NEUROANATOMY Lecture : 10

1. NEUROANATOMY Lecture : 10 Anatomy of the Facial (VII), Vestibulo-Cochlear (VIII), & Accessory Nerves (XI) Prepared and presented by: Dr. Iyad Mousa Hussein, MD, Ph.D in Neurology Head of Neurology Department Nasser Hospital

2. LECTURE OBJECTIVES: Roots, Nuclei, and Functions of the Facial Nerve. Parts, Course, and Relations of the Facial Nerve. Branches Lesions of the Facial Nerve. Divisions of the Vestibulo-Cochlear Nerve. Function, Pathway, and Lesion of the Cochlear Division. Function, Pathway, and Lesion of the Vestibular Division. Origin, Functions, and Roots of the Accessory Nerve. Course, Relations, and Branches of the Accessory Nerve.

3. The Facial Nerve (VII) • It is a mixed nerve which contains motor, sensory and • parasympathetic fibers. • It is more important as a motor than as a sensory nerve. • It is a mixed nerve only while it is found inside the skull, but • after leaves the skull is becomes a purely motor nerve and • supplies muscles of facial expression. • It is the 7-th cranial nerve and gives 7 motor branches.

4. Roots of the Facial Nerve Facial nerve (motor nerve):is a purely motor nerve supplies all the muscles of face expression. Nerve intermedius: consist of sensory and parasympathetic fibers.

6. Nuclei of the Facial Nerve Facial motor nucleus: lies in the lower part of pons and gives rise to the fibers of facial nerve which supplies the facial muscles including orbicularis oculi, orbicularis oris, buccinator and platysma. Superior salivary nucleus: lies in the pons (secretomotor parasympathetic function) for: a. Submandibular salivary, sublingual and lacrimal glands (Chorda tympani nerve). b. Glands of the palate, nose and nasopharynx (Greater superior petrosal nerve). 3. Solitary nucleus: lies in the medulla. It receives taste sensations from the anterior 2/3 of the tongue. Fibers from the superior salivary nucleus and solitary nucleus constitute the nerve intermedius component of the facial nerve.

8. Function of the Facial Nerve Motor function to muscles of facial expression. Parasympathetic to all glands of head (submandibular, sublingual and lacrimal glands) except the parotid gland (glossopharyngeal nerve). Sensory for ear and tympanic membrane. Taste for anterior 2/3 of the tongue.

9. Parts of the Facial Nerve Intracranial Part: the part which starts from the brain stem and ends at the internal auditory meatus. Intracanal (petrosal) Part: the part which lies inside the petrous part (facial canal or Fallopian canal) of the temporal bone. Extracranial Part: the part of the nerve after it comes out from the stylomastoid foramen.

14. Course and Relations of the Facial Nerve Intracranial Course of the Facial Nerve. Extracranial Course of the Facial Nerve.

15. A. Intracranial Course of the Facial Nerve • The facial nerve emerges from the lower border of the pons • at ponto-cerebellar angle. • It leaves the cranial cavity by entering the internal auditory • meatus. • It runs through a facial canal (Fallopian canal) inside • petrous temporal bone of the temporal bone. • In the facial canal, motor part of the facial nerve becomes • adherent to its sensory and parasympathetic parts. • Finally it passes to reach the stylomastoid foramen.

21. Extracranial Course of the Facial Nerve It leaves the facial canal through the stylomastoid foramen. Immediately After it leaves the skull it gives 2 branches. It turns forwards making a curve around the lateral side of base of styloid process. It enters the posteromedial surface of parotid gland (lying superficial to ECA). It ends inside the substance of the parotid gland by dividing into five terminal branches

22. Extracranial Course of the Facial Nerve • It leaves the facial canal through the stylomastoid foramen. • It turns forwards making a curve around the lateral side of • base of styloid process. • It enters the posteromedial surface of parotid gland (lying • superficial to ECA). • It ends inside the substance of the parotid gland by dividing • into five terminal branches

26. Branches of the Facial Nerve • Branches of the facial nerve inside the Fallopian • canal: • The greater superficial petrosal nerve • Small branch to the stapedius muscle. • The chorda tympani • B. After it leaves the skull it gives 7 branches: • Immediately After it leaves the skull it gives 2 branches: • The posterior auricular nerve. • The nerve to: the posterior belly of the digastric muscle and to the stylohyoid muscle. • The five terminal branches of the facial nerve: • Temporal nerve (from temporofacial branch). • Zygomatic nerve (from temporofacial branch). • Buccal nerve (from cervicofacial branch). • Marginal mandibular nerve (from cervicofacial branch). • Cervical nerve (from cervicofacial branch).

27. Temporal nerve Zygomatic nerve Buccal nerve Marginal mandibular N. Cervical nerve

29. Extracranial Course of the Facial Nerve • It leaves the facial canal through the stylomastoid foramen. • It turns forwards making a curve around the lateral side of • base of styloid process. • It enters the posteromedial surface of parotid gland (lying • superficial to ECA). • It ends inside the substance of the parotid gland by dividing • into five terminal branches

34. Branches of the Facial Nerve A. Branches of the Facial Nerve Inside the Fallopian canal The greater superficial petrosal nerve (Parasympathetic): -Arises from the facial nerve at the geniculate ganglion. - It passes through anterior surface of the petrous temporal and runs in a groove to the foramen lacerum, where is unites with the deep petrosal nerve (sympathetic) to form the nerve of pterygoid canal. . - This nerve carries preganglionic parasympathetic fibers to the lacrimal, nasal and palatine glands (relay in the sphenopalatine ganglion). 2. Small branch to the stapedius muscle (Motor nerve). 3. The chorda tympani (special sensory and Parasympathetic): -Leaves the facial canal through a tunnel in the posterior wall of the middle ear. - It runs to the medial side of sphenoid and joins the lingual nerve in the infratemporal fossa. - Relay in the submandibular ganglion and supplies the taste of anterior 2/3 of the tongue and preganglionic parasympathetic fibers to the submandibular and sublingual salivary glands.

40. Branches of the Facial Nerve • B. After it Leaves the Skull • Immediately After it leaves the skull it gives 2 branches: • The posterior auricular nerve:which curves upwards behind the root of the auricle and supplies the occipitalis muscle and the superior posterior auriculares muscle. • The nerve to: the posterior belly of the digastric muscle and to the stylohyoid muscle.

43. Branches of the Facial Nerve • The five terminal branches of the facial nerve: • Temporal nerve: from temporofacial branch. • Zygomatic nerve: from temporofacial branch. • a. The upper zygomatic branch. • b. The lower zygomatic branch. • 3. Buccal nerve: from cervicofacial branch. • 4. Mandibular nerve: from cervicofacial branch. • 5. Cervical nerve: from cervicofacial branch.

47. 1.The Temporal Nerve • Emerges from temporofacial branch of the facial • nerve at the upper pole of the parotid gland. • It runs upwards and forwards to supply: • 1. Occipitofronales muscle • 2. Upper part of the orbicularis muscle. • 3. Superior anterior auriculares muscle.

50. 2. The Zygomatic Nerve • Emerges from temporofacial branch of the facial • nerve at the anterior border of the parotid gland, and it • divided into: • The upper zygomatic branch:supplies the • orbicularis oculi. • b. The lower zygomatic branch:supplies the • muscle between the eye and mouth including the • muscle of the nose.