Week 5 - Facial Nerve, Parotid Region & Muscles of Facial Expression Flashcards
What is the borders of parotid bed ?
Zygomatic arch, lower border of mandible between SC, external acoustic meatus and masseter.
What is the parotid sheath ?
Tough fibrous capsule, derived from investing layer of deep cervical fascia.
What pathway does the parotid duct (Stensen’s duct) take ?
Anterior and horizontally, then through buccinator and into oral cavity (at upper 7s).
What structures are within parotid gland ?
Retromandibular vein, external carotid artery, parotid lymph nodes, CNVII i.e. parotid plexus of facial nerve.
What is the blood supply to the parotid gland ?
External carotid artery via posterior auricular artery.
Then splits to give superficial temporal and maxillary artery.
What is the venous drainage from parotid gland ? And from there where does it drain into ?
Maxillary and superficial temporal veins > retromandibular vein where anterior branch drains to IJV and posterior branch into EJV.
What cranial nerve is responsible for parasympathetic innervation of parotid gland ?
Glossopharyngeal nerve (CNIX).
What nerves innervate the parotid sheath and skin ?
Auriculotemporal nerve (branch of CNV3) and great auricular nerve (branch of cervical plexus C2 to C3).
Where does the nerve innervation responsible for sympathetic innervation of the parotid gland come from ?
Superior cervical ganglion and nerve plexus on ECA.
What are the boundaries of the infratemporal portion of the facial nerve ?
From where nerve leaves pons to exiting the skull (stylomastoid foramen).
What are the boundaries of the extratemporal portion of the facial nerve ?
From leaving the skull at stylomastoid foramen.
What foramina does the facial nerve exit the skull ?
Stylomastoid foramen.
What are the 5 terminal branches of the facial nerve ?
Temporal, zygomatic, buccal, marginal mandibular, cervical.
What 2 branches does the facial nerve give off as it leaves skull via stylomastoid foramen ?
Posterior auricular and digastric branch.
What does the temporal branch of facial nerve innervate ?
Muscles of temple, forehead and supra-orbital area (exception - temporalis).
What does the zygomatic branch of facial nerve innervate ?
Muscles of infraorbital area, lateral nasal area and upper lip.
What does the buccal branch of facial nerve innervate ?
Muscles of cheek, upper lip and corners of the mouth.
What does the marginal mandibular branch of facial nerve innervate ?
Muscles of lower lip and chin.
What does the cervical branch of facial nerve innervate ?
Platysma.
What is the symptom associated with Bells Palsy ?
Unilateral palsy of upper and lower parts of the face.
What treatment can be given to treat Bells Palsy ?
Steroids, anti-viral medications, cover eye.
What muscles specifically does the facial nerve innervate ?
Buccinator, obicularis oris, obicularis oculi, occipitofrontalis, platysma.
What pharyngeal arch are all the muscles of facial expression and those innervated by the facial nerve derived from ?
All derived from second pharyngeal arch.
What is the origin of the frontal and occipital belly of the occipitofrontalis ?
Frontal belly - epicranial aponeurosis.
Occipital belly - lateral 2/3 of superior nuchal line.
What is the insertion of the frontal and occipital belly of occipitofrontalis ?
Frontal belly - subcutaneous tissue of eyebrows and forehead.
Occipital belly - epicranial aponeurosis.
What is the action of the frontal and occipital belly of occipitofrontalis ?
Frontal belly - wrinkle forehead and raise eyebrows.
Occipital belly - retract scalp.
What is the innervation of the frontal and occipital belly of occipitofrontalis ?
Frontal belly - temporal branch of facial nerve.
Occipital belly - posterior auricular branch of facial nerve.
What is the innervation of the obicularis oculi ?
Temporal and zygomatic branches of facial nerve.
What is the action of the obicularis oculi ?
Keep eye lubricated and protect eye from injury by spreading lacrimal fluid.
Two parts of obicularis oculi ?
Orbital (outermost) and palpebral (innermost).
What are the two sphincter muscles of the face ?
Obicularis oculi and obicularis oris.
What is the innervation of obicularis oris ?
Buccal and marginal mandibular branch of facial nerve.
What is the origin of obicularis oris ?
Buccinator and medial surface of maxilla and mandible.
What is the insertion of obicularis oris ?
Mucous membranes of the lips.
What is the innervation of buccinator ?
Buccal branch of facial nerve.
What is the origin of buccinator ?
Posterior of alveolar processes of maxilla.
Pterygomandibular raphe.
What is the insertion of buccinator ?
Fibres merge with obicularis oris.
What is the function of buccinator ?
Keep food on occlusal surfaces of the teeth alongside the tongue.
What lies posterior to the buccinator ?
Buccal fat pad.
Where does the parotid duct lie ?
Superficial to buccinator.
Pierces buccinator and buccal fat pad into oral cavity at 2nd molar tooth.
What is the origin of platysma ?
Subcutaneous tissue of infra and supra clavicular tissue.
What is the insertion of platysma ?
Base of mandible.
What is the innervation of platysma ?
Cervical branch of facial nerve.
What is the function of platysma ?
Depress the mandible.
What is the function of dilator muscles of the face ?
Widen mouth, lift or depress corners.
What are the 5 terminal branches of the facial nerve (CNVII) ?
Temporal.
Zygomatic.
Buccal.
Marginal mandibular.
Cervical.
What are the early branches of the facial nerve (CNVII) ?
Greater, lesser and external petrosal.
Nerve to stapedius.
Posterior digastric.
Posterior auricular.
What are the two major arteries which supply the face ?
Internal carotid (ophthalmic branch).
External carotid.
What are the two major veins which drain the face ?
Facial vein (and transverse facial).
Retromandibular.
What two veins unite to become the EJV ?
Retromandibular and facial vein.
What vein does the posterior auricular vein drain directly into ?
EJV.
What is significant about the blood flow in the danger triangle ?
No valves in the veins so blood flows in both directions. So can cause infection spread and facial lacerations to cause big swellings (due to loose connective tissue).
What vein do the veins deep to the danger triangle drain into ?
Cavernous sinus.
