Cranial Nerves

Cranial nerves is a collection of twelve nerves that arise from the brain stem that provide innervation mostly to the head, face, and neck.
The importance of cranial nerves provide innervation to most of the special senses that are on your face including vision, smell, taste, hearing.
Other functions include muscles of the tongue, vestibular, facial expression, and many others.

CN I: Optic

Vision

CN II: Olfactory

Smell

CN III: Oculomotor

Muscles of the eye except Abducens and Superior Oblique

CN IV: Trochlear

Muscle of the Eye: Superior Oblique

CN V: Trigeminal

Mixed Nerve

 

Sensory to face

Motor - Mastication

 

Testing:

Sensory: light touch or sharp/dull on forehead (opthalamic (V1), cheek (maxillary (V2), and chin (mandibular (V3))

Corneal Reflex: touch cornea (eye) with cotton

Motor: clench teeht tightly while palpating temporalis and masseter, move jaw side-to-side

 

CN VI: Abducens

Muscle of the Eye: Abducens

CN VII: Facial

Mixed Nerve

 

Testing:

Motor: resting symmetrical face, raise eyebrows, close eyes tightly, smile, puff out cheeks, pucker lips

Sensory: taste (sweet, sour, salty, or bitter anterior 2/3 of tongue)

CN VIII: Vestibulocochlear

Sensory Nerve

 

Testing:

Cochlear: Whisper or rub fingers together next to ear and have patient identify if they can hear and which ear. Tuning fork on mastoid process

Vestibular: Nystagmus (involuntary movements of eyes with change in head position), Balance testing, Head impulse test

CN IX: Glossopharyngeal

Mixed Nerve

Motor to stylopharyngeus - elevates larynx and pharynx during speaking and swallowing

Parasympathetic to parotid glands 

Posterior 1/3 of the tongue and taste

Medulla Oblongata

Jugular Foramen or Foramen Ovale

Testing: Open mouth and say "ah", Sip of water, voice quality/speech, gag reflex 

CN X: Vagus

Mixed Nerve

Medial swallowing and phonation

Involuntary muscle control of organs (cardiac, pulmonary, espohageal)

Glands in the intestinal tract

External ear and tympanic membrane

Carotid and aortic bodies

Taste sensation to the pharynx

Medulla Oblongata

Jugular Foramen (Occipital Bone)

Testing: Open mouth and say "ah"

CN XI: Accessory

Motor Nerve

Muscles of posterior neck: Trapezius and Sternocleidoccipitomastoid (SCOM)

Trapezius: shruggling of shoulders

SCOM: tilting and turn of head

Origin: Nucleus Ambiguus

Jugular Foramen (Occiptal Bone)

Testing: Resisted shoulder shrug and rotation in both directions

CN XII: Hypoglossal

Motor Nerve

Tongue, Speech, and Swallowing

Tongue: Protrustion, retraction, depression, and shape

Muscles:

Genioglossus - protrusion of tongue

Hyoglossus - retracts tongue and depresses sides

Styloglossus - upward movement of tongue

Intrinsics of Tongue - shaping of tongue

Origin: Medulla Oblongata

Hypoglossal Canal (Occipital Bone)

Testing: Sticking out tongue