Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 791: Which of the following nerves does not have a root value of C5, C6, or C7?

A. Lateral pectoral nerve
B. Musculocutaneous nerve
C. Lateral root of median nerve
D. Ulnar nerve (Correct Answer)

Explanation: ***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.

Question 792: In obstruction of the second part of the axillary artery, the anastomosis between which arteries will maintain the blood supply to the upper limb?

A. Dorsal scapular artery and subscapular artery (Correct Answer)
B. Anterior and posterior circumflex humeral arteries
C. Posterior circumflex humeral and circumflex scapular arteries
D. Suprascapular and anterior circumflex humeral arteries

Explanation: Dorsal scapular artery and subscapular artery - This anastomosis forms part of the scapular anastomosis, which is crucial for collateral circulation around the shoulder joint and axillary artery. - The dorsal scapular artery (a branch of the subclavian artery, or occasionally the deep branch of the transverse cervical artery) connects with the subscapular artery (a branch of the third part of the axillary artery) and its circumflex scapular branch, bypassing the obstruction [1]. - This provides effective collateral circulation when the second part of the axillary artery is obstructed. Anterior and posterior circumflex humeral arteries - These arteries originate from the third part of the axillary artery and primarily supply the humeral head and surrounding shoulder joint [1]. - While they anastomose around the surgical neck of the humerus, they are distal to an obstruction in the second part of the axillary artery and do not provide an alternative blood supply around the obstruction. Posterior circumflex humeral and circumflex scapular arteries - The posterior circumflex humeral artery is distal to the obstruction, originating from the third part of the axillary artery. - Although the circumflex scapular artery (a branch of the subscapular artery) participates in the scapular anastomosis, its anastomosis with the posterior circumflex humeral artery would still be affected by an occlusion in the second part of the axillary artery as they are both branches distal to the obstruction. Suprascapular and anterior circumflex humeral arteries - The suprascapular artery (from the thyrocervical trunk) contributes to the scapular anastomosis and is proximal to the obstruction, supplying the supraspinatus and infraspinatus muscles. - However, the anterior circumflex humeral artery arises from the third part of the axillary artery and is distal to an obstruction in the second part, so their anastomosis would not effectively bypass the blockage.

Question 793: Which of the following muscles is not supplied by the Median Nerve?

A. Opponens pollicis
B. Adductor pollicis (Correct Answer)
C. Abductor pollicis brevis
D. Flexor pollicis brevis

Explanation: **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 794: A 45-year-old patient presents with numbness in the skin over the hypothenar eminence. Which nerve is responsible for this sensory innervation?

A. Ulnar nerve (Correct Answer)
B. Radial nerve
C. Median nerve
D. Anterior interosseous nerve

Explanation: ***Ulnar nerve*** - The **ulnar nerve** provides sensory innervation to the **hypothenar eminence** (the fleshy mass at the base of the little finger), the palmar and dorsal aspects of the little finger, and the ulnar half of the ring finger [1]. - Numbness in this specific area is a classic symptom of **ulnar nerve compression** or damage, often occurring at the elbow (**cubital tunnel syndrome**) or wrist (**Guyon's canal syndrome**). *Radial nerve* - The **radial nerve** primarily innervates the posterior aspect of the arm and forearm, and the dorsum of the hand, including the thumb, index, middle, and radial half of the ring finger. - It does not supply sensory innervation to the hypothenar eminence. *Median nerve* - The **median nerve** provides sensory innervation to the palmar surface of the thumb, index, middle, and radial half of the ring finger, and the dorsal tips of these fingers [1]. - It is responsible for sensation over the **thenar eminence** (at the base of the thumb), not the hypothenar eminence. *Anterior interosseous nerve* - The **anterior interosseous nerve (AIN)** is a motor branch of the median nerve that primarily innervates deep forearm muscles [2]. - It has **no sensory function** and therefore does not provide sensation to any part of the hand [2].

Question 795: Muscles primarily involved in a tight grip of the hand are?

A. Opponens pollicis
B. Long flexors (Correct Answer)
C. Short flexors
D. Long extensors

Explanation: Long flexors - The long flexor muscles of the forearm, such as the flexor digitorum profundus and flexor pollicis longus, are critical for producing the powerful flexion needed for a tight grip [1]. - These muscles have long tendons that cross the wrist and insert into the distal phalanges, providing the necessary leverage and force for strong pinching and gripping [1]. Short flexors - Short flexors, like the flexor digiti minimi brevis and flexor pollicis brevis, primarily contribute to fine motor control and positioning of the digits rather than generating the main power for a tight grip [1]. - Their shorter moment arms and limited bulk mean they provide less overall force compared to the powerful long flexors. Opponens pollicis - The opponens pollicis is essential for opposition of the thumb, which is the movement of the thumb across the palm to touch the fingertips of other fingers [1]. - While integral to prehension and fine manipulation, it doesn't primarily contribute to the overall strength of a tight grip which involves all fingers. Long extensors - Long extensors (e.g., extensor digitorum, extensor pollicis longus) are responsible for extending the fingers and wrist. - They work in opposition to the flexors and are not directly involved in generating the force required to create a tight grip.

Question 796: All of the following movements occur during abduction of the shoulder except which of the following?

A. Elevation of humerus
B. Medial rotation of scapula (Correct Answer)
C. Acromioclavicular joint movement
D. Axial rotation of clavicle

Explanation: ***Medial rotation of scapula*** - During **shoulder abduction**, the scapula primarily performs **upward rotation**, not medial rotation. - **Upward rotation** helps to position the glenoid fossa for wider range of motion, while medial rotation would restrict abduction. *Elevation of humerus* - This is the fundamental movement of **abduction**, where the arm actually lifts away from the body. - The **deltoid** and **supraspinatus muscles** are key players in elevating the humerus. *Axial rotation of clavicle* - The **clavicle rotates posteriorly** around its longitudinal axis during abduction, particularly beyond 90 degrees. - This rotation allows the **scapula** to further rotate upward, contributing to the full range of motion. *Acromioclavicular joint movement* - The **acromioclavicular (AC) joint** moves to facilitate **scapular rotation**, which is essential for achieving full shoulder abduction. - Specifically, the scapula rotates on the clavicle at the AC joint, enabling the glenoid to track the humeral head.

Question 797: Inability to adduct the thumb is due to the injury of which nerve?

A. Median nerve
B. Ulnar nerve (Correct Answer)
C. Radial nerve
D. Musculocutaneous nerve

Explanation: ***Ulnar nerve*** - The **adductor pollicis muscle**, responsible for thumb adduction, is solely innervated by the **deep branch of the ulnar nerve** [1]. - Injury to the ulnar nerve proximally or to its deep branch will result in weakness or paralysis of this muscle, leading to the inability to adduct the thumb. *Median nerve* - The median nerve primarily innervates the **thenar muscles** responsible for **thumb flexion**, abduction, and opposition (e.g., abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) [1]. - Its injury would impair these movements, but not directly thumb adduction, which is distinctly an ulnar nerve function. *Radial nerve* - The radial nerve innervates muscles responsible for **wrist and finger extension**, including extensors of the thumb [1]. - While it plays a role in thumb movement, it does not directly control adduction. *Musculocutaneous nerve* - The musculocutaneous nerve primarily innervates the muscles of the **anterior compartment of the arm**, such as the biceps brachii and brachialis, which are responsible for elbow flexion and forearm supination. - It does not innervate any muscles involved in hand or thumb movements.

Question 798: The ape thumb deformity occurs due to a lesion of the:

A. Radial nerve
B. Median nerve (Correct Answer)
C. Ulnar nerve
D. Musculocutaneous nerve

Explanation: ***Median nerve*** - A lesion of the **median nerve** paralyses the thenar muscles, which are responsible for **opposition** and **abduction of the thumb** [1]. - This results in the characteristic "ape thumb" position where the thumb falls back into the plane of the other fingers and cannot be properly opposed [1]. *Radial nerve* - A radial nerve lesion primarily affects the **extensor muscles** of the wrist and fingers, leading to **wrist drop**. - It does not directly cause the ape thumb deformity, as the thenar muscles are supplied by the median nerve [1]. *Ulnar nerve* - An ulnar nerve lesion typically results in a **claw hand deformity**, affecting the medial two fingers due to paralysis of the interossei and medial two lumbricals. - It does not involve the thenar muscles in a way that would produce an ape thumb deformity. *Musculocutaneous nerve* - The musculocutaneous nerve innervates muscles in the **anterior compartment of the arm** (e.g., biceps brachii, brachialis), affecting forearm flexion. - It has no direct involvement in the innervation of the muscles of the hand responsible for thumb movement or the ape thumb deformity.

Question 799: The cubital fossa is bounded laterally by the:

A. Biceps brachii
B. Triceps brachii
C. Brachioradialis (Correct Answer)
D. Coracobrachialis

Explanation: ***Brachioradialis*** - The **brachioradialis** muscle forms the lateral boundary of the cubital fossa. - This muscle arises from the lateral supracondylar ridge of the humerus and inserts onto the distal radius. *Biceps brachii* - The **biceps brachii** muscle lies within the cubital fossa, but it is not a boundary. - Its tendon passes through the fossa to insert onto the radial tuberosity. *Triceps brachii* - The **triceps brachii** is located in the posterior compartment of the arm and does not form a boundary of the cubital fossa. - It functions to extend the elbow joint. *Coracobrachialis* - The **coracobrachialis** muscle is situated in the medial compartment of the upper arm, far from the cubital fossa. - It acts to flex and adduct the arm at the shoulder joint.

Question 800: Muscles attached to the greater tubercle of the humerus include which of the following?

A. Latissimus dorsi
B. Teres major
C. Pectoralis major
D. Supraspinatus (Correct Answer)

Explanation: ***Supraspinatus*** - The **supraspinatus muscle** is one of the four rotator cuff muscles and inserts onto the **superior facet of the greater tubercle** of the humerus. - Its primary function is to **abduct the arm** in the initial 15 degrees. *Latissimus dorsi* - The **latissimus dorsi** inserts onto the **floor of the bicipital groove** of the humerus, not the greater tubercle. - It is primarily responsible for **extension, adduction, and internal rotation** of the arm. *Teres major* - The **teres major muscle** inserts onto the **medial lip of the bicipital groove** (intertubercular sulcus) of the humerus. - Its actions are similar to the latissimus dorsi, including **adduction, extension, and internal rotation** of the arm. *Pectoralis major* - The **pectoralis major muscle** inserts onto the **lateral lip of the bicipital groove** (intertubercular sulcus) of the humerus. - Its main actions are **adduction, internal rotation**, and **flexion of the humerus**.

Practice by Chapter

Pectoral Region and Axilla

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Arm and Cubital Fossa

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Forearm and Hand

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Joints of Upper Limb

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Nerves of Upper Limb

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Arterial Supply and Venous Drainage

Practice Questions

Lymphatic Drainage

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Muscles and Their Actions

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Applied Anatomy and Clinical Correlations

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Surface Anatomy and Landmarks

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Upper Limb — MCQs

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