniated intervertebral disc impinging on the right C5 nerve roots. Which of the following movements would most likely be affected?

Flexion of the elbow. ***Flexion of the elbow*** - The **C5 nerve root** is a primary contributor to the innervation of the **biceps brachii** and **brachialis** muscles, which are the prime movers for elbow flexion. - The C5 myotome specifically includes elbow flexion as one of its key motor functions. - Impingement of the C5 nerve root would therefore most directly impact the strength and function of **elbow flexion**, leading to weakness in this movement. *Extension of the fingers* - Finger extension is primarily mediated by the **C7 and C8 nerve roots** via the posterior interosseous nerve (branch of the radial nerve). - C5 does not significantly contribute to finger extension. *Extension of the shoulder* - Shoulder extension involves muscles primarily innervated by the **C6, C7, and C8 nerve roots** (e.g., latissimus dorsi via thoracodorsal nerve, teres major). - While C5 contributes to some shoulder movements (particularly **shoulder abduction** via the deltoid), it is not primarily responsible for shoulder extension. *Flexion of the wrist* - Wrist flexion is primarily served by muscles innervated by the **C6, C7, and C8 nerve roots** (e.g., flexor carpi radialis - C6/C7, flexor carpi ulnaris - C7/C8). - The C5 nerve root has minimal to no role in wrist flexion.

Q: Teres minor is supplied by

Axillary nerve. ***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.

Q: A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

Posterior Interosseous nerve injury. Posterior Interosseous Nerve (PIN) injury - The Posterior Interosseous Nerve is the deep motor branch of the radial nerve that specifically innervates the extensor muscles of the fingers and thumb - These muscles include: Extensor Digitorum, Extensor Indicis, Extensor Digiti Minimi, Extensor Pollicis Longus and Brevis [1] - PIN injury causes inability to extend the MCP joints and interphalangeal joints of the fingers [1] - Wrist extension is preserved because the Extensor Carpi Radialis Longus (ECRL) and often ECRB are innervated by the radial nerve proper before it gives off the PIN [1] - This results in a characteristic finger drop without wrist drop Radial nerve injury - A high radial nerve injury (proximal, above the elbow) would cause both wrist drop AND finger extension loss - However, radial nerve injury at the spiral groove (most common site) typically spares the PIN or affects it less severely - The question asks specifically about isolated inability to extend MCP joints, which is the hallmark of PIN injury, not general radial nerve injury - Radial nerve proper gives branches to triceps, brachioradialis, and ECRL before dividing into PIN and superficial branch Ulnar nerve injury - The ulnar nerve innervates intrinsic hand muscles (interossei, lumbricals to digits 4-5, hypothenar muscles, adductor pollicis) [1] - Ulnar nerve injury causes claw hand deformity with MCP hyperextension (not loss of extension) and IP joint flexion - This is the opposite of what is described in the question Median nerve injury - The median nerve innervates the thenar muscles, lateral two lumbricals, and forearm flexors [1] - Median nerve injury causes ape hand deformity with loss of thumb opposition and flexion - It does not affect MCP joint extension, which is an extensor function

Q: Tetracycline injection causes palsy of which nerve?

Radial. ***Radial*** - Tetracycline injections, especially when given in the deltoid region, can inadvertently injure the **radial nerve** due to its superficial course. - Damage to the radial nerve typically results in **wrist drop** and sensory deficits over the dorsum of the hand. *Ulnar* - The **ulnar nerve** is commonly injured at the elbow (cubital tunnel syndrome) or wrist (Guyon's canal). - Injury typically results in weakness of intrinsic hand muscles and sensory loss in the little finger and ulnar half of the ring finger, which is not characteristic of an injection injury in the deltoid region. *Median* - The **median nerve** is more frequently injured at the wrist (carpal tunnel syndrome) or elbow. - Injury causes difficulty with thumb opposition and sensation in the first three and a half digits on the palmar side. *Superficial peroneal* - The **superficial peroneal nerve** is found in the lower leg and foot, innervating the lateral compartment muscles and providing sensation to the dorsum of the foot. - It would not be affected by an injection in the upper arm or shoulder region.

Q: Which is the primary muscle causing supination of the forearm?

Supinator. ***Supinator*** - The **supinator muscle** is the **primary muscle** responsible for **supination** of the forearm, rotating the palm anteriorly or superiorly. - It is a deep muscle of the **posterior compartment** of the forearm. - Its action is especially prominent when **supinating against resistance** or in very slow movements, as it works synergistically with the biceps brachii. *Biceps brachii* - While the **biceps brachii** is also a powerful **supinator** of the forearm, especially when the elbow is flexed, it is a **secondary supinator**. - It is primarily a major **flexor** of the elbow, whereas the supinator is dedicated specifically to supination. *Brachioradialis* - The **brachioradialis** is primarily a **flexor** of the forearm at the elbow joint. - It helps to bring the forearm into a **mid-prone or mid-supine position** from either full pronation or full supination, but does not actively supinate. *Anconeus* - The **anconeus** is a small muscle that assists the **triceps brachii** in **extension of the forearm** at the elbow. - It helps to **stabilize the elbow joint** and slightly abducts the ulna during pronation, but has no role in supination.

Q: Which muscle in the hand is unique for originating from the tendon of another muscle?

Lumbricals. ***Lumbricals*** - The **lumbrical muscles** in the hand are unique as they originate from the **tendons of the flexor digitorum profundus muscle** [1]. - This unusual origin allows them to act on both the metacarpophalangeal (MCP) joints (flexion) and the interphalangeal (IP) joints (extension) [1]. *Palmaris longus* - The **palmaris longus** muscle originates from the **medial epicondyle of the humerus**, not from the tendon of another muscle. - It inserts into the **palmar aponeurosis** and is absent in a significant portion of the population. *Flexor carpi radialis (FCR)* - The **flexor carpi radialis** originates from the **medial epicondyle of the humerus**. - It is a primary flexor and abductor of the wrist, inserting into the bases of the second and third metacarpal bones. *Adductor pollicis* - The **adductor pollicis** has two heads, transverse and oblique, both originating from the **carpal bones** and **metacarpals**, not from the tendon of another muscle. - Its main function is to adduct the thumb, pulling it towards the palm.

Q: Which of the following structures is not found in the midpalmar space?

1st lumbrical. ***1st lumbrical*** - The **1st lumbrical** is typically found within the **thenar space** or the **central compartment of the palm**, not the midpalmar space [1]. - Its position is associated with the **index finger's flexor tendons**, which do not traverse the midpalmar space. *2nd lumbrical* - The **2nd lumbrical** is located in the **midpalmar space**, situated on the radial side of the **flexor digitorum profundus (FDP) tendon** to the third digit [1]. - It arises from the radial side of the **FDP tendon** of the **middle finger** [1]. *FDP of 3rd finger* - The **flexor digitorum profundus (FDP) tendon** to the **third finger** (middle finger) passes through the **midpalmar space** [1]. - These tendons, along with their associated lumbricals, are key components of the **midpalmar space**. *FDP of 4th finger* - The **flexor digitorum profundus (FDP) tendon** to the **fourth finger** (ring finger) also travels through the **midpalmar space** [1]. - The midpalmar space contains the **FDP tendons** for the middle, ring, and little fingers, as well as their corresponding lumbricals (2nd, 3rd, and 4th).

Q: Which muscle will be paralyzed when the radial nerve is injured just below the spiral groove?

Extensor Carpi Radialis Brevis. Extensor Carpi Radialis Brevis - The radial nerve travels in the spiral groove of the humerus and gives off branches in a specific sequence. - Proximal to the spiral groove: Branches to triceps and anconeus - Within/at the spiral groove: Branches to brachioradialis and extensor carpi radialis longus (ECRL) - Just distal to the spiral groove: Branch to extensor carpi radialis brevis (ECRB) [1] - this is the first branch after exiting the spiral groove - More distally: The nerve divides into superficial and deep branches (posterior interosseous nerve) [1] - An injury just below the spiral groove would paralyze ECRB while sparing muscles innervated proximal to or within the groove (triceps, anconeus, brachioradialis, ECRL). Supinator - The supinator is innervated by the deep branch of the radial nerve (posterior interosseous nerve), which branches off more distally in the proximal forearm. - This muscle would only be affected by injuries distal to the bifurcation of the radial nerve into superficial and deep branches, not by an injury just below the spiral groove. Extensor Digitorum - The extensor digitorum is supplied by the posterior interosseous nerve, which is a continuation of the deep branch [1]. - This innervation occurs significantly distal to the spiral groove in the posterior forearm compartment. - It would be affected by posterior interosseous nerve injuries, not by lesions just below the spiral groove. Abductor Pollicis Longus - The abductor pollicis longus is innervated by the posterior interosseous nerve in the distal forearm [1]. - This is the most distal of all the options and would only be affected by posterior interosseous nerve palsy, not by radial nerve injury at the spiral groove level [1].

Question 1

Which muscle of the arm has additional supinator action?

Accepted Answer

Biceps

Answer

Brachialis

Answer

Coracobrachialis

Answer

Triceps

Question 2

Which of the following statements about the lumbrical muscles is correct?

Accepted Answer

Flex MCP joints and extend IP joints

Answer

All lumbricals are supplied by the median nerve

Answer

Origin from the tendons of flexor digitorum superficialis

Answer

All lumbricals are supplied by the ulnar nerve

Question 3

A patient has a herniated intervertebral disc impinging on the right C5 nerve roots. Which of the following movements would most likely be affected?

Accepted Answer

Flexion of the elbow

Answer

Extension of the fingers

Answer

Extension of the shoulder

Answer

Flexion of the wrist

Question 4

Teres minor is supplied by

Accepted Answer

Axillary nerve

Answer

Suprascapular nerve

Answer

Lower subscapular nerve

Answer

Thoracodorsal nerve

Question 5

A person is not able to extend his metacarpophalangeal joint. Injury to which of the following nerve result in this?

Accepted Answer

Posterior Interosseous nerve injury

Answer

Radial nerve injury

Answer

Ulnar nerve injury

Answer

Median nerve injury

Question 6

Tetracycline injection causes palsy of which nerve?

Accepted Answer

Radial

Answer

Median

Answer

Ulnar

Answer

Superficial peroneal

Question 7

Which is the primary muscle causing supination of the forearm?

Accepted Answer

Supinator

Answer

Brachioradialis

Answer

Anconeus

Answer

Biceps brachii

Question 8

Which muscle in the hand is unique for originating from the tendon of another muscle?

Accepted Answer

Lumbricals

Answer

Palmaris longus

Answer

Adductor pollicis

Answer

Flexor carpi radialis (FCR)

Question 9

Which of the following structures is not found in the midpalmar space?

Accepted Answer

1st lumbrical

Answer

2nd lumbrical

Answer

FDP of 4th finger

Answer

FDP of 3rd finger

Question 10

Which muscle will be paralyzed when the radial nerve is injured just below the spiral groove?

Accepted Answer

Extensor Carpi Radialis Brevis

Answer

Extensor Digitorum

Answer

Supinator

Answer

Abductor Pollicis Longus

Upper Limb — MCQs

Upper Limb — MCQs

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