A 42-year-old woman comes to the physician because of increasing pain in the right hip for 2 months. The pain is intermittent, presenting at the lateral side of the hip and radiating towards the thigh. It is aggravated while climbing stairs or lying on the right side. Two weeks ago, the patient was treated with a course of oral prednisone for exacerbation of asthma. Her current medications include formoterol-budesonide and albuterol inhalers. Vital signs are within normal limits. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. The patient is placed in the left lateral decubitus position. Abducting the extended right leg against the physician's resistance reproduces the pain. The remainder of the examination shows no abnormalities. An x-ray of the pelvis shows no abnormalities. Which of the following is the most likely diagnosis?
Q22
A 38-year-old man is brought to the emergency department after suffering a motor vehicle accident as the passenger. He had no obvious injuries, but he complains of excruciating right hip pain. His right leg is externally rotated, abducted, and extended at the hip and the femoral head can be palpated anterior to the pelvis. Plain radiographs of the pelvis reveal a right anterior hip dislocation and femoral head fracture. Which sensory and motor deficits are most likely in this patient's right lower extremity?
Q23
A 19-year-old man comes to the emergency department for right wrist pain and swelling 2 hours after falling on an outstretched hand while playing softball. The pain worsened when he attempted to pitch after the fall. He has eczema and type 1 diabetes mellitus. Current medications include insulin and topical clobetasol. He appears uncomfortable. Examination shows multiple lichenified lesions over his forearms. The right wrist is swollen and tender; range of motion is limited by pain. There is tenderness to palpation in the area between the tendons of the abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus muscle. The thumb can be opposed actively towards the other fingers. Muscle strength of the right hand is decreased. Which of the following is the most likely diagnosis?
Q24
A 64-year-old man with osteoarthritis of the knee comes to the physician for evaluation of weakness in his foot. Physical examination shows a swelling in the popliteal fossa. There is weakness when attempting to plantarflex and invert his right foot. He is unable to curl his toes. Further evaluation of this patient is most likely to show decreased sensation over which of the following locations?
Q25
A 39-year-old male who recently presented with acetaminophen overdose was admitted to the MICU, where several attempts were made at obtaining intravenous access without success. The decision was made to place a right axillary arterial line, which became infected and was removed by the medical student while the patient was still intubated. It was later noticed that he had substantial swelling and bruising of the upper extremity. Given his sedation, a proper neuro exam was not performed at that time. Several days later, after the patient's liver function improved, he was successfully extubated. On exam, he complained of lack of sensation over the palmar and dorsal surface of the small finger and half of the ring finger, as well as weak digit abduction, weak thumb adduction, and weak thumb-index finger pinch of the affected extremity. What is the most likely cause and corresponding location of the injury?
Q26
A 47-year-old woman presents to her primary care provider because of numbness and tingling on the palmar aspects of both hands. She denies any symptoms at the base of her thumbs. The symptoms are worse on the right (dominant hand) and are increased with activities such as driving or brushing her hair. She frequently wakes up with pain and has to shake her hand for pain relief. She has had rheumatoid arthritis for 9 years, for which she takes methotrexate. Her blood pressure is 124/76 mm Hg, the heart rate is 75/min, and the respiratory rate is 15/min. Lightly tapping over the middle of the anterior aspect of the right wrist leads to a tingling sensation in the palm. In this patient, electromyography (EMG) will most likely show which of the following results?
Q27
Three hours after undergoing left hip arthroplasty for chronic hip pain, a 62-year-old man complains of a prickling sensation in his left anteromedial thigh and lower leg. He has never had these symptoms before. He has hyperlipidemia and coronary artery disease. He has had recent right-sided gluteal and thigh pain with ambulation. Vital signs are within normal limits. Sensation to pinprick and light touch are decreased on the anteromedial left thigh as well as medial lower leg. Neurologic exam shows left leg strength 3/5 on hip flexion and 2/5 on knee extension. Patellar reflex is decreased on the left. The remainder of neurologic exam is normal. Dorsalis pedis, popliteal, and femoral pulses are 2+ bilaterally. The surgical incision is without erythema or drainage. Which of the following is the most likely underlying cause of this patient's symptoms?
Q28
A 48-year-old male presents to his primary care provider with a two-week history of low back pain and left leg pain. He reports that his symptoms started while he was working at his job as a construction worker. He has since experienced intermittent achy pain over his lumbar spine. He has also noticed pain radiating into his left leg and weakness in left ankle dorsiflexion. On exam, he demonstrates the following findings on strength testing of the left leg: 5/5 in knee extension, 4/5 in ankle dorsiflexion, 4/5 in great toe extension, 5/5 in ankle plantarflexion, and 5/5 in great toe flexion. The patellar reflexes are 5/5 bilaterally. He is able to toe walk but has difficulty with heel walking. Weakness in which of the following compartments of the leg is most likely causing this patient’s foot drop?
Q29
A 2-day-old boy is evaluated in the nursery for minimal movement in his left upper limb. He was born at 41 weeks gestation by an assisted forceps-vaginal delivery to a 42-year-old obese woman. Birth weight was 4.4 kg (9.7 lb). The mother had 4 previous vaginal deliveries, all requiring forceps. Examinations of the left upper limb show that the arm hangs by his side and is rotated medially. His forearm is extended and pronated, and his wrist and fingers are flexed. Moro reflex is present only on the right side. Which of the following muscles was spared from the injury sustained during delivery?
Q30
A 12-year-old boy is brought to his orthopedic surgeon for evaluation of leg pain and positioning. Specifically, over the past several months he has been complaining of thigh pain and has more difficulty sitting in his wheelchair. His medical history is significant for spastic quadriplegic cerebral palsy since birth and has undergone a number of surgeries for contractures in his extremities. At this visit his legs are found to be scissored such that they cross each other at the knees and are difficult to separate. Surgery is performed and the boy is placed into a cast that keeps his legs abducted to prevent scissoring. Overactivity of the muscles innervated by which of the following nerves is most consistent with this patient's deformity?
Upper/Lower Limb US Medical PG Practice Questions and MCQs
Question 21: A 42-year-old woman comes to the physician because of increasing pain in the right hip for 2 months. The pain is intermittent, presenting at the lateral side of the hip and radiating towards the thigh. It is aggravated while climbing stairs or lying on the right side. Two weeks ago, the patient was treated with a course of oral prednisone for exacerbation of asthma. Her current medications include formoterol-budesonide and albuterol inhalers. Vital signs are within normal limits. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. The patient is placed in the left lateral decubitus position. Abducting the extended right leg against the physician's resistance reproduces the pain. The remainder of the examination shows no abnormalities. An x-ray of the pelvis shows no abnormalities. Which of the following is the most likely diagnosis?
A. Osteoarthritis of the hip
B. Osteonecrosis of femoral head
C. Lumbosacral radiculopathy
D. Greater trochanteric pain syndrome (Correct Answer)
E. Iliotibial band syndrome
Explanation: ***Greater trochanteric pain syndrome***
- The patient's symptoms of **lateral hip pain** radiating to the thigh, aggravated by activity and lying on the affected side, and **tenderness over the greater trochanter** are classic for **greater trochanteric pain syndrome** (GTPS).
- Pain reproduction with **abduction against resistance** (a specific test for GTPS) and normal X-rays further support this diagnosis.
*Osteoarthritis of the hip*
- Typically causes **groin pain** that can radiate to the buttock or knee, not primarily lateral hip pain.
- X-rays would likely show signs of **joint space narrowing**, osteophytes, or subchondral sclerosis, which are absent here.
*Osteonecrosis of femoral head*
- While **corticosteroid use** is a risk factor, osteonecrosis usually presents with **groin or buttock pain** and would likely show abnormalities on X-ray (advanced stages) or MRI (early stages).
- The specific tenderness and pain reproduction with abduction against resistance are not typical for osteonecrosis.
*Lumbosacral radiculopathy*
- Would typically present with pain radiating **down the leg** in a dermatomal pattern, often accompanied by **neurological deficits** such as sensory loss, weakness, or reflex changes.
- The examination findings of isolated lateral hip tenderness and pain with resisted abduction do not support radiculopathy.
*Iliotibial band syndrome*
- More commonly affects **runners** or cyclists and causes pain along the **lateral aspect of the knee**, although it can present as lateral hip pain.
- While it can manifest with lateral hip pain, the focal tenderness over the greater trochanter and pain on resisted abduction make **GTPS** a more precise diagnosis.
Question 22: A 38-year-old man is brought to the emergency department after suffering a motor vehicle accident as the passenger. He had no obvious injuries, but he complains of excruciating right hip pain. His right leg is externally rotated, abducted, and extended at the hip and the femoral head can be palpated anterior to the pelvis. Plain radiographs of the pelvis reveal a right anterior hip dislocation and femoral head fracture. Which sensory and motor deficits are most likely in this patient's right lower extremity?
A. Loss of sensation laterally below the knee, weak thigh extension and knee flexion
B. Numbness of the ipsilateral scrotum and upper medial thigh
C. Sensory loss to the dorsal surface of the foot and part of the anterior lower and lateral leg and foot drop
D. Paresis and numbness of the medial thigh and medial side of the calf, weak hip flexion and knee extension
E. Numbness of the medial side of the thigh and inability to adduct the thigh (Correct Answer)
Explanation: ***Numbness of the medial side of the thigh and inability to adduct the thigh***
- An **anterior hip dislocation** is caused by forced **abduction** and **external rotation**, putting the **obturator nerve** at risk due to its anatomical course through the **obturator foramen** and proximity to the hip joint.
- Damage to the **obturator nerve** (L2-L4) results in **sensory loss** over the **medial thigh** and paralysis of the **adductor muscles** (adductor longus, brevis, magnus, gracilis), leading to an inability to adduct the thigh.
*Loss of sensation laterally below the knee, weak thigh extension and knee flexion*
- **Sensory loss laterally below the knee** and **weak thigh extension/knee flexion** are characteristic of **sciatic nerve** or common **peroneal nerve injury**, which is more common in **posterior hip dislocations**.
- The presented case describes an **anterior dislocation**, making **obturator nerve** injury more likely than sciatic nerve injury.
*Numbness of the ipsilateral scrotum and upper medial thigh*
- **Numbness of the ipsilateral scrotum** and **upper medial thigh** is associated with injury to the **ilioinguinal nerve** or **genitofemoral nerve**.
- While these nerves supply portions of the **medial thigh** and **genitalia**, they are not typically injured in **anterior hip dislocations** which primarily affect deeper structures like the **obturator nerve**.
*Sensory loss to the dorsal surface of the foot and part of the anterior lower and lateral leg and foot drop*
- **Sensory loss to the dorsal surface of the foot**, **anterior lower and lateral leg**, and **foot drop** are classic signs of **common peroneal nerve** injury due to its superficial course around the fibular head.
- Although the common peroneal nerve is a branch of the **sciatic nerve**, direct injury specifically to the **common peroneal nerve** in an anterior hip dislocation is less probable than obturator nerve injury, and foot drop is characteristic of more severe neural compromise, typically seen in **posterior dislocations or direct trauma**.
*Paresis and numbness of the medial thigh and medial side of the calf, weak hip flexion and knee extension*
- **Paresis and numbness of the medial thigh** are consistent with **obturator nerve** injury. However, **numbness of the medial side of the calf** and **weak hip flexion/knee extension** point towards **femoral nerve** injury.
- While the **femoral nerve** can be injured, the prominent clinical picture of **anterior hip dislocation** points more directly to the **obturator nerve** findings of medial thigh numbness and adduction weakness, rather than primarily femoral nerve symptoms.
Question 23: A 19-year-old man comes to the emergency department for right wrist pain and swelling 2 hours after falling on an outstretched hand while playing softball. The pain worsened when he attempted to pitch after the fall. He has eczema and type 1 diabetes mellitus. Current medications include insulin and topical clobetasol. He appears uncomfortable. Examination shows multiple lichenified lesions over his forearms. The right wrist is swollen and tender; range of motion is limited by pain. There is tenderness to palpation in the area between the tendons of the abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus muscle. The thumb can be opposed actively towards the other fingers. Muscle strength of the right hand is decreased. Which of the following is the most likely diagnosis?
A. De Quervain's tenosynovitis
B. Colles' fracture
C. Transscaphoid perilunate dislocation
D. Scaphoid fracture (Correct Answer)
E. Lunate dislocation
Explanation: ***Scaphoid fracture***
- The history of a **fall on an outstretched hand (FOOSH)**, especially when attempting to pitch again, combined with **tenderness in the anatomical snuffbox** (area between the tendons of the abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus muscle), is highly indicative of a **scaphoid fracture**.
- **Limited range of motion** and decreased muscle strength due to pain, even with active thumb opposition, further supports this diagnosis.
*De Quervain's tenosynovitis*
- This is an **inflammatory condition** affecting the tendons on the thumb side of the wrist, typically exacerbated by repetitive thumb movements.
- While it can cause pain in a similar area, it usually develops gradually and is not immediately precipitated by an acute **FOOSH injury**.
*Colles' fracture*
- A **Colles' fracture** involves a fracture of the **distal radius** with dorsal displacement, often presenting with a "dinner fork" deformity.
- While it also results from a **FOOSH injury**, the key finding of **anatomical snuffbox tenderness** points away from a Colles' fracture and towards a scaphoid injury.
*Transscaphoid perilunate dislocation*
- This severe injury involves a **dislocation of the carpal bones** around the lunate, often with an associated scaphoid fracture.
- While a scaphoid fracture is part of this, the primary presentation would involve more obvious **carpal instability** and significant radiographic abnormalities beyond a simple scaphoid fracture.
*Lunate dislocation*
- A **lunate dislocation** involves the displacement of the lunate bone, typically volarly, and often presents with a characteristic "spilled teacup" sign on radiographs.
- Although it can result from a **FOOSH injury**, the specific finding of **anatomical snuffbox tenderness** is more indicative of a scaphoid fracture.
Question 24: A 64-year-old man with osteoarthritis of the knee comes to the physician for evaluation of weakness in his foot. Physical examination shows a swelling in the popliteal fossa. There is weakness when attempting to plantarflex and invert his right foot. He is unable to curl his toes. Further evaluation of this patient is most likely to show decreased sensation over which of the following locations?
A. First dorsal web space
B. Sole of the foot (Correct Answer)
C. Lateral border of the foot
D. Medial plantar arch
E. Second dorsal web space
Explanation: ***Sole of the foot***
- The patient's inability to **plantarflex the foot**, weakness with **inversion**, and inability to **curl the toes** indicate damage to the **tibial nerve**.
- A **popliteal fossa mass** (likely Baker's cyst) can compress the tibial nerve as it courses through this region.
- The **tibial nerve** supplies sensation to the **sole of the foot** via its medial and lateral plantar branches and innervates the muscles responsible for plantarflexion, foot inversion (tibialis posterior), and toe flexion.
*First dorsal web space*
- Sensation over the **first dorsal web space** is primarily supplied by the **deep fibular (peroneal) nerve**.
- Injury to this nerve would typically affect **dorsiflexion** and **toe extension**, not the plantarflexion and toe flexion deficits described.
*Lateral border of the foot*
- Sensation along the **lateral border of the foot** is predominantly supplied by the **sural nerve**.
- This nerve is primarily cutaneous and does not contribute to motor function related to plantarflexion or toe curling.
*Medial plantar arch*
- While the **medial plantar nerve** (a branch of the tibial nerve) supplies sensation to part of the plantar surface, the term "sole of the foot" more comprehensively describes the entire plantar sensory distribution of the tibial nerve.
- The motor deficits described indicate a proximal **tibial nerve** lesion affecting the entire nerve distribution.
*Second dorsal web space*
- Sensation to the **second dorsal web space** is primarily provided by the **superficial fibular (peroneal) nerve**.
- Motor deficits associated with fibular nerve injury would be dorsiflexion and eversion weakness, not the symptoms described.
Question 25: A 39-year-old male who recently presented with acetaminophen overdose was admitted to the MICU, where several attempts were made at obtaining intravenous access without success. The decision was made to place a right axillary arterial line, which became infected and was removed by the medical student while the patient was still intubated. It was later noticed that he had substantial swelling and bruising of the upper extremity. Given his sedation, a proper neuro exam was not performed at that time. Several days later, after the patient's liver function improved, he was successfully extubated. On exam, he complained of lack of sensation over the palmar and dorsal surface of the small finger and half of the ring finger, as well as weak digit abduction, weak thumb adduction, and weak thumb-index finger pinch of the affected extremity. What is the most likely cause and corresponding location of the injury?
A. Compression of ulnar nerve secondary to coagulopathy (Correct Answer)
B. Compression of median nerve secondary to coagulopathy
C. Stretch injury to ulnar nerve secondary to frequent repositioning
D. Needle injury to ulnar nerve secondary to blind line placement
E. Needle injury to median nerve secondary to blind line placement
Explanation: ***Compression of ulnar nerve secondary to coagulopathy***
- The described sensory deficits (palmar and dorsal surface of the small finger and half of the ring finger) and motor deficits (weak digit abduction, weak thumb adduction, and weak thumb-index finger pinch) are classic signs of **ulnar nerve injury**.
- The patient's history of an infected axillary arterial line, substantial upper extremity swelling/bruising, and likely **coagulopathy** (given acetaminophen overdose and liver dysfunction) predispose to hemorrhage and compression of the ulnar nerve in the axillary region or more distally.
*Compression of median nerve secondary to coagulopathy*
- **Median nerve injury** would typically present with sensory loss over the thumb, index, middle finger, and radial half of the ring finger, as well as weakness in thumb abduction and opposition. These findings are inconsistent with the patient's symptoms.
- While coagulopathy could cause nerve compression, the specific neurological deficits point away from the median nerve.
*Stretch injury to ulnar nerve secondary to frequent repositioning*
- While repositioning can cause stretch injuries, the context of an infected arterial line insertion, swelling, and bruising strongly suggests a **compressive etiology** rather than just a stretch injury.
- The degree of injury and the associated swelling make compression a more probable cause than simple stretch.
*Needle injury to ulnar nerve secondary to blind line placement*
- While blind line placement can cause needle injury, the delayed onset of symptoms after line removal, combined with the presence of **substantial swelling and bruising**, suggests a developing hematoma or compressive process rather than direct acute needle trauma.
- Direct needle injury would typically manifest immediately or very soon after the attempted placement.
*Needle injury to median nerve secondary to blind line placement*
- As with other median nerve options, the sensory and motor symptoms provided in the clinical vignette do not align with a **median nerve injury**.
- Furthermore, the clinical picture points to a compressive injury developing over time due to bleeding rather than a direct needle strike onto a nerve, especially given the axillary location where the median nerve is well protected within the neurovascular bundle.
Question 26: A 47-year-old woman presents to her primary care provider because of numbness and tingling on the palmar aspects of both hands. She denies any symptoms at the base of her thumbs. The symptoms are worse on the right (dominant hand) and are increased with activities such as driving or brushing her hair. She frequently wakes up with pain and has to shake her hand for pain relief. She has had rheumatoid arthritis for 9 years, for which she takes methotrexate. Her blood pressure is 124/76 mm Hg, the heart rate is 75/min, and the respiratory rate is 15/min. Lightly tapping over the middle of the anterior aspect of the right wrist leads to a tingling sensation in the palm. In this patient, electromyography (EMG) will most likely show which of the following results?
A. Neuropathic changes in the palmar branch of the median nerve
B. Denervation in C7 innervated paraspinal, arms, and shoulder muscles
C. Focal slowing of conduction velocity in the median nerve in the carpal tunnel (Correct Answer)
D. Widespread symmetrical neuropathic changes without focal abnormalities
E. Widespread denervation in proximal muscles with normal sensory nerves
Explanation: ***Focal slowing of conduction velocity in the median nerve in the carpal tunnel***
- The patient's symptoms (numbness, tingling in palmar hands, worsening with activity, nocturnal pain relieved by shaking, **Tinel's sign** at the wrist) are classic for **carpal tunnel syndrome (CTS)**, caused by compression of the **median nerve** at the wrist.
- **Electromyography (EMG)** and **nerve conduction studies (NCS)** are confirmatory tests for CTS, demonstrating slowed conduction velocity specifically through the carpal tunnel.
*Neuropathic changes in the palmar branch of the median nerve*
- The **palmar cutaneous branch** of the median nerve typically branches off **proximal to the carpal tunnel** and supplies sensation to the base of the thumb.
- Since the patient specifically denies symptoms at the base of her thumbs, isolated involvement of the palmar cutaneous branch is unlikely in this case, pointing to compression within the carpal tunnel.
*Denervation in C7 innervated paraspinal, arms, and shoulder muscles*
- **C7 radiculopathy** would involve symptoms in the C7 dermatome and myotome, potentially affecting muscles in the arm and shoulder.
- Her symptoms are primarily wrist and hand-focused, without signs of cervical spine involvement or widespread muscle weakness.
*Widespread symmetrical neuropathic changes without focal abnormalities*
- This pattern suggests a **generalized peripheral neuropathy**, which would likely present with more diffuse and possibly symmetrical symptoms, often involving the feet first.
- This patient's symptoms are distinctly focal and related to the distribution of the median nerve in the hand.
*Widespread denervation in proximal muscles with normal sensory nerves*
- This presentation is more consistent with a **motor neuron disease** or a **myopathy**, where there is primarily motor involvement and sensory nerves are typically spared.
- The patient's primary symptoms are sensory (numbness and tingling), and there is no indication of widespread muscle weakness or atrophy typical of denervation in proximal muscles.
Question 27: Three hours after undergoing left hip arthroplasty for chronic hip pain, a 62-year-old man complains of a prickling sensation in his left anteromedial thigh and lower leg. He has never had these symptoms before. He has hyperlipidemia and coronary artery disease. He has had recent right-sided gluteal and thigh pain with ambulation. Vital signs are within normal limits. Sensation to pinprick and light touch are decreased on the anteromedial left thigh as well as medial lower leg. Neurologic exam shows left leg strength 3/5 on hip flexion and 2/5 on knee extension. Patellar reflex is decreased on the left. The remainder of neurologic exam is normal. Dorsalis pedis, popliteal, and femoral pulses are 2+ bilaterally. The surgical incision is without erythema or drainage. Which of the following is the most likely underlying cause of this patient's symptoms?
A. Surgical site infection
B. Obturator nerve injury
C. Sural nerve injury
D. Femoral nerve injury (Correct Answer)
E. Femoral artery occlusion
Explanation: ***Femoral nerve injury***
- The patient's symptoms of **prickling sensation (paresthesia)** in the anterior-medial thigh and medial lower leg, **decreased sensation to pinprick and light touch** in these areas, and **weakness in hip flexion (iliopsoas)** and **knee extension (quadriceps)**, along with a **decreased patellar reflex**, are all classic signs of **femoral nerve dysfunction**.
- The femoral nerve can be susceptible to injury during **hip arthroplasty** due to retraction, direct trauma, or hematoma formation, especially if the patient is slim or has anatomical variations.
*Surgical site infection*
- This typically presents with signs of **inflammation** such as erythema, warmth, severe pain, and sometimes drainage from the incision site, which are absent here.
- Neurological deficits like specific motor weakness and sensory loss in a nerve distribution are *not* primary features of a surgical site infection.
*Obturator nerve injury*
- An obturator nerve injury would primarily affect **adduction of the thigh** and might cause sensory changes in the medial thigh, but would *not* cause weakness in hip flexion or knee extension, nor would it affect the patellar reflex.
- The sensory distribution described (anteromedial thigh and medial lower leg) is more consistent with femoral nerve involvement than obturator nerve.
*Sural nerve injury*
- **Sural nerve injury** primarily causes sensory deficits along the **posterolateral aspect of the lower leg and ankle**, and the lateral aspect of the foot.
- It would *not* cause motor weakness in hip flexion or knee extension, nor would it affect the patellar reflex.
*Femoral artery occlusion*
- **Femoral artery occlusion** would cause symptoms of **acute limb ischemia**, including severe pain, pallor, pulselessness, poikilothermia (coldness), paresthesias, and paralysis (the "6 Ps").
- While paresthesias are present, the patient has **intact distal pulses (2+ bilaterally)** and no signs of pallor or coldness, ruling out significant arterial occlusion.
Question 28: A 48-year-old male presents to his primary care provider with a two-week history of low back pain and left leg pain. He reports that his symptoms started while he was working at his job as a construction worker. He has since experienced intermittent achy pain over his lumbar spine. He has also noticed pain radiating into his left leg and weakness in left ankle dorsiflexion. On exam, he demonstrates the following findings on strength testing of the left leg: 5/5 in knee extension, 4/5 in ankle dorsiflexion, 4/5 in great toe extension, 5/5 in ankle plantarflexion, and 5/5 in great toe flexion. The patellar reflexes are 5/5 bilaterally. He is able to toe walk but has difficulty with heel walking. Weakness in which of the following compartments of the leg is most likely causing this patient’s foot drop?
A. Lateral compartment
B. Superficial posterior compartment
C. Deep posterior compartment
D. Anterior compartment (Correct Answer)
E. Medial compartment
Explanation: ***Anterior compartment***
- Weakness in **ankle dorsiflexion** and **great toe extension**, coupled with difficulty **heel walking**, indicates a foot drop due to dysfunction of muscles in the anterior compartment, such as the **tibialis anterior**, **extensor hallucis longus**, and **extensor digitorum longus**.
- These muscles are primarily innervated by the **deep fibular nerve**, which is susceptible to compression from conditions like **lumbar radiculopathy** (L4-L5 nerve root involvement).
*Lateral compartment*
- Muscles in the lateral compartment (**fibularis longus** and **brevis**) are responsible for **eversion** of the foot.
- Weakness in this compartment would manifest as difficulty everting the foot, not primarily ankle dorsiflexion or great toe extension deficits.
*Superficial posterior compartment*
- This compartment contains muscles like the **gastrocnemius** and **soleus**, which are primarily responsible for **ankle plantarflexion**.
- The patient exhibits 5/5 strength in ankle plantarflexion and is able to toe walk, indicating these muscles are functioning well.
*Deep posterior compartment*
- Muscles in the deep posterior compartment (**tibialis posterior**, **flexor digitorum longus**, **flexor hallucis longus**) are involved in **inversion** and **toe flexion**.
- The patient has 5/5 strength in great toe flexion, suggesting intact function of these muscles, and his primary deficit is in dorsiflexion.
*Medial compartment*
- There is no distinct "medial compartment" of the leg in the anatomical sense comparable to the other listed compartments; rather, various muscles contribute to medial actions.
- The symptoms described specifically point to weakness in dorsiflexion and toe extension, localizing the problem to the anterior compartment.
Question 29: A 2-day-old boy is evaluated in the nursery for minimal movement in his left upper limb. He was born at 41 weeks gestation by an assisted forceps-vaginal delivery to a 42-year-old obese woman. Birth weight was 4.4 kg (9.7 lb). The mother had 4 previous vaginal deliveries, all requiring forceps. Examinations of the left upper limb show that the arm hangs by his side and is rotated medially. His forearm is extended and pronated, and his wrist and fingers are flexed. Moro reflex is present only on the right side. Which of the following muscles was spared from the injury sustained during delivery?
A. Biceps
B. Supraspinatus
C. Infraspinatus
D. Deltoid
E. Triceps (Correct Answer)
Explanation: ***Triceps***
- The patient's presentation is consistent with **Erb-Duchenne palsy**, affecting the **C5-C6 nerve roots** of the brachial plexus.
- The **triceps muscle** is innervated by the **radial nerve** originating from **C6, C7, and C8**, with **C7 and C8 providing the predominant innervation**.
- Since the injury involves primarily **C5-C6**, and the triceps depends mainly on **C7-C8**, it is **functionally spared** in Erb's palsy.
*Biceps*
- The **biceps muscle** is innervated by the **musculocutaneous nerve** (C5-C6) and is responsible for **flexion and supination** of the forearm.
- Its involvement explains the **extended and pronated** forearm observed in Erb's palsy.
*Supraspinatus*
- The **supraspinatus muscle** is innervated by the **suprascapular nerve** (C5-C6) and is crucial for the **initiation of shoulder abduction**.
- Injury to its innervation contributes to the arm hanging by the side.
*Infraspinatus*
- The **infraspinatus muscle** is also innervated by the **suprascapular nerve** (C5-C6) and is responsible for **external rotation** of the humerus.
- Its paralysis leads to the **medially rotated** arm seen in Erb's palsy.
*Deltoid*
- The **deltoid muscle** is innervated by the **axillary nerve** (C5-C6) and primarily functions in **shoulder abduction** and shoulder flexion/extension.
- Damage to this innervation contributes to the inability to abduct the arm.
Question 30: A 12-year-old boy is brought to his orthopedic surgeon for evaluation of leg pain and positioning. Specifically, over the past several months he has been complaining of thigh pain and has more difficulty sitting in his wheelchair. His medical history is significant for spastic quadriplegic cerebral palsy since birth and has undergone a number of surgeries for contractures in his extremities. At this visit his legs are found to be scissored such that they cross each other at the knees and are difficult to separate. Surgery is performed and the boy is placed into a cast that keeps his legs abducted to prevent scissoring. Overactivity of the muscles innervated by which of the following nerves is most consistent with this patient's deformity?
A. Nerve to the iliopsoas
B. Sciatic nerve
C. Femoral nerve
D. Superior gluteal nerve
E. Obturator nerve (Correct Answer)
Explanation: ***Obturator***
- The **obturator nerve** innervates the **adductor muscles** of the thigh (adductor longus, brevis, magnus, gracilis, and obturator externus).
- **Overactivity** of these muscles leads to thigh adduction, causing the characteristic **"scissoring" gait** seen in some patients with cerebral palsy.
*Nerve to the iliopsoas*
- The **iliopsoas muscle** is a primary **hip flexor**, important for activities like sitting and standing.
- While involvement of hip flexors can cause contractures, it would manifest as difficulty extending the hip, not a scissoring deformity.
*Sciatic nerve*
- The **sciatic nerve** innervates the **hamstring muscles** (semitendinosus, semimembranosus, biceps femoris) and most muscles of the leg and foot.
- Its overactivity or spasticity would primarily affect knee flexion and foot movements, not hip adduction or scissoring.
*Femoral nerve*
- The **femoral nerve** innervates the **quadriceps femoris muscles** (rectus femoris, vastus lateralis, medialis, intermedius) and the sartorius.
- Overactivity would lead to strong knee extension and hip flexion, not the adducted and scissored leg position described.
*Superior gluteal nerve*
- The **superior gluteal nerve** innervates the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae** muscles, which are primarily hip abductors and internal rotators.
- Overactivity of these muscles would cause hip abduction, which is the opposite of the scissoring deformity.
