Mouth-Tongue Teeth-Esop Dec 2011-2012 SEM II -Prof Farid

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Human Structure and Function II

Anatomy of the Digestive system

- Oral cavity, tongue and teeth

Captain Assoc Prof. Dr Farid Bin Che Ghazali,

Health campus , Universiti Sains Malaysia.

Semester II

2011 / 2012

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Digestive System: Mouth, Pharynx, Digestive Tube

Plus: Salivary Glands, Pancreas, Liver

Hollow Passage: Mouth to Anus = Digestive Tract

Regional Specializations

Modifications correlate to functions

Functional component = lining (Mucous Membrane)

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ORAL CAVITY

Vestibule

Boundaries

Anteriorly and laterally - lips and cheeks

Posteriorly and medially - teeth and gums

Contents

Termination of the parotid duct

Oral cavity proper

Boundaries

Anteriorly and laterally - teeth and gums

Superiorly - hard palate

inferiorly - tongue and sublingual structures

Posteriorly - palatoglossal and palatopharyngeal arches

Contents

Teeth and gums ,Tongue

Sublingual structures

Frenulum of the tongue,Submandibular ducts & Sublingual folds

Palatine tonsils

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MOUTH & PHARYNX

Mucosa

Stratified squamous epithelium (not cornified)

Basement membrane = basal attachment

Lamina Propria – vascular papillae

Lymphocytic infiltration – pharynx

Lamina muscularis mucosae – absent

Repaced by elastic network (pharynx)

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Submucosa

Lax layer where present

Attaches: mucosa to muscles & bone

Absent on hard palate (part), gums, dorsum of tongue

Glands

Compound tubulo-alveolar

Regional

Serous, Mucous, mixed Sero-mucous

Location: submucosa

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Superficial tissues attached: deep lying skeletal muscle or bone

Blood vessels, lymphatics, nerves:

coarse plexuses

submucosa

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LIP

Outer surface: skin (thin, cornified)

Hair follicles, sebaceous glands, sweat glands

Inner surface: typical mucous membrane

Submucosa: present, not well defined

Stratified squamous epithelium (thicker than epidermis)

Central Core: Skeletal muscle Orbicularis oris; Mimetic

muscles

Labial glands – rounded groups; Sero-mucous (mucous dominant); submucosal

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Transition Zone – at margin

Thick epithelium: much eleidin

Vascular papillae – tall, indent epithelium

Blood capillaries show through epithelium

Glands: absent (drying of lips)

A, Stratified squamous epithelium,

nonkeratinized; B, Lamina propria; C,

Seromucous salivary gland

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CHEEK

Lip plan continued laterally

Mucosa – short papillae; abundant elastic fibers; no glands

Lamina propria – bound to muscle layer (at intervals)

Submucosa: looser, fat-containing

Mixed (largely mucous) glands – invade muscle (M. buccinator)

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GUM

Mucosa attached to alveolar bone

Epithelium moves inward at margin

Gingival Sulcus (~2 mm.)

Bottom of groove – epithelium attached to tooth

Zone of attachment shifts with age

Epithelium resembles labial mucosa

Lamina Propria: dense, fibrous tissue

Binds gum to cementum & alveolar bone

Gum line: papillae very tall, vascular

Zone attachment: no papillae

Mast cells

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TEETH

Tooth = modified soft papilla, hard covering

Hard exposed surface (enamel) – ectodermal

Concealed portion (dentin) – mesodermal

Unique organ – first set replaced by permanent set

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Ground preparation Demineralised preparation

15 Tooth

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Tooth Structure

Free Crown

1 to 3 Roots

Crown – Root junction = Neck

At gum margin

Root in alveolus

Periodontal membrane –

joins root & alveolar wall

Pulp Chamber

Crown into root

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Tooth wall – 3 specialized substances:

1) Dentine – borders pulp

Collagenous mesh

Calcified ground substance

Harder than bone (72% inorganic)

Uncalcified areas (crown) = interglobular spaces

Adjacent to cementum = Granular layer of Tomes

Dentinal canaliculi – radially striate

1 – 3 μ dia.; to 4 mm. long

Lined with Dentinal Sheath of Neumann

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Dentine, continued Dentinal Fiber of Tomes (in canaliculus) = specialized osteoblast = odontoblast

Calcification obliterates

Incremental Lines of Owen & of Ebner

Layered deposits

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2) Enamel – over crown

Hardest tissue – 97% inorganic salts

Calcium phosphate = 90%

Structural unit = Enamel Prism

Enclosed by Enamel Sheath

Prism = separate cell

Entends: dentine to surface

Diameter = 3 – 6 μ

12 million prisms / molar

Cross banded, beaded (surface)

Transverse: hexagonal (humans appear semicircular); bundled

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3) Cementum – over root

Thin layer

Invests denine of root

Bone cells in lacunae; typical bone matrix

Lamellation: inconstant; irregular

Vessels absent

Old age: Haversian systems

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Dental Pulp (“nerve” of tooth – not really “a nerve”

Fills pulp cavity

Soft, gelatinous

Cells: fusiform; stellate – like mesenchymal cells

Reticular fibers in ground substance

Odontoblasts line cavity

cell processes enter dentinal canaliculus

the Dentinal Fibers of Tomes

Also: nerves & blood vessels

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Periodontal Membrane

= periosteum (between alveolar bone & root

Merges with gum; supports gum

Neck region: forms dentinal ligament

Dense, coarse collagenous fibers; Fibroblasts; Osteoblasts

NO ELASTIC FIBERS

Sharpey’s fibers: membrane to alveolar bone; membrane to cementum

= Suspensory Ligament of Teeth

Prof. Madya Dr. Farid Che Ghazali

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TONGUE

Mouth/Pharynx

Mobile organ

Structural: mass of skeletal muscle with mucous membrane covering

Median sulcus – over deep lingual septum

V separates anterior third from posterior two thirds

angle forward

foramen caecum (apex)

Body (oral); Root (pharyngeal)

Lingual papillae – dorsal surface

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Lingual tonsils – dorsum

The Mucosa:

Stratified Squamous Epth.

Tightly bound

Lamina Propria – compact, unites with muscle

Vertical projections with epithelium = lingual papillae 4 types lingual papillae: Filiform, Fungiform, Vallate, Foliate

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Filiform Papillae

= plush of tongue

Parallel rows

Primary columnar elevation of lamina propria

5 – 30 tall secondary papillae

Epithelium over papillae – end in tapered points

“Cat of Nine Tails”

Hard & scaly (not cornified)

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Fungiform Papillae

Knob-like

Scattered, single, among filiform papillae

Larger & fewer than filiform papillae

Narrow stalk, rounded top

Size: 1.8 mm. high; 1 mm. wide

C.T. core; secondary papillae

1 to several taste buds

Modified fungiform papillae: conical (3 mm. high) - few

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Vallate Papillae

V-shaped row; V separates tongue body & root

7 to 11 papillae

Largest papillae: 0.5 to 1.5 mm. high; 1 to 3 mm. wide

Top – below surface of tongue

Trench around periphery

General surface of tongue

Inverted cone shape

C.T. core; secondary papillae

~200 taste buds lateral surface; trench wall ~50

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Number of taste buds highly variable

Von Ebner’s Glands (serous) – may project into muscle

Tongue surface

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Foliate Papillae

Parallel folds; lateral margin tongue

Body-root junction

Regress in adult rudimentary

Infants: 4 to 8; each side tongue

Taste buds – middle region

Von Ebner’s glands open into bottom of trench

Rabbits: highly developed

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Taste Buds

Taste buds are most numerous in the fungiform,

circumvallate and foliate papillae. In addition,

taste buds are found in the palate, palatoglossal

and palatopharyngeal arches and in the pharynx

and larynx.

In histological sections they appear as ovoid

lightly stained bodies, which extend

perpendicular from the basement membrane to

a little opening formed in the epithelium, the

taste pore. The elongated cells that form the

taste bud can functionally be divided into three

groups: sensory cells, supporting (or

sustentacular) cells, and basal cells. Sensory

cells extend microvilli into the taste pore. These

microvilli contain the receptors for the different

basic taste modalities (sweet, salty, bitter and

acid). Basal cells regenerate the two other cell

types.

(Cell turnover is quite high, and it is thought that

the cells of the taste buds are replaced (on

average) every 10th day).

Prof. Madya Dr. Farid Che Ghazali

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Lingual Glands

Several sets: Anterior; Glands of Von Ebner; Mucous Glands of the Root

Anterior Glands: under apex of tongue

mixed sero-mucous glands

several ducts/gland group

Glands of Von Ebner: near vallate & foliate papillae

purely serous

4 to 38 ducts (vallate trenches)

Mucous Glands of Root

lymphoid area into body

purely mucous

ducts into pits lingual tonsils

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Muscle

halved incompletely (fibrous lingual septum)

Skeletal muscle – 2 groups

Intrinsic group: M. lingualis, confined to tongue

Extrisic group: arise outside tongue; insert into tongue

hyoglossus, genioglossus, styloglossus, palatoglossus, chondroglossus

Fibers in bundles: all directions, common direction in bundle

Fibers: in loose, fatty areolar C.T.

Insertion: perimysial C.T.

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Blood Vessels:

plexus in lamina propria

capillaries into papillae

Lymphatics:

drain papillae plexus in lamina propria

Nerve Fibers:

Efferent nerve fibers: muscle, glands, blood vessels

Sensory nerve fibers: end freely, general sensibilities; taste buds (= gustatory)

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Palate

Roof of mouth

2 sides: oral, nasal

Oral side: oral type mucosa

Nasal side: respiratory mucosa

Uvula (conical) – at end

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Hard Palate

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Hard Palate:

Oral Side:

Stratified squamous epithelium

tall papillae – densely fibrous lamina propria

Submucosa: except at raphe

Anterior 1/3 fatty

Posterior 2/3 pure mucous glands

Middle layer: maxillary & palate bones

Nasal Side:

Pseudostratified columnar epithelium, ciliated

Mixed sero-mucous glands

deep elastic fibers

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Soft Palate:

Continuation of hard palate

Oral side similar to hard palate

lamina propria infiltrated with lymphocytes

Dense layer elastic fibers between mucosa-submucosa

Middle layer: skeletal muscle

Nasal side similar to hard palate

exception: near free margin: stratified squamous epithelium

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Pharynx

Flattened, conical chamber

Superior & Inferior regions

Superior = respiratory – naso-pharynx

Nasal mucosa

Inferior = oro-pharynx (behind palatine arches); laryngo-pharynx

Tonsilar ring at beginning

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Epithelium:

naso-pharynx: pseudostratified columnar, ciliated; specialized goblet cells

Changes at lower levels to: stratified columnar then stratified squamous

oro- & laryngo-pharynx: soft, stratified squamous

Lamina Propria:

naso-pharynx basement membrane distinct

C.T. papillae

Oro- & laryngo-pharynx: scattered, solitary lymph nodules

deepest layers: thick elastic layer

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Submucosa:

Well developed: naso-pharynx (laterally); near esophagus

Other regions: elastic layer against muscle

Small mucous glands – regions of stratified epithelium

Musclularis:

2 layer (skeletal muscle)

Inner longitudinal; outer oblique/circular

Adventitia:

thin, fibrous (most regions)

other regions: muscles attached to bones of skull

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Pharyngotympanic tube

Auditory tube

Eustachian tube

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Oropharynx

• Digestive function

• Anterior: anterior tonsillar pillar

• Posterior: superior constrictor

• Superior: soft palate

• Inferior: base of tongue, superior epiglottis

• Laterally: palatoglossal and palatopharyngeal arches

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Epiglottis

This is a slightly curved, leaf-

shaped structure, the stalk of the

epiglottis is attached to the deep

aspect of the laryngeal

prominence.

This cartilage overhangs the

ventricle of the larynx.

The epiglottis is connected to

the: Tongue by the median and

lateral glossoepiglottic folds.

Arytenoids cartilages by the

aryepiglottic and false vocal

folds.

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Palatine Tonsil…

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Lingual Tonsil

Lymphatic nodules at arrows

Several lymphoid follicles, which represent a portion of the lingual tonsil, are

present. They protrude slightly above the surface of the posterior tongue. Variable

distribution extending to epiglottis or the palatine tonsil.

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Pharyngeal Tonsil

Respiratory epithelium

Pharyngeal tonsils

resemble those of

the palate but with

ciliated,

pseudostratified

epithelium rather

than stratified

squamous

epithelium lining the

surface and crypts.

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A, Condylar head; B, Tubercle of temporal bone; C, Articular fossa;

D, Articular disk; E, Upper synovial cavity; F, Lower synovial cavity;

G, Lateral pterygoid muscle; H, Upper portion of posterior disk and

capsule; I, Lower portion of posterior disk and capsule

• The Pharyngeal walls made up of mucosa, submucosa,

pharyngobasilar fascia, constrictor m., buccopharyngeal

fascia

• Lateral walls made up of ant. and post. tonsillar pillars,

tonsillar fossa with the palatine tonsil, lateral phayngeal

wall

• Soft palate made up of palatine aponeurosis, tensor and

levator veli palatini, uvular m, palatoglossus,

palatopharyngeus

Important notes