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