Cranial Nerve Exam (OSCE)

CN I (Olfactory)

The olfactory nerves consist of small unmyelinated axons that originate in the olfactory epithelium in the roof of the nasal cavity; they pierce the cribriform plate of the ethmoid and terminate in the olfactory bulb.

Ask for any abnormality in smell

TESTING SMELL.

Ensure the patency of the nasal passages.

1. Have the patient close his/her eyes;

2. Test each nostril separately while the other is occluded.

3. Ask to identify familiar odors, such as coffee, cloves, and peppermint.

Noxious substances, such as ammonia or alcohol, should not be used because they also stimulate receptors of the trigeminal nerve and give a false-positive response

Abnormalities

The common cold is the most frequent cause of anosmia. Frontal lobe tumors may compress the olfactory bulb and/or tracts and cause anosmia rarely.

Loss of smell

o Frontal lobe tumors

o Fractures of the cribriform plate of the ethmoid bone.

o Parkinson’s disease

o Aging

o Use of cocaine

CN III (Oculomotor), IV (Trochlear), VI(Abducens)

• Mnemonic LR6SO4
  • Lateral rectus muscle by CN VI, superior oblique by CN IV

Position

• eyelid (penlight in front of patient), move in an H pattern
• eye position in primary gaze

Eye Movement

• nystagmus

CN V (Trigeminal)

Sensation

• all three divisions of CN V bilaterally
  • stroke across forehead, cheek and chin with a cotton wool

Motor

• clench teeth - palpate bulk of masseter and temporalis
• open mouth - inspect symmetry (pterygoids, masseter)

CN VII (Facial)

Motor

• raise eyebrows to wrinkle forehead - frontalis
• close eyes tight - orbicularis oculi
• puff your cheeks out - orbicularis oris
• tense neck muscles - platysma

CN VIII (Auditory/Vestibulocochlear)

• whisper test
• Rhinne
• Weber

CN IX (Glossopharyngeal), X (Vagus)

• swallowing
• say “pa” (labial VII)
• “ta” (lingual IX, X, XII)
• “ka” (palatal IX, X)
• say “ah” - check for symmetrical movement of palate and uvula

CN XI (Accessory)

• sternocleidomastoid - have patient turn head against your hand
• temporalis
• Shoulder shrugging

CN XII (Hypoglossal)

• position of extruded tongue in neutral position
• side to side tongue movements
• note any fasciculations