Anatomy of facial nerve-sadia [Autosaved].pptx

Anatomy of facial nerve-sadia

1. NERVE SUPPLY OF FACE PRESENTED BY- DR.SADIA TASNIM DR.MRITTIKA SARKAR DEPARTMENT OF GENERAL ANATOMY RANGPUR COMMUNITY DENTAL COLLEGE

2. CONTENTS Introduction Motor nerve. Facial nerve course. Functional components Segments Clinical anatomy. Disorders of facial nerve function Sensory nerve supply Distribution of cutaneous nerves. Maxillary division of trigeminal nerve Mandibular division of trigeminal nerve Clinical anatomy of trigeminal nerve Examination of trigeminal nerve.

3. INTRODUCTION Nerve supply of the face is innervated by both sensory and motor nerves. Motor nerve supply is carried out by the Facial nerve. The chief sensory nerve supply of the face is carried by trigeminal nerve through its three branhes .

4. MOTOR NERVE Facial nerve is the motor nerve of the face. It is the 7 th of 12 th paired cranial nerve. It derives from the 2 nd branchial arch.

5. It has five terminal branches.which is- 1.Temporal- frontalis,auricular,orbicularis oculi muscles. 2.Zygomatic -orbicularis oculi (lower eyelid part). 3.Buccal- muscles of cheek & upper lip. 4.Marginal mandibular - muscles lower lip. 5.Cervical- platysma.

6. FACIAL NERVE COURSE

7. FUNTIONAL COMPONENTS OF FACIAL NERVE Branchiomotor fibers- to supply the muscles which are developed from the 2 nd branchial arch.like muscles of- Facial expression Buccinator Stylohyoid Posterior belly of digastic Platysma Stapedius

8. Preganglionic secreto-motor fibres- for the submandibular,sublingual,lacrimal glands and glands of soft palate and nasal cavity . Taste fibres- from the anterior two-thirds of the tounge and from the soft palate. Cuteneous Somato-Sensory fibres- from the concha of the auricle are probably conveyed by the facial nerve.

9. SEGMENTS Brain stem/intramedullary segment- brainstem nuclei to the exit point. Cisternal Segment - exit point to the entrance into the internal auditory canal. Meatal/canal segment- course through the internal auditory canal.

10. Labyrinthine segment- to the geniculate ganglion. Short horizontal segment- to the pyramidal eminence of the posterior wall of the tympanic cavity. Mastoid segment- to the stylomastoid foramen. Extratemporal/Peripheral segment- to the pes anserinus

11. CLINICAL ANATOMY The facial nerve is examined by testing the following muscle- 1.Test for Frontalis Ask the patient to look upwards without moving his head and look for the normal horizontal wrinkles on the forehead.

12. 2.Test for dilators of mouth- Ask the patient to show teeth .

13. 3.Test for orbicularis oris- Tight closure of the eyes.

14. 4.Test for Buccinator muscle- Puffing the mouth and then blowing forcibly as in whistling.

15. DISORDERS OF FACIAL NERVE FUNCTION 1.Infranuclear leison/Bell’s Palsy- Infranuclear lesion of the facial nerve,at the stylomastoid foramen is known as bell’s palsy. Features of bell’s palsy- Upper and lower quarters of the face on the same side get paralysed. The face becomes asymmetrical. Face is drawn uo to the normal side. The affected side is motionless.

16. Wrinkles disappear from the forehead. The eyes cannot be closed. Any attempt to smile draws the mouth to the normal side. During mastication,food accumulates between the teeth and ceek. Articulation of labialis is impaired.

17. 2.Supranuclear Leison of facial nerve- It is a part of hemiplegia with injury of corticonuclear fibres. Only the lower quarter of the opposite side of the face is paralysed. The upper quarter with the frontalis and orbicularis oculi escapes due to its bilateral representation in the cerebral cortex. Only voluntary movements are affected. Emoitional expressions remain normal.as there are separate pathways for voluntary and emotional movements.

18. SENSORY NERVE SUPPLY The trigeminal nerve through its 3 branches is the chief sensory nerve of the face . It derives from the 1 st branchial arch. Trigeminal nerve is the 5 th cranial nerve. Three divisions of trigeminal nerve are- a)V1-Opthalmic division b)V2-Maxillary division c)V3-Mandibular division

19. Three divisions of trigeminal nerve further divides into- i)Opthalmic division- 1.supratrochlear branch . 2.supraorbital branch. 3. lacrimal branch . 4. infratrochlear branch. 5.external nasal branch.

20. ii)Maxillary division- 6.infraorbital branch. 7.zygomaticofacial branch. 8.zygomaticotemporal branch. iii) Mandibullary division- 09.auriculo-temporal branch. 10.buccal branch. 11.mental branch.

21. AREA OF DISTRIBUTION OF THE CUTENOUS NERVES 1.Supra trochlear nerve -supplies the muscles of upper eyelid and forehead. 2.Supraorbital nerve -supplies the muscles of upper eyelid,frontal air sinus,scalp 3.Lacrimal nerve -supplies the muscles of lateral part of upper eyelid. 4.Infratrochlear nerve -the muscles of medial parts of both eyelids. 5.External nasal nerve -lower part of dorsum and tip of the nose

22. 6.Infraorbital nerve -spplies the lower eyelid,side of the nose and upper lip. 7.Zygomaticofacial nerve -supplies the upper part of the cheek. 8.Zygomaticotemporal nerve -supplies the anterior part of temporal region. 9.Auriculotemporal nerve -supplies the upper 2/3 rd of lateral side of auricle,temporal region. 10.Buccal nerve -supplies the skin of lower part of the cheek. 11.Mental nerve -supplies the skin over chin.

23. After arising from trigeminal ganglion,maxillary nerve passes through the foramen rotundum and within the phenopalatine fossa it gives rise- the palatine nerves and the middle, posterior, and anterior superior alveolar nerves. which supply the- upper teeth maxillary sinus Nasopharynx soft palate, roof of the mouth tonsils. Distal to the sphenopalatine fossa, the maxillary nerve splits into an inferior palpebral branch to the lower eyelid, a nasal branch to the side of the nose, and a superior labial branch to the upper lip. MAXILLARY DIVISION OF TRIGEMINAL NERVE

24. MANDIBULAR DIVISION OF TRIGEMINAL NERVE mandibular nerve transmits the sensory information from the lower third of the face.The mandibular nerve originates from the trigeminal ganglion and exits the skull through the foramen ovale & enters the infratemporal fossa.it further divides into : -anterior and posterior. The anterior division ramifies and produces motor branches for- the masticatory muscles & one sensory branch,the buccal nerve which innervates the cheek. Buccal nerve Masseteric nerve Deep temporal nerves Nerve to lateral pterygoid muscle

25. The posterior division divides into three sensory branches: The auriculotemporal Lingual Inferior alveolar nerves. The latter gives off a motor branch which innervates the anterior belly of the digastric muscle and the mylohyoid muscle. 1.Auriculotemporal branch- supplies auricle anterior to the external acoustic meatus,external surface of tympanic membrane & skin of posterior part of temporal region. 2.Lingual branch- provides the sensory innervation to the anterior ⅔ of the tongue, floor of the oral cavity and mandibular gingiva. 3.Inferior alveolar branch- The inferior alveolar nerve may exist as 2 distinct branches, major and minor . The major branch exits through the mental foramen to innervate the lower lip and chin, while the minor branch innervates the molars and premolars to then continue as the incisive nerve to innervate incisors.

26. CLINICAL ANATOMY OF TRIGEMINAL NERVE Trigeminal neuralgia may involve one or more of the three divisions of the trigeminal nerve. It causes attacks of very severe burning and sclding pain along the distribution of the affected nerve.

27. EXAMINATION OF TRIGEMINAL NERVE For the examination of trigeminal nerve,the 3 divisions are evaluated by- Ask the patient to close the eyes. Using a pinprick to test facial sensation. By brushing a wisp of cotton to the areas of the face supplied by the three divisions of the trigeminal nerve to detect tactile sensory competence.

28. Pain is relieved either- By injecting 90% alcohol into the affected division of the trigeminal ganglion. Or by, Sectioning the affected nerve,main sensory root or the spinal tract of the trigeminal nerve.

29. SOURCES Essentials of human anatomy(head & neck)-A.K.DATTA Human Anatomy-BD CHAURASSIA’s

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