Lecture 1: Face/Parotid Region Flashcards
Mylohyoid
Mylohyoid line of mandible»_space; hyoid bone
N to mylohyoid (CNV3)
Geniohyoid (deep to mylohyoid)
Mental spine of mandible»_space; hyoid
Hypoglossal n
Digastric
ANTERIOR
Digastric fossa of mandible
N to mylohyoid
POSTERIOR
Mastoid notch
Facial n
Meet at intermediate tendon to attach on hyoid.
Stylohyoid
Styloid process of TEMPORAL bone» hyoid
Facial n
Hypoglossal n
Leaves skull via hypoglossal canal –> neck, below angle of mandible
- Crosses ECA and lingual a
Deep to mylohyoid m to reach tongue
Muscles of facial expression
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
Clinical note: facial swelling
Subcutaneous tissue between cutaneous attachments of facial muscles = loose -> enables fluid/blood to accumulate
Occipitofrontalis (occipital)
Attaches to superior nuchal line
action: contraction –> refracts scalp
Innervation: posterior auricular branch of facial n
SHARE TENDON: epicranial aponeurosis
Occipitofrontalis (frontal)
skin and subcutaneous tissue of eyebrows and forehead
Action: contraction –> protracts scalp
Inn: Temporal branches of facial n
Scalp
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
Orbicularis Oris
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
Buccinator
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
Tonus of orbicularis oris and buccinator
Compress cheeks/lips against teeth/gums
+tongue, keep food between occlusal surfaces during mastication
Mobius syndrome
CN6 and 7 (asymmetry of facial expression and severe tooth decay)
Platysma
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
Levator anguli oris
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
Depressor angluli oris
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
Zygomaticus major
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)
Zygomatic minor
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
Risorius
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)
Levator labii superioris
Originates from inferior orbital margin
Inserts into upper lip
Action: raise upper lip
Innervation: buccal branch of facial n
Depressor labii inferioris
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
Orbicularis oculi
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
Corrugator supercilli
-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
Mentalis
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
Clin app: Class II bites
smal mandible cf to maxilla, mentalis = hyperactive when lips closed. dimpling of chin = hyperactive mentalist muscles
Levvator labi superioris alaeque nasi and alar part of nasalis
Attachments:
- Frontal processes of maxilla
- Alar cartilage
Action:
-Depresses ala laterally (dilates nasal aperture)
Inn: buccal branch of facial nw
Clinical correlation
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
Parotid gland
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
Parotid duct
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):
- Parotid plexus of facial n (CN7) + branches
- Retromandibular vein
- ECA
On parotid sheath and within gland = parotid lymph nodes
Parotid plexus
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
