Week 5 - Facial Nerve, Parotid Region & Muscles of Facial Expression

Question 1

What is the borders of parotid bed ?

Answer 1

Zygomatic arch, lower border of mandible between SC, external acoustic meatus and masseter.

Question 2

What is the parotid sheath ?

Answer 2

Tough fibrous capsule, derived from investing layer of deep cervical fascia.

Question 3

What pathway does the parotid duct (Stensen’s duct) take ?

Answer 3

Anterior and horizontally, then through buccinator and into oral cavity (at upper 7s).

Question 4

What structures are within parotid gland ?

Answer 4

Retromandibular vein, external carotid artery, parotid lymph nodes, CNVII i.e. parotid plexus of facial nerve.

Question 5

What is the blood supply to the parotid gland ?

Answer 5

External carotid artery via posterior auricular artery.
Then splits to give superficial temporal and maxillary artery.

Question 6

What is the venous drainage from parotid gland ? And from there where does it drain into ?

Answer 6

Maxillary and superficial temporal veins > retromandibular vein where anterior branch drains to IJV and posterior branch into EJV.

Question 7

What cranial nerve is responsible for parasympathetic innervation of parotid gland ?

Answer 7

Glossopharyngeal nerve (CNIX).

Question 8

What nerves innervate the parotid sheath and skin ?

Answer 8

Auriculotemporal nerve (branch of CNV3) and great auricular nerve (branch of cervical plexus C2 to C3).

Question 9

Where does the nerve innervation responsible for sympathetic innervation of the parotid gland come from ?

Answer 9

Superior cervical ganglion and nerve plexus on ECA.

Question 10

What are the boundaries of the infratemporal portion of the facial nerve ?

Answer 10

From where nerve leaves pons to exiting the skull (stylomastoid foramen).

Question 11

What are the boundaries of the extratemporal portion of the facial nerve ?

Answer 11

From leaving the skull at stylomastoid foramen.

Question 12

What foramina does the facial nerve exit the skull ?

Answer 12

Stylomastoid foramen.

Question 13

What are the 5 terminal branches of the facial nerve ?

Answer 13

Temporal, zygomatic, buccal, marginal mandibular, cervical.

Question 14

What 2 branches does the facial nerve give off as it leaves skull via stylomastoid foramen ?

Answer 14

Posterior auricular and digastric branch.

Question 15

What does the temporal branch of facial nerve innervate ?

Answer 15

Muscles of temple, forehead and supra-orbital area (exception - temporalis).

Question 16

What does the zygomatic branch of facial nerve innervate ?

Answer 16

Muscles of infraorbital area, lateral nasal area and upper lip.

Question 17

What does the buccal branch of facial nerve innervate ?

Answer 17

Muscles of cheek, upper lip and corners of the mouth.

Question 18

What does the marginal mandibular branch of facial nerve innervate ?

Answer 18

Muscles of lower lip and chin.

Question 19

What does the cervical branch of facial nerve innervate ?

Answer 19

Platysma.

Question 20

What is the symptom associated with Bells Palsy ?

Answer 20

Unilateral palsy of upper and lower parts of the face.

Question 21

What treatment can be given to treat Bells Palsy ?

Answer 21

Steroids, anti-viral medications, cover eye.

Question 22

What muscles specifically does the facial nerve innervate ?

Answer 22

Buccinator, obicularis oris, obicularis oculi, occipitofrontalis, platysma.

Question 23

What pharyngeal arch are all the muscles of facial expression and those innervated by the facial nerve derived from ?

Answer 23

All derived from second pharyngeal arch.

Question 24

What is the origin of the frontal and occipital belly of the occipitofrontalis ?

Answer 24

Frontal belly - epicranial aponeurosis.
Occipital belly - lateral 2/3 of superior nuchal line.

Question 25

What is the insertion of the frontal and occipital belly of occipitofrontalis ?

Answer 25

Frontal belly - subcutaneous tissue of eyebrows and forehead. Occipital belly - epicranial aponeurosis.

Question 26

What is the action of the frontal and occipital belly of occipitofrontalis ?

Answer 26

Frontal belly - wrinkle forehead and raise eyebrows. Occipital belly - retract scalp.

Question 27

What is the innervation of the frontal and occipital belly of occipitofrontalis ?

Answer 27

Frontal belly - temporal branch of facial nerve. Occipital belly - posterior auricular branch of facial nerve.

Question 28

What is the innervation of the obicularis oculi ?

Answer 28

Temporal and zygomatic branches of facial nerve.

Question 29

What is the action of the obicularis oculi ?

Answer 29

Keep eye lubricated and protect eye from injury by spreading lacrimal fluid.

Question 30

Two parts of obicularis oculi ?

Answer 30

Orbital (outermost) and palpebral (innermost).

Question 31

What are the two sphincter muscles of the face ?

Answer 31

Obicularis oculi and obicularis oris.

Question 32

What is the innervation of obicularis oris ?

Answer 32

Buccal and marginal mandibular branch of facial nerve.

Question 33

What is the origin of obicularis oris ?

Answer 33

Buccinator and medial surface of maxilla and mandible.

Question 34

What is the insertion of obicularis oris ?

Answer 34

Mucous membranes of the lips.

Question 35

What is the innervation of buccinator ?

Answer 35

Buccal branch of facial nerve.

Question 36

What is the origin of buccinator ?

Answer 36

Posterior of alveolar processes of maxilla. Pterygomandibular raphe.

Question 37

What is the insertion of buccinator ?

Answer 37

Fibres merge with obicularis oris.

Question 38

What is the function of buccinator ?

Answer 38

Keep food on occlusal surfaces of the teeth alongside the tongue.

Question 39

What lies posterior to the buccinator ?

Answer 39

Buccal fat pad.

Question 40

Where does the parotid duct lie ?

Answer 40

Superficial to buccinator. Pierces buccinator and buccal fat pad into oral cavity at 2nd molar tooth.

Question 41

What is the origin of platysma ?

Answer 41

Subcutaneous tissue of infra and supra clavicular tissue.

Question 42

What is the insertion of platysma ?

Answer 42

Base of mandible.

Question 43

What is the innervation of platysma ?

Answer 43

Cervical branch of facial nerve.

Question 44

What is the function of platysma ?

Answer 44

Depress the mandible.

Question 45

What is the function of dilator muscles of the face ?

Answer 45

Widen mouth, lift or depress corners.

Question 46

What are the 5 terminal branches of the facial nerve (CNVII) ?

Answer 46

Temporal. Zygomatic. Buccal. Marginal mandibular. Cervical.

Question 47

What are the early branches of the facial nerve (CNVII) ?

Answer 47

Greater, lesser and external petrosal. Nerve to stapedius. Posterior digastric. Posterior auricular.

Question 48

What are the two major arteries which supply the face ?

Answer 48

Internal carotid (ophthalmic branch). External carotid.

Question 49

What are the two major veins which drain the face ?

Answer 49

Facial vein (and transverse facial). Retromandibular.

Question 50

What two veins unite to become the EJV ?

Answer 50

Retromandibular and facial vein.

Question 51

What vein does the posterior auricular vein drain directly into ?

Answer 51

EJV.

Question 52

What is significant about the blood flow in the danger triangle ?

Answer 52

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).

Question 53

What vein do the veins deep to the danger triangle drain into ?

Answer 53

Cavernous sinus.