Clinical medicineLesson 2 of 4 in the course The Neurological Exam

Cranial Nerve Examination: Sensory, Ocular, and Brainstem Tests

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces how the cranial nerve exam connects nerve functions to specific tests, with a focus on smell and vision.

The twelve cranial nerves serve the head and neck, with the vagus nerve also carrying autonomic functions to organs in the thoracic and upper abdominal cavities. Rather than relying only on memorizing nerve names, the exam groups nerves by what they do: carry sensory information, control movement, or provide parasympathetic output.

All flashcards

What is anosmia?
Anosmia is loss of the sense of smell. It may occur with aging or after trauma that damages olfactory fibers.
How is smell commonly screened?
Present a familiar odor, such as coffee or mint, to one nostril at a time and ask the patient to identify it.
What does a 20/60 Snellen result indicate?
At 20 feet, the patient can see letters that a person with typical acuity could see from 60 feet.
How is peripheral vision screened at the bedside?
The patient fixes their gaze forward while the examiner introduces fingers from the sides and asks when they become visible.
Why can optic-chiasm compression cause peripheral vision loss?
Fibers crossing at the chiasm originate from the medial retinae and carry information from the peripheral visual fields.

Quiz questions

  1. In unilateral conductive hearing loss, where may a Weber-test tone seem louder?Answer: In the affected ear.
  2. Which nerves provide the sensory and motor limbs of the gag reflex, respectively?Answer: CN IX and CN X.
  3. Which cranial nerve activates the lateral rectus muscle to abduct the eye?Answer: CN VI.
  4. When unilateral hypoglossal weakness causes tongue deviation on protrusion, in which direction does the tongue deviate?Answer: Toward the weak side.
  5. Why does shining light in one eye normally constrict both pupils?Answer: The pretectal region projects to both Edinger–Westphal nuclei.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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