Anatomical Landmarks

Department of Preclinical Prosthodontics Anatomical Landmarks

Anatomical Landmarks - Maxillary Edentulous Foundation

1. Labial Frenum

It is a fold of mucous membrane in the midline

It contains no muscle and has no action of its own

It starts superiorly in a fan shape and converges as it descends to its terminal attachment

on the labial side of the ridge

The labial notch in the labial flange of the denture should be just wide enough to allow

the frenum to pass through it

2. Labial Vestibule

The labial vestibule is divided into left & right vestibules by the labial frenum.

The mucous membrane lining the vestibule is a relatively thin lining mucosa. The sub-

mucosa is thick & contains a large amount of areolar tissue & elastic fibers

The Orbicularis oris forms the outer surface of the labial vestibule. The fibers of the

Orbicularis oris run in a horizontal direction & anastomose with the fibers of the

Buccinator .

The labial vestibule lodges the labial flange of the denture.

Over extended flanges impinge on the mucosa and may lacerate it, or tend to get

dislodged during functional movements made by the patient

Boundaries :

Anteriorly : Labial mucosa , Orbicularis oris

Posteriorly : Labial slope of residual alveolar ridge

Medially : Labial Frenum

Laterally : Buccal Frenum, Buccal vestibule

3. Buccal Frenum

1


It is a single or double fold of mucous membrane that forms a dividing line between the

labial & buccal vestibules

The Orbicularis oris pulls the buccal frenum forward

The Buccinator pulls it backwards

The Levator anguli oris takes attachment beneath the frenum

The buccal frenum requires more clearance for its action

4. Buccal Vestibule

Lies opposite the tuberosity & extends from the buccal frenum to the hamular notch

It is lined by lining mucosa

The root of the zygoma lies opposite the first molar region and becomes prominent with

the ridge resorption. So relief over this area is given to prevent soreness to the underlying

tissue

The size & shape of the buccal vestibule is determined by the Ramus , the coronoid

process of the mandible & the Masseter

The buccal vestibule lodges the buccal flange of the denture

Over extended flanges impinge on the mucosa and may lacerate it, or tend to get

dislodged during functional movements made by the patient

Overly thick flanges cause buccal fullness in appearance

Note : The Buccal Vestibule should be examined with the mouth as nearly closed as

possible

Boundaries :

Anteriorly : Buccal Frenum

Posteriorly : Hamular notch

Laterally : Buccal mucosa, Fibers of Buccinator , Modiolus

Medially : Buccal slope of residual alveolar ridge

2


5. Maxillary Tuberosity

Bulbous extension of the residual alveolar ridge in the 2nd & 3rd molar regions

The maxillary tuberosity terminates in the hamular notch

Fibrous enlargements & excess tissues prevent the proper location of the occlusal plane

and may intervene with the lower denture. Therefore excess tissue around the enlarged

tuberosity must be surgically excised.

Maxillary posterior teeth arrangement should end just anterior to the tuberosity area.

6. Pterygomaxillary Notch / Hamular Notch

It is situated between the tuberosity & the hamulus of the medial pterygoid plate

The mucous membrane consists of thick submucosa made of loose areolar tissue

The tissue in the deepest part of the hamular notch can be displaced by the posterior

palatal border of the denture to achieve posterior palatal seal. It forms the distal limit of

the buccal vestibule

It marks the distal most extension of the maxillary denture base.

7. Posterior Palatal Seal Area

“The soft tissue along the junction of the hard & soft palates on which pressures within

physiological limits can be applied by a denture to aid in retention of the denture”

The Posterior Palatal Seal extends medially from one tuberosity to the other

Laterally , the “Pterygomaxillary seal” extends through the Pterygomaxillary notches

The Posterior palatal seal area lies between the Anterior & Posterior Vibrating lines

Marks the distal extension of the maxillary denture base.

Overextension may cause intolerance in the patient and result in gagging.

Vibrating Line

The Vibrating Line is an imaginary line across the posterior part of the palate marking the

division between the movable and immovable tissues of the soft palate. This can be

identified when the movable tissues are functioning - GPT

3


The Anterior vibrating line marks the beginning of motion in the soft palate when the

individual says “ah”

The Posterior Vibrating Line extends from one hamular notch to the other.

Both the Vibrating Lines are always on Soft Tissue.

Distally, the denture should at least extend up to the posterior vibrating line. Ideally it

should extend around 2mm beyond the PVL for better retention.

8. Fovea Palatinae

These are two indentations near the mid palatine raphe, present one on either side of the

midline.

They are always present in soft tissue.

They do not mark the junction of the hard & soft palates

They are present very close to the Posterior Vibrating line , either anterior or posterior to

it.

They serve as an ideal guide for locating the posterior border of the maxillary denture.

9.Median Palatal Raphe

Formed by the union of the palatine processes of the maxillae & the union of the palatine

bone

It extends from the incisive papilla to the distal end of the hard palate

The submucosa is extremely thin in this region and the mucosa is practically in contact

with the underlying bone

The mucosa overlying the mid palatine suture is non resilient and this region has to be

relieved

10. Palatal Rugae

This is the Secondary Stress Bearing Area of the Maxilla.

The palate is set at an angle to the residual ridge & is covered with keratinized

epithelium.

It contains folds of fibrous connective tissue.

4


11. Incisive Papilla

Situated on a line immediately behind and between the maxillary central incisors

Nasopalatine nerves & blood vessels pass through the incisive foramen, which is located

beneath the incisive papilla.

Relief should be provided to the incisive papilla to prevent impingement of the denture

on the nasopalatine nerves & blood vessels.

Location of the incisive papilla on the ridge indicates the amount of resorption that has

occurred in the residual ridge.

12. Residual Alveolar Ridge

The ridge is covered by stratified squamous epithelium and contains submucosa

containing dense collagen fibers.

The submucosal layer provides adequate resiliency to support the maxillary denture

It is the Primary Stress Bearing Area of the Maxilla

5


Anatomical Landmarks - Mandibular Edentulous Foundation

1. Labial Frenum

Contains a band of fibrous connective tissue that helps to attach the Orbicularis oris.

The labial frenum is quite sensitive and active. The denture should have adequate relief

around it to maintain a seal without causing soreness.

The frenum is best demonstrated by forward pull of the lower lip

2. Labial Vestibule

Runs from labial frenum to buccal frenum on either side of the midline

Depth of the sulcus is determined by the turn of the mucobuccal fold

The Mentalis muscle is active in this region

Boundaries :

Anteriorly : Labial mucosa , Mucolabial fold, Orbicularis oris

Posteriorly : Labial slope of mandibular residual alveolar ridge

Laterally : Buccal Frenum, Buccal vestibule

The labial vestibule lodges the labial flange of the denture.

The depth & width of the vestibule should be accurately recorded to prevent over

extensions and overly thick flanges in the final denture which may cause impingement

onto the soft tissue, or lip fullness respectively

6


3.Buccal Frenum

Overlies the Depressor anguli oris muscle

May be seen as single or multiple folds of mucous membrane

Reflects in an antero-posterior direction towards the slope of the crest of the alveolar

mucosa distal to the canine region

Adequate relief should be provided in this region so as to have a maximum seal ,

avoiding over extensions so as not to displace the denture when the lip is moved.

4. Buccal Vestibule

Extends from buccal frenum to the posterior distal corner of the retromolar pad -

Zarb & Bolender

Extent is influenced by the Buccinator muscle.

The Masseter influences the disto buccal edge of the buccal vestibule & forms the

“Masseteric Notch” Winkler

The buccal vestibule should be recorded correctly in the impression making procedures

by guiding the patient to give the correct functional movements so as to record the

functional width and depth of the vestibule and also the Masseteric notch on the

distobuccal flange to prevent dislodgement of the denture during functional movements

made by the patient.

5.Buccal Shelf Area

It is a horizontal shelf of bone seen along the buccal slope of the residual alveolar ridge

The Buccinator attaches to the External oblique ridge of the buccal shelf

The area between the mandibular buccal frenum and the anterior ridge of the Masseter is

called as the Buccal Shelf or the Buccal Flange Area

The Buccal shelf is very wide and present at nearly right angles to the direction of the

vertical occlusal forces, thereby offering excellent resistance to these forces. This is the

Primary Stress Bearing area of the Mandible

Boundaries

Anteriorly : Buccal Frenum7


Distally : Retromolar Pad

Laterally : External Oblique Ridge

Medially : Crest of residual alveolar ridge

6.External Oblique Ridge

Smooth ridge seen on the buccal surface of the body of the mandible

Extends from anterior border of ramus and diminishes in prominence in the inferior &

anterior region towards the mental foramen

If the denture flanges are overextended till the anterior border of the ramus, the denture

impinges on the Buccinator and adjacent tissues, which results in soreness & limits the

function of the Buccinator

7.Retromolar Pad

It is a triangular soft pad of tissue at the distal end of the lower ridge

It is covered by thin non keratinized epithelium

Contents

Fibers of the Buccinator

Fibers of the Superior Constrictor of the Pharynx

Pterygomandibular raphe

Tendon of the Temporalis

Glandlar Tissue

Loose Areolar Tissue

It determines the posterior limit of the mandibular denture .

Must be covered by the denture to attain a perfect border seal posteriorly. The

Pterygomandibular raphe limits the extension of the denture border posteriorly.

8. Pear Shaped Pad / Retromolar Papilla

8


The most distal extension of the attached keratinized mucosa overlying the mandibular

ridge crest formed by the scarring pattern following extraction of the mandibular third

molar, seen as a small elevation is referred to as the Retromolar papilla

9. Lingual Frenum

It is the anterior attachment of the tongue

It overlies the Genioglossus muscle which arises from the superior genial tubercle

It exhibits different configurations in both height & width

The lingual frenum area is shallow & should be registered in function.

In function it often comes close to the crest of the ridge, though it is much lower in the

rest position. Registering it in function determines the exact height of the lingual flange

of the denture.

10.Sublingual Fold / Sublingual Cresent area

This is a crescent shaped area on the floor of the mouth following the inner wall of the

mandible, tapering towards the molars.

It is formed by the sublingual gland and the submandibular gland duct (Wharton’s duct)

It is a fold of mucous membrane from the tongue to the residual ridge

Should not be recorded in an over compressed state in the impression

11.Mylohyoid Ridge

Sharp bony linear elevation found on the lingual side of the body of the mandible

Soft tissues overlying the ridge hide its sharpness, which can be found by palpation

Thin sharp ridges cause soreness of overlying mucosa in denture wearers.

Mylohyoid muscle

Takes attachment form the mylohyoid ridge

Forms “Floor of the Mouth”

Takes attachment along the ridge and approaches the level of the alveolar crest

9


posteriorly.

Angle of the posterior lingual flange is influenced by this muscle

12.Retromylohyoid Space / Fossa

Posterior limit of the alveololingual sulcus

Present posterior to the Mylohyoid mscle

The lingual flange of the denture moves posteriorly towards the mandible producing a

typical “S” shaped curve in the lingual flange.

The fossa extends from the end of the mylohyoid ridge to the retromylohyoid curtain.

Boundaries

Anteriorly : Mylohyoid ridge , Mylohyoid muscle

Posteriorly : Retromylohyoid curtain

* Posterolateral portion of Retromylohyoid curtain overlies

the Superior Constrictor of the Pharynx

* Posteromedial portion of Retromylohyoid curtain covers

the Palatoglossus muscle & the lateral surface of the

tongue

Laterally : Ramus

Medially : Disto-lateral surface of Tongue

Inferiorly : Submandibular gland.

13. Residual Alveolar Ridge

Crest of the ridge is covered by fibrous connective tissue

The ridge mainly consists of cancellous bone without a cortical plate covering it

The overlying mucous membrane is capable of providing good soft tissue support for the

denture, but the crest of the ridge cannot withstand vertical occlusal forces.

This in unfavorable to be the Primary Stress Bearing area of the mandible

It is therefore the Secondary Stress Bearing area of the Mandible

10


14. Alveololingual Sulcus

It is the space between the residual ridge and the tongue

It extends from the lingual frenum to the retromylohyoid curtain

It consists of three regions

Pre-mylohyoid Region / Anterior Region

Extends from the lingual frenum to the premylohyoid fossa.The depression seen here

corresponds to a prominence in the impression known as “Premylohyoid Eminence”

Mylohyoid Region / Middle Region

Extends from Premylohyoid fossa to the distal end of the mylohyoid ridge

The sulcus curves medially from the body of the mandible. The curvature is because of

the prominence of the mylohyoid ridge

Post-mylohyoid Region / Posterior Region

Flange passes into the retromylohyoid fossa. The flange turns laterally towards the ramus

to fill the fossa and give a typical “S” form.

The lingual flange of the tray is shaped to slope towards the tongue to facilitate

the impression material to flow below the prominence of the mylohyoid ridge. This

permits the distolingual flange of the fabricated denture to extend below the ridge. Else

the flange must terminate at the level of the ridge, thereby compromising retention.

When the flange of the denture slopes towards the tongue and extends below the

mylohyoid ridge, the tongue can rest on top of the flange and can help to stabilize the

denture and control it without interfering with the functions of the soft tissues.

11

Documents

Anatomical Landmarks