Dermatomes and myotomes Practice Questions

Question 1

A 50-year-old man arrives to the clinic complaining of progressive weakness. He explains that for 3 months he has had difficulty climbing the stairs, which has now progressed to difficulty getting out of a chair. He denies diplopia, dysphagia, dyspnea, muscle aches, or joint pains. He denies weight loss, weight gain, change in appetite, or heat or cold intolerance. He reports intermittent low-grade fevers. He has a medical history significant for hypertension and hyperlipidemia. He has taken simvastatin and losartan daily for the past 6 years. His temperature is 99.0°F (37.2°C), blood pressure is 135/82 mmHg, and pulse is 76/min. Cardiopulmonary examination is normal. The abdomen is soft, non-tender, non-distended, and without hepatosplenomegaly. Muscle strength is 3/5 in the hip flexors and 4/5 in the deltoids, biceps, triceps, patellar, and Achilles tendon reflexes are 2+ and symmetric. Sensation to pain, light touch, and vibration are intact. Gait is cautious, but grossly normal. There is mild muscle tenderness of his thighs and upper extremities. There is no joint swelling or erythema and no skin rashes. A complete metabolic panel is within normal limits. Additional lab work is obtained as shown below:

Serum:
Na+: 141 mEq/L
Cl-: 100 mEq/L
K+: 4.3 mEq/L
HCO3-: 23 mEq/L
Urea nitrogen: 18 mg/dL
Glucose: 128 mg/dL
Creatinine: 1.0 mg/dL
Alkaline phosphatase: 69 U/L
Aspartate aminotransferase (AST): 302 U/L
Alanine aminotransferase (ALT): 210 U/L
TSH: 6.9 uU/mL
Thyroxine (T4): 5.8 ug/dL
Creatine kinase: 4300 U/L
C-reactive protein: 11.9 mg/L
Erythrocyte sedimentation rate: 37 mm/h

Which of the following is the most accurate diagnostic test?

Accepted Answer

Muscle biopsy

Answer

Statin cessation

Answer

Autoantibodies

Answer

Electromyography

Answer

Fine needle aspiration

Question 2

A 25-year-old man comes to the physician for severe back pain. He describes the pain as shooting and stabbing. On a 10-point scale, he rates the pain as a 9 to 10. The pain started after he lifted a heavy box at work; he works at a supermarket and recently switched from being a cashier to a storekeeper. The patient appears to be in severe distress. Vital signs are within normal limits. On physical examination, the spine is nontender without paravertebral muscle spasms. Range of motion is normal. A straight-leg raise test is negative. After the physical examination has been completed, the patient asks for a letter to his employer attesting to his inability to work as a storekeeper. Which of the following is the most appropriate response?

Accepted Answer

I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job.

Answer

“Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”

Answer

You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing.

Answer

The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional.

Answer

The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy.

Question 3

A 78-year-old woman is accompanied by her family for a routine visit to her primary care provider. The family states that 5 months prior, the patient had a stroke and is currently undergoing physical therapy. Today, her temperature is 98.2°F (36.8°C), blood pressure is 112/72 mmHg, pulse is 64/min, and respirations are 12/min. On exam, she is alert and oriented with no deficits in speech. Additionally, her strength and sensation are symmetric and preserved bilaterally. However, on further neurologic testing, she appears to have some difficulty with balance and a propensity to fall to her right side. Which of the following deficits does the patient also likely have?

Accepted Answer

Truncal ataxia

Answer

Hemiballismus

Answer

Hemispatial neglect

Answer

Intention tremor

Answer

Contralateral eye deviation

Question 4

A 41-year-old woman presents with back pain for the past 2 days. She says that the pain radiates down along the posterior right thigh and leg. She says the pain started suddenly after lifting a heavy box 2 days ago. Past medical history is irrelevant. Physical examination reveals a straight leg raise (SLR) test restricted to 30°, inability to walk on her toes, decreased sensation along the lateral border of her right foot, and diminished ankle jerk on the same side. Which of the following nerve roots is most likely compressed?

Accepted Answer

First sacral nerve root (S1)

Answer

Fourth lumbar nerve root (L4)

Answer

Second sacral nerve root (S2)

Answer

Third sacral nerve root (S3)

Answer

Fifth lumbar nerve root (L5)

Question 5

A 22-year-old man is rushed to the emergency department after a motor vehicle accident. The patient states that he feels weakness and numbness in both of his legs. He also reports pain in his lower back. His airway, breathing, and circulation is intact, and he is conversational. Neurologic exam is significant for bilateral lower extremity flaccid paralysis and impaired pain and temperature sensation up to T10-T11 with normal vibration sense. A computerized tomography scan of the spine is performed which shows a vertebral burst fracture of the vertebral body at the level of T11. Which of the following findings is most likely present in this patient?

Accepted Answer

Bowel incontinence

Answer

Intact vibration sense

Answer

Flaccid paralysis at the level of the lesion

Answer

Spasticity below the lesion

Answer

Impaired proprioception sense

Question 6

You are seeing an otherwise healthy 66-year-old male in clinic who is complaining of localized back pain and a new rash. On physical exam, his vital signs are within normal limits. You note a vesicular rash restricted to the upper left side of his back. In order to confirm your suspected diagnosis, you perform a diagnostic test. What would you expect to find on the diagnostic test that was performed?

Accepted Answer

Multinucleated giant cells

Answer

Gram negative bacilli

Answer

Branching pseudohyphae

Answer

Pear shaped motile cells

Answer

Gram positive cocci

Question 7

A 67-year-old man comes to the physician because of progressive burning pain and intermittent "electrical shocks" in his right chest for 3 months. Over the last 2 weeks, the pain has increased to an extent that he can no longer tolerate clothing on the affected area. Three months ago, he had a rash around his right nipple and axilla that resolved a week later. The patient had a myocardial infarction 2 years ago. He has smoked one pack of cigarettes daily for 47 years. Current medications include aspirin, simvastatin, metoprolol, and ramipril. His temperature is 36.9°C (97.9°F), pulse is 92/min, and blood pressure is 150/95 mm Hg. Examination shows increased sensation to light touch over the right chest. The remainder of the physical examination shows no abnormalities. Which of the following is the most appropriate next step in management?

Accepted Answer

Oral gabapentin

Answer

Sublingual nitrates

Answer

Oral famciclovir

Answer

Intrathecal glucocorticoids

Answer

Oral tricyclic antidepressants

Question 8

A 59-year-old woman presents to the emergency room with severe low back pain. She reports pain radiating down her left leg into her left foot. She also reports intermittent severe lower back spasms. The pain started after lifting multiple heavy boxes at her work as a grocery store clerk. She denies bowel or bladder dysfunction. Her past medical history is notable for osteoporosis and endometrial cancer. She underwent a hysterectomy 20 years earlier. She takes alendronate. Her temperature is 99°F (37.2°C), blood pressure is 135/85 mmHg, pulse is 85/min, and respirations are 22/min. Her BMI is 21 kg/m^2. On exam, she is unable to bend over due to pain. Her movements are slowed to prevent exacerbating her muscle spasms. A straight leg raise elicits severe radiating pain into her left lower extremity. The patient reports that the pain is worst along the posterior thigh and posterolateral leg into the fourth and fifth toes. Palpation along the lumbar vertebral spines demonstrates mild tenderness. Patellar reflexes are 2+ bilaterally. The Achilles reflex is decreased on the left. Which nerve root is most likely affected in this patient?

Accepted Answer

S1

Answer

L5

Answer

S2

Answer

L3

Answer

L4

Question 9

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?

Accepted Answer

Disc herniation at the L3/L4 vertebra

Answer

Vertebral compression fracture

Answer

Disc herniation at the L4/L5 vertebra

Answer

Spinal metastasis from lung cancer

Answer

Lumbar muscle sprain

Question 10

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?

Accepted Answer

Anterior compartment

Answer

Lateral compartment

Answer

Superficial posterior compartment

Answer

Deep posterior compartment

Answer

Medial compartment

Dermatomes and myotomes

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Embryological basis of dermatomes

Cervical dermatomes and myotomes

Thoracic dermatomes and myotomes

Lumbar dermatomes and myotomes

Sacral dermatomes and myotomes

Sensory testing of dermatomes

Motor testing of myotomes

Dermatome overlap and clinical implications

Segmental innervation patterns

Radiculopathy patterns by level

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