Facial nerve Flashcards
Fibres of facial nerve
- General somatic afferent (GSA)
- Special visceral afferent (SVA)
- General visceral efferent (GVE)
- Special visceral efferent (SVE, brachiomotor)
Origin of facial nerve
Cerebellopontine angle(motor and sensory roots)
Facial nerve exits skull through
Stylomastoid foramen
Facial nerve nuclei
- Motor nucleus of facial nerve (SVE)
- Superior salivatory nucleus (GVE)
- Nucleus of solitary tract (SVA)
- Principal sensory nucleus of trigeminal nerve (GSA)
Associated ganglia of facial nerve
Geniculate ganglion(pterygopalatine ganglion, otic ganglion, submandibular ganglion)
What are the main parts of the facial nerve
- Intracranial
- Intratemporal
- Extracranial
Parts and branches of the intracranial part of the facial nerve
Origin-> Internal accoustic meatus(no branches)
Parts and branches of the Intratemportal part of the facial nerve
- Internal accoustic meatus-> Stylomastoid foramen
- Greater petrosal nerve
- Nerve to stapedius muscle
- Chorda tympani
Parts and branches of the Extracranial part of the facial nerve
- After stylomastoid foramen
- Posterior auricular nerve
- Digastric branch
- Stylohyoid branch
- Parotid plexus(Temporal, Zygomatic, Buccal, Marginal, cervical)
Main functions of facial nerve
- Motor innervation to muscles of facial expression (SVE)
- Taste to anterior two thirds of tongue and palate (SVE)
- Parasympathetic innervation of lacrimal, nasal, palatine and salivary glands(except parotid)(GVE)
- Sensation to part of auricle and retroauricular region
Sensations of facial nerve
- Motor and sensory
Intracranial course of Facial nerve
Origin of motor root of facial nerve
- Motor nucleus of facial nerve at lower pontine tegmentum
Intracranial course of Facial nerve
Merge with fibres of the **superior salivatory nucleus **and then pass to floor of fourth ventricle
Motor root axons
Intracranial course of Facial nerve
- The motor root axons loop around the nucleus of this nerve before exiting brainstem at the cerebellopontine angle
Abducens nerve
Intracranial course of Facial nerve
Fibres of the sensory root travel towards this structure to reach the nucleus of solitary tract
Medulla
Intracranial course of Facial nerve
Nucleus of solitary tract
Visceral sensory part of brainstem involved with relaying signals of satiety
Further fibers projected to principal sensory nucleus of trigeminal nerve
Intratemporal course of Facial nerve
Facial nerve roots course as they leave cranial cavity
Via **internal acoustic meatus **to enter facial canal in petrous part of temporal bone
Here they fuse to form facial nerve proper
Intratemporal course of Facial nerve
Facial nerve roots make sharp anterior to posterior turn at this point
Geniculum of facial nerve
Intratemporal course of Facial nerve
Facial nerve roots enlarge at this point
Geniculate ganglion
Intratemporal course of Facial nerve
Contains the cell bodies of the sensory neurons of the facial nerve
Geniculate ganglion
Intratemporal course of Facial nerve
Arises directly from the geniculate ganglion
Greater petrosal nerve
Intratemporal course of Facial nerve
Arise before the facial nerve exits the temporal bone
- Nerve to stapedius muscle
- Chorda tympani
Extracranial course of Facial nerve
Facial nerve leaves facial canal through this foramen
Stylomastoid foramen
Extracranial course of Facial nerve
After exiting through stylomastoid foramen, the facial nerve gives off this nerve before entering the parotid gland
Posterior auricular nerve
Extracranial course of Facial nerve
After giving off the posterior auricular nerve, the facial nerve enters this gland where it has 5 terminal branches
Parotid gland
Intratemporal branches
On its course to foramen lacerum, merges with deep petrosal nerve carrying sympathetic fibers to form
Nerve of the pterygoid canal
Intratemporal branches
Greater petrosal nerve innervation
- Travels to pterygopalatine ganglion to provide parasympathetic innervation to:
* Lacrimal gland - Mucous glands of nasal cavity, Maxillary sinus and palate
Intratemporal branches
Second intratemporal branch of facial nerve
Nerve to stapedius muscle
Nerve to stapedius muscle innervation
- SVE/branchiomotor fibres
- Dampening vibrations and protecting hearing apparatus during exposure to loud sounds
Intratemporal branches
Final Intratemporal branch
Chorda tympani
Intratemporal branches
Traverses middle ear and exits via petrotympanic fissure
Chorda tympani
Intratemporal branches
The chorda tympani merges with this nerve
Posterior aspect of lingual nerve
Intratemporal branches
Chorda tympani innervation
- Anterior two thirds of tongue
- Submandibular and sublingual glands
Salivary secretions
Extracranial branches
First Extracranial branch
Posterior auricular nerve
Extracranial branches
Posterior auricular nerve innervation
- Motor-> occipitofrontalis muscle
- Intrinsic auricular muscles
- Skin around external acoustic meatus and retroauricular region
Extracranial branches
Digastric and stylohyoid innervation
Motor to there respective muscles
Extracranial branches
Facial nerve pierces parotid gland and bifurcates into
Superior and inferior trunks which give rise to five terminal branches
Extracranial branches
Terminal branches of facial nerve
To Zanzibar By Motor Car
* Temporal
* Zygomatic
* Buccal
* Marginal mandibular
* Cervical
To Zanzibar By Motor Car
Temporal branch innervation
- Frontalis
- Orbicularis occuli
- Currugator supercilii muscles
To Zanzibar By Motor Car
Zygomatic branches innervation
- Orbicularis oculi muscle
To Zanzibar By Motor Car
Buccal branches innervation
- Orbicularis oris
- Buccinator
- Zygomaticus muscles
To Zanzibar By Motor Car
Marginal mandibular branches innervation
- Depressor labii inferioris
- Depressor anguli oris
- Mentalis
To Zanzibar By Motor Car
Cervical branches innervation
Platysma muscle
Areas of the facial nerve, lesions can occur
- Intracanial
- Intratemporal
- Extracranial
Intratemporal facial nerve lesions
Damage to the nerve near its origin, the geniculate ganglion or within facial canal leads to these symptoms
- Loss of motor function
- Taste and autonomic functions affected
Intratemporal facial nerve lesions
Lesions affecting greater petrosal nerve result in
- Impaired lacrimal fluid production ipsilaterally
Intratemporal facial nerve lesions
Lesions affecting nerve to stapedius muscle result in
Hypersensitivity to sound
Intratemporal facial nerve lesions
Lesions affecting chorda tympani
- Reduced salivary secretion of submandibular and sublingual glands
- Loss of gustatory function of anterior two thirds of tongue ipsilaterally
Extracranial facial nerve lesions
After leaving skull, facial nerve damage along extracranial course affects
Motor fibres
Extracranial facial nerve lesions
Lesions affecting extracranial facial nerve fibres cause
Facial nerve palsy-paralysis or weakness in muscles of facial expression
Extracranial facial nerve lesions
Extracranial lesions aetiology
- Idopathic-bells palsy
- Infection-viral(Herpes)
- Iatrogenic-surgery(removal of parotid)
- Compression(forceps baby delivery)
Sudden ipsilateral facial paralysis with no detectable cause
Bells palsy
