Face and Parotid Region

Question 1

What are the 5 layers of the scalp?

Answer 1

• S= Skin
o thin EXCEPT in occipital region; contains sweat & sebaceous glands, hair follicles; abundant arterial supply, venous drainage, & lymphatic drainage
• C= Connective tissue
o thick, dense, richly vascularized & innervated; subcutaneous layer
• A= Aponeurosis (EPICRANIAL APONEUROSIS)
o strong tendinous sheet covering clavaria; serves as attachment for muscles of the forehead (frontalis), occiput (occipitalis), & temporal (temporalis) muscles
• L= Loose connective/areolar tissue
o sponge-like layer that allows free movement of scalp proper (first 3 layers) over the underlying calvaria; potential spaces that may distend with fluid as a result of injury/infection
• P= Pericranium (periosteum)
o dense layer of connective tissue that forms external periosteum of neurocranium

Question 2

What is the danger layer of scalp?

Answer 2

• SCALP INFECTIONS
o LOOSE CONNECTIVE TISSUE LAYER (4th Layer)= Danger Layer of the scalp due to ease of which pus or blood can spread within it

Question 3

Where can infections spread in the scalp? Where are they prevented from spreading and why?

Answer 3

o Prevented from spreading to neck – due to attachments of occipitalis muscles to occipital bone & mastoid portions of temporal bone
o Prevented from spreading laterally – due to epicranial aponeurosis (3rd layer) beins continuous with temporal fascia at superior temporal line
o Can spread to eyelids & root of nose – due to lack of attachment of frontalis muscle to bone (only attaches to skin & subcutaneous tissue)
o Can spread to cranial cavity & meninges – via emissary veins

Question 4

What arteries supply the scalp?

Answer 4

•	Arterial Supply from ECA:
o	Occipital
o	Posterior Auricular
o	Superficial Temporal
•	Arterial Supply from ICA:
•	SUPRAORBITAL ARTERY emerges from supraorbital foramen to supply the forehead
o	terminal branch of ophthalmic artery
•	SUPRATROCHLEAR ARTERY emerges from supratrochlear notch to supply medial forehead
o	terminal branch of opthalmic artery

Question 5

What nerves innervate the scalp with sensory?

Answer 5

-V1 does the anterior/superior part of the scalp.
-Great auricular n.
Skin over parotid region
Parotid sheath
-Lesser occipital n.
Supplies scalp posterior to auricle
-Greater occipital n.
Supplies scalp over occipital region

Question 6

What are the emissary veins & what is their clinical relevance?

Answer 6

• EMISSARY VEINS= connect the dural venous sinuses with veins outside of the cranium
o flow is typically in the direction AWAY from the brain
♣ BUT these veins do NOT have valves & are thus capable of BIDIRECTIONAL FLOW
o transverse/emissary foramina (variable in number & size)
o Clinical Relevance= potential sites for spread of infection from the scalp into cranial cavity & meninges

Question 7

What are the 3 divisions of the trigeminal nerve (CN V)? Be able to indicate their pattern of sensory distribution on a diagram. What are the major branches of each of the 3 divisions? How does each of these trigeminal branches (through what foramen etc) access the face

Answer 7

• CN V1= OPHTHALMIC NERVE
o Supraorbital Nerve branches directly off frontal nerve (larger, lateral); supplies skin of middle portion of superior eyelid & skin of lateral forehead & scalp; emerges from SUPRAORBITAL FORAMEN
o Supratrochlear Nerve branches directly off frontal nerve (smaller, more medial); supplies skin of medial portion of superior eyelid & skin of medial forehead; emerges from SUPRATROCHLEAR NOTCH
• CN V2= MAXILLARY NERVE
o Infraorbital Nerve terminal branch of CN V2 that emerges onto the face via the INFRORBITAL FORAMEN; supplies skin of the cheek, lateral nose, skin, & oral mucosa of upper lip
o Zygomaticofacial Nerve branches directly off Zygomatic Nerve; supplies skin on prominence of cheek
o Zygomaticotemporal Nerve branches directly off Zygomatic Nerve; supplies skin anterior to temporal fossa

• CN V3= MANDIBULAR NERVE
o Auriculotemporal Nerve supplies skin anterior to auricle & posterior 2/3 of temporal region
o (Long) Buccal Nerve supplies skin & oral mucosa of cheek & buccal gingiva of mandibular molars
o Mental Nerve supplies skin of chin & oral mucosa of lower lip; emerges from mental foramen along with mental artery

Question 8

How would you test each of the divisions of the trigeminal nerve?

Answer 8

• SENSORY FUNCTION:
• With patient’s eyes closed:
o test touch: lightly run cotton swab/tissue across each side of the face in the upper, middle, & lower regions of the face
♣ ask patient if they feel it & if the sensation feels the same on both sides
o test pain: gently prick patient with a safety pin on one side & then the other of each of the 3 divisions, asking if the sensation feels the same on each side
♣ also sharp vs. dull sensation
o corneal reflex: touch eyeball & observe for a blink
• MOTOR FUNCTION:
o ask patient to clench jaw & palpate masseter & temporal muscles for asymmetry

Question 9

What is trigeminal neuralgia?

Answer 9

• TRIGEMINAL NEURALGIA= sensory disorder of sensory root of CN V characterized by sudden attacks of excruciating, lightening-like jabs of facial pain (paroxysm)
o maxillary nerve (CN V2) is most frequently involved mandibular nerve (CN V3) ophthalmic nerve (CN V1) least frequently involved
o pain often initiated by touching a sensitive trigger zone of the skin

Question 10

What are the 5 branches of the facial nerve (CN VII)? What is the function of these facial nerve branches?

Answer 10

• Facial Nerve (CN VII)= motor innervation to the muscles of facial expression; branches emerge from parotid plexus
o Temporal
o Zygomatic superior to parotid duct; inferior to orbit
o Buccal inferior to parotid duct; external to buccinators (supplying it)
o Marginal Mandibular
o Cervical passes inferiorly (with retromandibular vein) to supply the platysma

Question 11

Through what bony opening does the facial nerve exit the cranial cavity? The base of the skull?

Answer 11

• CN VII exits the cranial cavity through the INTERNAL ACOUSTIC MEATUS runs through Facial Canal exits the base of the skull through the STYLOMASTOID FORAMEN

Question 12

What muscles are supplied with motor innervation just after CN VII exits the skull?

Answer 12

• Posterior auricular nerve (which also innervates occipitalis)
• Nerve to posterior belly of digastric
• Nerve to stylohyoid

Question 13

What are the 2 major sphincter muscles of facial expression?

Answer 13

• Orbicularis Oculi sphincter of they eye
o closes eye
• Orbicularis Ori sphincter of the mouth
o Closes mouth; compresses teeth against lips; protrusion of lips (kissing)

Question 14

Which branch of the facial nerve would be responsible for innervating each of the two sphincter muscles?

Answer 14

• Orbicularis Oculi sphincter of they eye
o MOTOR INNERVATION VIA TEMPORAL & ZYGOMATIC BRANCHES OF CN VII (FACIAL NERVE)
• Orbicularis Ori sphincter of the mouth
o MOTOR INNERVATION VIA BUCCAL BRANCH OF CN VII (FACIAL NERVE)

Question 15

List the muscles associated with lifting & depressing the corners of the mouth

Answer 15

• ELEVATORS:
o Zygomaticus Major Motor Innervation via BUCCAL BRANCH OF CN VII
o Levator Anguli Oris Motor Innervation via BUCCAL BRANCH OF CN VII
• DEPRESSOR:
o Depressor Anguli OrisMotor Innervation via MANDIBULAR & BUCCAL BRANCHES OF CN VII

Question 16

What function does the platysma play?

Answer 16

• PLATYSMA= depresses mandibile (against resistance); tenses skin of inferior face & neck (conveying tension & stress)

Question 17

What specific branch of facial nerve innervates the platysma?

Answer 17

Motor innervation for platysma is from the CERVICAL branch of CN VII

Question 18

What is the function of the buccinator?

Answer 18

• BUCCINATOR= presses cheek against molar teeth; works with tongue to keep food between occlusal surfaces of & out of oral vestibule; resists distension (when blowing, whistling, or sucking)

Question 19

What is the innervation of the buccinators?

Answer 19

They are innervated by the BUCCAL branch of CN VII

Question 20

What is the function of the frontalis muscle?

Answer 20

• FRONTALIS MUSCLE= raises eyebrows & wrinkles forehead; protracts scalp

Question 21

What is the specific innervation of the frontalis muscle?

Answer 21

• FRONTALIS Motor Innervation via TEMPORAL BRANCH OF CN VII

Question 22

Where does cutaneous sensory innervation above the frontalis muscle arise from?

Answer 22

• SUPRORBITAL & SUPRATROCHLEAR NERVES

o branches of CN V1 (from Frontal Nerve off of Ophthalmic Nerve)

Question 23

What is Bell’s Palsy? How does an individual affected with Bell’s Palsy appear?

Answer 23

• BELL’S PALSY= paralysis of muscles of facial expression due to injury to the facial nerve or its branches
o presents as unilateral FACIAL DROOPING
o affects facial nerve near the stylomastoid foramen such that patient loses ipsilateral motor innervation of upper & lower muscles of facial expression
♣ vs. stroke upper muscles of facial expression left intact; patient can lift brow (frontalis)

Question 24

Trace the origin & course of the facial artery & facial vein. What are the branches of each?

Answer 24

• FACIAL ARTERY: Branch of ECA; ascends deep to submandibular gland winds aroun inferior edge of mandible enters face
o Branches:
♣ Inferior Labial Artery runs medially in lower lip
♣ Superior Labial Artery runs medially in upper lip
♣ Lateral Nasal Artery runs medially to side of nose
♣ Angular Artery terminal branch; becomes angular artery when facial artery passes wing/ala of nose
• FACIAL VEIN: terminates in INTERNAL JUGULAR VEIN
o communicates with pterygoid plexus of veins via deep facial vein
o communicates with cavernous sinus via superior or inferior ophthalmic vein
o receives drainage from angular vein, nasal veins, & labial veins

Question 25

How can an infection track from the face to the cranial cavity?

Answer 25

• Spread of Infection to Cranium: **blood from medial angle of the eye, nose, & lips usually rains inferiorly into the facial vein; HOWEVER, because facial veins are VALVELESS blood may pass superiorly into the superior ophthalmic vein & enter the cavernous sinue
♣ VALVELESS= very little resistance to spread of infection & blood clots

Question 26

What is a cavernous sinus thrombosis?

Answer 26

• THROMBOPHLEBITIS of CAVERNOUS SINUS: infected thrombus can enter the cranial cavity by ascending the facial vein to angular vein to ophthalmic veins to cavernous sinus

Question 27

How is the retromandibular vein formed? Into what vessels does it drain?

Answer 27

• Retromandibular Vein= formed by union of superficial temporal vein & maxillary vein; superficial to ECA but deep to facial nerve
o runs posterior (retro) to the ramus of the mandible WITHIN the PAROTID GLAND
o ANTERIOR BRANCH joins FACIAL VEIN (eventually drains into IJV)
o POSTERIOR BRANCH joins POSTERIOR AURICULAR VEIN to form EXTERNAL JUGULAR VEIN

Question 28

What is the function of the parotid gland? Trace the parasympathetic & sympathetic pathways for the parotid gland from CNS to target

Answer 28

• PAROTID GLAND= largest salivary gland enclosed by tough parotid sheath (continuous with deep investing fascia of neck)
o CN VII runs through, but DOES NOT innervate the parotid gland
o empties saliva through parotid duct
• SENSORY INNERVATION= parotid sheath supplied by Great Auricular Nerve (C2, C3)
• Parasympathetic Innervation to the Parotid Gland
o CN IX (Glossopharyngeal) via the lesser petrosal nerve carrying PREganglionic PARAsympathetic fibers that synapse in the OTIC GANGLION
o POSTganglionic PARAsympathetic fibers hitch a ride on the AURICULOTEMPORAL NERVE (branch of CN V3)
• Sympathetic Innervation to the Parotid Gland
o Innervation is via the carotid plexus via branches of ECA