The facial nerve (CN VII) emerges from the brainstem between the pons and medulla and innervates muscles of facial expression. It develops from the second pharyngeal arch and supplies motor and sensory fibers to muscles derived from this arch, including those of facial expression. The facial nerve has 6 segments as it exits the skull and provides motor innervation to facial muscles as well as some sensory innervation to the ear and taste to the anterior two-thirds of the tongue via the chorda tympani.
4. Motor division from basal plate of
the embryonic pons
Sensory division from cranial
neural crest
The facial nerve supplies motor and
sensory innervation to muscles
formed by 2nd pharyngeal arch :
• Muscles of facial expression
• Posterior belly of the digastric
• Stylohyoid
• Stapedius
5. The anterior 2/3 of
tongue are derived
from 1st pharyngeal
arch, which gives
rise to CN V..
Nerve fibers for taste
are supplied by the
chorda tympani
branch of facial
nerve via special
visceral afferent
fibers.
6.
7. STRUCTURE
The path of the facial nerve can be
divided into 6 segment :
1. intracranial (cisternal) segment
2. meatal segment (brainstem to internal
auditory canal)
3. labyrinthine segment
4. tympanic segment
5. mastoid segment
6. extra temporal segment
13. 2. Facial sensation :
a. small amount of afferent innervation to
the oropharynx.
b. small amount of cutaneous sensation
carried by the nervus intermedius from
the skin in and around the auricle.
c. receives taste sensations from the
anterior 2/3 of the tongue via the chorda
tympani.