Upper Limb Practice Questions

Q: Which muscle initiates abduction at the shoulder joint?

Supraspinatus. ***Supraspinatus*** - The **supraspinatus muscle** is responsible for initiating abduction of the arm at the shoulder joint, specifically for the first 15-30 degrees. - Its tendon passes through the **subacromial space**, making it vulnerable to impingement and tears. *Subscapularis* - The **subscapularis** is primarily involved in **internal rotation** of the shoulder. - It also contributes to stabilization of the **glenohumeral joint**. *Deltoid* - The **deltoid muscle** is the principal abductor of the arm, but it takes over *after* the initial 15-30 degrees of abduction. - It is powerful for abduction from approximately **30 to 180 degrees**. *Infraspinatus* - The **infraspinatus muscle** is a key muscle for **external rotation** of the shoulder. - It also aids in stabilizing the **humeral head** within the glenoid cavity.

Q: The lateral boundary of the anatomical snuff box is formed by?

EPB. ***EPB*** - The **anatomical snuff box** is a triangular depression on the radial side of the wrist. - Its **lateral boundary** is formed by the tendons of **extensor pollicis brevis (EPB)** and **abductor pollicis longus (APL)**, which run together superficially [1]. - EPB is the primary structure cited in most exam contexts for the lateral boundary. *EPL* - The **extensor pollicis longus (EPL)** forms the **medial boundary** of the anatomical snuff box [1]. - It crosses obliquely over the wrist, lying deeper and medial to the EPB and APL tendons. *FPL* - The **flexor pollicis longus (FPL)** is located in the anterior compartment of the forearm [2]. - Its tendon crosses the wrist joint **anteriorly** and does not contribute to the boundaries of the anatomical snuff box [2]. - It flexes the interphalangeal joint of the thumb [2]. *Abductor Pollicis Brevis (APB)* - The **abductor pollicis brevis (APB)** is a thenar muscle in the palm of the hand. - It abducts the thumb at the carpometacarpal joint but does not form any boundary of the anatomical snuff box.

Q: The clavipectoral fascia is penetrated by which artery?

Thoracoacromial artery. The clavipectoral fascia is penetrated by which artery? ***Thoracoacromial artery*** - The **thoracoacromial artery** is a branch of the **axillary artery (second part)** that pierces the **clavipectoral fascia** along with other structures like the **cephalic vein**, **lateral pectoral nerve**, and **lymphatics**. - It then divides into four terminal branches: **pectoral**, **deltoid**, **acromial**, and **clavicular**, which supply relevant muscles and joints. *Anterior circumflex humeral artery* - This artery typically arises from the **third part of the axillary artery** and wraps around the surgical neck of the humerus. - It does not penetrate the **clavipectoral fascia** as it runs posterior to the coracobrachialis and biceps brachii muscles. *Axillary artery* - The **axillary artery** itself gives rise to branches that penetrate the clavipectoral fascia, but the main trunk of the axillary artery is located superficial to it, traversing the axilla. - It does not penetrate the fascia but rather gives off branches that do. *Subscapular artery* - The **subscapular artery** is the largest branch of the **axillary artery (third part)** and gives rise to the **circumflex scapular** and **thoracodorsal arteries**. - It runs along the inferior border of the subscapularis muscle and does not penetrate the **clavipectoral fascia**.

Q: Which of the following structures passes deep to the flexor retinaculum at the wrist along with the tendon of flexor digitorum profundus?

Median nerve. ***Median nerve*** - The **median nerve** passes through the **carpal tunnel**, deep to the **flexor retinaculum**, along with the tendons of the **flexor digitorum superficialis**, **flexor digitorum profundus**, and **flexor pollicis longus** [1]. - Compression of the **median nerve** in this confined space leads to **carpal tunnel syndrome**. *Ulnar nerve* - The **ulnar nerve** passes *superficial* to the **flexor retinaculum** within **Guyon's canal**, not deep to it [1]. - It accompanies the **ulnar artery** in this canal. *Radial nerve* - The **radial nerve** typically passes over the **anatomical snuffbox** or more proximally around the lateral epicondyle; it does not pass *deep* to the **flexor retinaculum** at the wrist. - Its superficial branch can be found on the dorsum of the hand. *Ulnar artery* - The **ulnar artery** passes *superficial* to the **flexor retinaculum**, alongside the **ulnar nerve**, within **Guyon's canal** [1]. - It contributes to the blood supply of the hand, forming the superficial palmar arch.

Q: Which statement considering the relations of nerves to the humerus is the most accurate?

Deltoid may atrophy following shoulder dislocation.. **Deltoid may atrophy following shoulder dislocation.** - **Shoulder dislocations**, particularly anterior dislocations, frequently injure the **axillary nerve** due to its close proximity to the humeral head and surgical neck. - Damage to the axillary nerve, which innervates the **deltoid muscle**, can lead to deltoid paralysis and subsequent **atrophy**, resulting in a flattened shoulder contour and impaired abduction. *The median nerve runs in the spiral groove.* - The **radial nerve**, not the median nerve, runs in the **spiral groove** (radial groove) of the humerus [1]. - The median nerve travels more anteriorly in the arm, alongside the brachial artery. *The axillary nerve runs around the anatomical neck.* - The **axillary nerve** wraps around the **surgical neck** of the humerus, not the anatomical neck. - The surgical neck is a common site for fractures, making the axillary nerve vulnerable to injury in such cases. *Mid-shaft humeral fractures will usually result in complete paralysis of triceps.* - Mid-shaft humeral fractures primarily risk damage to the **radial nerve**, which innervates the lateral and medial heads of the triceps [1]. - However, the **long head of the triceps** is innervated by the radial nerve more proximally and may remain partially functional, preventing complete paralysis of the entire triceps muscle.

Q: Which of the following is not a content of the cubital fossa?

Bicipital aponeurosis. ***Bicipital aponeurosis*** - The **bicipital aponeurosis** is part of the **roof** of the cubital fossa, not a content within the fossa itself. - It arises from the biceps brachii tendon and fans out medially to blend with the deep fascia of the forearm, protecting the underlying neurovascular structures (brachial artery and median nerve). - As a roof structure, it is distinct from the actual contents of the fossa. *Brachial artery* - The **brachial artery** is a key content of the cubital fossa, lying medial to the biceps tendon. - It bifurcates within the cubital fossa into the radial and ulnar arteries at the level of the radial neck. *Biceps brachii tendon* - The **biceps brachii tendon** is a central content of the cubital fossa, being the most lateral structure. - It inserts on the radial tuberosity and is responsible for powerful supination and flexion of the forearm. *Median nerve* - The **median nerve** is a content of the cubital fossa, running medial to the brachial artery (most medial structure). - It continues into the forearm between the two heads of pronator teres, providing motor innervation to most forearm flexors.

Q: Ulnar paradox is due to:

Flexor digitorum profundus (FDP). ***Flexor digitorum profundus (FDP)*** - The **ulnar paradox** occurs because a **distal ulnar nerve injury** (e.g., at the wrist) affects only the **intrinsic hand muscles** supplied by the ulnar nerve, sparing the **Flexor Digitorum Profundus (FDP)** to the ring and little fingers. - This allows the **FDP** (innervated by the ulnar nerve in its proximal forearm course, not at the wrist) to continue flexing the **distal interphalangeal (DIP) joints**, leading to a more pronounced **claw hand deformity** compared to a proximal injury. *Extensor carpi radialis brevis (ECRB)* - The **ECRB** is innervated by the **radial nerve** and is responsible for **wrist extension**, not affected in ulnar nerve injury. - It plays no direct role in the digital flexion deficits seen with ulnar nerve damage. *Radial nerve injury* - A **radial nerve injury** would predominantly affect the **extensors of the wrist and fingers**, leading to **wrist drop**, a completely different clinical presentation. - It does not cause a "claw hand" deformity or the effects on intrinsic hand muscles associated with the ulnar nerve. *Flexor pollicis longus (FPL)* - The **FPL** is innervated by the **anterior interosseous nerve**, a branch of the **median nerve**, and is responsible for **thumb IP joint flexion**. - Its function is unaffected by ulnar nerve lesions and is not involved in the ulnar paradox.

Q: Which of the following is not a branch of the posterior cord of the brachial plexus?

Long thoracic nerve. ### Long thoracic nerve - The **long thoracic nerve** originates directly from the **nerve roots C5, C6, C7** of the brachial plexus, **NOT from the posterior cord**. - It innervates the **serratus anterior muscle**, crucial for scapular protraction and upward rotation. - Damage causes **winged scapula** deformity. ### Axillary nerve - The **axillary nerve** is a **terminal branch of the posterior cord**, formed from C5-C6. - It supplies the **deltoid** and **teres minor muscles**, and provides sensory innervation to the lateral shoulder (regimental badge area). - Commonly injured in anterior shoulder dislocations or humeral surgical neck fractures. ### Thoracodorsal nerve - The **thoracodorsal nerve** (nerve to latissimus dorsi) is a **branch of the posterior cord**, deriving from C6-C8 [1]. - It exclusively innervates the **latissimus dorsi muscle**, responsible for shoulder adduction, extension, and internal rotation [1]. - Important in breast reconstruction surgery (latissimus dorsi flap). ### Radial nerve - The **radial nerve** is the **largest terminal branch of the posterior cord**, formed from C5-T1. - It innervates the **triceps brachii** and all extensor muscles of the forearm (wrist and finger extensors). - Provides sensory innervation to the posterior arm, forearm, and anatomical snuffbox. - Most commonly injured nerve of the upper limb (spiral groove fractures).

Q: Which of the following nerves does not have a root value of C5, C6, or C7?

Ulnar nerve. ***Ulnar nerve*** - The **ulnar nerve** arises from the **medial cord** of the brachial plexus and is formed primarily from **C8 and T1** nerve roots. - Unlike the other options, it does **not receive contributions from C5 or C6** nerve roots. - While some anatomical variations may include minimal C7 contribution, the ulnar nerve is predominantly C8-T1, making it distinct from the other nerves listed which all have clear C5, C6, and C7 components. *Lateral pectoral nerve* - The **lateral pectoral nerve** arises from the lateral cord and has root values from **C5, C6, and C7**. - It innervates the **pectoralis major muscle** [1]. *Musculocutaneous nerve* - The **musculocutaneous nerve** arises from the lateral cord and has root values from **C5, C6, and C7**. - It innervates the **biceps brachii**, **brachialis**, and **coracobrachialis muscles**. *Lateral root of median nerve* - The **lateral root of the median nerve** originates from the lateral cord and carries fibers from **C5, C6, and C7**. - It joins the medial root (from C8, T1) to form the median nerve.

Q: Which of the following muscles is not supplied by the Median Nerve?

Adductor pollicis. **Adductor pollicis** - The **adductor pollicis** muscle is primarily supplied by the **deep branch of the ulnar nerve**. - Its main function is to adduct the thumb towards the palm, which is crucial for a strong grip. *Opponens pollicis* - The **opponens pollicis** is supplied by the **recurrent branch of the median nerve** [1]. - This muscle allows for **opposition of the thumb**, bringing the thumb's tip to touch the tips of other fingers. *Flexor pollicis brevis* - The **flexor pollicis brevis** typically has a **dual innervation**; however, its superficial head is supplied by the **median nerve** [1], while its deep head can be supplied by the ulnar nerve. - Its primary action is **flexion of the thumb** at the metacarpophalangeal joint [1]. *Abductor pollicis brevis* - The **abductor pollicis brevis** is innervated by the **recurrent branch of the median nerve** [1]. - It is responsible for **abducting the thumb**, moving it away from the palm.

Question 1

Which muscle initiates abduction at the shoulder joint?

Accepted Answer

Supraspinatus

Answer

Deltoid

Answer

Infraspinatus

Answer

Subscapularis

Question 2

The lateral boundary of the anatomical snuff box is formed by?

Accepted Answer

EPB

Answer

FPL

Answer

Abductor Pollicis Brevis (APB)

Answer

EPL

Question 3

The clavipectoral fascia is penetrated by which artery?

Accepted Answer

Thoracoacromial artery

Answer

Anterior circumflex humeral artery

Answer

Axillary artery

Answer

Subscapular artery

Question 4

Which of the following structures passes deep to the flexor retinaculum at the wrist along with the tendon of flexor digitorum profundus?

Accepted Answer

Median nerve

Answer

Ulnar nerve

Answer

Radial nerve

Answer

Ulnar artery

Question 5

Which statement considering the relations of nerves to the humerus is the most accurate?

Accepted Answer

Deltoid may atrophy following shoulder dislocation.

Answer

The median nerve runs in the spiral groove.

Answer

The axillary nerve runs around the anatomical neck.

Answer

Mid-shaft humeral fractures will usually result in complete paralysis of triceps.

Question 6

Which of the following is not a content of the cubital fossa?

Accepted Answer

Bicipital aponeurosis

Answer

Brachial artery

Answer

Biceps brachii tendon

Answer

Median nerve

Question 7

Ulnar paradox is due to:

Accepted Answer

Flexor digitorum profundus (FDP)

Answer

Extensor carpi radialis brevis (ECRB)

Answer

Radial nerve injury

Answer

Flexor pollicis longus (FPL)

Question 8

Which of the following is not a branch of the posterior cord of the brachial plexus?

Accepted Answer

Long thoracic nerve

Answer

Thoracodorsal nerve

Answer

Axillary nerve

Answer

Radial nerve

Question 9

Which of the following nerves does not have a root value of C5, C6, or C7?

Accepted Answer

Ulnar nerve

Answer

Lateral pectoral nerve

Answer

Musculocutaneous nerve

Answer

Lateral root of median nerve

Question 10

Which of the following muscles is not supplied by the Median Nerve?

Accepted Answer

Adductor pollicis

Answer

Opponens pollicis

Answer

Abductor pollicis brevis

Answer

Flexor pollicis brevis

Upper Limb — MCQs

Upper Limb — MCQs

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