Autonomic nervous system anatomy US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Autonomic nervous system anatomy. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Autonomic nervous system anatomy US Medical PG Question 1: A 68-year-old man comes to the physician because of double vision and unilateral right eye pain that began this morning. His vision improves when he covers either eye. He has hypertension, mild cognitive impairment, and type 2 diabetes mellitus. The patient has smoked two packs of cigarettes daily for 40 years. His current medications include lisinopril, donepezil, metformin, and insulin with meals. His temperature is 37°C (98.6°F), pulse is 85/minute, respirations are 12/minute, and blood pressure is 132/75 mm Hg. His right eye is abducted and depressed with slight intorsion. He can only minimally adduct the right eye. Visual acuity is 20/20 in both eyes. Extraocular movements of the left eye are normal. An MRI of the head shows no abnormalities. His fingerstick blood glucose concentration is 325 mg/dL. Further evaluation is most likely to show which of the following?
- A. Ptosis (Correct Answer)
- B. Dilated and fixed pupil
- C. Bitemporal hemianopsia
- D. Miosis and anhidrosis
- E. Positive swinging-flashlight test
Autonomic nervous system anatomy Explanation: ***Ptosis***
- The patient's presentation of an **abducted and depressed right eye with minimal adduction** is highly suggestive of an **ischemic (diabetic) third nerve palsy**.
- Ischemic third nerve palsies characteristically **spare the pupillary fibers** (pupil remains normal in size and reactive) but affect the **somatomotor fibers** that innervate the extraocular muscles and the **levator palpebrae superioris**, leading to **ptosis**.
- The key clinical feature distinguishing ischemic from compressive CN III palsy is **pupil-sparing**, which is present in this case.
*Dilated and fixed pupil*
- A dilated and fixed pupil would indicate **compression of the oculomotor nerve**, often by an aneurysm (e.g., posterior communicating artery aneurysm).
- Compressive lesions affect the superficial **pupillomotor fibers** first, while ischemic third nerve palsies, as seen in patients with **diabetes**, typically affect the inner somatomotor fibers while **sparing the pupil**.
*Bitemporal hemianopsia*
- This visual field defect is characteristic of **optic chiasm compression**, commonly caused by a **pituitary adenoma**.
- This patient's symptoms are localized to a single eye and involve extraocular muscle dysfunction, not visual field loss.
*Miosis and anhidrosis*
- **Miosis** (constricted pupil) and **anhidrosis** (decreased sweating) on one side of the face, accompanied by **ptosis**, are classic signs of **Horner syndrome**.
- Horner syndrome results from a lesion in the **sympathetic pathway**, which is inconsistent with the extraocular muscle deficits observed in this patient.
*Positive swinging-flashlight test*
- A positive swinging-flashlight test (Marcus Gunn pupil) indicates an **afferent pupillary defect**, often seen in conditions affecting the **optic nerve** (e.g., optic neuritis, severe retinal disease).
- This patient's symptoms point to a **cranial nerve III palsy**, which affects efferent ocular movements and typically does not cause an afferent pupillary defect.
Autonomic nervous system anatomy US Medical PG Question 2: A 65-year-old male with a history of CHF presents to the emergency room with shortness of breath, lower leg edema, and fatigue. He is diagnosed with acute decompensated congestive heart failure, was admitted to the CCU, and treated with a medication that targets beta-1 adrenergic receptors preferentially over beta-2 adrenergic receptors. The prescribing physician explained that this medication would only be used temporarily as its efficacy decreases within 2-3 days due to receptor downregulation. Which of the following was prescribed?
- A. Epinephrine
- B. Norepinephrine
- C. Milrinone
- D. Isoproterenol
- E. Dobutamine (Correct Answer)
Autonomic nervous system anatomy Explanation: ***Dobutamine***
- **Dobutamine** is a beta-1 adrenergic agonist preferentially acting on beta-1 receptors in the heart, increasing contractility and heart rate during acute decompensated heart failure.
- Its efficacy reduces over time due to **receptor downregulation**, making it effective for only short-term use, typically less than 72 hours.
*Epinephrine*
- **Epinephrine** is a non-selective adrenergic agonist acting on both alpha and beta receptors, causing vasoconstriction and bronchodilation in addition to cardiac stimulation.
- It is typically used in emergency situations like **cardiac arrest** and **anaphylaxis**, not primarily for acute CHF exacerbation in this manner.
*Norepinephrine*
- **Norepinephrine** primarily acts on alpha-1 adrenergic receptors, causing significant vasoconstriction, and has some beta-1 agonistic effects.
- It is mainly used as a **vasopressor** in septic shock or severe hypotension to increase systemic vascular resistance, rather than directly improving cardiac output in decompensated CHF.
*Milrinone*
- **Milrinone** is a phosphodiesterase-3 inhibitor, increasing intracellular cAMP levels and leading to positive inotropy and vasodilation.
- While used in acute heart failure, its mechanism is distinct from adrenergic agonists, and its efficacy is not limited by a rapid receptor downregulation mechanism as described.
*Isoproterenol*
- **Isoproterenol** is a non-selective beta-adrenergic agonist, stimulating both beta-1 and beta-2 receptors, leading to increased heart rate and contractility, as well as bronchodilation and vasodilation.
- Due to its strong chronotropic effects and potential for severe arrhythmias and hypotension, it is rarely used in CHF and is primarily reserved for conditions like **bradycardia** or **torsades de pointes**.
Autonomic nervous system anatomy US Medical PG Question 3: A 72-year-old woman is brought in to the emergency department after her husband noticed that she appeared to be choking on her dinner. He performed a Heimlich maneuver but was concerned that she may have aspirated something. The patient reports a lack of pain and temperature on the right half of her face, as well as the same lack of sensation on the left side of her body. She also states that she has been feeling "unsteady" on her feet. On physical exam you note a slight ptosis on the right side. She is sent for an emergent head CT. Where is the most likely location of the neurological lesion?
- A. Pons
- B. Internal capsule
- C. Cervical spinal cord
- D. Medulla (Correct Answer)
- E. Midbrain
Autonomic nervous system anatomy Explanation: ***Medulla***
- This presentation describes **Wallenberg syndrome** (lateral medullary syndrome), characterized by **ipsilateral facial sensory loss**, **contralateral body sensory loss**, and **ataxia** due to involvement of the spinothalamic tracts, trigeminal nucleus, and cerebellar pathways.
- **Dysphagia** (choking) and **Horner's syndrome** (ptosis, miosis, anhidrosis) are also classic signs, specifically the ptosis seen here, pointing to an infarct in the **lateral medulla**.
*Pons*
- Lesions in the pons typically present with varying degrees of **cranial nerve deficits** (e.g., trigeminal, abducens, facial) and **motor or sensory deficits** affecting both sides of the body due to the decussation of tracts.
- The specific combination of **crossed sensory loss** and other symptoms seen here is not characteristic of isolated pontine lesions.
*Internal capsule*
- A lesion in the internal capsule would primarily cause **contralateral motor weakness (hemiparesis)** and **sensory loss** affecting both the face and body on the same side, without the ipsilateral facial involvement.
- It would not explain the **ataxia** or specific cranial nerve signs like ptosis.
*Cervical spinal cord*
- Spinal cord lesions result in **sensory and motor deficits below the level of the lesion**, affecting both sides of the body symmetrically, or ipsilaterally depending on the tract involved.
- They do not cause **facial sensory disturbances**, **dysphagia**, or **ataxia** in the manner described.
*Midbrain*
- Midbrain lesions typically involve the **oculomotor nerve** (CN III), causing eye movement abnormalities, and can result in **contralateral hemiparesis**.
- They do not produce the **crossed sensory deficits** (ipsilateral face, contralateral body) or **ataxia** characteristic of this case.
Autonomic nervous system anatomy US Medical PG Question 4: A 29-year-old man presents to his primary care provider complaining of not being able to get enough rest at night. He goes to bed early enough and has otherwise good sleep hygiene but feels drained the next day. He feels he is unable to perform optimally at work, but he is still a valued employee and able to complete his share of the work. About a month ago his wife of 5 years asked for a divorce and quickly moved out. He has cut out coffee after 12 pm and stopped drinking alcohol. He also exercises 3 days per week. Today, his blood pressure is 120/80 mm Hg, heart rate is 95/min, respiratory rate is 25/min, and temperature is 37.0°C (98.6°F ). On physical exam, his heart has a regular rate and rhythm and his lungs are clear to auscultation bilaterally. A CMP, CBC, and thyroid test are negative. Which of the following statements best describes this patient’s condition?
- A. Symptoms are usually self-limited and may persist for 2 years
- B. Symptoms typically resolve within 6 months after the stressor ends (Correct Answer)
- C. Symptoms develop within 3 months of the stressor
- D. Symptoms may be persistent if the stressor is chronic
- E. Symptoms represent a maladaptive response to an identifiable stressor
Autonomic nervous system anatomy Explanation: ***Symptoms typically resolve within 6 months after the stressor ends***
- This statement accurately describes the **temporal criterion for adjustment disorder** according to DSM-5. Once the stressor or its consequences have terminated, symptoms should resolve within 6 months.
- This patient experienced a clear stressor (divorce and wife moving out ~1 month ago) and developed symptoms in response. The diagnosis of adjustment disorder requires that these symptoms resolve within 6 months of the stressor's termination.
- His symptoms (poor sleep, feeling drained, suboptimal performance) represent a significant but not incapacitating response, consistent with adjustment disorder. Normal labs rule out medical causes.
- This temporal criterion distinguishes adjustment disorder from more chronic conditions and helps guide prognosis and treatment planning.
*Symptoms are usually self-limited and may persist for 2 years*
- Adjustment disorder symptoms should resolve within **6 months**, not 2 years, after the stressor or its consequences have ended.
- If symptoms persist beyond 6 months, this suggests either ongoing stressor consequences, a persistent subtype (for chronic stressors), or an alternative diagnosis should be considered.
*Symptoms develop within 3 months of the stressor*
- While this is a **correct diagnostic criterion** (symptoms must develop within 3 months of stressor onset), it only addresses timing of onset, not the complete picture.
- The question asks for the statement that "best describes" the condition, and the resolution timeline is more distinctive and prognostically important than onset timing alone.
*Symptoms may be persistent if the stressor is chronic*
- This describes the **persistent specifier** in DSM-5, which applies when the stressor or its consequences are ongoing (chronic stressor or enduring consequences).
- However, in this case, the stressor appears to be acute (wife moved out), not chronic, making this less applicable to the specific clinical scenario presented.
*Symptoms represent a maladaptive response to an identifiable stressor*
- This is a **core defining feature** of adjustment disorder - the development of emotional/behavioral symptoms in response to an identifiable stressor with marked distress or impairment.
- While accurate, this is a general characteristic shared across the definition and doesn't capture the specific **temporal criteria** (resolution within 6 months) that is most distinctive for adjustment disorder diagnosis and prognosis.
Autonomic nervous system anatomy US Medical PG Question 5: A 21-year-old man was involved in a motor vehicle accident and died. At autopsy, the patient demonstrated abnormally increased mobility at the neck. A section of cervical spinal cord at C6 was removed and processed into slides. Which of the following gross anatomic features is most likely true of this spinal cord level?
- A. Cuneate and gracilis fasciculi are present (Correct Answer)
- B. Least amount of white matter
- C. Prominent lateral horns
- D. Absence of gray matter enlargement
- E. Involvement with parasympathetic nervous system
Autonomic nervous system anatomy Explanation: **Cuneate and gracilis fasciculi are present**
- At the **C6 level** of the spinal cord, both the **fasciculus gracilis** (carrying information from the lower body) and the **fasciculus cuneatus** (carrying information from the upper body) are present in the dorsal column.
- The fasciculus cuneatus typically appears at **T6 and above**, making it visible at C6.
*Least amount of white matter*
- The cervical spinal cord, particularly at C6, contains a **significant amount of white matter** because it carries all ascending and descending tracts to and from the brain, including those for the upper and lower limbs.
- The **sacral segments** typically have the least amount of white matter due to fewer tracts remaining.
*Prominent lateral horns*
- **Lateral horns** are characteristic of the **thoracic and upper lumbar (T1-L2/L3)** spinal cord segments, where they house preganglionic sympathetic neurons.
- They are generally **absent or poorly developed** in the cervical spinal cord.
*Absence of gray matter enlargement*
- The **cervical enlargement** of the spinal cord, particularly pronounced from C4 to T1, contains an increased amount of gray matter to accommodate the innervation of the **upper limbs**.
- Therefore, the C6 level would show **significant gray matter enlargement**.
*Involvement with parasympathetic nervous system*
- The **parasympathetic nervous system** exits the spinal cord at the **sacral levels (S2-S4)** and as cranial nerves, not primarily from the cervical spinal cord through distinct horns.
- The cervical spinal cord is primarily associated with **somatic motor and sensory pathways** for the neck, shoulders, and upper limbs, and receives some sympathetic input, but is not where parasympathetic outflow predominantly originates.
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