Face and Parotid Region Flashcards
What are the 5 layers of the scalp?
• 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
What is the danger layer of scalp?
• 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
Where can infections spread in the scalp? Where are they prevented from spreading and why?
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
What arteries supply the scalp?
• 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
What nerves innervate the scalp with sensory?
-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
What are the emissary veins & what is their clinical relevance?
• 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
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
• 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
How would you test each of the divisions of the trigeminal nerve?
• 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
What is trigeminal neuralgia?
• 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
What are the 5 branches of the facial nerve (CN VII)? What is the function of these facial nerve branches?
• 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
Through what bony opening does the facial nerve exit the cranial cavity? The base of the skull?
• 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
What muscles are supplied with motor innervation just after CN VII exits the skull?
- Posterior auricular nerve (which also innervates occipitalis)
- Nerve to posterior belly of digastric
- Nerve to stylohyoid
What are the 2 major sphincter muscles of facial expression?
• 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)
Which branch of the facial nerve would be responsible for innervating each of the two sphincter muscles?
• 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)
List the muscles associated with lifting & depressing the corners of the mouth
• 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
What function does the platysma play?
• PLATYSMA= depresses mandibile (against resistance); tenses skin of inferior face & neck (conveying tension & stress)
What specific branch of facial nerve innervates the platysma?
Motor innervation for platysma is from the CERVICAL branch of CN VII
What is the function of the buccinator?
• 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)
What is the innervation of the buccinators?
They are innervated by the BUCCAL branch of CN VII
What is the function of the frontalis muscle?
• FRONTALIS MUSCLE= raises eyebrows & wrinkles forehead; protracts scalp
What is the specific innervation of the frontalis muscle?
• FRONTALIS Motor Innervation via TEMPORAL BRANCH OF CN VII
Where does cutaneous sensory innervation above the frontalis muscle arise from?
• SUPRORBITAL & SUPRATROCHLEAR NERVES
o branches of CN V1 (from Frontal Nerve off of Ophthalmic Nerve)
What is Bell’s Palsy? How does an individual affected with Bell’s Palsy appear?
• 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)
Trace the origin & course of the facial artery & facial vein. What are the branches of each?
• 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
How can an infection track from the face to the cranial cavity?
• 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
What is a cavernous sinus thrombosis?
• 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
How is the retromandibular vein formed? Into what vessels does it drain?
• 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
What is the function of the parotid gland? Trace the parasympathetic & sympathetic pathways for the parotid gland from CNS to target
• 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
