Biomechanics of Upper Limb — MCQs

10 questions

A 35-year-old tennis player presents with pain on the outer aspect of the elbow that worsens with gripping activities and wrist extension. The pain is localized over the lateral epicondyle. This condition most likely involves:

Which is a hinge joint :

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

What is a late complication of elbow dislocation?

Which muscle is tested using the empty can test in shoulder injuries?

Which muscles are paralyzed if there is hyperextension of metacarpophalangeal joint and flexion of the interphalangeal joint?

A 40-year-old man was repairing his wooden shed on Sunday morning. By afternoon, he felt that the hammer was becoming heavier and heavier. He felt pain in the lateral side of the elbow and also found that squeezing water out of sponge hurt his elbow. Which of the muscles are most likely involved-

A patient presents with upper limb swelling after undergoing a modified radical mastectomy (MRM). What is the most likely cause?

In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

Q10

In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

Biomechanics of Upper Limb Indian Medical PG Practice Questions and MCQs

Question 1: A 35-year-old tennis player presents with pain on the outer aspect of the elbow that worsens with gripping activities and wrist extension. The pain is localized over the lateral epicondyle. This condition most likely involves:

A. Inflammation of the flexor tendons at the medial epicondyle of the humerus
B. Inflammation of the biceps tendon at the shoulder
C. Inflammation of the triceps tendon at the elbow
D. Inflammation of the extensor tendons at the lateral epicondyle of the humerus (Correct Answer)

Explanation: ***Inflammation of the extensor tendons at the lateral epicondyle of the humerus*** - Pain on the **outer aspect of the elbow** that worsens with gripping and wrist extension is characteristic of **lateral epicondylitis**, also known as **tennis elbow**. - This condition involves inflammation and degeneration of the common **extensor tendons** originating from the **lateral epicondyle**, particularly the **extensor carpi radialis brevis**. *Inflammation of the flexor tendons at the medial epicondyle of the humerus* - This describes **medial epicondylitis**, or **golfer's elbow**, which causes pain on the **inner aspect of the elbow**. - It involves the **flexor-pronator mass tendons** and is aggravated by wrist flexion and forearm pronation, not wrist extension. *Inflammation of the biceps tendon at the shoulder* - **Bicipital tendonitis** presents with pain in the **anterior shoulder**, often radiating down the arm, and is typically exacerbated by lifting or overhead activities. - The pain is localized to the shoulder region and is not associated with wrist movements or elbow epicondyles. *Inflammation of the triceps tendon at the elbow* - **Triceps tendonitis** causes pain at the **posterior aspect of the elbow**, primarily with activities involving elbow extension against resistance. - While it affects the elbow, its location and aggravating factors differ from the described lateral elbow pain with gripping and wrist extension.

Question 2: Which is a hinge joint :

A. Knee
B. Atlanto Axial
C. Metacarpophalangeal
D. Elbow (Correct Answer)

Explanation: ***Elbow*** - The elbow joint is a classic example of a **hinge joint**, allowing for **flexion and extension** in one plane, similar to the action of a door hinge. - It is formed by the articulation of the **humerus** with the **ulna and radius**. *Knee* - While predominantly a hinge joint allowing **flexion and extension**, the knee also permits a small degree of **rotation** when flexed. - Its complex structure includes the **menisci and cruciate ligaments**, which provide stability and guide movement. *Atlanto Axial* - This is a **pivot joint**, allowing for the **rotation of the head** from side to side ("no" motion). - It is formed by the articulation between the first cervical vertebra (atlas) and the second cervical vertebra (axis). *Metacarpophalangeal* - These are **condyloid joints**, allowing for movement in **two planes**: flexion/extension and abduction/adduction. - They also permit **circumduction**, but not rotation, and are found at the base of the fingers.

Question 3: 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 4: What is a late complication of elbow dislocation?

A. Median nerve injury
B. Brachial artery injury
C. Myositis ossificans (Correct Answer)
D. None of the options

Explanation: **Myositis ossificans** - **Myositis ossificans** is the abnormal formation of **heterotopic bone** within muscle or other soft tissues, often developing weeks to months after joint trauma such as an elbow dislocation. - It typically presents as a painful, firm mass with restricted joint movement, especially **flexion** and **extension** at the elbow. *Median nerve injury* - **Median nerve injury** can occur at the time of the initial elbow dislocation (an **acute complication**), but it is not typically considered a late complication that develops over weeks or months. - Symptoms include numbness in the thumb, index, and middle fingers, as well as weakness in **thumb opposition** and **flexion** of the index finger. *Brachial artery injury* - **Brachial artery injury** is an **acute complication** of severe elbow dislocation, leading to compromise of distal blood flow. - Signs include absence of pulses, pallor, paresthesia, and pain in the forearm and hand, requiring immediate surgical intervention. *None of the options* - This option is incorrect because **myositis ossificans** is a well-recognized late complication of elbow dislocation.

Question 5: Which muscle is tested using the empty can test in shoulder injuries?

A. Infraspinatus
B. Supraspinatus (Correct Answer)
C. Subscapularis
D. Biceps brachii

Explanation: **Supraspinatus** - The **empty can test** (also known as the Jobe test) specifically assesses the integrity and strength of the **supraspinatus muscle** and tendon. - The test involves abducting the arm to 90 degrees, internally rotating it ("empty can" position), and then asking the patient to resist a downward force, which elicits pain or weakness if the supraspinatus is injured. *Infraspinatus* - The **infraspinatus muscle** is primarily responsible for external rotation of the shoulder. - It is typically tested with specific **external rotation resistance tests**, not the empty can test. *Subscapularis* - The **subscapularis muscle** is the primary internal rotator of the shoulder. - It is evaluated using specific tests like the **Gerber Lift-off test** or the **belly-press test**. *Biceps brachii* - The **biceps brachii** muscle is involved in shoulder flexion and elbow flexion and supination. - Its integrity is assessed with tests like **Speed's test** or **Yergason's test**, which evaluate the long head of the biceps tendon.

Question 6: Which muscles are paralyzed if there is hyperextension of metacarpophalangeal joint and flexion of the interphalangeal joint?

A. Extensor digitorum
B. Adductor pollicis
C. Pronator quadratus muscle
D. Interossei and lumbricals (Correct Answer)

Explanation: ***Interossei and lumbricals*** - Paralysis of the **interossei** and **lumbricals** leads to an imbalance in muscle forces, causing the **extensor digitorum** to hyperextend the **metacarpophalangeal (MCP)** joints. Together with the interossei, these muscles normally bring about flexion of the MP joints and extension of the interphalangeal (IP) joints [1]. - The unopposed action of the **flexor digitorum profundus** and **superficialis** then causes flexion of the **proximal interphalangeal (PIP)** and **distal interphalangeal (DIP)** joints, resulting in a **claw hand** deformity. *Extensor digitorum* - Paralysis of the **extensor digitorum** would primarily result in an inability to extend the fingers, leading to a **flexed posture** rather than hyperextension of the MCP joints. - It would not cause the characteristic flexion of the interphalangeal joints seen in this condition. *Adductor pollicis* - Paralysis of the **adductor pollicis** would affect the thumb's ability to adduct, impacting pinch strength and grasp, but it does not directly cause the described finger deformity. - This muscle is primarily involved in thumb movement, not the general finger mechanics described. *Pronator quadratus muscle* - The **pronator quadratus muscle** is responsible for **pronation of the forearm**. - Its paralysis would affect forearm rotation at the wrist, but it has no direct role in the movement or posture of the metacarpophalangeal or interphalangeal joints.

Question 7: A 40-year-old man was repairing his wooden shed on Sunday morning. By afternoon, he felt that the hammer was becoming heavier and heavier. He felt pain in the lateral side of the elbow and also found that squeezing water out of sponge hurt his elbow. Which of the muscles are most likely involved-

A. Triceps brachii and anconeous
B. Biceps brachii and supinator
C. Flexor digitorum superficialis
D. Extensor carpi radialis longus and brevis (Correct Answer)

Explanation: ***Extensor carpi radialis longus and brevis*** - The symptoms described, such as **lateral elbow pain** and pain with actions like hammering and squeezing, are classic for **lateral epicondylitis**, also known as **tennis elbow**. - **Extensor carpi radialis longus** and **brevis** are the primary muscles that originate from the **lateral epicondyle**, and their tendons are commonly affected in this condition. *Triceps brachii and anconeus* - The **triceps brachii** is responsible for elbow extension; injury to this muscle or the anconeus would typically cause pain in the **posterior aspect of the elbow**. - Pain specifically localized to the **lateral elbow** with gripping and wrist extension activities is not characteristic of triceps or anconeus involvement. *Biceps brachii and supinator* - The **biceps brachii** is a primary supinator and elbow flexor, while the **supinator** muscle also aids in supination; involvement of these would typically cause pain in the **anterior elbow** or with supination against resistance. - These muscles are generally not associated with pain in the **lateral epicondyle** with wrist extension and gripping activities. *Flexor digitorum superficialis* - The **flexor digitorum superficialis** is involved in flexing the fingers and wrist and originates from the **medial epicondyle** of the humerus. - Injury to this muscle would cause pain on the **medial side of the elbow** (golfer's elbow), not the lateral side, and is typically exacerbated by repetitive wrist flexion.

Question 8: A patient presents with upper limb swelling after undergoing a modified radical mastectomy (MRM). What is the most likely cause?

A. Angiosarcoma
B. Recurrence
C. Upper limb Lymphedema (Correct Answer)
D. Metastasis

Explanation: ***Upper limb Lymphedema*** - **Lymphedema** is a common complication after **modified radical mastectomy (MRM)** due to the removal of axillary lymph nodes and subsequent disruption of lymphatic drainage pathways. - This disruption leads to an accumulation of lymphatic fluid in the interstitial tissues, causing **swelling** in the ipsilateral upper limb. *Angiosarcoma* - **Angiosarcoma** (Stewart-Treves syndrome) is a very rare, aggressive tumor that can occur in the chronic lymphedematous limb after mastectomy. - It presents as multiple **violaceous nodules or plaques** in the affected limb, which is not described as the initial finding. *Recurrence* - **Recurrence** of breast cancer in the axilla or chest wall could cause swelling, but it would typically involve a palpable mass, skin changes, or pain, which are not mentioned as the primary symptom. - While recurrence can lead to lymphatic obstruction, **lymphedema** is a more direct and common post-operative complication. *Metastasis* - **Metastasis** to the axillary or supraclavicular lymph nodes could cause lymphatic obstruction and swelling. - However, lymphedema from direct surgical disruption of lymphatics is a more immediate and common cause of upper limb swelling following MRM, especially without other signs of widespread disease.

Question 9: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

A. Coracoacromial ligament
B. Costoclavicular ligament
C. Coracoclavicular ligament (Correct Answer)
D. Coracohumeral ligament

Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong extra-articular ligament that connects the **coracoid process** of the scapula to the **inferior surface of the clavicle**, effectively suspending the scapula from the clavicle. - This ligament plays the **primary and crucial role** in transmitting forces from the upper limb through the **scapula and clavicle** to the **axial skeleton**, particularly during weight-bearing activities. - It is the key structure that maintains the connection between the upper limb (via scapula) and the axial skeleton (via clavicle). *Coracoacromial ligament* - The **coracoacromial ligament** forms the roof of the **subacromial space** and is primarily involved in preventing superior displacement of the humeral head. - It does not transmit the weight of the upper limb to the axial skeleton but rather protects structures within the subacromial space by forming the coracoacromial arch. *Costoclavicular ligament* - The **costoclavicular ligament** connects the **first rib to the clavicle**, stabilizing the **sternoclavicular joint**. - While it provides important stability at the sternoclavicular joint (part of the transmission pathway), the primary transmission of upper limb weight occurs through the **coracoclavicular ligament** connecting the scapula to clavicle. *Coracohumeral ligament* - The **coracohumeral ligament** connects the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**, reinforcing the shoulder joint capsule. - It primarily helps support the weight of the upper limb when the arm is adducted, but it does not transmit this weight to the axial skeleton.

Question 10: In a 24 year old man, weight of the upper limb is transmitted to the axial skeleton by:

A. Coracoclavicular ligament (Correct Answer)
B. Costoclavicular ligament
C. Coracohumeral ligament
D. Coracoacromial ligament

Explanation: ***Coracoclavicular ligament*** - The **coracoclavicular ligament** is a strong fibrous band connecting the **coracoid process** of the scapula to the **undersurface of the clavicle**, effectively suspending the scapula and upper limb from the clavicle. - This ligament is crucial as it transmits the **weight of the upper limb** to the clavicle, which then articulates with the axial skeleton (sternum) via the sternoclavicular joint. *Costoclavicular ligament* - This ligament connects the **first rib** to the **undersurface of the clavicle**, stabilizing the sternoclavicular joint. - While important for sternoclavicular joint stability, it primarily functions to limit **clavicular elevation** and does not directly transmit the primary weight of the upper limb to the axial skeleton in the same way as the coracoclavicular ligament. *Coracohumeral ligament* - The **coracohumeral ligament** is located in the shoulder joint, connecting the **coracoid process of the scapula** to the **greater and lesser tubercles of the humerus**. - Its main roles are to **strengthen the superior part of the joint capsule** and prevent inferior displacement of the humeral head, not to transmit the overall weight of the upper limb to the axial skeleton. *Coracoacromial ligament* - This ligament extends between the **coracoid process** and the **acromion of the scapula**, forming the **coracocromial arch**. - Its primary function is to protect the superior aspect of the **glenohumeral joint** and prevent superior displacement of the humeral head; it does not bear the weight of the upper limb to the axial skeleton.

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