A 16-year-old boy presents to the emergency room with severe right shoulder pain following a painful overhead swing during a competitive volleyball match. On physical examination, the patient has limited active range of motion of the right shoulder and significant pain with passive motion. Suspecting a rotator cuff injury, the physician obtains an MRI, which indicates a minor tear in the tendon of the rotator cuff muscle that is innervated by the axillary nerve. Which of the following muscles was affected?
Q42
A 35-year-old man is brought to the trauma bay by ambulance after sustaining a gunshot wound to the right arm. The patient is in excruciating pain and states that he can't move or feel his hand. The patient states that he has no other medical conditions. On exam, the patient's temperature is 98.4°F (36.9°C), blood pressure is 140/86 mmHg, pulse is 112/min, and respirations are 14/min. The patient is alert and his Glasgow coma scale is 15. On exam, he has a single wound on his right forearm without continued bleeding. The patient has preserved motor and sensation in his right elbow; however, he is unable to extend his wrist or extend his fingers further. He is able to clench his hand, but this is limited by pain. On sensory exam, the patient has no sensation to the first dorsal web space but has preserved sensation on most of the volar surface. Which of the following structures is most likely injured?
Q43
A 27-year-old female ultramarathon runner presents to the physician with complaints of persistent knee pain. She describes the pain to be located in the anterior area of her knee and is most aggravated when she performs steep descents down mountains, though the pain is present with running on flat roads, walking up and down stairs, and squatting. Which of the following would most likely be an additional finding in this patient’s physical examination?
Q44
A 57-year-old man presents to the ED complaining of back and left leg pain. He was lifting heavy furniture while helping his daughter move into college when all of sudden he felt a sharp pain at his back. The pain is described as severe, worse with movement, and shoots down his lateral thigh. The patient denies any bowel/urinary incontinence, saddle anesthesia, weight loss, or weakness. He denies any past medical history but endorses a family history of osteoporosis. He has been smoking 1 pack per day for the past 20 years. Physical examination demonstrated decreased sensation at the left knee, decreased patellar reflex, and a positive straight leg test. There is diffuse tenderness to palpation at the lower back but no vertebral step-offs were detected. What is the most likely etiology for this patient’s pain?
Q45
A 46-year-old man is brought to the emergency department for the onset of severe pain in his right knee that occurred when he tripped while descending a staircase. As he landed, he heard and felt an immediate popping sensation in his right knee. His medical history is positive for obesity, hypertension, type 2 diabetes mellitus, severe asthma, and hyperlipidemia. He currently takes lisinopril, hydrochlorothiazide, metformin, atorvastatin, an albuterol inhaler, and a fluticasone inhaler. He recently completed a hospitalization and week-long regimen of systemic corticosteroids for a severe exacerbation of his asthma. The patient's family history is not significant. In the emergency department, his vital signs are normal. On physical examination, his right knee is warm and swollen and he rates the pain as 9/10. He cannot stand or walk due to pain. He is unable to extend his right knee. A knee X-ray is ordered. Which of the following would best describe the cause of this presenting condition?
Q46
An 80-year-old woman is brought to the emergency department for left hip pain 30 minutes after she fell while walking around in her room. Examination shows left groin tenderness. The range of motion of the left hip is limited because of pain. An x-ray of the hip shows a linear fracture of the left femoral neck with slight posterior displacement of the femur. Which of the following arteries was most likely damaged in the patient's fall?
Q47
A 32-year-old man comes to the physician because of a 1-month history of intermittent tingling of his hand. He is an avid cyclist and has recently started training for a cycle marathon. Physical examination shows decreased grip strength in the right hand and wasting of the hypothenar eminence. On asking the patient to grasp a piece of paper between his right thumb and right index finger in the first web space, there is hyperflexion of the right thumb interphalangeal joint. Which of the following additional findings is most likely in this patient?
Q48
A 43-year-old woman comes to the physician because of tingling and weakness in her left arm for the past 2 days. An image of the brachial plexus is shown. Nerve conduction study shows decreased transmission of electrical impulses in the labeled structure. Physical examination is most likely to show impairment of which of the following movements?
Q49
A 40-year-old male presents to the physician's office complaining of an inability to push doors open. He has had this problem since he was playing football with his children and was tackled underneath his right arm on his lateral chest. On examination, he has a winged scapula on the right side. Which of the following nerves is most likely the cause of this presentation?
Q50
A 30-year-old man presents with weakness in his right hand. He says he has been an avid cyclist since the age of 20. He denies any recent trauma. Physical examination reveals decreased sensations over the 4th and 5th digits with difficulty extending the 4th and 5th digits. Strength is 4 out of 5 in the extensor muscles of the right hand and wrist. When the patient is asked to extend his fingers, the result is shown in the image. Which of the following nerves is most likely damaged in this patient?
Upper/Lower Limb US Medical PG Practice Questions and MCQs
Question 41: A 16-year-old boy presents to the emergency room with severe right shoulder pain following a painful overhead swing during a competitive volleyball match. On physical examination, the patient has limited active range of motion of the right shoulder and significant pain with passive motion. Suspecting a rotator cuff injury, the physician obtains an MRI, which indicates a minor tear in the tendon of the rotator cuff muscle that is innervated by the axillary nerve. Which of the following muscles was affected?
A. Teres major
B. Supraspinatus
C. Teres minor (Correct Answer)
D. Infraspinatus
E. Subscapularis
Explanation: ***Correct: Teres minor***
- **Teres minor** is the only rotator cuff muscle innervated by the **axillary nerve** (C5-C6)
- Functions as an **external rotator** of the shoulder and stabilizes the humeral head
- The axillary nerve courses through the **quadrangular space** (bordered by teres minor superiorly, teres major inferiorly, long head of triceps medially, and surgical neck of humerus laterally)
- Injury to this muscle can occur with overhead activities, though less commonly injured than supraspinatus
*Incorrect: Supraspinatus*
- Innervated by the **suprascapular nerve** (C5-C6), not the axillary nerve
- Most commonly injured rotator cuff muscle, particularly with overhead activities
- Functions primarily in **abduction** (initiates first 15° of abduction)
*Incorrect: Infraspinatus*
- Innervated by the **suprascapular nerve** (C5-C6), not the axillary nerve
- Functions as the primary **external rotator** of the shoulder
- Second most commonly injured rotator cuff muscle
*Incorrect: Subscapularis*
- Innervated by the **upper and lower subscapular nerves** (C5-C7), not the axillary nerve
- Only rotator cuff muscle on the **anterior** surface of the scapula
- Functions as an **internal rotator** of the shoulder
*Incorrect: Teres major*
- **NOT part of the rotator cuff** (forms part of the posterior axillary fold)
- Innervated by the **lower subscapular nerve** (C5-C7), not the axillary nerve
- Functions as an **internal rotator, adductor, and extensor** of the shoulder
Question 42: A 35-year-old man is brought to the trauma bay by ambulance after sustaining a gunshot wound to the right arm. The patient is in excruciating pain and states that he can't move or feel his hand. The patient states that he has no other medical conditions. On exam, the patient's temperature is 98.4°F (36.9°C), blood pressure is 140/86 mmHg, pulse is 112/min, and respirations are 14/min. The patient is alert and his Glasgow coma scale is 15. On exam, he has a single wound on his right forearm without continued bleeding. The patient has preserved motor and sensation in his right elbow; however, he is unable to extend his wrist or extend his fingers further. He is able to clench his hand, but this is limited by pain. On sensory exam, the patient has no sensation to the first dorsal web space but has preserved sensation on most of the volar surface. Which of the following structures is most likely injured?
A. Recurrent motor branch of the median nerve
B. Main median nerve
C. Lower trunk
D. Ulnar nerve
E. Radial nerve (Correct Answer)
Explanation: ***Radial nerve***
- The inability to **extend the wrist and fingers** (wrist drop) is a classic sign of **radial nerve injury**, as it innervates the extensors of the forearm and hand.
- **Loss of sensation in the first dorsal web space** is also characteristic of radial nerve damage, as this area is supplied by the superficial radial nerve.
*Recurrent motor branch of the median nerve*
- This nerve primarily innervates the **thenar muscles** (flexor pollicis brevis, abductor pollicis brevis, opponens pollicis), affecting **thumb opposition**.
- Injury would primarily lead to **weakness in thumb movements**, not wrist or finger extension, and would spare sensation in the first dorsal web space.
*Main median nerve*
- The median nerve primarily innervates the **flexors of the forearm and hand**, and contributes to sensation on the **volar aspect of the thumb**, index, middle, and radial half of the ring finger.
- Injury would cause difficulty with **flexion of the wrist and fingers**, and loss of sensation on the volar surface, which is largely preserved in this patient.
*Lower trunk*
- The lower trunk of the brachial plexus (C8-T1) gives rise to the ulnar nerve and part of the median nerve, affecting **flexion of the wrist and fingers**, and intrinsic hand muscles.
- Injury would result in more widespread weakness affecting the **intrinsic hand muscles** and flexion, and would include sensory loss in the **ulnar nerve distribution**, which is not described.
*Ulnar nerve*
- The ulnar nerve primarily innervates the **intrinsic hand muscles** (excluding the thenar group) and the **flexor carpi ulnaris** and **medial half of flexor digitorum profundus**.
- Injury would typically cause **weakness in intrinsic hand functions** (e.g., finger abduction/adduction, ring and little finger flexion) and sensory loss on the **ulnar side of the hand**, not the dorsal web space.
Question 43: A 27-year-old female ultramarathon runner presents to the physician with complaints of persistent knee pain. She describes the pain to be located in the anterior area of her knee and is most aggravated when she performs steep descents down mountains, though the pain is present with running on flat roads, walking up and down stairs, and squatting. Which of the following would most likely be an additional finding in this patient’s physical examination?
A. Pain upon pressure placed on the lateral aspect of the knee
B. Pain upon pressure placed on the medial aspect of the knee
C. Pain upon compression of the patella while the patient performs flexion and extension of the leg (Correct Answer)
D. Excessive posterior displacement of the tibia
E. Excessive anterior displacement of the tibia
Explanation: ***Pain upon compression of the patella while the patient performs flexion and extension of the leg***
- The patient's symptoms (anterior knee pain aggravated by activity, especially descents, stairs, and squatting) are classic for **patellofemoral pain syndrome (runner's knee)**.
- The **patellofemoral grind test** (compressing the patella during knee flexion and extension) is a specific diagnostic maneuver that reproduces this pain in affected individuals.
*Pain upon pressure placed on the lateral aspect of the knee*
- This finding is more characteristic of conditions like **iliotibial band syndrome** or **lateral meniscus injury**, which typically present with lateral knee pain.
- The patient describes general anterior knee pain, not specifically lateral pain.
*Pain upon pressure placed on the medial aspect of the knee*
- This suggests conditions such as **medial collateral ligament (MCL) injury**, **pes anserine bursitis**, or **medial meniscus injury**.
- These conditions typically present with medial knee pain, which does not match the patient's anterior knee pain.
*Excessive posterior displacement of the tibia*
- This indicates **posterior cruciate ligament (PCL) insufficiency**, which is assessed by the posterior drawer test or sag sign.
- PCL injuries typically result from direct trauma to the anterior tibia or hyperflexion, and pain is often localized posteriorly or deep within the knee, not specifically anteriorly aggravated by the described activities.
*Excessive anterior displacement of the tibia*
- This finding is indicative of an **anterior cruciate ligament (ACL) rupture**, assessed by the Lachman test or anterior drawer test.
- ACL injuries usually result from a twisting injury or hyperextension and often present with acute swelling, instability, and giving way, which are not the primary complaints of this patient with chronic, activity-related anterior knee pain.
Question 44: A 57-year-old man presents to the ED complaining of back and left leg pain. He was lifting heavy furniture while helping his daughter move into college when all of sudden he felt a sharp pain at his back. The pain is described as severe, worse with movement, and shoots down his lateral thigh. The patient denies any bowel/urinary incontinence, saddle anesthesia, weight loss, or weakness. He denies any past medical history but endorses a family history of osteoporosis. He has been smoking 1 pack per day for the past 20 years. Physical examination demonstrated decreased sensation at the left knee, decreased patellar reflex, and a positive straight leg test. There is diffuse tenderness to palpation at the lower back but no vertebral step-offs were detected. What is the most likely etiology for this patient’s pain?
A. Vertebral compression fracture
B. Disc herniation at the L4/L5 vertebra
C. Spinal metastasis from lung cancer
D. Disc herniation at the L3/L4 vertebra (Correct Answer)
E. Lumbar muscle sprain
Explanation: ***Disc herniation at the L3/L4 vertebra***
- The patient's symptoms of **acute back pain radiating down the lateral thigh** after lifting, combined with **decreased sensation at the left knee** and a **decreased patellar reflex**, are classic signs of L3/L4 nerve root compression.
- A **positive straight leg test** also supports nerve root irritation, and the absence of red flag symptoms like incontinence or saddle anesthesia makes a simple disc herniation more likely than other serious conditions.
*Vertebral compression fracture*
- While lifting heavy objects can cause compression fractures, these usually present with more **severe, localized pain** that is not typically radiating with specific dermatomal or reflex changes.
- Absence of **vertebral step-offs** or significant predisposing factors for a fracture (e.g., severe osteoporosis, trauma) makes this less likely given the specific neurological findings.
*Disc herniation at the L4/L5 vertebra*
- An L4/L5 disc herniation would typically cause symptoms related to the **L5 nerve root**, such as pain radiating down the **lateral leg into the foot**, **weakness in dorsiflexion of the ankle** or **big toe**, and potentially a **decreased medial hamstring reflex**.
- The patient's reported symptoms (lateral thigh pain, decreased knee sensation, decreased patellar reflex) are more consistent with **L4 nerve root** involvement.
*Spinal metastasis from lung cancer*
- Although the patient has a **smoking history** and could be at risk for lung cancer, this diagnosis typically presents with more **insidious onset** of unexplained back pain, often with **weight loss**, and sometimes with more profound neurological deficits or bone pain not relieved by rest.
- The acute onset after an inciting event and specific neurological findings of a single nerve root are less suggestive of metastasis.
*Lumbar muscle sprain*
- A muscle sprain would typically present with **localized back pain**, often worsened by movement, but would **not involve radicular pain** shooting down the leg, nor would it cause specific **neurological deficits** like decreased sensation or reflex changes.
- The positive straight leg test and neurological findings rule out a simple muscle sprain.
Question 45: A 46-year-old man is brought to the emergency department for the onset of severe pain in his right knee that occurred when he tripped while descending a staircase. As he landed, he heard and felt an immediate popping sensation in his right knee. His medical history is positive for obesity, hypertension, type 2 diabetes mellitus, severe asthma, and hyperlipidemia. He currently takes lisinopril, hydrochlorothiazide, metformin, atorvastatin, an albuterol inhaler, and a fluticasone inhaler. He recently completed a hospitalization and week-long regimen of systemic corticosteroids for a severe exacerbation of his asthma. The patient's family history is not significant. In the emergency department, his vital signs are normal. On physical examination, his right knee is warm and swollen and he rates the pain as 9/10. He cannot stand or walk due to pain. He is unable to extend his right knee. A knee X-ray is ordered. Which of the following would best describe the cause of this presenting condition?
A. Quadriceps tendon tear (Correct Answer)
B. Meniscal tear
C. Avascular necrosis of the femur
D. Traction apophysitis of the tibia
E. Femoral fracture
Explanation: ***Quadriceps tendon tear***
- The patient's inability to **extend his right knee**, along with the history of a "pop" and severe pain after a fall, is highly indicative of a quadriceps tendon tear.
- The quadriceps tendon connects the quadriceps muscle group to the patella, and rupture results in loss of active knee extension—patients cannot perform a straight leg raise.
- Recent use of **systemic corticosteroids** can weaken tendons, predisposing individuals to such injuries, especially during a forceful eccentric contraction like catching oneself during a fall.
- Classic physical exam findings include a palpable **suprapatellar gap** and inability to extend the knee against gravity.
*Meniscal tear*
- While a meniscal tear can cause sudden knee pain and a popping sensation, it typically doesn't result in a complete inability to **extend the knee actively**.
- Patients with meniscal tears often present with mechanical symptoms like **locking, catching, or clicking**, which are not described here.
- Range of motion may be limited by pain or mechanical block, but the extensor mechanism remains intact.
*Avascular necrosis of the femur*
- This condition involves the death of bone tissue due to disrupted blood supply, often causing **gradual onset pain** that worsens with weight-bearing over weeks to months.
- Risk factors include chronic corticosteroid use, but it does not typically present with an acute "pop" and immediate functional loss after a traumatic event like a fall.
- Imaging would show collapse of the femoral head, not an acute soft tissue injury.
*Traction apophysitis of the tibia*
- Traction apophysitis (e.g., Osgood-Schlatter disease) is an **overuse injury** commonly seen in adolescents due to repetitive stress on the tibial tuberosity growth plate.
- It presents with gradual onset anterior knee pain and does not explain the acute onset of severe pain and inability to extend the knee in a 46-year-old man after a fall.
- This is a pediatric/adolescent condition, not seen in middle-aged adults with closed growth plates.
*Femoral fracture*
- A femoral fracture would cause severe pain and inability to bear weight, but the primary deficit would be the inability to move the entire leg due to bone instability and severe pain.
- The specific, isolated deficit in **active knee extension** with preservation of passive range of motion points to a disruption of the extensor mechanism (tendon injury) rather than a bone fracture.
- X-ray would show obvious fracture line in the femoral shaft or neck, which would be a more dramatic presentation.
Question 46: An 80-year-old woman is brought to the emergency department for left hip pain 30 minutes after she fell while walking around in her room. Examination shows left groin tenderness. The range of motion of the left hip is limited because of pain. An x-ray of the hip shows a linear fracture of the left femoral neck with slight posterior displacement of the femur. Which of the following arteries was most likely damaged in the patient's fall?
A. Superior gluteal artery
B. Deep circumflex iliac
C. Deep femoral artery
D. Obturator
E. Medial circumflex femoral (Correct Answer)
Explanation: ***Medial circumflex femoral***
- This artery is the **primary blood supply** to the femoral head and neck, making it highly vulnerable to injury in cases of femoral neck fractures.
- Damage to the medial circumflex femoral artery significantly increases the risk of **avascular necrosis** of the femoral head.
*Superior gluteal artery*
- The superior gluteal artery primarily supplies the **gluteus medius** and **minimus muscles**.
- It is **not directly involved** in the primary blood supply to the femoral head and neck.
*Deep circumflex iliac*
- This artery mainly supplies the **iliac fossa** and the **abdominal wall muscles**.
- It does not contribute significantly to the blood supply of the femoral neck.
*Deep femoral artery*
- The deep femoral artery, also known as the **profunda femoris artery**, is the main supply to the **thigh muscles**.
- While it gives rise to the circumflex arteries, it is not the artery directly compromised in a femoral neck fracture.
*Obturator*
- The obturator artery primarily supplies the **adductor muscles** of the thigh and contributes a small branch to the femoral head via the **ligamentum teres**.
- This contribution is **insufficient** to maintain viability of the femoral head, especially in trauma to the femoral neck.
Question 47: A 32-year-old man comes to the physician because of a 1-month history of intermittent tingling of his hand. He is an avid cyclist and has recently started training for a cycle marathon. Physical examination shows decreased grip strength in the right hand and wasting of the hypothenar eminence. On asking the patient to grasp a piece of paper between his right thumb and right index finger in the first web space, there is hyperflexion of the right thumb interphalangeal joint. Which of the following additional findings is most likely in this patient?
A. Loss of sensation over the dorsum of the medial half of the hand
B. Inability to extend the ring finger at the metacarpophalangeal joint
C. Inability to flex the index finger at the interphalangeal joints
D. Loss of sensation over the palmar aspect of the middle finger
E. Inability to extend the little finger at the proximal interphalangeal joints (Correct Answer)
Explanation: ***Inability to extend the little finger at the proximal interphalangeal joints***
- The patient's symptoms (tingling, decreased grip strength, hypothenar eminence wasting, and **Froment's sign**) indicate **ulnar nerve compression at Guyon's canal** (handlebar palsy) from cycling.
- The ulnar nerve innervates the **3rd and 4th lumbricals** (medial two), which extend the PIP and DIP joints of the ring and little fingers.
- The ulnar nerve also innervates the **interossei muscles**, which assist in MCP flexion and IP extension.
- Loss of these intrinsic muscles results in **claw hand deformity** affecting the 4th and 5th digits, with hyperextension at MCP joints and flexion (inability to extend) at PIP and DIP joints.
- This is a classic finding in ulnar nerve palsy.
*Inability to extend the ring finger at the metacarpophalangeal joint*
- Extension at the MCP joint is primarily performed by the **extensor digitorum** (innervated by the **radial nerve**).
- The patient's findings indicate ulnar nerve compression, not radial nerve injury.
- In ulnar nerve palsy, the unopposed extensor digitorum actually causes MCP **hyperextension**, not inability to extend.
*Inability to flex the index finger at the interphalangeal joints*
- Flexion of the index finger IP joints is controlled by **flexor digitorum superficialis** (FDS) and **flexor digitorum profundus** (FDP).
- Both muscles to the index finger are innervated by the **median nerve**, not the ulnar nerve.
- This finding would indicate median nerve injury (e.g., carpal tunnel syndrome or anterior interosseous syndrome).
*Loss of sensation over the palmar aspect of the middle finger*
- Palmar sensation of the middle finger is supplied by the **median nerve**.
- The ulnar nerve supplies sensation to the medial 1.5 digits (little finger and medial half of ring finger).
- This finding would indicate median nerve pathology, not ulnar nerve compression.
*Loss of sensation over the dorsum of the medial half of the hand*
- The **dorsal cutaneous branch of the ulnar nerve** branches approximately 5-8 cm proximal to the wrist and passes **superficially**, NOT through Guyon's canal.
- In **Guyon's canal compression** (handlebar palsy), the dorsal cutaneous branch is **SPARED**, so dorsal sensation remains intact.
- The patient would have palmar sensory loss over the medial 1.5 digits but **preserved dorsal sensation**.
- Loss of dorsal sensation would suggest a more proximal ulnar nerve lesion (at the elbow or forearm), not at the wrist.
Question 48: A 43-year-old woman comes to the physician because of tingling and weakness in her left arm for the past 2 days. An image of the brachial plexus is shown. Nerve conduction study shows decreased transmission of electrical impulses in the labeled structure. Physical examination is most likely to show impairment of which of the following movements?
A. Opposition of the thumb
B. Flexion of the forearm
C. Abduction of the shoulder above 100 degrees
D. Extension of the wrist and fingers (Correct Answer)
E. Flexion of the metacarpophalangeal joints
Explanation: ***Extension of the wrist and fingers***
- The image and description indicate the injury affects the **posterior cord** of the brachial plexus, which gives rise to the **radial nerve**.
- The **radial nerve** innervates the muscles responsible for **extension of the wrist and fingers**, so damage to its parent cord would impair these movements.
*Opposition of the thumb*
- **Opposition of the thumb** is primarily mediated by the **median nerve**, which arises from the lateral and medial cords, not the posterior cord.
- Damage to the posterior cord due to injury would not affect this movement directly.
*Flexion of the forearm*
- **Flexion of the forearm** is primarily controlled by the **musculocutaneous nerve** and a portion by the **median nerve**.
- Both of these nerves originate from the lateral and medial cords, not the posterior cord, making impairment unlikely with posterior cord injury.
*Abduction of the shoulder above 100 degrees*
- **Abduction of the shoulder above 100 degrees** primarily requires **scapular rotation** mediated by the **trapezius muscle** (accessory nerve) and **serratus anterior** (long thoracic nerve).
- While the **axillary nerve** (from the posterior cord) innervates the **deltoid** for initial shoulder abduction, the question stem emphasizes **wrist and finger symptoms**, suggesting the labeled structure is specifically the **radial nerve** branch rather than the axillary nerve branch.
- This makes extension deficits more likely than shoulder abduction impairment.
*Flexion of the metacarpophalangeal joints*
- **Flexion of the metacarpophalangeal joints** is predominantly carried out by the **lumbricals and interossei muscles**, which are primarily innervated by the **ulnar nerve** and partially by the **median nerve**.
- These nerves originate from the medial and lateral cords, not the posterior cord, making impairment unlikely.
Question 49: A 40-year-old male presents to the physician's office complaining of an inability to push doors open. He has had this problem since he was playing football with his children and was tackled underneath his right arm on his lateral chest. On examination, he has a winged scapula on the right side. Which of the following nerves is most likely the cause of this presentation?
A. Phrenic nerve
B. Spinal accessory nerve
C. Long thoracic nerve (Correct Answer)
D. Greater auricular nerve
E. Musculocutaneous nerve
Explanation: ***Long thoracic nerve***
- The **long thoracic nerve** innervates the **serratus anterior muscle**, which is responsible for scapular protraction and upward rotation.
- Damage to this nerve, often from trauma to the lateral chest wall (tackled underneath the arm), leads to paralysis of the serratus anterior and a characteristic **winged scapula** with lateral and inferior prominence.
- Patients have difficulty with **pushing movements** (protraction) and overhead activities.
*Phrenic nerve*
- The **phrenic nerve** primarily innervates the **diaphragm** and is crucial for respiration.
- Damage to the phrenic nerve would cause respiratory compromise, not a winged scapula or difficulty pushing doors.
*Spinal accessory nerve*
- The **spinal accessory nerve (cranial nerve XI)** innervates the **sternocleidomastoid** and **trapezius muscles**.
- Injury to this nerve can cause scapular winging due to **trapezius paralysis**, but the winging is typically **medial** with the inferior angle moving medially, unlike the lateral winging from serratus anterior paralysis.
- The mechanism of injury (lateral chest trauma during tackling) and inability to push are classic for **long thoracic nerve** injury, not spinal accessory nerve.
*Greater auricular nerve*
- The **greater auricular nerve** is a cutaneous nerve that provides sensation to the skin over the parotid gland, mastoid process, and auricle.
- Damage to this nerve would result in sensory loss in these areas and is unrelated to muscle weakness or a winged scapula.
*Musculocutaneous nerve*
- The **musculocutaneous nerve** innervates the **biceps brachii**, **brachialis**, and **coracobrachialis muscles**, responsible for elbow flexion and forearm supination.
- Damage to this nerve would primarily affect these movements and sensation in the lateral forearm, not leading to a winged scapula.
Question 50: A 30-year-old man presents with weakness in his right hand. He says he has been an avid cyclist since the age of 20. He denies any recent trauma. Physical examination reveals decreased sensations over the 4th and 5th digits with difficulty extending the 4th and 5th digits. Strength is 4 out of 5 in the extensor muscles of the right hand and wrist. When the patient is asked to extend his fingers, the result is shown in the image. Which of the following nerves is most likely damaged in this patient?
A. Median nerve
B. Musculocutaneous nerve
C. Axillary nerve
D. Ulnar nerve (Correct Answer)
E. Radial nerve
Explanation: ***Ulnar nerve***
- The symptoms, including weakness in the **right hand**, decreased sensation over the **4th and 5th digits**, and difficulty extending the 4th and 5th digits (which suggests **ulnar claw**), are characteristic of **ulnar nerve damage**.
- **Avid cycling** can lead to compression of the ulnar nerve in the **Guyon's canal** (handlebar palsy) or at the **cubital tunnel** in the elbow, causing these specific signs.
*Median nerve*
- Damage to the median nerve typically affects the **thumb**, **index**, **middle finger**, and radial half of the ring finger, causing **ape hand deformity** or **carpal tunnel syndrome**.
- It controls movements like **thumb opposition** and **flexion of the first three digits**, which are not primarily described as impaired here.
*Musculocutaneous nerve*
- This nerve primarily innervates the **biceps brachii**, **brachialis**, and **coracobrachialis muscles**, affecting **elbow flexion** and **forearm supination**.
- It provides sensory innervation to the **lateral forearm**, symptoms not consistent with this patient's presentation.
*Axillary nerve*
- Damage to the axillary nerve results in weakness of the **deltoid** and **teres minor muscles**, leading to impaired **shoulder abduction** and external rotation.
- Sensory loss would be over the **lateral aspect of the shoulder**, which is unrelated to the described hand symptoms.
*Radial nerve*
- Radial nerve damage typically results in **wrist drop** and impaired **extension of the fingers and thumb** due to innervation of the extensors.
- While there is difficulty extending the 4th and 5th digits, the sensory loss pattern (4th and 5th digits) and specific **ulnar claw** appearance are more indicative of ulnar nerve involvement.
