Education facial nerve

2. FACIAL NERVE

3. Cranial nerves

4. Contents
 Introduction
 Functional components
 Nuclei associated with nerve
 Course and relations
 Branches
 Applied anatomy
 Syndromes related to facial nerve

5. Introduction
 The facial nerve is a mixed cranial
nerve with motor, parasympathetic,
and sensory branches.
 The facial nerve (CN VII) is the
seventh paired cranial nerve.

6. The facial nerve is associated with the
derivatives of the second pharyngeal arch:
 Motor – muscles of facial expression,
posterior belly of the digastric,
stylohyoid and stapedius muscles.
 Sensory – a small area around the
concha of the external ear.
 Special Sensory – provides special
taste sensation to the anterior 2/3 of
the tongue via the chorda tympani
 Parasympathetic – supplies to glands
of the head and neck

7. Functional Components
1. Special visceral efferent muscles responsible for facial
expression and for elevation of the hyoid bone .
2. General visceral efferent These fibres are secretomotor to the
submandibular and sublingual salivary glands,the lacrimal gland.
3. General visceral afferent component carries afferent impulses from
the above mentioned glands.
4. Special visceral afferent fibres carry taste sensations from the palate
and from anterior two thirds of the tongue .
5. General somatic afferent fibres innervate a part of the skin of the
ear.

8. Nuclei
 1. Motor nucleus or branchiomotor.
 2. Superior salivatory nucleus.
 3. Lacrimatory nucleus
 4. Nucleus of the tractus solitarius

10. Course of facial nerve
 It can be divided into two parts:
 Intracranial – the course of the nerve
through the cranial cavity, and the
cranium itself.
 Extracranial – the course of the nerve
outside the cranium, through the face
and neck.

11. Intracranial
 The nerve arises in the pons, an area of the
brainstem. It begins as two roots; a large motor
root, and a small sensory root
 Leaves the brain at lower border of pons
 Passes into internal acoustic meatus
 Emerges from temporal bone at stylomastoid
foramen

12. Extracranial
 The facial nerve crosses the lateral side of the base of
the styloid process.
 It enters the posteromedial surface of the parotid
gland,
 Behind the neck of the mandible, it divides into its five
terminal branches which emerge along the anterior
border of the parotid gland.

13. Branches of facial nerve

14.  Within the parotid gland, the facial nerve terminates by
bifurcating into five motor branches. These innervate the
muscles of facial expression:

15. Applied anatomy
 Bells ’s palsy: Sudden paralysis of facial nerve at
the stylomastoid foramen .
 Asymmetry of face
 Inability to close the eye,
 Disappearance of nasolabial fold
 Loss of wrinkling of skin of forehead on the same
side.

16. Testing of facial nerve
Motor Function.—
 (1) Ask the patient to show his teeth when the angle of the mouth will
be drawn to the healthy side.
 (2) Ask the patient to puff out the cheeks, the paralysed side blows out
more than the normal side.
 (3) Ask the patient to shut his eyes. he will not be able to close the eye
on the affected side.
 (4) Ask the patient to
move his eyebrows
upwards; the paralysis
side remains immobile.

17. Syndromes related to facial
nerve
 Ramsay-Hunt syndrome:
Involvement of geniculate ganglia by herpes zoster
results in this syndrome.
 (a) Hyperacusis.
 (b) Loss of lacrimation.
 (c) Loss of sensation of
taste in anterior two third
of tongue.
 (d) Bell’s palsy and lack
of salivation.
 (e) Vesicles on the auricle.

18. Crocodile tears syndrome:
 Lacrimation during eating occurs due to aberrant
regeneration after trauma.
 This is called Frey’s syndrome.
Moebius syndrome
It is a rare cause of congenital facial palsy due to
hypoplasia of the facial motor nucleus.

19.  Millard-Gubler syndrome:
Homolateral impairment of CN VII and contralateral
motor deficiency respecting the face
 Foville syndrome:
Homolateral impairment of CN VII, homolateral
impairment of CN VI, paralysis of the laterality towards
the lesion and contralateral motor deficiency respecting
the face.

21. References
 Facial nerve: From anatomy to
pathology F. Toulgoat a,∗ , J.L.
Sarrazinb,c , F. Benoudibac , Y.
Pereond, E. Auffray-Calvier a , B.
Daumas-Duport a , A. Lintia-Gaultier a ,
H.A. Desal a
 Textbook of human anatomy-
B.D.Chaurasia