Anatomy Sheet: Oral cavity

Done by: rasha Rakan

edited by: khansaa Mahmoud

The oral cavity has 2 parts:

1. Oral vestibule: outer part that consists of outside the teeth,

between the teeth, the cheeks and lips

2. Oral cavity proper: the part enclosed the teeth

When we close our mouth, oral vestibule and cavity proper is

in continuity through the openings between the teeth or

behind the molar teeth )الضروس( (retro moral area)

Lower jaw is called mandible, and upper jaw is called maxilla,

they contain alveolar processes where the which is bone that

contains the alveolar sockets.

The mouth is covered by mucous membrane that is

composed of stratified squamous epithelium, some of it is

keratinized (non-movable parts like the hard palate and

dorsum of the tongue) and some non-keratinized (the

remaining parts like the soft palate, floor of the mouth and

lateral surface of the tongue).

In the floor of the mouth there’s a movable organ, the tounge

which is partly sitting in the cavity proper and partly sitting

into the oropharynx.

Superiorly there’s the hard palate.

The oral cavity proper is separated from the oropharynx by

sphincter that closes during swallowing to prevent the food

from coming back into

the mouth until the

bolus of food is

passing down into the

esophagus.

The sphincter is

composed of:

1. Palatopharyngeal

arch (posterior pillar of

fauces

2.Palatoglossal arch

(anterior pillar of

fauces)

Between them there’s

the palatine tonsil.

The teeth of children, the

eruption of them beings

at 6 month.

The first to appear is the

lower incisor tooth.

By the 24th month all the

teeth are complete.

The replacement begins

at the 6th year, the first to

be replaced are the

molars, and permanent teeth begins to appear.

The permanent teeth complete by the age of 25, when the

wisdom teeth (third and last molar teeth) أسنان العقل appear (it

starts from the age of 17 to 25)

Permanent teeth

Milk teeth are 20 teeth

Permanent teeth are 32 (including 3rd molar)

Incisors have sharp ends القواطع, canine tooth األنياب conical in

shape أسطوانية الشكل, premolar teeth are bicuspid (tow

tubercles), molar teeth have many tubercles that may reach

to 5, they are used for granting tooth

The tooth is composed of the following:

1. Crown

2. Neck

3. Root can be 1-3 roots

Incisors, canine and premolars have only one root, while the

molars have 2-3 roots (upper molars have 3 roots, and the

lower ones have 2 roots)

Inside the tooth there’s cavity, inside it there’s pulp that is

composed of artery, vein and nerve.

Periodontal membrane

The cavity is covered by a white material that’s called

Dentine

Outside the dentine there’s a socket تجويف the roots are

sitting in, this alveolar socket is in the alveolar processes

that are lower (mandibular) and upper (maxillary) ,العظم

Around the dentin there’s a material called cementum or

cement that’s calcified bony area.

The crown is covered by inorganic hard material that’s called

Enamel

The teeth are covered by a red vascular mucous membrane

inside it there’s tough collagenous tissue called the Gum ,

but it’s loose around the neck so it doesn’t play any role in

fixing the teeth, and you can enter a tooth pick between the

gum and the tooth.

The fixing role is done by periodontal membrane, it is like the

membrane that covers the bones of our body (periosteum

membrane).

The upper teeth are supplied by the anterior and posterior

superior alveolar nerves, that are branches of the maxillary

nerve.

Trigeminal (cranial nerve #5) nerve branches into 3 nerves :

1. Ophthalmic nerve

2. Maxillary nerve,

passes through

infraorbital canal and

exits through infraorbital

foramen and branches

into posterior and

anterior superior alveolar

nerves

The upper gum is

supplied by infraorbital nerve( another branch of maxillary

nerve) and posterior superior alveolar nerve

3. Mandibular nerve branches into:

A. inferior alveolar nerve

that supplies the lower

teeth, that enters the

mandibular foramen and

passes through the

mandible and exits through

mantel foramen to give

mantel nerve

B. Mylohyoid nerve

C. Lingual nerve that

supplies the tongue

Infraorbital

Nerve

The lower gum is supplied by anteriorly by the mental nerve

and posteriorly by the buccal nerve (branch of the

mandibular nerve and works as a sensory nerve of the mouth

area)

We are looking at the base of the skull. We are going to

study the roof of the mouth, the hard palate

1. It is composed of:

A. Palatine processes of the maxilla:

(one on the right and the other on the left and they meet in

the middle)

B. Palatine bone that takes the shape of L and it has a

vertical and horizontal planes, the later completes the

hard palate.

Hard palate

Pterygoid

Fossa

2. Incisive foramen: a central orifice. Nasopalatine nerve

(a branch of the maxillary nerve) and greater palatine

artery pass through it, to supply the hard palate.

3. Greater palatine foramen Great palatine nerve passes

through it

Lesser palatine foramen Lesser palatine nerve passes

through it

4. The lingual side of the gum (الجهة الداخلية للثة باتجاه اللسان) is

supplied anteriorly by the nasopalatine nerve, and

posteriorly by the greater and lesser palatine nerves.

5. The Pterygoid bone has median and lateral plates and

between them there’s the pterygoid fossa. The median

pterygoid plate has a project called Hamulus.

Inferiorly is covered by stratified

keratinized squamous epithelium

6. Mucous membrane (stratified squamous epithelium),

underneath it mucoperiosteum (mucosa), and there’s a lot of

salivary glands (mucus and serous glands) and taste buds.

We conclude that the hard palate is bone covered by mucosa

(mucoperiosteum) and modified mucous membrane. It

continues posteriorly as soft palate.

Soft palate اللهاة is the movable part, and it moves while

swallowing the food. It ends with a project called uvula.

When we swallow food the soft palate closes the oropharynx

and prevents the food from going up into the nasopharynx.

Thus the soft palate separates the oropharynx and the

nasopharynx.

Hard and soft palate

We are sitting

inside the

oropharynx and

looking to the front

and we can see the

soft palate and the

uvula.

Soft palate is composed of stratified non-keratinized

squamous epithelium, and muscles.

The muscles:

1. Tensor veli palatine originates from Eustachian (auditory)

tube (a canal that connects between the pharynx and the

middle ear) and base of the skull (between the spine of the

sphenoid and pterygoid fossa). The muscle becomes tendon

and wraps on the Hamulus and then fanning )تنفرد كالمروحة(and

continues medially to connect with the tensor veli from the

other side in the middle to form aponeurosis (غشاء عريض)

2. Levator veli palatine palatine originates from Eustachian

(auditory) tube and the medial side of the petrous temporal

bone and does insertion in the edge of the soft palate.

Levator means elevation so it elevates the soft palate.

Muscles of soft palate posterior view

Below the soft palate we have 2 muscles and both of them are covered by mucous membrane: 1. Palatoglossus muscle originates from the soft palate coming down into the tongue. 2. Palatopharyngeus muscle originates from the soft palate coming down into the pharynx. Anterior and posterior pillar arches and the palatine tonsil in between are located here. All the muscles of soft palate is supplied by vagus nerve through pharyngeal plexus except “Tensor veli palatine” supplied by the medial pterygoid nerve, a branch of mandibular nerve.

Oral Mucosa

All of the oral mucosa is made up of a thick stratified squamous epithelium, supported by a lamina propria (loose CT under stratified squamous). The epithelium is thick because the epithelial lining of the oral cavity is subject to a lot of wear and tear. التمزق والجروح وخشونة الطعام

In mobile areas, such as the soft palate, underside of the tongue, floor of the mouth, and mucosal surfaces of the cheeks and lips, the epithelium is not keratinised.

In other areas, such as the gums (gingivae), hard palate, and most of the upper surface of the tongue, the epithelium is keratinised.

Underneath the oral mucosa, there is a tough

collagenous submucosal layer to attach the mucous

membrane with the mandible and the maxilla bone, with

accessory salivary glands, except where the oral mucosa

lies over bone, where the submucosa is thin.

Histology of the Hard palate

Histology of the lip

Oral surface mucosa

S. Q.NON-k = Stratified squamous non keratinised epith.

Outside the lip there’s skin, and the skin has hair follicles and Sebaceous gland غدد دهنية that secrets sebumدهن أو زيت .

Vermillion border is the red area in the lip, and it’s red because it is rich in blood supply. It is red skin, and contains stratum lucidum which is transparent, so it reflexes the red color of the vessels. Then we oral surface and under it lamina propria, and then labial salivary glands.

Gums = Gingivae

They consist of mucosal tissue that covers the alveolar processes of the maxilla and mandible and finish at the neck of each tooth. The gingivae functions to cover the alveolar bone and surround the teeth. the gingiva is the only clinically visible component of the periodontium

inside the mouth. Healthy gingiva will appear pink in

colour

The gingival margin follows a scalloped-like course across the dentition due to the interdental papillae, which fill the interdental spaces beneath the tooth contacts.

There are two types of gingiva,

Two portions of the gingiva can be identified:

Free gingiva and attached gingiva

The free gingiva surrounds the tooth and creates a cuff or collar of gingiva measured from the margin of the attached gingiva extending coronally about 1.5mm.

The inner surface of the free gingiva (next to the tooth) forms the gingival wall of the sulcus.

The healthy patient

will present with a sulcus measuring approximately 1-3mm in depth

Histology

the tissue on the outer surface of the free gingiva, the papillae and the attached gingiva is stratified squamous keratinized epithelium.

The inner surface of the free gingival margin (sulcus) is stratified squamous non keratinized epithelium.

The gingival connective tissue consists of a dense network of collagen fibers. Collagen fibers function to provide firmness to the gingiva and to attach the gingiva to the underlying cementum and alveolar bone. The connective tissue of the gingiva is also rich in blood, lymphatic vessels, nerves

☺ دون النجومما تقنع بوال