Face Flashcards
What is the intracranial course of the facial nerve?
Originates between the pons and medulla > Internal acoustic meatus >Facial canal (petrous part of the temporal bone) >exists through the stylomastoid foramen
Branches of the facial nerve
Divides into 5 branches within the parotid gland
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular
- Cervical
Branches before entering the parotid gland
- Digastric
- Posterior auricular
- Cervicofacial
- Temporofacial
Which cranial nerves transmit parasympathetic fibres?
Oculomotor, glossopharyngeal, vagus and facial
What is the surface anatomy of the parotid duct?
The middle third of a line drawn between the intertragic notch and the middle of the philtrum
Where does the parotid duct open?
Crosses the masseter, pierces the buccinator and opens adjacent to the upper 2nd molar (stensen’s duct)
Which structures pass through the parotid gland?
Facial nerve (most superficial structure)
External carotid artery
Retormandibular vein
Auriculotemporal nerve
Deep parotid lymph nodes
What are the relations of the parotid gland?
Anterior - masseter, medial pterygoid, superficial temporal and maxillary arteries, facial nerve and stylomandibular ligament
Posterior - posterior belly of digastric muscles, SCM, Stylohyoid, internal carotid artery, mastoid process and styloid process
What is the arterial supply of the parotid gland?
Branches of the external carotid artery
What is the venous drainage of the parotid gland?
Retromandibular vein (union of the superficial temporal and maxillary veins)
What is the lymphatic drainage of the parotid gland?
Deep and superficial parotid LN > upper and lower deep cervical lymph nodes
What is the innervation of the parotid gland?
Parasympathetic - secretomotor from the otic ganglion
Sympathetic - superior cervical ganglion
Sensory - greater auricular nerve
What is the surface anatomy of the parotid gland
Upper end - curved line from the tragus to the centre of the mastoid bone
Anterior border - a line from the tragus to the centre of the posterior border of the masseter then to the point 2cm below and behind the angle of the mandible
Posterior - straight line from the mastoid process to a point 2cm below and behind the angle of the mandible
What type of secretions does the parotid gland produce?
Serous
parasympathetic stimulation produces watery serous saliva
Sympathetic stimulation produces low volume, enzyme rich saliva
Name some differential diagnoses of a parotid swelling
Infection - parotitis, mumps
Obstructed duct - calculi, external compression
Neoplasm- pleomorphic adenoma, warthin’s tumour
Deep parotid lymph node
What is Frey syndrome?
Damage to the parasympathetic fibres from the auriculotemporal nerve results in excessive gustatory sweating in response to saliva production
Where can the facial artery be palpated
Where it crosses the inferior border of the mandible adjacent to the anterior border of the masseter
Where is the submandibular duct opening located?
Opens in the floor of the mouth on either side of the lingual frenulum
What type of secretions does the submandibular gland produce?
Mucous and serous
Which nerves are at risk on submandibular gland excision?
Lingual nerve
Hypoglossal nerve > leads to deviation of the tongue towards the affected side on protrusion
Marginal mandibular branch of the facial nerve
What is the difference between and UMN and LMN facial palsy?
UMN lesions spare the upper part of the face
LMN - all parts of the face are involved
Which regions are drained by the pre-aurciular LNs
Upper half of the face
Temporal region
Auricle and EAM
Gums
What is the nerve supply of the tongue?
Motor
- Hypoglossal nerve
- except for palatoglossus which is innervated by the vagus nerve
Sensory
- Posterior root of the tongue > vagus
- anterior 2/3 - mandibular nerve via the lingual
- posterior1/3 - glossopharyngeal
Taste
- posterior root of the tongue - vagus
- anterior 2/3 of the tongue - glossopharyngeal
- posterior 1/3 of the tongue - Facial nerve via chorda tympani
Name the extrinsic muscles of the tongue
Styloglossus
hyloglossus
genioglossus
palatoglossus
Which muscle retracts the tongue?
Styloglossus
Which is the nerve supply to the tongue
All extrinsic muscles are innervated by hypoglossal nerve except for palatoglossus which is innervated by the vagus nerve
What forms the roof of the middle ear?
Tegmen tympani
How do middle ear infections cross the skull?
By direct erosion of the tegmen tympani which allows spread to the mastoid air cells causing mastoiditis
Describe the clinical picture of meningism
Photophobia
Stiff neck
Fever
Which structures pass through the IAM?
Facial nerve
Vesticubulocochlear nerve
What disease process can lead to irreversible damage of the CN VIII?
Acoustic neuroma
Why do patients with acoustic neuromas hear sounds loudly on the affected side?
They often have involvement of the facial nerve with paralysis of stapedius
What are the relations of the middle ear?
Roof - Tegmen tympani- separates the tympanic cavity from the MCF
Floor - thin bone separates the tympanic cavity from the superior bulb of the IJV
Anterior wall - Thin bone, separates the tympanic cavity from the ICA. At upper part there are openings into two canals - auditory tube and canal for tensor tympani
Posterior - Aditus to the mastoid antrum superiorly and pyramid inferiorly
Lateral wall - tympanic membrane and lateral wall of epitympanic recess
Medial wall - lateral wall of the inner ear
