Face Flashcards
What classification system is used to describe fractures of the midface?
Le Fort fracture classification
Le Fort I
‘Floating palate’
Horizontal fracture, from maxillary sinus through nasal septum and ridge of upper dental row and continues the same on opposite side.
Le Fort II
‘Floating maxilla’
Pyramidal fracture, upper teeth form base of pyramid, nasofrontal suture at its apex.
Passes through lateral wall of maxillary sinus, infraorbital ridge and the nasal bone and continues the same on opposite side.
Le Fort III
‘Floating face’
Transverse fracture- craniofacial disjunction.
Passes from zygomatic arch, through orbital wall and nasofrontal suture and continues the same on opposite side.
Briefly outline the cutaneous innervation of the face
Derived from 3 branches of the trigeminal nerve:
V1- ophthalmic nerve
V2- maxillary nerve
V3- mandibular nerve
Branches of the ophthalmic nerve
- Supraorbital nerve
- Supratrochlear nerve
- Infratrochlear nerve
- Lacrimal nerve
- External nasal nerve
Acronym: SLIES
Branches of the maxillary nerve
- Infraorbital nerve
- Zygomaticofacial nerve
- Zygomaticotemporal nerve
Branches of the mandibular nerve
- Auriculotemporal nerve
- Buccal nerve
- Mental nerve
How would V1, V2 and V3 be assessed during a cranial nerve exam?
V1- corneal reflex, cotton near eye
V2- pin prick/fine touch
V3- clench teeth (supplies muscles of mastication)
Which nerve innervates the muscles of facial expression?
Facial nerve (CN VII)
Describe the course of the facial nerve intracranially and extracranially
- Internally runs through internal acoustic meatus alonside labryinthine artery
- Emerges through stylomastoid foramen
- Runs between superficial and deep lobe of parotid gland before dividing into 5 branches
5 branches of the facial nerve
- Temporal nerve
- Zygomatic nerve
- Buccal nerve
- Marginal mandibular nerve
- Cervical nerve
Location of the facial muscles
Facial muscle lie in the subcutaneous tissue of the face, scalp and neck
Forehead facial muscles
- Frontalis
- Corrugator
- Occipitalis
- Procerus
Eye facial muscles
- Orbicularis oculi
Divided into 3 parts: orbital, palpebral, lacrimal
Nose facial muscles
- Nasalis
- Levator labii superioris alaeque nasi
Cheek facial muscles
- Buccinator
Mouth facial muscles
- Orbicularis oris
- Risorus
- Zygomaticus major
- Zygomaticus minor
- Levator labii superioris
- Levator anguli oris
- Depressor anguli oris
Chin facial muscles
- Mentalis
- Depressor labii inferioris
What are the 4 muscles of mastication and their innervation?
- Temporalis
- Masseter
- Medial pterygoid
- Lateral pterygoid
All innervated by the mandibular branch of the trigeminal nerve
Describe the temporalis muscle
- Fan shaped
- Elevates the mandible to close the mouth
- Retracts the mandible
Describe the masseter muscle
- Quadrilateral muscle covering most lateral aspect of ramus of mandible
- Elevates mandible to close the mouth
Describe the medial pterygoid
- Rhomboidal
- Elevates the mandible to close the mouth
Describe the lateral pterygoid
- Triangular
- 2 heads, superior and inferior
- Acts bilaterally to protract mandible (pushes forwards)
- Unilateral action to move mandible side to side
Angle’s classification - Class I
Maxillary first molar is slightly posterior to the mandibular first molar.
Angle’s classification - Class II
Maxillary first molar is anteriorly positioned relative to the mandibular first molar.
Angles’s classification - Class III
Maxillary first molar is severely posteriorly positioned relative to the mandibular first molar.
What process describes the loss of bone following significant tooth loss?
Bone resorption/bone atrophy
Alveolar bone of the maxilla and mandible is maintained by the presence of teeth.
Describe the main features of the parotid gland
- Largest salivary gland
- 2 lobes, superficial and deep
- Yellowish colour
- Pyramidal shape
- Contained within tough fibrous capsule
Which viral disease affects the parotid gland?
Mumps
Describe the course of the parotid duct
- Runs over the masseter
- Pierces the buccinator
- Enters oral cavity opposite the crown of the maxillary second molar
What feature can occasionally be present on the parotid duct?
An accessory parotid gland- this is extra parotid tissue on top of the duct
What 3 structures pass through the parotid gland?
- Facial nerve
- Retromandibular vein
- External carotid artery
What is the sensory and autonomic innervation of the parotid gland?
Sensory:
- Auriculotemporal nerve
- Great auricular nerve
Autonomic (parasympathetic):
- Presynaptic from lesser petrosal nerve
- Postsynpatic from auriculotemporal nerve
Synpase at otic ganglion
Describe the arterial supply to the face
From the 8 branches of the external carotid artery:
Superior thyroid Ascending lingual Lingual Facial Occipital Posterior auricular Maxillary Superficial temporal
How does the facial artery being tortuous help its role?
Allows for more stretch during facial actions e.g. mastication
Describe the venous drainage of the face
Maxillary v + superficial temporal v -> retromandibular v
Retromandibular v divides into posterior and anterior
Anterior rm v + facial vein -> common facial vein, drains into internal jugular vein
Posterior rm v + posterior auricular vein -> drain into external jugular vein
How is the facial vein linked to the cavernous sinus?
Facial vein is connected to the inferior and superior ophthalmic veins which drain into the cavernous sinus.
The deep facial vein can also access the cavernous sinus through the pterygoid plexus.
What is the clinical application of the proximity of facial vein to cavernous sinus?
Danger Triangle of the Face:
Infections in the triangle can be extremely dangerous, can spread into the cranium via the facial vein or deep facial vein.
What term is used to describe the veins connecting the extracranial circulation to the intercranial circulation?
Emissary veins:
E.g. the ophthalmic veins.
These veins don’t have valves so can spread infection easily from cranium to face.
What is an advantage of emissary veins?
They can release pressure in the cranium (to an extent)
