anatomy 7 second

7/28/2019 Anatomy 7 Second

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Dr. Tahani Abualteen

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The oral cavity & salivary glands

Oral cavity: The cavity that extends from lips anteriorly to oral part of pharynx posteriorely and contains the

tongue & teeth

Divided into 2 parts (spaces):1. Vestibule:

Space between lips & cheeks from the outside, gingiva& teeth from the inside

Contains opening of parotid gland duct (opposite toupper 2nd molar)

Divided into 6 sulci by labial & buccal freniupper &lower labial sulci (opposite to anterior teeth), upper &

lower right buccal sulci (opposite to posterior teeth),

upper & lower left buccal sulci (opposite to posterior

teeth)

2. Oral cavity proper: Main part of oral cavity Space enclosed by teeth anteriolaterally Vestibule communicates with cavity proper at:

- Behind the 3rd molar (where the vestibule opens into the cavity proper)- Free way space "inter-occlusal space" (2-4 mm transient gap between upper and lower

jaw teeth when jaw muscles are relaxedand at their physiological rest)

Oral cavity proper:o Boundaries:

Roofhard palate ONLY** Soft palate is the roof of oropharynx

Floorreflection of Mucous membrane under the tongue Anteriorly communicates with Vestibule (through free way space) Posteriorely communicates with oropharynx (through oropharyngeal isthmus)

** Pharynx is a large structure and part of it is located behind the nasal cavity (naso-pharynx),other part is located behind the oral cavity (oropharynx) and other part located behind the

larynx (laryngio-pharynx)

** Larynx is located anterior to pharynx and extends from level of C4-C6 and continues to

become the trachea

** Pharynx is three times larger than the larynx and extends from base of skull to C6

o 2 openings: Oral fissure from vestibule to outside anteriorly (opening between upper & lower lips) Oropharyngeal opening (isthmus) from cavity proper to oropharynx posteriorely

** Isthmus = tiny/small tunnel between 2 large spaces


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Teeth:o 2 sets

1. Deciduous (primary) teeth: 5 in each quadrant (central incisor, lateral incisor, canine, 1st molar, 2nd molar) Start eruption around 6 months of age Fully erupted by the age of 2 years 1st primary tooth to erupt is lower central incisors Sequence of eruption: central incisor lateral incisor 1st molar canine 2nd molar

2. Permanent teeth: 8 in each quadrant (central incisor, lateral incisor, canine, 1st premolar, 2nd premolar, 1st

molar, 2nd molar, 3rd molar)

Start eruption around 6 years of age Fully erupted by the age of 12 yearsafter the eruption of 2nd molars NOT 3rd molars

** 3rd molar = wisdom tooth and it erupts at older age (17-30 years of age) 1st permanent tooth to erupt is lower 1st molar ( because it has no predecessor to slow its

eruption)

** Each permanent molar needs 6 years to form and fully erupt (1st molar at age of 6,

2nd molar at age of 12, 3rd molar at age of 18)

o Innervation of the teeth: Maxillary teeth:

- Anterior teethanterior superior alveolar nerve-

Premolars & mesial root of 1

st

molar

middle superior alveolar nerve- Distal and palatal roots of 1st molar, 2nd and 3rd molarsposterior superior alveolar nerve** These nerves innervate teeth, pulp, PDL, alveolar process

Maxillary facial gingiva:- Opposite to anterior teeth anterior superior alveolar nerve & infraorbital nerve- Opposite to premolarsmiddle superior alveolar nerve & infraorbital nerve- Opposite to molarsposterior superior alveolar nerve

Mandibular teeth:- Anterior teethincisive branch of inferior alveolar nerve- Posterior teethinferior alveolar nerve

** These nerves innervate teeth, pulp, PDL, alveolar process

Mandibular facial gingiva:- Opposite to anterior teeth & premolars mental branch of inferior alveolar nerve- Opposite to molarsbuccal nerve

** Opposite to the area between 1st & 2nd premolars, there's the mental foramen at which

the inferior alveolar nerve terminates into mental branch (getting out of the mental

foramen to supply buccal gingiva opposite to premolars & anteriors and skin of chin)

and incisive branch (remaining inside the mandibular canal to supply anterior teeth)


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Tongue:o A muscular organ that is covered with mucous membrane (its epithelium is stratified Sequamous)

** Skeletal muscles are needed forspeech, mastication and movement

** Mucous membrane is needed fortaste and other general sensations

o Divided into: Oral part: anterior 2/3s (below the hard palate in oral cavity) Pharyngeal part: posterior 1/3 (below the soft palate in oropharynx)

o Surfaces: Upper surface (palatal, dorsal) opposite to hard palate Tip & margins opposite to teeth Lower surface (ventral) opposite to floor of mouth Root where Genioglossus and Hyoglossus muscles connect the tongue to hyoid bone

posteriorely and mandible anteriorly

** We will speak about the mucous membrane covering at first and then skeletal muscles:

o Dorsum of The Tongue: Covered by rough, keratinized & thick mucous membrane (which is different from that of

ventral surface of tongue)

Median fissure groove/sulcus in the middle of anterior 2/3s of tongue it exists becauseanterior 2/3s of tongue is actually 2 identical halves that are separated from one another

by a fibrous septum which when connects to the mucous membrane superiorly, it pulls it

down creating this groove

Sulcus terminalisinverted V-shaped groove/sulcus that separates anterior 2/3s oftongue (oral part, originating from 1

stbranchial arch) from posterior 1/3 (pharyngeal

part, originating from 3rd

branchial arch)

Foramen cecum

blind (obliterated) opening found at apex of sulcus terminalis

thatmarks the site of Thyroglossal duct


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** This foramen represents the embryological remnants of Thyroglossal duct (through which

cells forming the thyroid gland emigrate down from tongue area into the root of the neck)

** At birthThyroglossal duct obliterates and foramen cecum demarcates the remnants

of the upper part of this duct

** There's another foramen cecum but in the skull anterior to crista galli Lingual papillae: 4 types

- Filiform hair-like projectionssmallest & most numerouscovered by

keratinized epithelium to give rough

texture to dorsum of tongue to serve as

protection from friction with food and then

prevention of ulcers and erosions

** These papillae don't contain taste buds,

they are more related to protection and

general sensation (nerve endings related to

lingual nerve are found in them)

- Fungiform mushroom-like projections found at tip & margins of tongue

contain taste buds (receptors)

- Circumvallate large round projections 8-12 in number found in front of

sulcus terminaliscontain taste buds

(receptors)

- Foliate linear folds on the sides, near terminal sulcus contain taste buds (receptors)** Lingual papillae are foldings/projections of mucous membrane covering the dorsum of

the tongue

** Functions of lingual papillae: protection (by providing a rough texture) and increased

surface area (and so increased taste sensation and taste receptors)

** There's no taste map on the tongue because it's wrong to say we only taste sweet

anterior, salt and acid in the middle and bitter posterior

Since taste buds are located in papillae and these papillae are distributed everywhere

(anterior, lateral, posterior) then all tastes can be tasted anywhere (e.g. sweet can be

tasted, anteriorly, posteriorely and on the margins as well)

Lingual Tonsil:- Lingual tonsil = aggregation of lymphoid nodules on posterior 1/3 of the tongue that is

considered part of Waldeyers ring** No lingual papillae on posterior 1/3 of tongue (because there's no need to increase

surface area or provide protection)

** Lingual tonsil represents higher degree of protection in posterior 1/3 of tongue

- Waldeyers ring = ring of6 tonsils(of 4 kinds) located behind the nose and oral cavity toprovide the first line of defense = 1 pharyngeal tonsil (at roof of nasopharynx)


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2 tubal tonsils (at opening ofEustachian tube at lateral wall of

nasopharynx)

2 palatine tonsils (at lateral walls oforopharynx)

1 lingual tonsil (on dorsum ofposterior 1/3 of tongue)

** Tonsillitis most commonly affects the palatine tonsils

o Ventral Surface of The Tongue: Covered by smooth, non-keratinized,

transparent & thin mucous membrane

Frenulum fold of mucous membrane connectstongue to floor of mouth

Deep lingual veins, arteries & nerves showthrough the transparent mucous membrane

** Deep lingual arteryfrom lingual artery(from external carotid artery)

** Deep lingual nervefrom lingual nerve(from mandibular nerve (V3))

Fimberiated fold (plica fimbriata)demarcating line between the end of the dorsal surface

(which is covered by thick keratinized mucous

membrane) and the beginning of the ventral surface(which is covered by thin non-keratinized mucous

membrane)

Tied tongue (Ankyloglossia):- If the Frenulum is excessively large orextends too

far anteriorlyit will tie tongue more with floorof mouth limiting tongue mobility

- It is a congenital anomaly- Produces feeding (suckling) problems in infants and then speech problems- Treatment: surgical cut of part of the Frenulum

Sublingual absorption:- Smooth & thin mucosal layer at ventral tongue surface allows forquick transmucosal

absorption of drugs (e.g. Nitroglycerin (vasodilator in angina pectoris patients))- Technique: the pill is placed under the tongue to get absorbed & enters through the thin

mucous membrane into deep lingual veinwithin 1 minute (and through the venous

circulation nitroglycerine (for example) can reach coronary arteries to dilate them and

enable more blood supply and more oxygenation to muscles of heart)


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o Muscles of the tongue: 2 types Intrinsic:

- Inside the tongue and NOT attached to bone- 3 directions: longitudinal (anteroposterior), transverse (from side to side), & vertical

(superoinferior)- Innervationhypoglossal nerve (XII)- Actionchange tongue shape (dont move the tongue)

Extrinsic:- 4 (5?) muscles- Attached to bone (because they come from outside of tongue into inside)

1. Styloglossus from styloidprocess superiorly to the tongue

When this contracts, itmoves tongue backward

upward (to its swallowing

position)

2. Genioglossus from superiorgenial tubercle inferiorly to the

tongue

When this musclecontracts, it actually does

nothing because it is

usually under a constant

state of contraction, to

prevent the tongue from collapsing posteriorely & obstructing airway

If this muscle relaxes, tongue will drop backward, and obstructs the airwaysand leads to suffocation " "

If this muscle hyper-contracts, it will move the tongue forwardprotruding itout of mouth

Genioglossus and airway patency:** Usual contraction of Genioglossus is important to keep the tongue in its

position, but hyper-contraction leads to protrusion of tongue out of mouth

** When patient is deeply anaesthetized during general anesthesia,

Genioglossus may relax & the base of the tongue moves posteriorely and

patient suffocates

To keep airways patent and prevent tongue from going backward,

intubation should be done (oral/nasal tube all the way down into larynx)

** In emergency cases (e.g. patients in coma) and when CPR " " is

to be done, the first step to stick to, is to maintain the airways (by putting

the patient with his head up or to the side to make sure the tongue isn't

relapsing backward)


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3. Palatoglossus from soft palate superiorly to the tongue When this muscle contracts, it elevates posterior part of tongue

4. Hyoglossus from hyoid bone inferiorly to the tongue When this muscle contracts, it moves tongue backward downward (to its rest

position)

- All of these muscles are innervated by the hypoglossal nerve EXCEPT Palatoglossusmuscle which is supplied by the nerve supplying the soft palatal muscles (Vagus nerve

via pharyngeal plexus)

o Innervation to The Tongue: Sensory:

- General: Anterior 2/3sLingual nerve from

mandibular nerve (V3) Posterior 1/3Glossopharyngeal (IX) "

"- Special:

Anterior 2/3sChorda tympani from facialnerve (VII)

Posterior 1/3Glossopharyngeal (IX)** Glossopharyngeal is specialized in the

posterior 1/3 of tongue and oropharynx

** There are NO papillae in the posterior 1/3of tongue

** Papillae aren't related to taste buds but to increase surface area (and so

increased taste sensation and taste receptors)

** Glossopharyngeal nerve carries taste sensation from circumvallate papillae

(which are just anterior to sulcus terminalis) NOT from posterior 1/3 per se

** Chorda tympani carries taste sensation from Fungiform and foliate papillae

** Lingual nerve carries general sensation from Filiform papillae

** Taste buds (without papilla) are found on soft palate, posterior wall of pharynx,

and epiglottis

Motor:- Hypoglossal nerve (XII) except Palatoglossus muscle

** Tongue receives its innervation from 4 cranial nerves: trigeminal (V), facial (VII),

glossopharyngeal (IX) and hypoglossal (XII)

o Arterial Blood Supply to The Tongue: Lingual artery:

- The main blood supply for the tongue- From external carotid artery- Pass deep to Hyoglossus muscle- Divides into 3 Branches:


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1. Dorsal lingual artery goes toposterior 1/3 of tongue

2. Deep lingual artery goes toanterior 2/3s of tongue

3.

Sublingual artery

goes tofloor of mouth, sublingual salivary

glands and mylohyoid muscle

(NOT TO TONGUE)

Tonsillar artery- From facial artery- Supplies palatine tonsils mainly and may give some branches to supply the tongue

Ascending pharyngeal artery- As it ascends on pharynx, it might supply the pharyngeal part of tongue

o Lymph drainage: Tip drains to submental lymph nodes Lateral Anterior 2/3ssubmandibular Lymph nodes Medial Anterior 2/3sinferior deep cervical lymph nodes Posterior 1/3superior deep cervical lymph nodes

Submandibular Salivary Gland: Mixed gland (mucous & serousmainly serous) 70% of saliva in mouth comes from submandibular gland Rests on posterior Border of mylohyoid musclewhich divides it into 2 parts: large superficial (in

neck) & small deep (in mouth) Relations to superficial part:

o Anteriorlyanterior belly of digastrico Posteriorely Stylohyoid & posterior belly of

digastric

o MediallyMylohyoid & Hyoglossus musclesLingual nerve & Hypoglossal nerve

oLaterally

Submandibular fossa of the mandible

Relations to deep part:o AnteriorlySublingual salivary glando Posteriorely Stylohyoid & posterior belly of

digastric

o MediallyHyoglossus & Styloglossus muscleso LaterallyMylohyoid muscleo SuperiorlyLingual nerve, Mucous membrane of the floor of the moutho InferiorlyHypoglossal nerve

Submandibular duct (Wartons):o Same length as parotid duct (~ 5cm)


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o Arises from deep part of the gland passes anteriorlyopens beside the Frenulum of thetongue into sublingual papilla (called sublingual because of its location below the tongue but it is

still related to submandibular gland and represents the opening of Warton's duct)

Sublingual Salivary Gland: Mixed gland (mucous & serousmainly mucous) 5% of saliva in mouth comes from sublingual gland Beneath mucous membrane of floor of mouth Opens into sublingual Fold in the floor of mouth through 8-20 ducts Relations to the gland:

o AnteriorlyGland of the opposite sideo Posteriorely Deep part of submandibular glando MediallyGenioglossus muscle, Lingual nerve, Submandibular ducto LaterallySublingual fossa of the mandibleo SuperiorlyMucous membrane of the floor of the moutho InferiorlyMylohyoid muscle

Parotid salivary gland: Purely serous gland 25% of saliva in mouth comes from parotid gland Relations to the gland:

o SuperiorlyTemporomandibular Joint (TMJ), External auditory meatus (EAM)o LaterallySkin & Superficial fascia, Great auricular nerve (C2, C3)o Medially Parotid Bed, which composed of:

AnteromedialRamus, Masseter & Medial pterygoid PosteromedialCarotid Sheath, Styloid process & related muscles, Mastoid process, SCM &

posterior belly of digastric

anatomy 7 second

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