Lecture 1: Face/Parotid Region

Question 1

Mylohyoid

Answer 1

Mylohyoid line of mandible&raquo_space; hyoid bone

N to mylohyoid (CNV3)

Question 2

Geniohyoid (deep to mylohyoid)

Answer 2

Mental spine of mandible&raquo_space; hyoid

Hypoglossal n

Question 3

Digastric

Answer 3

ANTERIOR
Digastric fossa of mandible
N to mylohyoid

POSTERIOR
Mastoid notch
Facial n

Meet at intermediate tendon to attach on hyoid.

Question 4

Stylohyoid

Answer 4

Styloid process of TEMPORAL bone» hyoid

Facial n

Question 5

Hypoglossal n

Answer 5

Leaves skull via hypoglossal canal –> neck, below angle of mandible
- Crosses ECA and lingual a

Deep to mylohyoid m to reach tongue

Question 6

Muscles of facial expression

Answer 6

subcutaneous tissue of anterior/posterior scalp, face and neck

• Attach to bone or fascia and pull the skin
• All develop from mesoderm in second pharyngeal arches

Question 7

Clinical note: facial swelling

Answer 7

Subcutaneous tissue between cutaneous attachments of facial muscles = loose -> enables fluid/blood to accumulate

Question 8

Occipitofrontalis (occipital)

Answer 8

Attaches to superior nuchal line
action: contraction –> refracts scalp
Innervation: posterior auricular branch of facial n

SHARE TENDON: epicranial aponeurosis

Question 9

Occipitofrontalis (frontal)

Answer 9

skin and subcutaneous tissue of eyebrows and forehead
Action: contraction –> protracts scalp
Inn: Temporal branches of facial n

Question 10

Scalp

Answer 10

Skin: thin except in occipital region, many sweat/sebaceous glands and hair follicles

CT: thick vascularized subcutaneous layer, cutaneous nerves

epicranial Aponeurosis: broad, strong, tendinous sheet – attachment for occipitofrontalis muscle

Loose areolar tissue

Pericranium: dense layer of CT forms external periosteum of neurocranium

Question 11

Orbicularis Oris

Answer 11

Encircles mouth within lips, controlling entry/exit through oral fissure
*speech

Attachments:

• Medial maxilla and mandible, angle of mouth
• Inserts within mucous membrane of lips

Action:
Tonic-closes mouth
Phasic-compresses and protrudes lips

Innervation:
Buccal and marginal mandibular branches of facial n

Question 12

Buccinator

Answer 12

Laterally -alveolar processes of maxillae and mandible to pterygomandibular raphe (thickening of buccopharyngeal fascia)
-blend w/ orbiculares oris

deeper/more medial, deep to mandible so it’s more closely related to buccal mucosa than skin of face

• buccal branch of facial n
• Keeps cheek taut, prevents it from folding/being injured during chewing
• Helps cheeks resist forces generated by whistling and sucking

Question 13

Tonus of orbicularis oris and buccinator

Answer 13

Compress cheeks/lips against teeth/gums

+tongue, keep food between occlusal surfaces during mastication

Question 14

Mobius syndrome

Answer 14

CN6 and 7 (asymmetry of facial expression and severe tooth decay)

Question 15

Platysma

Answer 15

Subcutaneous tissue of neck

Attachments:

• subcutaneous tissue of supra- and infraclavicular regions
• Base of mandible, skin of cheek, angle of mouth and orbicularis oris

ACTION:
-superior attachment: tenses skin, producing vertical skin ridges
INFERIOR: helps depress mandible and draw corners of mouth inferiorly, as in a grimace

Question 16

Levator anguli oris

Answer 16

canine fossa of maxilla immediately inferior to infraorbital foramen
-Inserts into angle of mouth, blends with fibers of orbicularis oris
Action: lifts angles of mouth
Innervation: buccal branch of facial n

Question 17

Depressor angluli oris

Answer 17

Triangular muscle, originates from external oblique line of mandible
- Ascending fibers converge at apex to insert into angle of mouth from below and blend w/ fibers of orbicularis oris
Action: pulls angles of mouth downward
Innervation: marg and branch of facial n

Question 18

Zygomaticus major

Answer 18

Arises from LATERAL aspect of zygomatic bone
Downward/medial to insert into angle of mouth and blend with orbicularis oris
Action: draws angle of mouth upward and backward
Buccal branch of facial n (and some fibers from zygomatic branch)

Question 19

Zygomatic minor

Answer 19

Anterior aspect of zygomatic bone
Downward and medial to insert into skin of upper lip

action: elevation of upper lip
buccal branch of facial n

Question 20

Risorius

Answer 20

Arises from parotid and masseteric fascia, and buccal skin
- inserts transversely into angle of mouth
ACTION: retracts angle of mouth posteriorly
Innervation: mandibular and/or buccal branch of facial n (highly variable)

Question 21

Levator labii superioris

Answer 21

Originates from inferior orbital margin
Inserts into upper lip

Action: raise upper lip
Innervation: buccal branch of facial n

Question 22

Depressor labii inferioris

Answer 22

Arises from lowest portion of oblique line of mandible
Inserts into skin of lower lip
Action: depresses lower lip
Innervation: marginal mandibular branch of facial n

Question 23

Orbicularis oculi

Answer 23

Originates from medial orbital margin and lacrimal bone
Inserts into skin around orbit

2 parts: palpebral (blinking), orbital (forceful closing)

Innervation: temporal and zygomatic branches of facial n

Question 24

Corrugator supercilli

Answer 24

-Medial end of superciliary arch (ridge superior to supraorbital margin)
-Skin overlying superciliary arch and supraorbital margin
Action: draws eyebrows medially and inferiorly
Innervation: temporal branch of facial n

Question 25

Mentalis

Answer 25

``` Attachments: -body of mandible anterior to roots of inferior incisors -skin of chin Action: -elevates/protrudes lower lip Innervation: -marg mand branch of facial n ```

Question 26

Clin app: Class II bites

Answer 26

smal mandible cf to maxilla, mentalis = hyperactive when lips closed. dimpling of chin = hyperactive mentalist muscles

Question 27

Levvator labi superioris alaeque nasi and alar part of nasalis

Answer 27

Attachments: - Frontal processes of maxilla - Alar cartilage Action: -Depresses ala laterally (dilates nasal aperture) Inn: buccal branch of facial nw

Question 28

Clinical correlation

Answer 28

True nasal breathers flare nostrils distinctly Habitual mouth breathing, caused by chronic nasal obstruction diminishes/eliminates ability to flare nostrils - Children who are chronic mouth breathers dev improper bite because alignment of teeth maintained by normal pds of occlusions and labial closure

Question 29

Parotid gland

Answer 29

Enclosed within tough fascial capsule, PAROTID SHEATH, derived from investing layer of deep cervical fascia - Irregular shape because area occupied by gland, parotid bed, anteroinferior to EAM, where it's wedged between ramus of mandible and mastoid process - Fatty tissue between lobes of gland = flexibility for motion of mandible - Apex of parotid gland posterior to angle of mandible, and its base related to zygomatic arch

Question 30

Parotid duct

Answer 30

Passes horizontally from anterior edge of gland and at anterior border of masseter, duct turns medially, pierces buccinator and enters oral cavity through small orifice opposite 2nd maxillary molar Embedded within gland (superficial to deep): 1. Parotid plexus of facial n (CN7) + branches 2. Retromandibular vein 3. ECA On parotid sheath and within gland = parotid lymph nodes

Question 31

Parotid plexus

Answer 31

Temperofacial and cervicofacial trunks of facial n give rise to parotid plexus - Variations exist but 5 terminal branches emerge as follows: * Temperofacial trunk: gives rise to temporal, zygomatic and buccal branches * Cervicofacial trunk: buccal, mandibular and cervical branches