Facial nerve and palsy

The facial nerve is the seventh (VII) of twelve paired cranial nerves.

It emerges from the brainstem between the Pons and the Medulla.
Facial nerve is a mixed nerve, having 2 roots:
1. Medial motor root.
2. Lateral sensory root (nervous intermedius),which contains sensory & parasympathetic fibers.
Waardenburg syndrome

1. Facial Nerve and Palsy Musa Abu Sabha

2. Facial nerve The facial nerve is the seventh (VII) of twelve paired cranial nerves. It emerges from the brainstem between the Pons and the Medulla .

3. Nuclei: 1. Facial nucleus - Special Visceral Efferent (SVE). 2. Superior salivary nucleus – General Visceral Efferent (GVE). 3. Lacrimatory nucleus - General Visceral Efferent (GVE). Facial nerve is a mixed nerve , having 2 roots: 1. Medial motor root . 2. Lateral sensory root (nervous intermedius), which contains sensory & parasympathetic fibers .

4. Function : 1. Motor function: Muscles of facial expression. Posterior belly of digastrics muscle. Stylohyoid muscle. Stapedius muscle of the middle ear. 2. Sensory function: Taste sensations from the anterior two-thirds of the tongue. Oropharynx above the palatine tonsil. 3. Secretomotor function (parasympathetic innervation ): Submandibular & sublingual salivary glands. Lacrimal glands. Nasal glands.

5. Course The motor part arises from the facial nerve nucleus in the pons . Sensory part arises from the nervus intermedius . The two roots emerge from the anterior surface of the brain between the pons and Medulla oblongata. They pass laterally & forward in the posterior cranial fossa to opening of the internal acoustic meatus . At the bottom of the meatus, the nerve enters the facial canal & runs laterally above the vestibule of the labyrinith until it reaches the medial wall of the tympanic cavity. Cont …

6. Course

7. Here , the nerve expands from the sensory geniculate ganglion to give : Branches inside the facial canal: 1. Greater petrosal nerve : provides parasympathetic innervation to lacrimal gland, as well as special taste sensory fibers to the palate via the nerve of pterygoid canal ( Vidian Nerve). 2. Nerve to stapedius : provides motor innervation for stapedius muscle in middle ear. 3. Chorda tympani : provides parasympathetic innervation to submandibular gland, sublingual gland and special sensory taste fibers for the anterior 2/3 of the tongue.

8. Then it descends in the posterior wall of the middle ear , behind the pyramid, then through the stylomastoid foramen & passes through the parotid gland . Though it passes through the parotid gland , it doesn’t innervate it . Branches distal to stylomastoid foramen: 1 . Posterior auricular nerve : controls movements of some of the scalp muscles around the ear. 2. Branch to Posterior belly of Digastric and Stylohyoid muscle .

9. As the facial nerve runs forward within the substance of the parotid gland, it divides into its 5 terminal branches : 1. Temporal branch 2. Zygomatic branch. 3. Buccal branch. 4. Mandibular branch. 5. Cervical branch. ** M astidectomy to remove cholesteatoma carries a risk of facial paralysis .

10. Testing the facial nerve: Voluntary facial movements , such as: Wrinkling the brow Showing teeth Frowning Closing the eyes tightly Pursing the lips Puffing out the cheeks There should be no noticeable asymmetry.

11. Facial Paralysis

12. UMN lesion: In an UMN lesion, called central seven , only the lower part of the face on the opposite side will be affected, due to the bilateral control to the upper facial muscles . LMN lesion: LMN lesions can result in Bell's palsy, manifested as both upper and lower facial weakness on the same side of the lesion .

13. Bell's palsy The most common cause of unilateral facial paralysis . Bell palsy is an acute, unilateral, peripheral, lower-motor-neuron facial-nerve paralysis that gradually resolves over time in 80-90% of cases . The cause of Bell palsy remains unknown , though it appears to be a polyneuritis with possible viral, inflammatory, autoimmune, and ischemic etiologies. Increasing evidence implicates herpes simplex type I and herpes zoster virus reactivation from cranial-nerve ganglia.

14. should be conservative and guided by the severity and probable prognosis in each particular case. Studies have shown the benefit of high-dose corticosteroids for acute Bell palsy. Although antiviral treatment has been used in recent years, evidence is now available indicating that it may not be useful . Treatment of Bell palsy

15. House Brackmann facial nerve grading system

16. House Brackmann facial nerve grading system

17. House Brackmann facial nerve grading system

18. Waardenburg syndrome

19. Waardenburg syndrome Autosomal dominant disorder with an incidence of 1 in 40,000 that manifests with sensorineural deafness , pigmentation defects of the skin, hair and iris and various defects of neural crest-derived tissues .

20. Case Report

21. Case Report

22. Conclusion