Upper/Lower Limb — MCQs

Q: Identify the arrow marked nerve

Lateral pectoral nerve. ***Lateral pectoral nerve*** - The arrow points to a nerve originating from the **lateral cord of the brachial plexus**, traveling laterally to innervate the **pectoralis major muscle**. - Its position, lateral to the medial pectoral nerve and supplying the pectoralis major, confirms it as the lateral pectoral nerve. *Medial pectoral nerve* - The medial pectoral nerve typically arises from the **medial cord of the brachial plexus** and passes through both **pectoralis major** and **pectoralis minor**. - It lies more medially and generally pierces the pectoralis minor, unlike the nerve indicated. *Long thoracic nerve* - The long thoracic nerve innervates the **serratus anterior muscle** and runs along the lateral aspect of the chest wall. - Its course is distal and distinct from the nerve shown, which is clearly positioned in the pectoral region. *Thoracodorsal nerve* - The thoracodorsal nerve innervates the **latissimus dorsi muscle** and descends on the posterior axillary wall. - It is not located in the shown pectoral region and has a different trajectory. *Nerve to subclavius* - The nerve to subclavius arises from the **upper trunk of the brachial plexus** (C5-C6) and descends to innervate the **subclavius muscle**. - It has a more superior course compared to the lateral pectoral nerve and is not visible in the position indicated by the arrow.

Q: A patient with a nerve injury was asked to form an "O" with their index finger and thumb but was unable to do so. Which muscle is most likely affected?

Opponens pollicis. ***Opponens pollicis*** - The **opponens pollicis** muscle is responsible for **opposition of the thumb**, a complex movement involving flexion, abduction, and medial rotation of the thumb at the carpometacarpal joint. - Inability to form an "O" sign with the index finger and thumb is a classic clinical test for impaired opposition, often indicating a problem with the **median nerve** or the opponens pollicis muscle it innervates. *Abductor pollicis brevis* - The **abductor pollicis brevis** primarily abducts the thumb, moving it away from the palm. - While necessary for thumb function, its primary role is not the opposition motion required to touch the fingertips in an "O" shape. *Flexor pollicis brevis* - The **flexor pollicis brevis** primarily flexes the thumb at the metacarpophalangeal joint. - While it contributes to thumb movements, it is not the primary muscle responsible for the complex motion of opposition. *Adductor pollicis* - The **adductor pollicis** adducts the thumb, bringing it towards the palm and index finger. - Innervated by the **ulnar nerve**, this muscle is important for pinch grip but is not the primary muscle for opposition movement. *Palmar interossei* - The **palmar interossei** muscles adduct the fingers, pulling them towards the middle finger. - These muscles are involved in finger adduction, not direct thumb opposition, and are typically innervated by the ulnar nerve.

Q: A patient diagnosed with sciatica has tender hamstrings. Which of the following nerves supplies a hybrid muscle that is partially spared in this patient?

Common peroneal nerve. ***Common peroneal nerve*** - The **short head of the biceps femoris** is a unique "hybrid" muscle, supplied by the **common peroneal nerve**, while the **long head** is supplied by the **tibial nerve**. - If the hamstrings are tender and sciatica is present, but this specific muscle's function is spared, it points towards the common peroneal nerve being the relevant nerve for the spared portion. *Femoral* - The **femoral nerve** primarily innervates the **anterior compartment of the thigh**, including the quadriceps femoris. - It does not supply any part of the hamstring muscles. *Obturator* - The **obturator nerve** primarily innervates the **medial compartment of the thigh**, which consists of adductor muscles. - It does not contribute to the innervation of the hamstring muscles. *Superior gluteal* - The **superior gluteal nerve** innervates the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae** muscles. - It does not supply any hamstring muscles. *Tibial* - The **tibial nerve** innervates most of the hamstring muscles (semitendinosus, semimembranosus, and the long head of the biceps femoris). - If the hamstrings are tender, involvement of the tibial nerve would likely lead to more widespread hamstring weakness rather than a partially spared scenario involving the short head of the biceps femoris.

Q: Which artery is palpated behind the medial malleolus and in front of the Achilles tendon?

Posterior tibial artery. ***Posterior tibial artery*** - This artery is directly accessible for palpation in the **retromalleolar groove**, situated between the medial malleolus and the Achilles tendon. - It is a common site for assessing **peripheral circulation** in the foot. *Peroneal artery* - The peroneal artery is located **deep within the posterior compartment** of the leg, making it difficult to palpate at the ankle. - It primarily supplies the lateral compartment and is not typically palpable at the described location. *Anterior tibial artery* - The anterior tibial artery runs along the **anterior compartment** of the lower leg and, at the ankle, becomes the dorsalis pedis artery. - It is best palpated on the **dorsum of the foot** as the dorsalis pedis artery, not behind the medial malleolus. *Dorsalis pedis artery* - This artery is a continuation of the anterior tibial artery and is found on the **dorsum of the foot**, typically lateral to the extensor hallucis longus tendon. - While an important pulse point, it is not located behind the medial malleolus. *Popliteal artery* - The popliteal artery is located in the **popliteal fossa** behind the knee, where it can be palpated with deep pressure. - It is proximal to the ankle and divides into the anterior and posterior tibial arteries, making it anatomically distant from the medial malleolus.

Q: A patient presents with pain in the back of the thigh and leg after lifting heavy weights. Which spinal segment is most likely involved?

S1. ***S1*** - Pain radiating to the **back of the thigh and leg** after lifting heavy weights is the classic presentation of **S1 radiculopathy**, typically from L5-S1 disc herniation. - The S1 nerve root innervates the **posterior thigh via the sciatic nerve**, continues down the **posterior leg**, and extends to the **lateral foot and little toe**. - Clinical findings include diminished or absent **Achilles reflex**, weakness of **plantar flexion** (gastrocnemius/soleus), and sensory changes along the posterior leg and lateral foot. - This is the **most common** presentation of sciatica from heavy lifting. *L3* - L3 nerve root involvement typically causes pain in the **anterior and medial thigh** with weakness of **hip flexion and knee extension** (quadriceps). - The pain pattern does not match the posterior distribution described in this clinical scenario. *L4* - L4 radiculopathy presents with pain and numbness in the **medial leg and foot**, weakness of **ankle dorsiflexion** (tibialis anterior), and diminished **patellar reflex**. - The pain distribution is anteromedial, not posterior as described in this case. *L5* - L5 nerve root impingement causes pain radiating to the **lateral calf and dorsum of the foot**, weakness of **great toe extension** (extensor hallucis longus), and **foot drop**. - While L5 can cause posterior thigh pain, the classic distribution extends laterally down the leg, not primarily posterior. *S2* - S2 radiculopathy is uncommon and typically presents with **perineal/perianal pain** and **saddle anesthesia** rather than isolated posterior leg pain. - S2 contributes to bladder and bowel function; isolated S2 involvement would not present with the classic sciatica pattern described.

Q: Identify the arrow marked nerve ![img-2.jpeg](img-2.jpeg)

Medial pectoral nerve. ***Medial pectoral nerve*** - The arrow points to a nerve that is seen perforating the **pectoralis minor muscle**. This is a key anatomical landmark for the **medial pectoral nerve**. - This nerve supplies both the **pectoralis major** and **pectoralis minor** muscles, originating from the medial cord of the brachial plexus. *Long thoracic nerve* - The **long thoracic nerve** typically runs superficial to the serratus anterior muscle, not perforating the pectoralis minor. - Injury to this nerve results in **winged scapula** due to paralysis of the serratus anterior, which is distinct from the function of the nerve shown. *Thoracodorsal nerve* - The **thoracodorsal nerve** primarily innervates the **latissimus dorsi muscle** and typically runs along the lateral border of the scapula and axilla, not in the anterior chest wall where the pectoralis minor is located. - It arises from the **posterior cord of the brachial plexus**. *Lateral pectoral nerve* - The **lateral pectoral nerve** arises from the lateral cord and typically supplies only the **pectoralis major muscle**. - It often passes **medial to the pectoralis minor muscle** or penetrates the muscle from a more lateral aspect, but does not perforate it in the characteristic way shown for the medial pectoral nerve. *Suprascapular nerve* - The **suprascapular nerve** arises from the **upper trunk of the brachial plexus** and passes through the **suprascapular notch** beneath the superior transverse scapular ligament. - It innervates the **supraspinatus** and **infraspinatus** muscles and is located in the posterior shoulder region, not in the anterior chest wall where the structure shown is located.

Q: A patient underwent a coronary artery bypass graft (CABG) using the great saphenous vein. Post-surgery, the patient experiences neuralgia on the medial aspect of the leg and foot. Which nerve is most likely injured?

Saphenous nerve. ***Saphenous nerve*** - The **saphenous nerve** is a cutaneous branch of the femoral nerve that runs closely with the **great saphenous vein** along the medial aspect of the leg and foot. - Due to its proximity to the vein, it is highly susceptible to **injury** during the harvesting of the great saphenous vein for CABG, leading to **neuralgia** in its sensory distribution. *Common peroneal nerve* - The **common peroneal nerve** innervates the lateral and anterior compartments of the leg, affecting dorsiflexion and eversion of the foot. - Damage to this nerve typically results in **foot drop** and sensory loss over the dorsum of the foot, which is inconsistent with the patient's symptoms. *Tibial nerve* - The **tibial nerve** supplies the posterior compartment of the leg and the plantar aspect of the foot. - Injury would cause loss of plantarflexion and sensation on the sole of the foot, which is not described. *Sural nerve* - The **sural nerve** provides sensation to the posterolateral aspect of the leg and the lateral side of the foot and ankle. - While it runs near superficial veins, its sensory distribution does not match the described **medial leg and foot neuralgia**. *Superficial peroneal nerve* - The **superficial peroneal nerve** (superficial fibular nerve) provides sensation to the dorsum of the foot and anterolateral leg. - Injury would cause sensory loss over the dorsal foot, not the medial aspect of the leg and foot.

Q: A young boy presents with multiple humerus fractures, resulting in loss of sensation over the lateral side of the forearm, along with difficulty in elbow flexion and forearm supination. What is the most likely nerve injury responsible for these symptoms?

Musculocutaneous nerve. ***Musculocutaneous nerve*** - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion** and **forearm supination**, and provides sensation to the **lateral forearm** via the lateral cutaneous nerve of the forearm. - A fracture of the humerus can damage this nerve, leading to the observed **motor and sensory deficits**. *Median nerve* - The median nerve primarily controls **flexion of the wrist and fingers**, and **pronation of the forearm**, as well as sensation to the palmar aspect of the thumb, index, middle, and radial half of the ring finger. - Its injury would not typically cause difficulty with **elbow flexion** or sensory loss over the **lateral forearm**. *Axillary* - The axillary nerve primarily innervates the **deltoid** and **teres minor muscles**, important for shoulder abduction and external rotation. - An injury would lead to **weakness in shoulder abduction** and sensory loss over the lateral shoulder (regimental badge area), not the lateral forearm. *Radial nerve* - The radial nerve controls **extension of the wrist and fingers** and sensation over the posterior arm, forearm, and hand. - Injury typically results in **wrist drop** and difficulty extending the arm, not primarily elbow flexion or lateral forearm sensation. *Ulnar nerve* - The ulnar nerve innervates intrinsic hand muscles and flexor carpi ulnaris, controlling **finger abduction/adduction** and **ulnar wrist flexion**. - Sensory distribution includes the medial hand and medial 1.5 fingers, not the **lateral forearm**. - Injury causes **claw hand deformity** and sensory loss in the medial hand, not the symptoms described.

Q: Pen Test is for which nerve

Median Nerve. ***Median Nerve*** - The **pen test** (or pen-holding test) assesses the ability to perform **precision grip** by pinching a pen between the thumb and index finger - This tests **thumb opposition and flexion**, which are controlled by the **thenar muscles** (abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis) innervated by the median nerve - The median nerve also controls the **lateral two lumbricals** for fine finger movements essential for holding objects like a pen - **Clinical significance**: Inability to perform this test indicates median nerve injury (e.g., carpal tunnel syndrome) *Musculocutaneous* - Innervates the **anterior compartment of the arm**: biceps brachii, brachialis, and coracobrachialis - Controls **elbow flexion** and provides sensory innervation to the lateral forearm - Does not control hand muscles or precision grip functions *Radial nerve* - Innervates **extensors of the wrist, fingers, and thumb** in the posterior compartment of the forearm - Controls **wrist extension** and **finger extension** at the MCP joints - Radial nerve injury causes **wrist drop**, not impaired precision grip *Ulnar nerve* - Controls most **intrinsic hand muscles** including interossei, medial two lumbricals, and adductor pollicis - Tested by **Froment's sign** (compensatory thumb IP flexion when pinching paper due to adductor pollicis weakness) - Ulnar nerve injury affects **power grip** and finger abduction/adduction, not the precision pinch required for the pen test *Axillary nerve* - Innervates the **deltoid** and **teres minor** muscles in the shoulder - Controls **shoulder abduction** and provides sensation over the lateral upper arm - Has no role in hand function or precision grip

Upper/Lower Limb US Medical PG Practice Questions and MCQs

Question 1: Identify the arrow marked nerve

A. Medial pectoral nerve
B. Lateral pectoral nerve (Correct Answer)
C. Long thoracic nerve
D. Thoracodorsal nerve
E. Nerve to subclavius

Explanation: ***Lateral pectoral nerve*** - The arrow points to a nerve originating from the **lateral cord of the brachial plexus**, traveling laterally to innervate the **pectoralis major muscle**. - Its position, lateral to the medial pectoral nerve and supplying the pectoralis major, confirms it as the lateral pectoral nerve. *Medial pectoral nerve* - The medial pectoral nerve typically arises from the **medial cord of the brachial plexus** and passes through both **pectoralis major** and **pectoralis minor**. - It lies more medially and generally pierces the pectoralis minor, unlike the nerve indicated. *Long thoracic nerve* - The long thoracic nerve innervates the **serratus anterior muscle** and runs along the lateral aspect of the chest wall. - Its course is distal and distinct from the nerve shown, which is clearly positioned in the pectoral region. *Thoracodorsal nerve* - The thoracodorsal nerve innervates the **latissimus dorsi muscle** and descends on the posterior axillary wall. - It is not located in the shown pectoral region and has a different trajectory. *Nerve to subclavius* - The nerve to subclavius arises from the **upper trunk of the brachial plexus** (C5-C6) and descends to innervate the **subclavius muscle**. - It has a more superior course compared to the lateral pectoral nerve and is not visible in the position indicated by the arrow.

Question 2: A patient with a nerve injury was asked to form an "O" with their index finger and thumb but was unable to do so. Which muscle is most likely affected?

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

Explanation: ***Opponens pollicis*** - The **opponens pollicis** muscle is responsible for **opposition of the thumb**, a complex movement involving flexion, abduction, and medial rotation of the thumb at the carpometacarpal joint. - Inability to form an "O" sign with the index finger and thumb is a classic clinical test for impaired opposition, often indicating a problem with the **median nerve** or the opponens pollicis muscle it innervates. *Abductor pollicis brevis* - The **abductor pollicis brevis** primarily abducts the thumb, moving it away from the palm. - While necessary for thumb function, its primary role is not the opposition motion required to touch the fingertips in an "O" shape. *Flexor pollicis brevis* - The **flexor pollicis brevis** primarily flexes the thumb at the metacarpophalangeal joint. - While it contributes to thumb movements, it is not the primary muscle responsible for the complex motion of opposition. *Adductor pollicis* - The **adductor pollicis** adducts the thumb, bringing it towards the palm and index finger. - Innervated by the **ulnar nerve**, this muscle is important for pinch grip but is not the primary muscle for opposition movement. *Palmar interossei* - The **palmar interossei** muscles adduct the fingers, pulling them towards the middle finger. - These muscles are involved in finger adduction, not direct thumb opposition, and are typically innervated by the ulnar nerve.

Question 3: A patient diagnosed with sciatica has tender hamstrings. Which of the following nerves supplies a hybrid muscle that is partially spared in this patient?

A. Femoral
B. Common peroneal nerve (Correct Answer)
C. Obturator
D. Tibial
E. Superior gluteal

Explanation: ***Common peroneal nerve*** - The **short head of the biceps femoris** is a unique "hybrid" muscle, supplied by the **common peroneal nerve**, while the **long head** is supplied by the **tibial nerve**. - If the hamstrings are tender and sciatica is present, but this specific muscle's function is spared, it points towards the common peroneal nerve being the relevant nerve for the spared portion. *Femoral* - The **femoral nerve** primarily innervates the **anterior compartment of the thigh**, including the quadriceps femoris. - It does not supply any part of the hamstring muscles. *Obturator* - The **obturator nerve** primarily innervates the **medial compartment of the thigh**, which consists of adductor muscles. - It does not contribute to the innervation of the hamstring muscles. *Superior gluteal* - The **superior gluteal nerve** innervates the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae** muscles. - It does not supply any hamstring muscles. *Tibial* - The **tibial nerve** innervates most of the hamstring muscles (semitendinosus, semimembranosus, and the long head of the biceps femoris). - If the hamstrings are tender, involvement of the tibial nerve would likely lead to more widespread hamstring weakness rather than a partially spared scenario involving the short head of the biceps femoris.

Question 4: Which artery is palpated behind the medial malleolus and in front of the Achilles tendon?

A. Peroneal artery
B. Anterior tibial artery
C. Dorsalis pedis artery
D. Posterior tibial artery (Correct Answer)
E. Popliteal artery

Explanation: ***Posterior tibial artery*** - This artery is directly accessible for palpation in the **retromalleolar groove**, situated between the medial malleolus and the Achilles tendon. - It is a common site for assessing **peripheral circulation** in the foot. *Peroneal artery* - The peroneal artery is located **deep within the posterior compartment** of the leg, making it difficult to palpate at the ankle. - It primarily supplies the lateral compartment and is not typically palpable at the described location. *Anterior tibial artery* - The anterior tibial artery runs along the **anterior compartment** of the lower leg and, at the ankle, becomes the dorsalis pedis artery. - It is best palpated on the **dorsum of the foot** as the dorsalis pedis artery, not behind the medial malleolus. *Dorsalis pedis artery* - This artery is a continuation of the anterior tibial artery and is found on the **dorsum of the foot**, typically lateral to the extensor hallucis longus tendon. - While an important pulse point, it is not located behind the medial malleolus. *Popliteal artery* - The popliteal artery is located in the **popliteal fossa** behind the knee, where it can be palpated with deep pressure. - It is proximal to the ankle and divides into the anterior and posterior tibial arteries, making it anatomically distant from the medial malleolus.

Question 5: A patient presents with pain in the back of the thigh and leg after lifting heavy weights. Which spinal segment is most likely involved?

A. L4
B. L5
C. S1 (Correct Answer)
D. S2
E. L3

Explanation: ***S1*** - Pain radiating to the **back of the thigh and leg** after lifting heavy weights is the classic presentation of **S1 radiculopathy**, typically from L5-S1 disc herniation. - The S1 nerve root innervates the **posterior thigh via the sciatic nerve**, continues down the **posterior leg**, and extends to the **lateral foot and little toe**. - Clinical findings include diminished or absent **Achilles reflex**, weakness of **plantar flexion** (gastrocnemius/soleus), and sensory changes along the posterior leg and lateral foot. - This is the **most common** presentation of sciatica from heavy lifting. *L3* - L3 nerve root involvement typically causes pain in the **anterior and medial thigh** with weakness of **hip flexion and knee extension** (quadriceps). - The pain pattern does not match the posterior distribution described in this clinical scenario. *L4* - L4 radiculopathy presents with pain and numbness in the **medial leg and foot**, weakness of **ankle dorsiflexion** (tibialis anterior), and diminished **patellar reflex**. - The pain distribution is anteromedial, not posterior as described in this case. *L5* - L5 nerve root impingement causes pain radiating to the **lateral calf and dorsum of the foot**, weakness of **great toe extension** (extensor hallucis longus), and **foot drop**. - While L5 can cause posterior thigh pain, the classic distribution extends laterally down the leg, not primarily posterior. *S2* - S2 radiculopathy is uncommon and typically presents with **perineal/perianal pain** and **saddle anesthesia** rather than isolated posterior leg pain. - S2 contributes to bladder and bowel function; isolated S2 involvement would not present with the classic sciatica pattern described.

Question 6: Identify the arrow marked nerve ![img-2.jpeg](img-2.jpeg)

A. Long thoracic nerve
B. Thoracodorsal nerve
C. Lateral pectoral nerve
D. Medial pectoral nerve (Correct Answer)
E. Suprascapular nerve

Explanation: ***Medial pectoral nerve*** - The arrow points to a nerve that is seen perforating the **pectoralis minor muscle**. This is a key anatomical landmark for the **medial pectoral nerve**. - This nerve supplies both the **pectoralis major** and **pectoralis minor** muscles, originating from the medial cord of the brachial plexus. *Long thoracic nerve* - The **long thoracic nerve** typically runs superficial to the serratus anterior muscle, not perforating the pectoralis minor. - Injury to this nerve results in **winged scapula** due to paralysis of the serratus anterior, which is distinct from the function of the nerve shown. *Thoracodorsal nerve* - The **thoracodorsal nerve** primarily innervates the **latissimus dorsi muscle** and typically runs along the lateral border of the scapula and axilla, not in the anterior chest wall where the pectoralis minor is located. - It arises from the **posterior cord of the brachial plexus**. *Lateral pectoral nerve* - The **lateral pectoral nerve** arises from the lateral cord and typically supplies only the **pectoralis major muscle**. - It often passes **medial to the pectoralis minor muscle** or penetrates the muscle from a more lateral aspect, but does not perforate it in the characteristic way shown for the medial pectoral nerve. *Suprascapular nerve* - The **suprascapular nerve** arises from the **upper trunk of the brachial plexus** and passes through the **suprascapular notch** beneath the superior transverse scapular ligament. - It innervates the **supraspinatus** and **infraspinatus** muscles and is located in the posterior shoulder region, not in the anterior chest wall where the structure shown is located.

Question 7: The "O sign" formed by the thumb and index finger is affected. Which muscle is most likely injured?

A. Opponens pollicis
B. Flexor pollicis longus (Correct Answer)
C. Flexor pollicis brevis
D. Abductor pollicis brevis
E. Flexor digitorum profundus (index finger)

Explanation: ***Flexor pollicis longus*** - The **"O sign"** (or **"OK sign"**) tests the ability to form a tight **tip-to-tip pinch** between the thumb and index finger, creating a circular "O" shape. - This requires **flexion of the thumb interphalangeal (IP) joint** via the **flexor pollicis longus (FPL)** and **flexion of the index finger distal interphalangeal (DIP) joint** via the **flexor digitorum profundus (FDP)**. - Both FPL and FDP to the index/middle fingers are innervated by the **anterior interosseous nerve (AIN)**, a branch of the median nerve. - **AIN palsy** results in inability to flex the thumb IP and index DIP joints, causing the **"O sign"** to become flattened (pinch sign or **"teardrop sign"**). - Injury to **FPL** specifically impairs thumb IP flexion, directly affecting the ability to form the **"O sign"**. *Flexor digitorum profundus (index finger)* - The **FDP to the index finger** is also innervated by the **AIN** and is essential for flexing the DIP joint of the index finger. - Isolated FDP injury would affect the index finger's contribution to the "O sign" but both FPL and FDP are typically affected together in AIN palsy. - This is a plausible answer, making this a higher-order question testing understanding of the anatomy. *Opponens pollicis* - The **opponens pollicis** enables **opposition** of the thumb, bringing the thumb pad to the finger pads (pad-to-pad pinch). - It is innervated by the **recurrent branch of the median nerve**, not the AIN. - Opposition is different from the **tip-to-tip pinch** required for the "O sign," which requires IP joint flexion, not just opposition at the carpometacarpal joint. *Flexor pollicis brevis* - The **flexor pollicis brevis** flexes the thumb at the **metacarpophalangeal (MCP) joint**, not the IP joint. - The superficial head is innervated by the recurrent branch of the median nerve, while the deep head is innervated by the ulnar nerve. - While it contributes to thumb flexion, it does not flex the thumb IP joint, which is essential for forming the **"O sign"**. *Abductor pollicis brevis* - The **abductor pollicis brevis** abducts the thumb away from the palm in a plane perpendicular to the palm. - It is innervated by the **recurrent branch of the median nerve**. - Abduction is not required for forming the **"O sign"**, which primarily tests flexion at the IP and DIP joints.

Question 8: A patient underwent a coronary artery bypass graft (CABG) using the great saphenous vein. Post-surgery, the patient experiences neuralgia on the medial aspect of the leg and foot. Which nerve is most likely injured?

A. Common peroneal nerve
B. Sural nerve
C. Tibial nerve
D. Saphenous nerve (Correct Answer)
E. Superficial peroneal nerve

Explanation: ***Saphenous nerve*** - The **saphenous nerve** is a cutaneous branch of the femoral nerve that runs closely with the **great saphenous vein** along the medial aspect of the leg and foot. - Due to its proximity to the vein, it is highly susceptible to **injury** during the harvesting of the great saphenous vein for CABG, leading to **neuralgia** in its sensory distribution. *Common peroneal nerve* - The **common peroneal nerve** innervates the lateral and anterior compartments of the leg, affecting dorsiflexion and eversion of the foot. - Damage to this nerve typically results in **foot drop** and sensory loss over the dorsum of the foot, which is inconsistent with the patient's symptoms. *Tibial nerve* - The **tibial nerve** supplies the posterior compartment of the leg and the plantar aspect of the foot. - Injury would cause loss of plantarflexion and sensation on the sole of the foot, which is not described. *Sural nerve* - The **sural nerve** provides sensation to the posterolateral aspect of the leg and the lateral side of the foot and ankle. - While it runs near superficial veins, its sensory distribution does not match the described **medial leg and foot neuralgia**. *Superficial peroneal nerve* - The **superficial peroneal nerve** (superficial fibular nerve) provides sensation to the dorsum of the foot and anterolateral leg. - Injury would cause sensory loss over the dorsal foot, not the medial aspect of the leg and foot.

Question 9: A young boy presents with multiple humerus fractures, resulting in loss of sensation over the lateral side of the forearm, along with difficulty in elbow flexion and forearm supination. What is the most likely nerve injury responsible for these symptoms?

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

Explanation: ***Musculocutaneous nerve*** - The **musculocutaneous nerve** innervates the biceps brachii and brachialis muscles, responsible for **elbow flexion** and **forearm supination**, and provides sensation to the **lateral forearm** via the lateral cutaneous nerve of the forearm. - A fracture of the humerus can damage this nerve, leading to the observed **motor and sensory deficits**. *Median nerve* - The median nerve primarily controls **flexion of the wrist and fingers**, and **pronation of the forearm**, as well as sensation to the palmar aspect of the thumb, index, middle, and radial half of the ring finger. - Its injury would not typically cause difficulty with **elbow flexion** or sensory loss over the **lateral forearm**. *Axillary* - The axillary nerve primarily innervates the **deltoid** and **teres minor muscles**, important for shoulder abduction and external rotation. - An injury would lead to **weakness in shoulder abduction** and sensory loss over the lateral shoulder (regimental badge area), not the lateral forearm. *Radial nerve* - The radial nerve controls **extension of the wrist and fingers** and sensation over the posterior arm, forearm, and hand. - Injury typically results in **wrist drop** and difficulty extending the arm, not primarily elbow flexion or lateral forearm sensation. *Ulnar nerve* - The ulnar nerve innervates intrinsic hand muscles and flexor carpi ulnaris, controlling **finger abduction/adduction** and **ulnar wrist flexion**. - Sensory distribution includes the medial hand and medial 1.5 fingers, not the **lateral forearm**. - Injury causes **claw hand deformity** and sensory loss in the medial hand, not the symptoms described.

Question 10: Pen Test is for which nerve

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

Explanation: ***Median Nerve*** - The **pen test** (or pen-holding test) assesses the ability to perform **precision grip** by pinching a pen between the thumb and index finger - This tests **thumb opposition and flexion**, which are controlled by the **thenar muscles** (abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis) innervated by the median nerve - The median nerve also controls the **lateral two lumbricals** for fine finger movements essential for holding objects like a pen - **Clinical significance**: Inability to perform this test indicates median nerve injury (e.g., carpal tunnel syndrome) *Musculocutaneous* - Innervates the **anterior compartment of the arm**: biceps brachii, brachialis, and coracobrachialis - Controls **elbow flexion** and provides sensory innervation to the lateral forearm - Does not control hand muscles or precision grip functions *Radial nerve* - Innervates **extensors of the wrist, fingers, and thumb** in the posterior compartment of the forearm - Controls **wrist extension** and **finger extension** at the MCP joints - Radial nerve injury causes **wrist drop**, not impaired precision grip *Ulnar nerve* - Controls most **intrinsic hand muscles** including interossei, medial two lumbricals, and adductor pollicis - Tested by **Froment's sign** (compensatory thumb IP flexion when pinching paper due to adductor pollicis weakness) - Ulnar nerve injury affects **power grip** and finger abduction/adduction, not the precision pinch required for the pen test *Axillary nerve* - Innervates the **deltoid** and **teres minor** muscles in the shoulder - Controls **shoulder abduction** and provides sensation over the lateral upper arm - Has no role in hand function or precision grip

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