Upper Limb Practice Questions

Q: What is the action of the anterior fibers of the deltoid muscle?

Flexion and medial rotation. The deltoid is a multipennate muscle with three distinct functional sets of fibers. Understanding its action requires looking at the orientation of these fibers relative to the glenohumeral joint axis. **Explanation of the Correct Answer (C):** The **anterior (clavicular) fibers** originate from the lateral third of the clavicle. Because they pass anterior to the center of the humeral head, their contraction pulls the humerus forward and rotates it inward. Therefore, the primary actions of the anterior fibers are **flexion and medial rotation** of the arm at the shoulder. **Analysis of Incorrect Options:** * **A. Flexion:** While correct, it is incomplete. The anterior fibers are also powerful medial rotators. * **B. Lateral rotation:** This is incorrect for the anterior fibers. Lateral rotation is performed by the **posterior fibers** and the infraspinatus/teres minor. * **D. Extension and lateral rotation:** These are the primary actions of the **posterior (spinous) fibers** of the deltoid, which originate from the spine of the scapula and pass behind the joint axis. **NEET-PG High-Yield Pearls:** * **The Multipennate Nature:** The **middle (acromial) fibers** are multipennate, making them the strongest part of the muscle, responsible for **abduction** from 15° to 90°. * **Axillary Nerve (C5, C6):** The deltoid is supplied by the axillary nerve. Damage (e.g., surgical neck fracture or shoulder dislocation) leads to loss of shoulder contour ("square shoulder") and inability to abduct the arm. * **Intramuscular Injections:** Usually given in the middle of the deltoid to avoid the axillary nerve, which winds around the surgical neck of the humerus.

Q: A 27-year-old patient presents with an inability to draw the scapula forward and downward because of paralysis of the pectoralis minor. Which of the following would most likely be a cause of his condition?

Fracture of the coracoid process. Explanation: The **Pectoralis minor** muscle originates from the 3rd, 4th, and 5th ribs and inserts into the **medial border and upper surface of the coracoid process** of the scapula. Its primary actions include pulling the scapula forward (protraction) and downward (depression). A fracture of the coracoid process can lead to an avulsion or functional loss of the pectoralis minor insertion, resulting in the inability to perform these specific movements. **Analysis of Options:** * **Fracture of the coracoid process (Correct):** As the site of insertion for the pectoralis minor, any structural disruption here directly affects the muscle's ability to act on the scapula. * **Fracture of the clavicle:** The pectoralis minor has no attachment to the clavicle. While a clavicular fracture might affect the pectoralis major or subclavius, it would not cause isolated paralysis of the pectoralis minor. * **Injury to the posterior cord:** The pectoralis minor is supplied by the **medial pectoral nerve** (C8, T1), which arises from the **medial cord** of the brachial plexus. The posterior cord gives rise to nerves like the axillary and radial nerves. * **Axillary nerve injury:** This nerve supplies the deltoid and teres minor muscles. Injury would result in loss of shoulder abduction and sensation over the "regimental badge" area, not pectoralis minor dysfunction. **NEET-PG High-Yield Pearls:** * **Coracoid Process Attachments:** Remember the mnemonic **"Short Head of Biceps, Coracobrachialis, and Pectoralis Minor"** (The "Triple C" or "B-C-P" attachments). * **Nerve Supply:** The **Medial Pectoral Nerve** pierces the pectoralis minor to reach the pectoralis major, supplying both. The **Lateral Pectoral Nerve** supplies only the pectoralis major. * **Clinical Significance:** The pectoralis minor serves as a key anatomical landmark, dividing the **axillary artery** into three parts.

Q: Which of the following statements about the supraspinatus is FALSE?

Abducts the arm to the horizontal level.. **Explanation:** The **supraspinatus** is a critical muscle of the rotator cuff, but its primary role in abduction is limited to the **initial 0–15 degrees**. **Why Option C is FALSE:** While the supraspinatus initiates abduction, the **deltoid** muscle is the primary abductor responsible for taking the arm from 15 degrees up to the horizontal level (90 degrees). Beyond 90 degrees, the serratus anterior and trapezius facilitate upward rotation of the scapula to achieve full overhead abduction. Therefore, stating that the supraspinatus abducts the arm to the horizontal level is anatomically incorrect. **Analysis of Other Options:** * **Option A:** Despite being part of the "rotator" cuff, the supraspinatus is the only member that **does not rotate** the humerus; its vector is purely for initiation of abduction and stabilization of the humeral head. * **Option B:** The muscle belly and tendon lie in the supraspinatus fossa and pass **deep to the coracoacromial arch** (formed by the coracoid process, acromion, and coracoacromial ligament). * **Option D:** Due to its position between the humeral head and the acromion, it is the **most common muscle injured** in rotator cuff tears and impingement syndrome. **High-Yield NEET-PG Pearls:** * **Nerve Supply:** Suprascapular nerve (C5, C6). * **Painful Arc Syndrome:** Pain during abduction between **60°–120°** usually indicates supraspinatus tendinitis or subacromial bursitis. * **Empty Can Test (Jobe’s Test):** Used clinically to assess supraspinatus integrity. * **Blood Supply:** Suprascapular and posterior circumflex humeral arteries.

Q: The cords of the brachial plexus are named relative to the axillary artery. Which muscle lies behind the axillary artery in relation to these cords?

Pectoralis minor. The **Pectoralis minor** muscle is the key anatomical landmark used to divide the axillary artery into three parts [1]. More importantly, it defines the position and naming of the **cords of the brachial plexus**: 1. **First part** (proximal to muscle): Cords are not yet formed (divisions are present). 2. **Second part** (behind the muscle): The cords are named **Lateral, Medial, and Posterior** based on their specific orientation to the axillary artery at this exact location [1]. 3. **Third part** (distal to muscle): The cords begin to branch into terminal nerves. Therefore, the Pectoralis minor is the muscle that physically overlies the second part of the axillary artery and the surrounding cords [1]. **Analysis of Incorrect Options:** * **Deltoid (A):** A superficial muscle of the shoulder; it does not serve as a landmark for the divisions of the axillary artery or the cords. * **Subclavius (B):** Located superiorly, it protects the neurovascular bundle as it passes under the clavicle but does not define the relationship of the cords to the artery. * **Teres major (C):** Marks the **inferior boundary** where the axillary artery becomes the brachial artery. It lies distal to the cords. **High-Yield NEET-PG Pearls:** * **The "Rule of 3s":** Pectoralis minor divides the axillary artery into **3 parts**; the 1st part has **1 branch**, the 2nd part has **2 branches**, and the 3rd part has **3 branches**. * **Clavipectoral Fascia:** Pierced by four structures: Lateral pectoral nerve, Thoraco-acromial artery, Cephalic vein, and Lymphatics. * **Safe Zone:** For axillary nerve blocks, the relationship of the cords to the artery behind the Pectoralis minor is crucial for successful anesthesia.

Q: The anterior interosseous nerve is a branch of which of the following?

Median nerve. ### Explanation **Correct Answer: C. Median nerve** The **Anterior Interosseous Nerve (AIN)** is the largest branch of the **median nerve** in the forearm. It arises in the cubital fossa between the two heads of the pronator teres [1]. It descends on the anterior surface of the interosseous membrane alongside the anterior interosseous artery [1]. **Why it is correct:** The AIN is a purely motor nerve (with sensory fibers only for joint capsules). It supplies the **"Deep Group"** of muscles in the anterior compartment of the forearm: 1. **Flexor pollicis longus (FPL)** 2. **Pronator quadratus (PQ)** 3. **Lateral half of Flexor digitorum profundus (FDP)** (supplying the index and middle fingers). **Why incorrect options are wrong:** * **Options A & B (Radial Nerve):** The radial nerve and its deep branch (Posterior Interosseous Nerve) supply the **posterior (extensor)** compartment of the forearm. * **Option D (Ulnar Nerve):** The ulnar nerve supplies the Flexor Carpi Ulnaris and the medial half of the FDP [1]. It does not give off the AIN. --- ### High-Yield Clinical Pearls for NEET-PG * **AIN Syndrome (Kiloh-Nevin Syndrome):** This is an isolated palsy of the AIN (often due to compression). * **The "OK Sign" Test:** Patients with AIN palsy cannot flex the distal phalanges of the thumb and index finger. When asked to make an "OK" sign, they produce a **"pinch"** (flat finger-to-finger contact) instead of a circle, due to paralysis of the FPL and the lateral half of the FDP. * **Sensory Note:** Unlike the main median nerve, the AIN has **no cutaneous distribution**. It only provides sensory innervation to the wrist and distal radio-ulnar joints.

Q: A 41-year-old male presents with weakness of the flexor pollicis longus and flexor digitorum profundus of the index finger. Which nerve is most likely involved?

Median nerve. ### Explanation The clinical presentation describes a classic **Anterior Interosseous Nerve (AIN) Syndrome**. **1. Why the Median Nerve is Correct:** The **Anterior Interosseous Nerve** is a purely motor branch of the **Median Nerve**. It arises in the proximal forearm and supplies three deep muscles: [1] * **Flexor Pollicis Longus (FPL):** Responsible for flexion of the thumb IP joint. * **Flexor Digitorum Profundus (FDP) of the index and middle fingers:** Responsible for flexion of the DIP joints. * **Pronator Quadratus:** Responsible for forearm pronation. Weakness in the FPL and the radial half of the FDP directly points to an injury of the AIN or the parent Median nerve. [1] **2. Why the Other Options are Incorrect:** * **Ulnar Nerve:** Supplies the medial half (ring and small fingers) of the FDP and most intrinsic hand muscles. Ulnar nerve injury would cause "claw hand" and weakness in finger abduction/adduction. * **Posterior Interosseous Nerve (PIN):** This is a branch of the **Radial Nerve**. It supplies the extensors of the wrist and fingers. Injury leads to "finger drop" without sensory loss, not flexor weakness. * **Radial Nerve:** Injury typically occurs at the axilla or radial groove, leading to "wrist drop" and loss of extension at the MCP joints. **3. Clinical Pearls for NEET-PG:** * **The "OK" Sign Test:** Patients with AIN syndrome cannot make a circle with their thumb and index finger (pulp-to-pulp contact instead of tip-to-tip) due to FPL and FDP weakness. * **Sensory Note:** The AIN has **no cutaneous sensory distribution**. If the patient also has numbness in the lateral 3.5 fingers, the lesion is in the main Median nerve (e.g., Carpal Tunnel or Pronator Syndrome), not the isolated AIN. [1] * **Kiloh-Nevin Syndrome:** Another name for isolated Anterior Interosseous Nerve palsy.

Q: Flexion of the metacarpophalangeal joint is produced by all except?

Extensor pollicis longus. The primary action of the **Extensor Pollicis Longus (EPL)** is the **extension** of the interphalangeal and metacarpophalangeal (MCP) joints of the thumb. As a member of the extensor compartment of the forearm, its mechanical pull is dorsal to the joint axis, making it an antagonist to flexion. Therefore, it does not contribute to the flexion of any MCP joint [1]. **Analysis of Options:** * **Lumbricals:** These originate from the tendons of the Flexor Digitorum Profundus and insert into the extensor expansions [2]. Because they pass **palmar** to the deep transverse metacarpal ligament (the MCP joint axis), they act as primary flexors of the MCP joints while simultaneously extending the IP joints (the "Z-position") [2]. * **Dorsal Interossei (DAB):** While their primary role is abduction, their insertion into the extensor hoods palmar to the MCP joint axis allows them to assist in MCP flexion [2]. * **Palmar Interossei (PAD):** Similar to the dorsal interossei, their primary role is adduction, but their anatomical course also facilitates MCP joint flexion [2]. **Clinical Pearls for NEET-PG:** * **The "Z-movement":** Flexion at MCP + Extension at IP joints is the combined action of Lumbricals and Interossei [2]. * **Nerve Supply:** Lumbricals 1 & 2 (Median Nerve); Lumbricals 3 & 4 and all Interossei (Ulnar Nerve) [3]. * **Claw Hand:** Paralysis of these intrinsic muscles leads to the opposite deformity: hyperextension at MCP and flexion at IP joints. * **EPL Landmark:** It forms the ulnar (posterior) boundary of the **Anatomical Snuffbox** and hooks around **Lister’s tubercle** on the radius [1].

Q: Compression of nerve roots by a cervical rib, a cause of thoracic outlet syndrome, primarily affects which nerve roots?

C8, T1. ### Explanation **1. Why C8 and T1 are correct:** A cervical rib is an accessory rib originating from the C7 vertebra. Because of its anatomical position, it most commonly compresses the **lower trunk of the brachial plexus**, which is formed by the **C8 and T1 nerve roots**. These roots must arch over the cervical rib (or its fibrous band) to reach the axilla. Compression leads to the neurological symptoms of Thoracic Outlet Syndrome (TOS), specifically affecting the intrinsic muscles of the hand (T1) and sensation along the medial aspect of the forearm and hand (C8). **2. Why other options are incorrect:** * **A (C5, C6):** These roots form the upper trunk of the brachial plexus. They are located much higher in the neck and are typically involved in Erb’s palsy, not compression by a cervical rib. * **B (C6, C7):** These roots contribute to the upper and middle trunks. While they are proximal to the thoracic outlet, they are not in direct contact with the anomalous rib. * **C (C7, C8):** While C8 is involved, C7 forms the middle trunk and is generally spared in classic cervical rib compression, which specifically targets the structures resting directly on the rib. **3. High-Yield Clinical Pearls for NEET-PG:** * **Vascular Involvement:** The cervical rib can also compress the **Subclavian Artery** (rarely the vein), leading to a diminished radial pulse and positive **Adson’s Test**. * **Gilliatt-Sumner Hand:** This refers to the characteristic wasting of the thenar and hypothenar eminence seen in neurogenic TOS. * **Differential Diagnosis:** Must be distinguished from Pancoast tumor (which also affects C8-T1) and Ulnar nerve entrapment at the elbow. * **Embryology:** A cervical rib results from the elongation of the transverse process of the 7th cervical vertebra.

Q: A man cannot perform abduction and internal rotation of the arm. Which muscle is responsible for both these movements?

Deltoid. ### Explanation The **Deltoid muscle** is a multipennate muscle with three distinct sets of fibers that act on the glenohumeral joint. Its unique functional anatomy allows it to participate in multiple, sometimes opposing, movements: 1. **Abduction:** The **multipennate acromial (middle) fibers** are the primary abductors of the arm from 15° to 90°. 2. **Internal Rotation:** The **anterior (clavicular) fibers** act as flexors and internal rotators of the humerus. 3. **External Rotation:** The **posterior (spinal) fibers** act as extensors and external rotators. Since the question specifies a muscle capable of *both* abduction and internal rotation, the Deltoid is the only option that fits both criteria. #### Analysis of Incorrect Options: * **Pectoralis major:** A powerful adductor and internal rotator. It cannot perform abduction (except for weak assistance in flexion by the clavicular head). * **Subscapularis:** Part of the rotator cuff; it is the primary internal rotator of the arm but does not perform abduction. * **Teres major:** Known as the "Lat's little helper," it performs adduction, internal rotation, and extension, but not abduction. #### NEET-PG High-Yield Pearls: * **Nerve Supply:** The Deltoid is supplied by the **Axillary Nerve (C5, C6)**. Damage to this nerve (e.g., surgical neck of humerus fracture) leads to loss of the rounded contour of the shoulder and inability to abduct the arm beyond 15°. * **Abduction Sequence:** * 0°–15°: Supraspinatus (Suprascapular nerve). * 15°–90°: Deltoid (Axillary nerve). * Above 90°: Serratus anterior and Trapezius (Scapular rotation). * **Intramuscular Injection:** The deltoid is a common site for IM injections; the needle is typically aimed at the middle of the muscle to avoid the axillary nerve, which winds around the surgical neck of the humerus.

Question 1

What is the action of the anterior fibers of the deltoid muscle?

Accepted Answer

Flexion and medial rotation

Answer

Flexion

Answer

Lateral rotation

Answer

Extension and lateral rotation

Question 2

A 27-year-old patient presents with an inability to draw the scapula forward and downward because of paralysis of the pectoralis minor. Which of the following would most likely be a cause of his condition?

Accepted Answer

Fracture of the coracoid process

Answer

Fracture of the clavicle

Answer

Injury to the posterior cord of the brachial plexus

Answer

Axillary nerve injury

Question 3

Which of the following statements about the supraspinatus is FALSE?

Accepted Answer

Abducts the arm to the horizontal level.

Answer

A rotator cuff muscle that does not rotate the humerus.

Answer

Located deep to the coracoacromial arch.

Answer

The most commonly involved muscle in rotator cuff injuries.

Question 4

The cords of the brachial plexus are named relative to the axillary artery. Which muscle lies behind the axillary artery in relation to these cords?

Accepted Answer

Pectoralis minor

Answer

Deltoid

Answer

Subclavius

Answer

Teres major

Question 5

The anterior interosseous nerve is a branch of which of the following?

Accepted Answer

Median nerve

Answer

Superficial branch of the radial nerve

Answer

Deep branch of the radial nerve

Answer

Ulnar nerve

Question 6

A 41-year-old male presents with weakness of the flexor pollicis longus and flexor digitorum profundus of the index finger. Which nerve is most likely involved?

Accepted Answer

Median nerve

Answer

Ulnar nerve

Answer

Posterior interosseous nerve

Answer

Radial nerve

Question 7

A patient presents with inability to extend the wrist following an accident. The patient reports no sensory loss. At what anatomical location is the affected nerve most likely injured?

Accepted Answer

Spiral groove of the humerus

Answer

Head of the radius

Answer

Near the medial epicondyle

Answer

Surgical neck of the humerus

Question 8

Flexion of the metacarpophalangeal joint is produced by all except?

Accepted Answer

Extensor pollicis longus

Answer

Lumbricals

Answer

Dorsal interossei

Answer

Palmar interossei

Question 9

Compression of nerve roots by a cervical rib, a cause of thoracic outlet syndrome, primarily affects which nerve roots?

Accepted Answer

C8, T1

Answer

C5, C6

Answer

C6, C7

Answer

C7, C8

Question 10

A man cannot perform abduction and internal rotation of the arm. Which muscle is responsible for both these movements?

Accepted Answer

Deltoid

Answer

Pectoralis major

Answer

Subscapularis

Answer

Teres major

Upper Limb — MCQs

Upper Limb — MCQs

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