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Lecture 21b – Muscle of Facial Expression and Mastication
Boundaries of Facial expression muscles
 Superior
o Superciliary arches
 Inferior
o Lower edge of mandible
 Posterior
o Ears
Two fundamental functions of the face
 Support of seeing, smelling, and eating
 Communication
Location
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The muscles of facial expression are located in the subcutaneous tissue of the scalp, face, and neck
In particular, they are concentrated around the orifices (eyes, nose, mouth)
Modiolus
• a mobile fibromuscular mass near the commissures of the lips
Palpable
• It represents the convergence of up to nine muscles
• It is important in integrating local muscular activity
Orbicularis Oculi
• The main action of orbicularis oculi is to close the eyelids
• Closure of the lids occurs in a lateral to medial direction
This assists in spreading tears (lacrimal fluid)
Orbicularis Oris
• The orbicularis oris rims the lips
• Its action is to squeeze the lips together
Speaking
Keeping food in oral cavity
Buccinator
• The buccinator is a powerful muscle forming the substance of the cheek
• It presses the cheek against the teeth
Expels air while speaking
Keep food between teeth
Zygomaticus Major
• Zygomaticus major elevates the labial commissures
Bilateral
Smile
Unilateral
Sneer
Sensory
• Sensory innervation to the face is provided by all three divisions of CN V
Opthalmic nerve (V1)
Maxillary nerve (V2)
Mandibular nerve (V3)
Distal Course and Branches
CN VII enters the internal acoustic meatus in the cranium and runs the longest interosseous course of any cranial nerve
It exits the stylomastoid foramen, enters the parotid gland and forms the parotid plexus
Plexus gives rise to five branches named after the regions of the face they supply
• 5 Branches: Temporal, zygomatic, buccal, marginal mandibular, cervical
• Ten zebras bit my chicken
Blood Supply
• Most superficial arteries of the face are branches or derivatives of branches of the external carotid artery
Facial Artery
• The facial artery is the major vessel supplying the face
• It terminates as the angular artery along the side of the nose
• Key branches include the superior and inferior labial arteries
• Course of Facial Artery
• The facial artery arises from the external carotid artery
• Initially it lies deep to the platysma
• It passes onto the face along the inferior border of the mandible just anterior to the masseter
• Pulse
Superficial Temporal
• The superficial temporal artery is the smaller terminal branch of the external carotid
• Temporal pulse
• Its key branch is the transverse facial artery
• Arises within parotid gland
Veins
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Most external facial veins accompany the arteries of the face
The facial veins are the major component
Like veins elsewhere they have abundant anastamoses
Drainage by alternate route during compression
Triangular Danger Zone
• This zone is marked by connections from the facial veins to the dural venous sinuses
• The facial veins are valveless
• Higher risk of infection spread
Lymphatic Drainage
• The forehead and anterior part of the face drain to the submandibular nodes
• Lateral parts of the face drain to parotid nodes
• Lower lip and chin drain to submental nodes
Muscles of mastication
• The temporal fossa is superior to the zygomatic arch
• The infratemporal fossa is inferior to the zygomatic arch
TMJ
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A synovial joint with articulation occurring between the head of the mandible and the mandibular fossa of the temporal bone
Unusual in that its articular surfaces are lined with fibrocartilage (rather than hyaline cartilage)
Modified hinge joint permitting varied movement
Gliding
Hinge movement
Elevation/depression
Some rotation (pivoting)
Joint Capsule of TMJ
o Understood in two parts
o The superior cavity is surrounded by a loose capsule*
o Permits physiological joint dislocation
o The lower joint capsule is tight*
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o The superior articular cavity permits the gliding movements of protrusion and retraction
o The inferior articular cavity permits elevation and depression
Ligaments
o Lateral ligament
o Part of joint capsule
o Sphenomandibular (extrinsic)
o Stylomandibular (extrinsic)
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Closed mouth to 15° depression of the mandible, only pure hinge action (rotation) occurs (head of mandible remains in fossa)
Wider than about one inch (~15°) rotation must be combined with gliding of the mandibular heads
Mandibular heads glide forward onto, and inferior to, the articular tubercle
Superior articular cavity widens
Chewing
• Pure vertical movement of the teeth is ineffective in crushing food
Lateral movement required
• Most grinding movement involves horizontal rotation about one condyle along with gliding movement of the other condyle
Resting condyle
• Pivots, or rotates horizontally (on a vertical axis through the head)
Swinging condyle
• Swings (glides) anteriorly
 Dislocated anteriorly - Mandible remains depressed and person is unable to close mouth
 Posterior dislocation is rare due to postglenoid tubercle and strong lateral ligament
 Excessive muscular contraction or a sideways blow
Masseter - mashing and pounding food between the molars
 zygomatic arch  masseteric tuberosity of mandibular angle
 masseteric branch of CN V3
 Elevate and protrude “jaw”
Temporalis - drives the front of the lower jaw into the front of the upper jaw bringing the incisors into occlusion
 Temporal fossa  coronoid process of mandible
 Temporal branch of CN V3
 Elevates and retracts “jaw”. Unliateral contraction
Medial Pterygoid – “principal muscle causing lateral movement of the jaw”
chewing/grinding
 Pterygoid fossa and lateral plate of pterygoid process medial surface of mandibular angle (pterygoid tuberosity)
 Medial pterygoid branch of CN V3
 Elevates the mandible
Lateral Pterygoid - chewing/grinding
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Superior part: infratemporal crest (greater wing of sphenoid bone) & inferior part: outer surface of pterygoid process  superior
part: articular disk of tmj joint & inferior part: condylar process of the mandible
Lateral condylar branch of CN V3
Bilateral contraction – initiates mouth opening by protruding the mandible and moving the articular disk forward. Unilateral
contraction – elevates the mandible to the opposite side during mastication
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Blood Supply
• The maxillary artery is the larger of the two terminal branches of the external carotid
Its origin is deep to the ramus of the mandible
• The artery has a wide distribution
Mandible, maxilla, muscles of mastication, nose, palate, dura mater
• Three parts based on relation to lateral pterygoid muscle
First (mandibular)
Second (pterygoid)
Key for muscles of mastication
Third (pterygopalatine)
Lecture 22 – Cranial Osteology
What is in each fossa?
• Anterior
Cribriform plate—CN I
• Middle
Optic canal—CN II and ophthalmic artery
Superior orbital fissure—CN III, IV, V1, VI, ophthalmic veins
Foramen rotundum—CN V2
Foramen ovale—CN V3
Foramen spinosum—middle meningeal artery (below pterion)
Foramen lacerum—nothing of consequence….
• Posterior
Internal auditory (acoustic) meatus—CN VII, VIII, labyrinthine artery
Jugular foramen—CN IX, X, XI and superior jugular bulb—origin of internal jugular vein (and inferior petrosal sinus)
Hypoglossal canal—CN XII
Foramen magnum—spinal cord, meninges, CSF, spinal arteries / veins, vertebral arteries, …….
Lecture 23 – Nasal Cavity
Several key functions of nose
 Modifies inspired air
 Olfaction
 Resonance
 Drainage route for mucus and lacrimal fluid
Two general parts (external nose and nasal cavity)
• Anterior edge of the external nose consists of a dorsum, between root and apex
• The inferior surface of the nose is pierced by two ellipsoidal openings known as the
nares (nostrils)
» The nares are bound laterally by the alae
The vestibule is the area just inside the nostril
 vibrissae (VI-bri-see) are located near the junction of skin and mucous membrane
• Filter dust particles
The cartilaginous part of the (external) nose consists of five main cartilages
• Cartilage permits nares to flare and makes them less susceptible to injury
Two lateral cartilages
Two alar cartilages
One septal cartilage
The alae also contain dense (fibrofatty) connective tissue
• The nasal group of muscles of facial expression generally acts to modify respiration
Nasalis (nay-ZAY-lis) and depressor septi nasi (SEPT-eye NAYZ-eye)
Widening of nares prior to inhalation
Levator labii superioris alaequae nasi
(lay-BEE-eye; AY-lee-qwee)
Secondary dilator of nares
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Bony part (external)
Piriform (anterior nasal) aperture
Nasal bone
Frontal processes of the maxillae
Nasal process of the frontal bone
Bony parts of nasal septum
• !Severe septal displacement may obstruct breathing*
• Direct blows to the nose may fracture cribriform plate of ethmoid bone
Nerve supply
• Cutaneous innervation to the external nose is supplied by branches of two nerves
Opthalmic nerve (V1)
Infratrochlear nerve (@root of nose)
External nasal (between dorsum and apex)
Maxillary nerve (V2)
Infraorbital (across upper cheek, lower eyelid and ala of nares)
Blood Supply
• Blood supply to nasal skin can be divided into two general areas
Lateral aspects and dorsum
Branches of ophthalmic and maxillary arteries
Alae and lower part of sept
Branches of facial artery
Nasal Cavity - an irregular space between roof of mouth and cranial base.
• Opens anteriorly through the nares
• Opens posteriorly into the nasopharynx through the choanae (KO-uh-nee)
• Each nasal cavity has a roof, floor, medial and lateral walls
• Roof – subdivided into frontonasal, ethmoidal, and spenoidal
• Floor – Two bony groups
• Palatine processes of maxilla
• Horizontal plates of the palatine bone
• Medial Wall – nasal septum (bony and cartilaginous parts)
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• Bony part = ethmoid (perpendicularly and superior) + vomer (perpendicular and
inferior)
• Lateral Wall
• Maxilla
• Lacrimal bone
• Ethmoid bone
• Inferior concha (CON-ka)
• Perpendicular plate of the palatine bone
Nasal cavity is lined with mucosa
• Vestibule is lined with skin
• Two areas of nasal mucosa
• Olfactory mucosa
• Respiratory mucosa
Nasal Conchae
• Conchae (CON-kee), or turbinates, are curtain-like projections of the lateral wall
• Superior and middle  ethmoid bone
• Inferior concha (CON-ka) is a separate bone articulating with the maxilla and palatine
bones
• Air Passages
• Underlying each of the conchae is a recess, or meatus (passage)
• Divided into a series of passages
• This forces inspired air to travel in a regular pattern over the largest possible
area of mucosa
• More warming, more trapping of particles
Blood Supply
• Three arteries off of external carotid supply the nastal cavity
• Opthalmic
• Maxillary
• Facial
• Five named branches off the three main arteries
• Anterior ethmoidal (from opt)
• Posterior ethmoidal (from opt)
• Sphenopalatine (from maxillary)
• Greater palatine (from maxillary)
• Septal branch of superior labial artery (from facial)
Most nosebleeds begin in anterior 1/3 of the nose in Kiesselbach’s area.
• Anastomoses of all 5 arteries supplying the nose
Best sites for ligation of a severe nosebleed
 External carotid, maxillary, or a/p ethmoidal
Venous Drainage
• Submucosal venous plexus
exists in most of the septum and lateral walls of the nasal cavity
Cycles of engorgement alternating between cavities
• Rehydration
• Veins
Veins draining the nasal cavities generally follow the arteries
Some venous blood drains into the dural venous sinuses
• Potential for spread of infection
Infection
• Vascular mucous membranes swell readily in response to infection
Rhinitis
• May may spread to various adjacent areas
Anterior cranial fossa via cribriform plate
Lacrimal apparatus and ocular conjunctiva via nasolacrimal duct
Ear via auditory tube
Lymphatic Drainage
• Drains in two directions from the nasal cavity
Anterior region
Drainage onto face and into submandibular nodes
Posterior region and paranasal sinuses
Upper deep cervical nodes
Sinuses
• Paranasal sinuses are air-filled extensions of the nasal cavity
• Four, bilateral sinuses named according to the bone in which they are located
Frontal, ethmoidal, sphenoidal, and maxillary
• Lighten the skull and improve speech resonance
• Mucosa of all sinuses is continuous with the respiratory mucosa of the nasal cavity
Potential for spread of infection (sinusitis)
• All sinuses open into the lateral wall of the nasal cavity by small apertures
• All sinuses are innervated by branches of the trigeminal nerve
• Frontal sinuses
more prominent in men
• Ethmoidal
**up to 18 cavities
Paper thin orbital plate separates the ethmoid cells from orbit
• infection risk
• Spenoid
Makes body fragile.
Pituitary gland, internal carotid a. adjacent.
• Maxillary
Largest of the paranasal sinuses
Occupy body of maxillae
Close relationship to the maxillary molars
Dental procedures can drive roots of the teeth into the sinus
• Openings
• Frontal sinuses drain through frontonasal ducts into the middle meatus
• Ethmoidal cells drain into the middle and superior meatus
• Sphenoid sinuses open into the sphenoethmoidal recesses
• Maxillary sinuses drain into the middle meatus via the maxillary ostium
Ostiomeatal Complex
• Refers to an area serving as a common pathway for drainage of the frontal, ethmoidal, and
maxillary sinuses
• Inflammation (sinusitis) of ethmoid cells can lead to blockage of
Ethmoidal sinuses present at birth
• Most common location of sinusitis in children
Lecture 23 – Oral Cavity and Pharynx
Oral Cavity
• Lined with mucosa
• Bony skeleton
Mandible (Now with teeth!)
Maxilla (Teeth here too!!)
Hyoid (no teeth but great horns!) [not as good as Satchmo…..]
• Walls and posterior part all soft tissue
• Muscular walls / floor aid in mastication and deglutition
Lateral Walls
• Mucosa—lingual and buccal
• Buccinator muscle
• Mandible & mastication mm
• Facial expression mm
• Parotid gland
• Facial nerve
• Skin
Floor
• Geniohyoid (C1)
• Mylohyoid (CN V)
Roof
• Palate (which is the floor of the nasal cavity….)
• Anterior—hard palate, mucosa covered
o bony structure
• Posterior—soft palate, mucosa covered,
o muscular structure
Soft Palate
• 4 paired muscles
• 1 unpaired muscle
• Tensor veli palatini (CN V) **
• Levator veli palatini (CN X)
• Palatopharyngeus (CN X)
• Palatoglossus (CN X) not shown
• Musculus uvulae (CN X)
• Sensory innervation CN V2
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• Medial pterygoid plate—”hamulus”. Changes the direction of tensor veli palatini action
Tooth Parts
Tongue
• Extrinsic (4) muscles—change position of tongue (mostly)
• Intrinsic (4) muscles—change shape of tongue (mostly)
• Multiple cranial nerves—V, VII, IX, X, XII innervate the tongue
• Essential for mastication and deglutition
Genioglossus Hyoglossus Styloglossus
Intrinsic Muscles of tongue
• Longitudinal (superior & inferior)
• Vertical
• Transverse
Blood Supply
Nerve Supply
• Via (5) different CNs
Palatoglossus (not shown)
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Salivary Glands
• 3 pairs of glands (parotid, submandibular, and sublingual)
• Each produces a different type of saliva…..
• Parotid = ectoderm
• Submandibular and sublingual = endoderm
• Parasympathetic secretory
• innervation from CN VII & CN IX
• Sublingual – multiple small ducts
• Submandibular – single large duct “sublingual caruncle”
Pharynx
• Muscular tube posterior to the nasal and oral cavities
• Path for air and sustenance
• Entrance = “isthmus of the fauces”
• 3 subdivisions
o “naso” – posterior to choanae and soft palate
o “oro” – posterior to oral cavity
o “laryngo” – site of split into airway and alimentary canal
• Pharynx layers
o Inside out:
 Mucosa—secretory
 Submucosa
 Pharyngobasilar fascia
 Fills in the gaps between the various muscles
 Muscle layer
 Constrictors are internal to the longitudinal mm
 Buccopharyngeal fascia
 Blends with pretracheal layer of deep cervical fascia
Slide 35-38* for detailed pictures of all three subdivisions
Laryngopharynx
• Larynx is completely surrounded by the pharynx
• Aditus, or opening into the larynx is the beginning of the separate airway
• Epiglottis DOES NOT block this opening when you swallow—just diverts things around the
aditus
Pharynx Muscles 1
• Superior constrictor
Pterygomandibular raphe with buccinator
Pharyngeal raphe , tubercle
• Middle constrictor
Stylohyoid ligament and hyoid bone
Pharyngeal raphe
• Inferior constrictor
Thyroid and cricoid cartilages
Pharyngeal raphe
Pharynx Muscles 1a
• Innervation from “pharyngeal plexus” nerves—motor CN X, sensory CN IX, X, sympathetics
from SCG
• “Nested funnels” act in sequence to squeeze food down into esophagus
• Above SC—Levator veli palatini m
• Between SC & MC—Stylopharyngeus m & CN IX
• Between MC & IC—superior laryngeal nerve & artery
• Below IC—recurrent laryngeal nn
Pharynx Muscles 2
• Longitudinal muscles
• Palatopharyngeus
Lateral surface of hard palate and palatine aponeurosis
Posterior superior border of thyroid cartilage
• Salpingopharyngeus
Cartilage of torus tubarius
Blends with palatopharyngeus
• Stylopharyngeus
Styloid process
Posterior superior border of thyroid cartilage
Pharynx Muscles 2a
• Innervation—pharyngeal plexus of nerves EXCEPT stylopharyngeus—motor & sensory from
CN IX
• Help elevate pharynx & larynx during swallowing or speech
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Lymphatics
• Right upper quadrant drains to right side, left drains to left side
• This has major clinical implications for metastasis of cancer
• Retropharyngeal sup./inf. Deep later cervical nodes  jugular trunk  junction of
subclavian and internal jugular veins