Neurology · MU Sofia

23. Autonomic nervous system: anatomy, physiology, clinical examination, autonomic-visceral sensation

Covers the division of the autonomic nervous system into sympathetic and parasympathetic parts, with their origins and main effects on organs, then physiological control of the cardiovascular, respiratory, gastrointestinal, genitourinary and thermoregulatory systems. Describes the clinical examination, including orthostatic testing with its blood pressure criteria, and autonomic syndromes such as Horner syndrome and autonomic failure. Ends with visceral sensation, visceral pain and referred pain, with a table of organs and their referral sites.

Inside: 6 sections · 1 labelled picture · 1 table · 14 flashcards · 2 min

Topic 23 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 6 sections, about 331 words (2 min of reading), with 14 flashcards.

In this note

  1. Autonomic nervous system - anatomy, physiology, clinical examiation.Autonomic-visceral sensation
  2. Autonomic Nervous System (ANS)
  3. Anatomy
  4. Physiology
  5. Clinical Examination of the ANS
  6. Autonomic Syndromes

Autonomic Nervous System (ANS)

The autonomic nervous system controls involuntary functions of internal organs, blood vessels, glands, smooth muscle, and cardiac muscle. It maintains homeostasis.

Divisions of the ANS

  • Sympathetic nervous system ("Fight or Flight")
  • Parasympathetic nervous system ("Rest and Digest")

Anatomy

1.Sympathetic Division

Origin: Thoracolumbar spinal cord (T1–L2)

Ganglia: Paravertebral sympathetic chain. Prevertebral ganglia

Main Effects

  • Pupil dilation (mydriasis)
  • Increased heart rate and blood pressure
  • Bronchodilation
  • Decreased gastrointestinal motility
  • Increased sweating

2.Parasympathetic Division

Origin

Craniosacral outflow: CN III, CN VII, CN IX, CN X, S2–S4 spinal segments

Main Effects

  • Pupil constriction (miosis)
  • Decreased heart rate
  • Increased gastrointestinal motility and secretion
  • Bladder emptying

Physiology

The ANS regulates:

  • Cardiovascular System: Heart rate. Blood pressure. Vascular tone
  • Respiratory System: Bronchial tone
  • Gastrointestinal System: Motility. Secretions
  • Genitourinary System: Micturition. Sexual function
  • Thermoregulation: Sweating. Skin blood flow
  • Eye: Pupil size. Accommodation

Clinical Examination of the ANS

1. Inspection

  • Observe: Skin color. Sweating. Trophic skin changes. Peripheral temperature

2. Pupillary Examination

  • Evaluate: Size. Symmetry. Light reflexes
  • Autonomic lesions may cause: Miosis. Mydriasis. Anisocoria

3. Cardiovascular Tests

  • Orthostatic (Postural) Test
  • Measure BP and pulse: Supine position. Standing position
  • Orthostatic Hypotension: Fall in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg after standing
  • Suggests autonomic dysfunction.

4. Sweating Assessment

  • Abnormalities: Hyperhidrosis (excess sweating). Anhidrosis (absence of sweating)

5. Bladder Function

  • Assess: Urinary retention. Urgency. Incontinence

6. Sexual Function

  • Assess: Erectile dysfunction.Ejaculatory disorders

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