6 Oral Region

STUDYAIMS

At the end of your study, you should be able to:

Understand the regions and boundaries of the oral cavity

Know the major anatomic features of the lips, cheeks, and gingivae Describe the external features of the tongue

Outline the intrinsic and extrinsic muscles of the tongue and their movements Describe the hard and soft palate and their anatomic features

Describe the anatomyof the oral cavityrelated to the soft palate

Know the muscles of the soft palate, their movements, and their innervation Outline the vascular supplyand innervation of the palate

Describe the parotid, submandibular, and sublingual salivaryglands, including their vascular supplyand innervation

36 / 425

GUIDE

Head and Neck: Oral Region

Oral Cavity

page 30 page 31

Divided into two regions

Oral vestibule

Narrow space between teeth and gingival and lips and cheeks

Size controlled byorbicularis oris, buccinator, risorius, and muscles controlling lips

Contains frenula (singular: frenulum)-midline mucosal folds from upper and lower lips to the gums

Oral cavityproper

Boundaries

Anteriorly: lips

Posteriorly: oropharyngeal isthmus to oropharynx

Roof: hard palate anteriorlyand soft palate posteriorly

Floor: mucosa beneath the tongue

Space occupied bytongue Anatomical features of the lips

Contain

Orbicularis oris muscle, and fibers of levator labii superioris, depressor anguli oris, zygomaticus major and risorius muscles Superior and inferior labial arteries and veins

a.From infraorbital and facial vessels superiorly

b.From facial and mental vessels inferiorly

Branches of infraorbital nerves (cranial nerve [CN] V2) superiorly

Branches of mental nerves (CN V3) inferiorly

Vermilion border: transition zone (border) of lip

Nasolabial grooves from nose to just lateral of angle of mouth separated lips from cheek

Philtrum: depression from nasal septum to vermilion border of upper lip

Labiomental groove separates lower lip from chin

Labial frenula: midline mucosal folds with a free edge that extend from upper and lower lips to the gums

Anatomical features of the cheeks

Lateral walls of oral cavity

Form zygomatic prominences over zygomatic bones

Principal muscle is buccinator

Buccal fat pad external to buccinator

Supplied bybuccal branches of maxillaryartery

Innervated bybuccal branches of mandibular nerve (CN V3)

Gingivae

Composed of fibrous tissue covered bymucous membrane

Firmlyattached to alveolar processes of mandible and maxilla and necks of teeth

Tongue

37 / 425

[Plate 58, Tongue]

page 31

page 32 page 32

page 33

Highlymobile organ composed largelyof muscle

Main functions

Pressing food into the pharynxduring swallowing

Assisting in the formation of words during speech

External features of the tongue anterior to sulcus terminalis

Root

Posterior one third

Attached to hyoid bone and mandible

Body: anterior two thirds

Apexor tip: pointed or rounded anterior end

Dorsum of tongue

V-shaped groove: sulcus terminalis

a.Divides tongue into oral and pharyngeal parts

b.Apexpoints to foramen cecum

Foramen cecum

a.Small pit

b.Remnant of embryonic thyroglossal duct

Numerous papillae of different types

Lingual papillae

Vallate

a.Anterior to sulcus terminalis

b.Large and flat-topped

c.Have taste buds

Foliate

a.Small folds on lateral side of tongue

b.Have taste buds

Filiform

a.Numerous and mainlyarranged in rows parallel to sulcus terminalis

b.Sensitive to touch

38 / 425

Fungiform

a.Mushroom-shaped

b.Found on tip and sides of tongue

c.Have taste buds

External features of the tongue posterior to sulcus terminalis

Posterior to palatoglossal arches

Roughened surface due to underlying lymphatic follicles = lingual tonsil

External features of inferior tongue

Lingual frenulum

Midline fold of mucosa from gingivae to posteroinferior surface of tongue

Connects tongue to floor of mouth

Sublingual caruncle

Papilla on either side of frenulum

Opening of duct of submandibular gland

Muscles

Both intrinsic and extrinsic muscles are paired

All muscles act coordinately

Fibrous septum separates muscles of each half of tongue

Extrinsic muscles

Alter position of tongue

Genioglossus

a.Most of bulk of tongue

b.Contributes to protrusion of tongue

c.Moves tongue from side to side

Hyoglossus

a.Depresses tongue

b.Aids in retraction

Styloglossus

a.Mingles with fibers of hyoglossus

b.Creates central trough or furrow with genioglossus during swallowing

c.Retracts tongue and curls side

Palatoglossus

a.Largelya soft palate muscle

b.Elevates posterior tongue

Intrinsic

Alter shape of tongue

Superior longitudinal: curls tip of tongue superiorly

Inferior longitudinal

a.Curls tip of tongue inferiorly

b.Acts with superior longitudinal muscle to shorten and thicken tongue

Transverse: narrows tongue and increases height

Vertical: flattens and broadens tongue

Vasculature

Arterial supply

Principallyfrom lingual artery, branch of external carotid

Dorsal lingual artery

Deep lingual artery

Sublingual artery

Minor contributions from tonsillar and ascending pharyngeal arteries

Venous drainage

Accompanies arterial supply

Dorsal lingual veins

Deep lingual veins (join sublingual veins)

All drain, either directlyor indirectlyto internal jugular vein

Lymphatic drainage takes one of four routes

Tip (apex) to submental nodes

Anterior medial two thirds to inferior deep cervical nodes

Anterior lateral two thirds to submandibular nodes

Posterior one third to superior deep cervical nodes

Innervation:

All muscles of tongue except palatoglossus supplied byhypoglossal nerve (CN XII)

Palatoglossus supplied bypharyngeal plexus (CN IXvia CN X)

Sensoryto anterior two thirds of tongue

General sensory: lingual nerve (CN V3)

Special sensory(taste): corda tympani (CN VII)

General and special sensoryto posterior one third of tongue: glossopharyngeal nerve (CN IX)

39 / 425

[Plate 55, Muscles Involved in Mastication (Continued)]

Muscle	Origin	Insertion	Innervation	Blood Supply	Main Actions
Genioglossus	Mental spine of	Dorsum of	Hypoglossal	Sublingual and submental arteries	Depresses and
	mandible	tongue and	nerve		protrudes tongue
		hyoid bone
Hyoglossus	Bodyand greater	Lateral and	Hypoglossal	Sublingual and submental arteries	Depresses and
	horn of hyoid	inferior aspect	nerve		retracts tongue
	bone	of tongue
Styloglossus	Styloid process	Lateral and	Hypoglossal	Sublingual artery	Retracts tongue and
	and stylohyoid	inferior aspect	nerve		draws it up for
	ligament	of tongue			swallowing
Palatoglossus	Palatine	Lateral aspect	Vagus nerve	Ascending pharyngeal arteries and	Elevates posterior
	aponeurosis of	of tongue	and pharyngeal	Palatine branches of facial and	tongue
	soft palate		plexus	maxillaryarteries

Palate

page 33

page 34 page 34

page 35

Forms roof of mouth and floor of nasal cavities

Consists of two parts

Hard palate anteriorly

Formed from bypalatine processes of maxillae and horizontal plates of palatine bones

Covered with periosteum and oral mucosa (inferiorly) and respiratorymucosa superiorly

Has five foramina

a.Incisive fossa behind central incisors transmits nasopalatine nerves via incisive canals

b.Paired greater palatine foramina medial to third molar transmits greater palatine vessels and nerves

c.Paired lesser palatine foramina posterior to greater palatine foramina transmits lesser palatine nerves and vessels

Mucous secreting palatine glands beneath mucosa Incisive papilla directlyposterior to maxillaryincisors Palatine raphe

a. Midline ridge/groove

40 / 425

b. Represents line of fusion of embryonic palatal plates Soft palate posteriorly

Moveable posterior third suspended from hard palate

No bonyskeleton

Attaches to hard palate via aponeurotic palate

a.Expanded tendineus aponeurosis of tensor veli palatini muscles

b.Thick anteriorly

Muscular palate (tensor veli palatini) posteriorly

Posterior curved free margin has conical projection: uvula

Anatomical features related to the soft palate

Arches

Join soft palate to tongue and pharynx

Palatoglossal arch

a.Mucosal fold

b.Contains palatoglossus muscle

Palatopharyngeal arch

a.Mucosal fold

b.Posterior to palatoglossal arch

c.Contains palatoglossus muscle

Form anterior and posterior boundaries of tonsillar fossa on either side

Tonsillar fossae

Contain palatine tonsils

Masses of lymphoid tissue between arches

Fauces

Term for passage from oral cavityto oropharynx

Bounded by

a.Soft palate superiorly

b.Root of tongue inferiorly

c.Palatoglossal and palatopharyngeal arches laterally

Muscles of soft palate

Four paired muscles descend from base of brain to palate

Levator veli palatine elevates soft palate during swallowing, opens auditorytube

Tensor veli palatini tenses soft palate during swallowing

Palatoglossus elevates posterior tongue

Palatopharyngeus tenses soft palate and pulls pharynxsuperiorlyand anteriorlyduring swallowing

Unpaired musculus uvulae shortens uvula Swallowing and the palate

Complexmechanism

Soft palate tenses to allow tongue to press against it

Tongue squeezes bolus of food to back of oral cavity

Soft palate elevates superiorlyand posteriorlyto prevent back flush of food into nasal cavity Arterial supply

Branches of descending palatine arteryon each side

Greater palatine artery

Lesser palatine artery

Ascending palatine arteryfrom facial artery Venous drainage via pterygoid venous plex Lymphatic drainage: deep cervical nodes Innervation

Sensoryfrom pterygopalatine ganglion (from CN V2)

Greater palatine nerve to hard palate

Nasopalatine nerve to anterior hard palate

Lesser palatine nerve to soft palate

Motor

Tensor veli palatini innervated bymedial pterygoid nerve from otic ganglion (CN V3)

All other muscles bycranial root of spinal accessorynerve (CN XI) via pharyngeal plexus

Muscle	Origin	Insertion	InnervationBlood supply		Main actions
Levator veli	Temporal (petrous	Palatine	Vagus	Ascending palatine artery	Elevates soft palate during
palatini	portion) bone	aponeurosis	nerve via	branch of facial arteryand	swallowing
			pharyngeal	descending palatine artery
			plexus	branch of maxillaryartery
Tensor veli	Scaphoid fossa of	Palatine	Mandibular	Ascending palatine artery	Tenses soft palate and
palatini	medial pterygoid plate,	aponeurosis	nerve	branch of facial arteryand	opens auditorytube during
	spine of sphenoid, and			descending palatine artery	swallowing and yawning
	auditorytube			branch of maxillaryartery
Palatopharyngeus	Hard palate and superior	Lateral	Vagus	Ascending palatine artery	Tenses soft palate; pulls
	palatine aponeurosis	pharyngeal	nerve via	branch of facial arteryand	walls of pharynxsuperiorly,
		wall	pharyngeal	descending palatine artery	anteriorly, and medially
			plexus	branch of maxillaryartery	during swallowing
Musculus uvulae	Nasal spine and palatine	Mucosa of	Vagus	Ascending palatine artery	Shortens, elevates, and
	aponeurosis	uvula	nerve via	branch of facial arteryand	retracts uvula
			pharyngeal	descending palatine artery
			plexus	branch of maxillaryartery

Salivary Glands

41 / 425

[Plate 61, Salivary Glands]

page 35 page 36

Functions

Moisten and lubricate food

Begin digestion of starches

Contribute to

Abilityto taste

Prevention of tooth decay Parotid gland:

Largest salivarygland

Thin waterysecretion

Found within investing cervical fascia

Occupies space between ramus of mandible and anterior border of sternocleidomastoid (SCM) muscle

Overlaps posterior masseter muscle

Deep part extends posteriorlyto mastoid process and external auditorymeatus

Parotid duct

Emerges at anterior border of gland

Runs over masseter

Pierces buccinator to enter mouth opposite upper second molar

Structures passing through the gland Facial nerve

a.Enters gland and branches into two stems

b.Two stems give rise to five branches that emerge from borders of gland

Superficial temporal vein

a.Runs through deeper part of gland

b.Unites with maxillaryvein within the gland to form retromandibular vein

External carotid arterythrough deep part of gland Arterial supply

External carotid artery

Superficial temporal arteries Venous drainage: retromandibular vein Innervation

Great auricular nerve (C2 and C3 spinal nerves)

Auriculotemporal nerve (CN V3)

Parasympathetic fibers from glossopharyngeal nerve (CN IX) via auriculotemporal from otic ganglion

42 / 425

Sympathetic fibers from external carotid plexus from cervical ganglia

Submandibular gland

Lies superior and inferior to posterior half of mandible

Divided into superficial and deep parts bymylohyoid muscle

Duct

Opens at sublingual papilla, one on either side of lingual frenulum

Lingual nerve loops under duct

Arterial supply: submental artery

Innervation

Secretomotor parasympathetic fibers

a.Presynaptic fibers from facial nerve via chorda tympani to submandibular ganglion

b.Postsynaptic fibers from cells in submandibular ganglion

Vasoconstrictive sympathetic fibers from superior cervical ganglion

Sublingual glands

Smallest and deepest of glands

Lie in floor of mouth within sublingual folds, between mandible and genioglossus muscle

Numerous ducts open along sublingual folds

Arterial supply

Sublingual arteryfrom lingual artery

Submental arteryfrom facial artery

Innervation same as that for submandibular gland

43 / 425