Define key terms associated with normal anatomy on panoramic images.
Identify and describe the bony landmarks of the maxilla, mandible, and surrounding structures as seen on panoramic images.
Identify air spaces and soft tissues as observed on panoramic images.
Bony Landmarks of the Maxilla and Surrounding Structures
The maxilla forms the:
Floor of the orbit of the eyes
Sides and floor of the nasal cavity
Hard palate
The lower border of the maxilla supports the maxillary teeth.
1. Mastoid Process
Location:
Posterior and inferior to the TMJ
Appearance:
Large rounded prominence of bone
Posterior inferior part of the temporal bone
Appears radiopaque
Not visible on intraoral images; seen only on extraoral images like panoramics.
2. Styloid Process
Characteristics:
Long, pointed, sharp projection of bone
Extending downward from the anterior surface of the temporal bone
Located medial to the mastoid process
Appearance:
Long tapering spine
Appears radiopaque
Not visible on intraoral images; seen only on panoramics.
3. Styloid Process Continued
Alternative Descriptions:
Anatomy: In the temporal bone
Location: Anterior and medial to mastoid process
Appearance:
Round opening
Appears as a small, ovoid radiolucency
Visible only on panoramic images.
4. Glenoid Fossa
Description:
Depressed area of the temporal bone
Appearance:
Concave surface above the mandibular condyle
Radiopaque
Not visible on intraoral images.
5. Articular Eminence
Description:
Rounded projection of the temporal bone
Location:
Anterior to the glenoid fossa
Appearance:
Radiopaque structure that cannot be seen on intraoral images.
6. Lateral Pterygoid Plate
Description:
Thin, wing-shaped bony extension of the sphenoid bone
Location:
Distal to the maxillary tuberosity region
Appearance:
Radiopaque; not seen on intraoral images.
7. Pterygomaxillary Fissure
Description:
Narrow space that separates the lateral pterygoid plate and maxilla
Appearance:
Radiolucent area resembling an elongated inverted teardrop.
8. Maxillary Tuberosity
Description:
Rounded bulge of bone posterior to the third molar region
Appearance:
Radiopaque; visible on intraoral images.
9. Infraorbital Foramen
Description:
Opening in bone inferior to the border of the orbit
Appearance:
Radiolucency situated inferior to the orbit; may be obscured by the maxillary sinus.
10. Maxillary Sinus
Description:
Bony cavity that contains the eyeball
Appearance:
Round radiolucent compartment with radiopaque borders located superior to the maxillary teeth.
11. Incisive Canal
Description:
Passageway through bone extending from the nasal cavity to the incisive foramen
Appearance:
Tubelike radiolucent area bordered by two thin radiopaque lines (cortical walls).
12. Incisive Foramen
Description:
Opening in bone located at the midline of the anterior portion of the hard palate
Appearance:
Small, ovoid radiolucent area between the roots of the maxillary central incisors; visible on intraoral images.
13. Nasal Cavity
Description:
V-shaped compartment of bone
Location:
Superior to the maxilla
Appearance:
Radiopaque; may be visible on intraoral images.
14. Nasal Septum
Description:
Vertical bony wall that divides the nasal cavity into the right and left fossae
Appearance:
Radiopaque; may not be symmetric on imaging and is visible on intraoral images.
15. Nasal Floor
Description:
Bony wall separating the nasal cavity from the oral cavity
Appearance:
Horizontal radiopaque band above the maxillary teeth; seen in intraoral images.
16. Maxillary Sinus
Description:
Paired cavities located within the maxilla
Location:
Superior to maxillary posterior teeth
Appearance:
Radiolucent; may be visible on intraoral images.
17. Zygomatic Process
Description:
Bony projection of the maxilla articulating with the zygoma (cheekbone)
Appearance:
J- or U-shaped radiopacity located above the maxillary first molar region; visible on intraoral images.
18. Zygoma
Description:
Articulates with the zygomatic process of the maxilla
Appearance:
Radiopaque; seen on intraoral images.
19. Hamulus
Description:
Small, hook-like projection of bone extending from the medial pterygoid plate of the sphenoid bone
Appearance:
Radiopaque hook situated posterior to the maxillary tuberosity; visible on intraoral images.
Bony Landmarks of the Mandible and Surrounding Structures
The mandible consists of:
Ramus
Angle
Body
20. Coronoid Process
Description:
Projection of bone extending from the anterior border of the ramus of the mandible
Location:
Rests in the glenoid fossa of the temporal bone
Appearance:
Rounded radiopacity; size and shape can vary based on anatomy and patient's position.
21. Mandibular Notch
Description:
Curved depression between the mandibular condyle and the coronoid process of the mandible
Appearance:
Radiopaque not visible on intraoral images.
22. Mylohyoid Ridge
Description:
Thin prominence of bone, shaped like a crow's beak
Location:
On the anterior-superior ramus of the mandible
Appearance:
Radiopaque and may be seen on maxillary molar PA images.
23. Mandibular Foramen
Description:
Tubular passageway through bone extending from the mandibular foramen to the mental foramen, housing inferior alveolar nerve and blood vessels
Appearance:
Radiolucent band outlined by two thin radiopaque lines (cortical walls) visible on intraoral images.
24. Mental Foramen
Description:
Opening located on the external surface of the mandible
Location:
Region of mandibular premolars
Appearance:
Radiolucency visible in the apical region of the mandibular premolars, can be seen on intraoral images.
25. Hyoid Bone
Description:
Horseshoe-shaped bone located below the mandible
Appearance:
Radiopaque structure that appears as a double image (left and right side) on panoramic images; may not always be visible depending on positioning.
26. Mental Ridge
Description:
Linear prominence of cortical bone located on the external surface of the anterior portion of the mandible
Appearance:
Radiopaque band extending from the premolar region to the midline; visible on intraoral images.
27. Mental Fossa
Description:
Scooped-out depressed area of bone located above the mental ridge
Appearance:
Radiolucent area above the mental ridge visible on intraoral images.
28. Lingual Foramen
Description:
Tiny opening or hole in bone located on the lingual aspect of the mandible
Appearance:
Radiolucent dot located inferior to the apices of the mandibular incisors, can be seen on intraoral images.
29. Lingual Ridge
Description:
Tiny bumps of bone on the lingual aspect of the mandible
Appearance:
Radiopacities surrounding the lingual foramen observed on intraoral images.
30. Lower Border of the Mandible
Description:
Thick linear prominence of cortical bone outlining the lower border of the mandible
Appearance:
Radiopaque; can be seen on some intraoral images.
31. Angle of the Mandible
Description:
Angle formed where the lower edge of the body meets the posterior edge of the ramus
Appearance:
Radiopaque area where the ramus joins the body of the mandible; not visible on intraoral images.
Air Spaces as Seen on Panoramic Images
Air spaces appear radiolucent and cannot be viewed on intraoral images.
1. Palatoglossal Air Space
Description:
Air space between the palate and the tongue
Appearance:
Horizontal well-defined radiolucent band located superior to the apices of maxillary teeth.
2. Nasopharyngeal Air Space
Description:
Air space in the pharynx located posterior to the nasal cavity
Appearance:
Diagonal radiolucent band located superior to the shadow of the soft palate and uvula.
3. Glossopharyngeal Air Space
Description:
Air space in the pharynx located posterior to the tongue and the oral cavity
Appearance:
Vertical radiolucent band superimposed over the ramus of the mandible; continuous with nasopharyngeal and palatoglossal air spaces.
Soft Tissues as Seen on Panoramic Images
Soft tissues show faint radiopacity not visible in intraoral images.
1. Tongue
Description:
Moveable muscular organ attached to the floor of the mouth
Appearance:
Faint dome-shaped radiopaque area superimposed over maxillary posterior teeth.
2. Soft Palate and Uvula
Description:
Form a muscular curtain that separates the oral cavity from the nasal cavity
Appearance:
Both appear as a faint diagonal radiopaque area projecting posteriorly and inferiorly from the maxillary tuberosity region.
3. Lip Line
Description:
Formed by the positioning of the patient’s lips
Appearance:
Areas of teeth not covered by the lips appear more radiolucent, while areas covered by the lips appear more radiopaque; can be seen on intraoral images of the central incisors.
4. Ear
Description:
Composed of cartilage with a thin covering of connective tissue and skin
Appearance:
Radiopaque shadow projecting anteriorly and inferiorly from the mastoid process, superimposed over the styloid process.