The Cranial Nerves are nerves that originate from the brain stem.

Are very specialized and important set of nerves.

There are 12 overall and they control a variety of functions both motor or sensory

Motor is the movement of a muscle [Efferent]

Sensory is the sight, touch or smells of the senses that are transmitted to the brain  [Afferent]

Many cranial nerves are either Motor  [Efferent] or Sensory [Afferent] but a some are both

Cranial Nerves:

I  Olfactory or smell  [Afferent]

  • Transmits sense of smell

II  Optic or vision [Afferent]

  • Transmits visual information from eye to brain

III  Oculomotor or movement of eyeball  [Efferent]

  • Innervates levator palprebrae of the eye
  • Innervates superior rectus of the eye
  • Innervates medial rectus of the eye
  • Innervates inferior rectus of the eye
  • Innervates inferior oblique of the eye
  • Affects the majority of eye movement
  • The exceptions are with Cranial nerves IV and VI

IV  Trochlear or muscles of eyeball  [Efferent]

  • Innervates superior oblique muscle of the eye
  • Allows for movements of eye including: lateral, depresses, and intorts

V  Trigeminal   [Afferent]  and  [Efferent]

  • V1 – opthalmic [Afferent]
  • V2 – maxillary  [Afferent]
  • V3 – mandibular  [Afferent] and [Efferent]
  • Receives sensation from the face.
  • Innervates facial muscles for mastication [chewing]

VI   Abducens or muscles of eyeball  [Efferent]

  • Innervates the lateral rectus of the eye
  • Affects the abduction of the eye

VII   Facial   [Afferent] and  [Efferent]

  • Motor innervation to the muscles of the face
  • Allows for facial expressions
  • Receives senses of taste from the anterior 2/3 of the tongue
  • Affects secretion of the salivary glands [except parotid]

VIII   Vestibulocochlear  [Afferent]

  • Senses Gravity
  • Senses Sound
  • Senses Rotation
  • Essential for balance and movement

IX   Glossopharyngeal  [Afferent]  and  [Efferent]

  • Receives taste from the posterior 1/3 of the tongue
  • Affects secretion of the Parotid gland
  • Affects some sensation of the Tonsils

X   Vagus [Afferent]  and  [Efferent]

  • Supplies motor innervation to most laryngeal and all pharyngeal muscles
  • Controls muscles for voice
  • Helps control soft palate

XI   Accessory or spinal   [Efferent]

  • Controls sternocleidomastoid
  • Controls trapezius muscles
  • Helps with shrugging shoulders

XII   Hypoglossal or tongue  [Efferent]

  • Provides motor innervation to the muscles of the tongue
  • Important for Speech
  • Important for Swallowing

 

Below is a Video of the Cranial Nerve Examination

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