Arm and Cubital Fossa — MCQs
All of the following muscles have dual nerve supply, EXCEPT?
The anterior humeral line and radiocapitellar alignment are most commonly disturbed in -
What is the nerve supply to the muscles of the flexor compartment of the arm?
Which of the following is not a content of the cubital fossa?
Traumatic anterior dislocation of shoulder with sensory loss in lateral side of forearm and weakness of flexion of elbow joint, most likely injured nerve is:
The lateral boundary of the cubital fossa is formed by
Name the muscle marked as colour blue in the extensor compartment of forearm. (Recent NEET Pattern 2019)
All of the following are affected in Erb's palsy EXCEPT
A 6-week-old boy is brought to the pediatrician. His parents report that he has not had significant use of his right arm since birth. Birth history is significant for a prolonged labor with difficult breech delivery. On physical examination, his arm hangs at his side and is in a medially rotated position with the forearm in pronation. He will actively use his left arm but does not move his affected right arm or hand. Injury to which of the following cervical nerve roots accounts for this patient's posture?
A patient presents with winging of the scapula. Which nerve is most likely involved?
Arm and Cubital Fossa Indian Medical PG Practice Questions and MCQs
Question 1: All of the following muscles have dual nerve supply, EXCEPT?
- A. Flexor digitorum profundus
- B. Pectineus
- C. Brachialis
- D. Flexor digitorum superficialis (Correct Answer)
Explanation: No changes were made to the original explanation because none of the provided references met the relevance criteria for the specific muscles and nerves discussed. ***Flexor digitorum superficialis*** - This muscle is solely innervated by the **median nerve**. - It works to **flex the middle phalanges** of the medial four digits. *Flexor digitorum profundus* - The medial half of the muscle, which supplies the ring and little fingers, is innervated by the **ulnar nerve**. - The lateral half, which supplies the index and middle fingers, is innervated by the **anterior interosseous nerve** (a branch of the median nerve). *Pectineus* - This muscle typically receives innervation from both the **femoral nerve** and the **obturator nerve**. - Its primary action is **adduction and flexion of the hip**. *Brachialis* - While primarily innervated by the **musculocutaneous nerve**, a small component also receives innervation from the **radial nerve**. - It is a powerful **flexor of the elbow joint**.
Question 2: The anterior humeral line and radiocapitellar alignment are most commonly disturbed in -
- A. Supracondylar Fracture of the humerus (Correct Answer)
- B. Monteggia Fracture dislocation
- C. Fracture of Proximal Radius
- D. Fracture lateral condyle of the humerus
Explanation: ***Supracondylar Fracture of the humerus*** - **Anterior humeral line** passes through the **anterior cortex of the humerus** and should intersect the middle third of the capitellum in a normal elbow. - In supracondylar fractures, particularly those with **posterior displacement**, this line is often displaced **anteriorly or posteriorly**, failing to intersect the capitellum correctly. Additionally, the **radiocapitellar alignment** refers to the relationship between the **radius head** and the **capitellum**. Fractures and displacements around the elbow joint, such as supracondylar fractures, can disrupt this alignment. *Fracture lateral condyle of the humerus* - While a fracture of the lateral condyle can affect the elbow joint, it primarily involves a part of the **articular surface** and not necessarily the overall alignment of the entire distal humerus relative to the capitellum in the same way a supracondylar fracture does. - The **lateral condyle** is a smaller segment, and its fracture may not significantly alter the anterior humeral line **unless there is significant displacement** that indirectly affects the alignment of the capitellum. *Monteggia Fracture dislocation* - A **Monteggia fracture** involves a fracture of the **ulna** with dislocation of the **radial head** at the elbow. - While radiocapitellar alignment is severely disrupted, the **anterior humeral line** itself, which assesses the distal humerus, is typically **unaffected** as the primary injury is in the forearm bones and the radial head. *Fracture of Proximal Radius* - A fracture of the proximal radius (e.g., **radial head or neck fracture**) primarily affects the **radial articular surface** and its alignment with the capitellum. - While **radiocapitellar alignment** would clearly be disturbed, the position of the **distal humerus** relative to the capitellum, which the anterior humeral line evaluates, usually remains intact.
Question 3: What is the nerve supply to the muscles of the flexor compartment of the arm?
- A. Musculocutaneous nerve (Correct Answer)
- B. Median nerve
- C. Radial nerve
- D. Ulnar nerve
Explanation: ***Musculocutaneous nerve*** - The **musculocutaneous nerve** is the primary nerve supplying all three muscles in the **flexor compartment of the arm**: the **biceps brachii**, **brachialis**, and **coracobrachialis**. - Its motor branches innervate these muscles, allowing for **flexion at the elbow** and **supination of the forearm**. *Median nerve* - The **median nerve** primarily innervates most muscles in the **flexor compartment of the forearm**, not the arm. - It plays a crucial role in **wrist and finger flexion**, as well as movements of the **thenar eminence**. *Radial nerve* - The **radial nerve** is the main nerve for the **extensor compartment of the arm and forearm**. - It is responsible for **elbow, wrist, and finger extension**. *Ulnar nerve* - The **ulnar nerve** primarily supplies intrinsic muscles of the hand and some flexor muscles in the forearm. - It has no motor supply to the muscles of the **flexor compartment of the arm**.
Question 4: Which of the following is not a content of the cubital fossa?
- A. Bicipital aponeurosis (Correct Answer)
- B. Brachial artery
- C. Biceps brachii tendon
- D. Median nerve
Explanation: ***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.
Question 5: Traumatic anterior dislocation of shoulder with sensory loss in lateral side of forearm and weakness of flexion of elbow joint, most likely injured nerve is:
- A. Ulnar nerve
- B. Axillary nerve
- C. Radial nerve
- D. Musculocutaneous nerve (Correct Answer)
Explanation: ***Musculocutaneous nerve*** - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion**. - It also provides sensory innervation to the **lateral forearm** via the **lateral cutaneous nerve of the forearm**, explaining the sensory loss described. *Ulnar nerve* - The ulnar nerve primarily innervates muscles of the **hand** and gives sensory supply to the medial 1 and 1/2 digits. - Its injury would typically lead to weakness in **finger adduction/abduction** and sensory loss in the medial hand, not the lateral forearm. *Axillary nerve* - The axillary nerve innervates the **deltoid** and **teres minor** muscles, causing weakness in **shoulder abduction** and external rotation upon injury. - Sensory loss would be over the **regimental badge area** (lateral shoulder), not the lateral forearm. *Radial nerve* - The radial nerve innervates the **extensor muscles of the wrist and fingers**, and the triceps. - Injury would result in **wrist drop** and sensory loss over the **posterior arm, forearm, and hand**, not lateral forearm sensory loss.
Question 6: The lateral boundary of the cubital fossa is formed by
- A. Biceps
- B. Brachialis
- C. Brachioradialis (Correct Answer)
- D. Pronator teres
Explanation: ***Brachioradialis*** - The **brachioradialis muscle** forms the **lateral boundary** of the cubital fossa. - It originates from the lateral supracondylar ridge of the humerus and inserts on the distal radius. - This muscle is a **flexor of the elbow** and assists in bringing the forearm to a neutral position from pronation or supination. *Pronator teres* - The **pronator teres muscle** forms the **medial boundary** of the cubital fossa. - It originates from the medial epicondyle of the humerus and coronoid process of the ulna, inserting on the lateral surface of the radius. - This muscle is primarily responsible for **pronation of the forearm** and assists in elbow flexion. *Brachialis* - The **brachialis muscle** forms part of the **floor of the cubital fossa** (along with the supinator muscle). - It lies deep to the biceps brachii and inserts on the coronoid process and ulnar tuberosity. - It is a powerful **elbow flexor**, acting directly on the ulna. *Biceps* - The **biceps brachii** does not form a boundary of the cubital fossa. - Its **tendon passes through the fossa** as content, while the **bicipital aponeurosis** contributes to the roof. - The biceps is a major flexor and supinator of the forearm.
Question 7: Name the muscle marked as colour blue in the extensor compartment of forearm. (Recent NEET Pattern 2019)
- A. Extensor carpi radialis
- B. Brachioradialis (Correct Answer)
- C. Extensor digitorum
- D. Extensor carpi ulnaris
Explanation: ***Brachioradialis*** - The **brachioradialis** muscle is a prominent superficial muscle in the lateral compartment of the forearm, shown in **blue** in the diagram, originating from the **lateral supracondylar ridge of the humerus** and inserting into the **radial styloid process**. - It primarily functions to **flex the elbow** and helps to bring the forearm into a midprone position. *Extensor carpi radialis* - The extensor carpi radialis muscles (longus and brevis) are located deep to the brachioradialis and extend the wrist, often distinguishable by their more distal insertion on the **metacarpals**. - They are typically not the most superficial and most lateral muscle spanning the entire forearm length as depicted in blue. *Extensor digitorum* - The **extensor digitorum** is located more medially than the brachioradialis and its tendons diverge to attach to the four medial fingers, a configuration not shown by the blue muscle. - This muscle is responsible for **extending the medial four digits**. *Extensor carpi ulnaris* - The **extensor carpi ulnaris** is situated on the **ulnar side** of the forearm, furthest from the blue-highlighted muscle, and its primary action is **wrist extension and ulnar deviation**. - It would be found along the posterior medial aspect of the forearm, not in the relatively lateral position shown in blue.
Question 8: All of the following are affected in Erb's palsy EXCEPT
- A. Dorsal scapular nerve
- B. Suprascapular nerve
- C. Lower trunk of brachial plexus (Correct Answer)
- D. Upper trunk of brachial plexus
Explanation: ***Lower trunk of brachial plexus*** - Erb's palsy primarily involves the **upper trunk** of the brachial plexus (C5-C6 nerve roots), which affects muscles innervated by these roots. - The **lower trunk** (C8-T1 nerve roots) is typically spared in Erb's palsy, distinguishing it from **Klumpke's palsy**. *Dorsal scapular nerve* - The dorsal scapular nerve originates from the **C5 root of the brachial plexus** and innervates the **rhomboids** and **levator scapulae**. - As Erb's palsy involves the C5 root, the dorsal scapular nerve and its associated muscles are commonly affected. *Suprascapular nerve* - The suprascapular nerve arises from the **upper trunk** of the brachial plexus (C5-C6) and innervates the **supraspinatus** and **infraspinatus** muscles. - Damage to the upper trunk in Erb's palsy directly impacts the function of the suprascapular nerve. *Upper trunk of brachial plexus* - Erb's palsy is specifically defined by an injury to the **upper trunk** of the brachial plexus, involving the C5 and C6 nerve roots. - This damage leads to weakness in muscles such as the **deltoid**, **biceps**, and **brachialis**, resulting in the characteristic **"waiter's tip"** posture.
Question 9: A 6-week-old boy is brought to the pediatrician. His parents report that he has not had significant use of his right arm since birth. Birth history is significant for a prolonged labor with difficult breech delivery. On physical examination, his arm hangs at his side and is in a medially rotated position with the forearm in pronation. He will actively use his left arm but does not move his affected right arm or hand. Injury to which of the following cervical nerve roots accounts for this patient's posture?
- A. C5 and C6 (Correct Answer)
- B. C7 and C8
- C. C4 and C5
- D. C6 and C7
Explanation: ***C5 and C6*** - The described "waiter's tip" posture – arm adducted, internally rotated, and forearm pronated – is classic for **Erb-Duchenne palsy**, resulting from damage to the **C5 and C6 nerve roots** [1]. - This injury commonly occurs during **difficult deliveries** involving shoulder traction, as seen in **breech presentations** [1]. *C7 and C8* - Damage to **C7 and C8** (and often T1) typically results in **Klumpke's palsy**, affecting the **intrinsic hand muscles** and causing a **claw hand deformity** [1]. - While a difficult birth can cause this, the patient's posture (medially rotated arm, pronated forearm) is not characteristic of Klumpke's palsy, which primarily affects lower brachial plexus elements. *C4 and C5* - Injury to **C4** can affect the **diaphragm** via the phrenic nerve, and along with C5, would primarily cause weakness of the **shoulder abductors** and **external rotators**. - While C5 is involved in the observed posture, isolated C4-C5 injury does not fully explain the severe adduction and internal rotation with forearm pronation that defines Erb's palsy. *C6 and C7* - Involvement of **C6 and C7** would lead to weakness in wrist extension, finger extension, and some elbow flexion. - While C6 is involved in Erb's palsy, the additional involvement of C7 alone would alter the specific presentation, often leading to more prominent wrist and finger extensor weakness, which is not the dominant feature described.
Question 10: A patient presents with winging of the scapula. Which nerve is most likely involved?
- A. Thoracodorsal nerve
- B. Lateral pectoral nerve
- C. Long thoracic nerve (Correct Answer)
- D. Musculocutaneous nerve
Explanation: ### Long thoracic nerve - The long thoracic nerve innervates the **serratus anterior muscle**, which is responsible for scapular protraction and upward rotation. - Damage to this nerve paralyzes the serratus anterior, leading to **winging of the scapula** as the medial border and inferior angle of the scapula become prominent. ### Thoracodorsal nerve - This nerve supplies the **latissimus dorsi muscle**, which is involved in adduction, extension, and internal rotation of the humerus [1]. - Injury to the thoracodorsal nerve would weaken movements of the shoulder, but not directly cause **scapular winging**. ### Lateral pectoral nerve - The lateral pectoral nerve innervates the **pectoralis major muscle** (upper and middle parts) [1]. - Damage to this nerve primarily affects shoulder adduction and internal rotation, but does not result in **scapular winging**. ### Musculocutaneous nerve - This nerve innervates the **coracobrachialis**, **biceps brachii**, and **brachialis muscles** in the anterior compartment of the arm. - Injury to the musculocutaneous nerve would impair elbow flexion and forearm supination, and is unrelated to **scapular movement**.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free