A 34-year-old man is brought to the emergency department 3 hours after being bitten by a rattlesnake. He was hiking in the Arizona desert when he accidentally stepped on the snake and it bit his right leg. His pulse is 135/min and blood pressure is 104/81 mm Hg. Examination shows right lower leg swelling, ecchymosis, and blistering. Right ankle dorsiflexion elicits severe pain. A manometer inserted in the lateral compartment of the lower leg shows an intracompartmental pressure of 67 mm Hg. In addition to administration of the antivenom, the patient undergoes fasciotomy. Two weeks later, he reports difficulty in walking. Neurologic examination shows a loss of sensation over the lower part of the lateral side of the right leg and the dorsum of the right foot. Right foot eversion is 1/5. There is no weakness in dorsiflexion. Which of the following nerves is most likely injured in this patient?
Q92
A 51-year-old woman comes to the physician because of progressively worsening lower back pain. The pain radiates down the right leg to the lateral side of the foot. She has had no trauma, urinary incontinence, or fever. An MRI of the lumbar spine shows disc degeneration and herniation at the level of L5–S1. Which of the following is the most likely finding on physical examination?
Q93
A 10-year-old boy is referred to a pediatric neurologist by his pediatrician for lower extremity weakness. The boy is healthy with no past medical history, but his parents began to notice that he was having difficulty at football practice the previous day. Over the course of the past 24 hours, the boy has become increasingly clumsy and has been “tripping over himself.” On further questioning, the boy had a viral illness the previous week and was out of school for 2 days. Today, the patient’s temperature is 99.3°F (37.4°C), blood pressure is 108/72 mmHg, pulse is 88/min, respirations are 12/min. On motor exam, the patient has 5/5 strength in hip flexion, 5/5 strength in knee extension and flexion, 3/5 strength in foot dorsiflexion, and 5/5 strength in foot plantarflexion. The findings are the same bilaterally. On gait exam, the patient exhibits foot drop in both feet. Which of the following areas would the patient most likely have diminished sensation?
Q94
An 18-year-old man comes to the clinic with his mom for “pins and needles” of both of his arms. He denies any past medical history besides a recent anterior cruciate ligament (ACL) tear that was repaired 1 week ago. The patient reports that the paresthesias are mostly located along the posterior forearms, left more than the right. What physical examination finding would you expect from this patient?
Upper/Lower Limb US Medical PG Practice Questions and MCQs
Question 91: A 34-year-old man is brought to the emergency department 3 hours after being bitten by a rattlesnake. He was hiking in the Arizona desert when he accidentally stepped on the snake and it bit his right leg. His pulse is 135/min and blood pressure is 104/81 mm Hg. Examination shows right lower leg swelling, ecchymosis, and blistering. Right ankle dorsiflexion elicits severe pain. A manometer inserted in the lateral compartment of the lower leg shows an intracompartmental pressure of 67 mm Hg. In addition to administration of the antivenom, the patient undergoes fasciotomy. Two weeks later, he reports difficulty in walking. Neurologic examination shows a loss of sensation over the lower part of the lateral side of the right leg and the dorsum of the right foot. Right foot eversion is 1/5. There is no weakness in dorsiflexion. Which of the following nerves is most likely injured in this patient?
A. Sural nerve
B. Tibial nerve
C. Saphenous nerve
D. Superficial peroneal nerve (Correct Answer)
E. Deep peroneal nerve
Explanation: ***Superficial peroneal nerve***
- The **superficial peroneal nerve** (also known as the superficial fibular nerve) is responsible for **foot eversion** (peroneus longus and brevis muscles) and provides sensory innervation to the **dorsum of the foot**, except for the web space between the first and second toes.
- The patient's inability to evert the foot and sensory loss on the dorsum of the foot, combined with a history of **compartment syndrome** and fasciotomy in the lateral compartment, strongly indicates injury to the superficial peroneal nerve.
*Sural nerve*
- The **sural nerve** provides sensory innervation to the **posterolateral aspect of the lower leg** and the lateral aspect of the foot.
- It does not innervate muscles involved in foot eversion or dorsiflexion, so its injury would not lead to the motor deficits described.
*Tibial nerve*
- The **tibial nerve** innervates the muscles of the posterior compartment of the leg, responsible for **plantarflexion** and inversion of the foot, and provides sensation to the sole of the foot.
- Its injury would lead to weakness in plantarflexion and sensory loss on the sole, not the symptoms described.
*Saphenous nerve*
- The **saphenous nerve** is a pure sensory nerve, supplying sensation to the **medial aspect of the lower leg and foot**.
- Its injury would result in sensory loss in this distribution but no motor deficits affecting foot eversion or dorsiflexion.
*Deep peroneal nerve*
- The **deep peroneal nerve** (also known as the deep fibular nerve) innervates the muscles of the anterior compartment of the leg, primarily responsible for **foot dorsiflexion** and toe extension, and provides sensation to the web space between the first and second toes.
- The patient has no weakness in dorsiflexion, ruling out significant injury to the deep peroneal nerve.
Question 92: A 51-year-old woman comes to the physician because of progressively worsening lower back pain. The pain radiates down the right leg to the lateral side of the foot. She has had no trauma, urinary incontinence, or fever. An MRI of the lumbar spine shows disc degeneration and herniation at the level of L5–S1. Which of the following is the most likely finding on physical examination?
A. Difficulty walking on heels
B. Exaggerated patellar tendon reflex
C. Diminished sensation of the anus and genitalia
D. Diminished sensation of the anterior lateral thigh
E. Weak Achilles tendon reflex (Correct Answer)
Explanation: ***Weak Achilles tendon reflex***
- A herniated disc at **L5-S1** typically compresses the **S1 nerve root**, which is responsible for the **Achilles tendon reflex**.
- **S1 radiculopathy** presents with weakness in plantarflexion, diminished or absent Achilles reflex, and sensory loss in the **lateral foot** (matching the patient's symptoms).
*Difficulty walking on heels*
- Difficulty walking on heels (**dorsiflexion weakness**) is primarily associated with **L4-L5 disc herniation** compressing the **L5 nerve root**.
- This symptom indicates **L5 radiculopathy**, which affects the tibialis anterior muscle, not S1.
*Exaggerated patellar tendon reflex*
- An exaggerated patellar tendon reflex (**hyperreflexia**) indicates an **upper motor neuron lesion** or spinal cord compression above the lumbar region.
- A disc herniation at **L5-S1** causes a **lower motor neuron lesion** with diminished reflexes, not hyperreflexia.
*Diminished sensation of the anus and genitalia*
- This symptom, along with urinary incontinence and saddle anesthesia, is characteristic of **cauda equina syndrome**, a surgical emergency.
- The patient lacks urinary incontinence and the specific unilateral pain pattern points to isolated **S1 radiculopathy**, not cauda equina syndrome.
*Diminished sensation of the anterior lateral thigh*
- Sensory loss in the **anterior lateral thigh** is associated with compression of the **lateral femoral cutaneous nerve** or **L2-L4 nerve roots**.
- This pattern is not consistent with **L5-S1 disc herniation**, which causes sensory changes in the lateral foot and posterior leg.
Question 93: A 10-year-old boy is referred to a pediatric neurologist by his pediatrician for lower extremity weakness. The boy is healthy with no past medical history, but his parents began to notice that he was having difficulty at football practice the previous day. Over the course of the past 24 hours, the boy has become increasingly clumsy and has been “tripping over himself.” On further questioning, the boy had a viral illness the previous week and was out of school for 2 days. Today, the patient’s temperature is 99.3°F (37.4°C), blood pressure is 108/72 mmHg, pulse is 88/min, respirations are 12/min. On motor exam, the patient has 5/5 strength in hip flexion, 5/5 strength in knee extension and flexion, 3/5 strength in foot dorsiflexion, and 5/5 strength in foot plantarflexion. The findings are the same bilaterally. On gait exam, the patient exhibits foot drop in both feet. Which of the following areas would the patient most likely have diminished sensation?
A. First dorsal webspace of foot (Correct Answer)
B. Lateral plantar foot
C. Anteromedial thigh
D. Medial plantar foot
E. Lateral foot
Explanation: ***First dorsal webspace of foot***
- The patient exhibits weakness in **foot dorsiflexion** and **foot drop**, which points to a lesion affecting the **deep fibular nerve** or its nerve roots (L4-L5).
- The **first dorsal webspace** of the foot is the specific cutaneous sensory innervation area for the **deep fibular nerve**.
*Lateral plantar foot*
- The **lateral plantar nerve**, a branch of the tibial nerve, innervates this area.
- Sensation here would be unlikely to be diminished given the primary motor deficits are related to dorsiflexion, which is supplied by the fibular nerve and not the tibial nerve.
*Anteromedial thigh*
- This area is primarily innervated by the **femoral nerve** (cutaneous branches) and the **obturator nerve**.
- The patient's symptoms are in the lower leg and foot, making this area less likely to have affected sensation.
*Medial plantar foot*
- The **medial plantar nerve**, a branch of the tibial nerve, innervates this area.
- Similar to the lateral plantar foot, this area is not directly related to the sensory distribution of the deep fibular nerve, which is responsible for dorsiflexion.
*Lateral foot*
- The **superficial fibular nerve** supplies sensation to the dorsum of the foot, excluding the first webspace, and the lateral lower leg.
- While related to the fibular nerve, the most specific sensory loss with foot drop and deep fibular nerve involvement is the first dorsal webspace.
Question 94: An 18-year-old man comes to the clinic with his mom for “pins and needles” of both of his arms. He denies any past medical history besides a recent anterior cruciate ligament (ACL) tear that was repaired 1 week ago. The patient reports that the paresthesias are mostly located along the posterior forearms, left more than the right. What physical examination finding would you expect from this patient?
A. Loss of finger abduction
B. Loss of forearm flexion and supination
C. Loss of arm abduction
D. Loss of thumb opposition
E. Loss of wrist extension (Correct Answer)
Explanation: ***Loss of wrist extension***
- The patient describes "pins and needles" predominantly along the **posterior forearms**, indicating **radial nerve involvement**.
- The **radial nerve** provides sensory innervation to the posterior forearm via the **posterior cutaneous nerve of the forearm**.
- Motor function: The radial nerve innervates the **extensor carpi radialis longus and brevis** and **extensor carpi ulnaris**, which are responsible for **wrist extension**.
- The recent **ACL repair surgery** suggests a **positional compression injury** to the radial nerves from prolonged arm positioning during the procedure.
- Expected finding: **Wrist drop** (inability to extend the wrist against gravity).
*Loss of finger abduction*
- **Finger abduction** is controlled by the **interossei muscles**, which are innervated by the **ulnar nerve**.
- The ulnar nerve provides sensory innervation to the **medial forearm** (via medial cutaneous nerve of forearm) and **medial 1.5 digits**, NOT the posterior forearm.
- Posterior forearm paresthesias do not indicate ulnar nerve involvement.
*Loss of forearm flexion and supination*
- **Forearm flexion** is primarily controlled by the **musculocutaneous nerve** (supplying the **biceps brachii** and **brachialis**).
- The musculocutaneous nerve becomes the **lateral cutaneous nerve of the forearm**, supplying the **lateral forearm**, not the posterior forearm.
- Supination involves the biceps (musculocutaneous) and supinator (radial nerve, posterior interosseous branch).
*Loss of arm abduction*
- **Arm abduction** is primarily controlled by the **deltoid** muscle (innervated by the **axillary nerve**) and **supraspinatus** (suprascapular nerve).
- Axillary nerve injury causes sensory loss over the **lateral shoulder** (regimental badge area), not the forearm.
*Loss of thumb opposition*
- **Thumb opposition** is a function of the **opponens pollicis** and **flexor pollicis brevis** (superficial head), primarily innervated by the **median nerve**.
- Median nerve compression typically causes paresthesias in the **lateral 3.5 digits** and **thenar eminence**, not the posterior forearm.
