radiology exam landmarks

Cortical bone

Dense outer layer of bone that appears radiopaque on an image.

Cancellous bone

Soft, spongy bone located between two layers of dense cortical bone, primarily radiolucent, composed of numerous bony trabeculae that form a lattice-like network of spaces filled with bone marrow.

Trabecular pattern

The trabecular pattern varies considerably from patient to patient and even within the same patient.

Trabeculae in the maxilla

Typically small and form a dense granular pattern.

Trabeculae in the mandible

Larger and coarser compared to those in the maxilla.

Radiopaque

The denser the tissue, the more radiation it will absorb.

Radiolucent

The thinner the tissue, the more radiation passes through the tissue and reaches the film.

Process

Marked prominence or projection.

Ridge

Linear prominence or projection.

Spine

Sharp, thornlike projection.

Tubercle

Small bump or nodule.

Tuberosity

Rounded prominence.

Canal

Tubelike passageway through bone that contains nerves and blood vessels.

Foramen

Opening or hole that permits the passage of nerves and blood vessels.

Fossa

Broad, shallow, scooped-out, or depressed area.

Sinus

Hollow space, cavity, or recess.

Septum

Bony wall or partition that divides two spaces or cavities.

Suture

Immovable joint representing a line of union between adjoining bones of the skull.

Maxilla

The upper jaw is composed of two paired bones, the maxillae.

Incisive Foramen

Opening or hole in bone that is located at the midline of the anterior portion of the hard palate directly posterior to the maxillary central incisors.

Superior Foramina of the Incisive Canal

Two tiny openings or holes in bone that are located on the floor of the nasal cavity.

Median Palatal Suture

Immovable joint between the two palatine processes of the maxilla.

Lateral Fossa

Smooth, depressed area of the maxilla located just inferior and medial to the infraorbital foramen between the canine and lateral incisors.

Nasal Cavity

Pear-shaped compartment of bone located superior to the maxilla.

Nasal Septum

Vertical bony wall or partition that divides the nasal cavity into the right and left nasal fossa.

Floor of the Nasal Cavity

Bony wall formed by the palatal processes of the maxilla and the horizontal portions of the palatine bones.

Anterior Nasal Spine

Sharp projection of the maxilla located at the anterior and inferior portion of the nasal cavity.

Inferior Nasal Conchae

Wafer-thin, curved plates of bone that extend from the lateral walls of the nasal cavity.

Maxillary Sinus

Paired cavities or compartments of bone located within the maxilla.

Septa within the Maxillary Sinus

Bony walls or partitions that appear to divide the maxillary sinus into compartments.

Nutrient Canals within the Maxillary Sinus

Tiny, tubelike passageways through bone that contain blood vessels and nerves.

Inverted Y

Intersection of the maxillary sinus and the nasal cavity.

Maxillary Tuberosity

Rounded prominence of bone that extends posterior to the third molar region.

Hamulus

Small hooklike projection of bone extending from the medial pterygoid plate of the sphenoid bone.

Zygomatic Process of the Maxilla

Bony projection of the maxilla that articulates with the zygoma or malar (cheek) bone.

Zygoma

Articulates with the zygomatic process of the maxilla.

Mandible

The largest and strongest bone of the face.

Genial Tubercles

Tiny bumps of bone on the lingual aspect of the mandible.

Lingual Foramen

Tiny opening or hole in bone located on the internal surface of the mandible.

Nutrient Canals

Tubelike passageways through bone containing nerves and blood vessels that supply the teeth.

Mental Ridge

Linear prominence of cortical bone located on the external surface of the anterior portion of the mandible.

Mental Fossa

Scooped-out, depressed area of bone located on the external surface of the anterior mandible.

Mental Foramen

Opening or hole in bone located on the external surface of the mandible in the region of the mandibular premolars.

Mandibular Canal

Tubelike passageway through bone that travels the length of the mandible.

Mylohyoid Ridge

Linear prominence of bone located on the internal surface of the mandible.

External Oblique Ridge

Linear prominence of bone located on the external surface of the body of the mandible.

Anterior Border of the Ramus

Anterior border of the ramus extends vertically downward from the coronoid process to the external oblique ridge.

Submandibular Fossa

Scooped-out, depressed area of bone located on the internal surface of the mandible inferior to the mylohyoid ridge.

Coronoid Process

Marked prominence of bone on the anterior ramus of the mandible.

Enamel

Outermost radiopaque layer of the crown of a tooth.

Dentin

Comprises most of the tooth structure, not as radiopaque as enamel.

Dentino-enamel junction (DEJ)

Junction between dentin and enamel.

Pulp cavity

A pulp chamber and pulp canals.

Lamina Dura

The wall of the tooth socket made of dense cortical bone.

Alveolar Crest

The most coronal portion of the alveolar bone found between teeth.

Periodontal Ligament Space

The space between the root of the tooth and the lamina dura.

Primary Dentition

Also known as deciduous dentition, comprised of 10 maxillary and 10 mandibular teeth.

Mixed Dentition

Between the ages of 6 and 12, mixed dentition (both primary and permanent teeth) is seen in the oral cavity.

Mastoid Process

Large radiopaque prominence posterior and inferior to TMJ

Styloid Process

Long radiopaque spine extending downward from the temporal bone

External Auditory Meatus

Ovoid radiolucency anterior to mastoid process

Glenoid Fossa

Concave radiopacity superior to mandibular condyle

Articular Eminence

Rounded radiopaque projection anterior to glenoid fossa

Lateral Pterygoid Plate

Thin radiopaque projection distal to maxillary tuberosity

Pterygomaxillary Fissure

Radiolucent space between lateral pterygoid plate and maxilla

Maxillary tuberosity

Radiopaque bulge distal to the third molar region

Infraorbital Foramen

Ovoid radiolucency inferior to orbit

Orbit

Round radiolucency with radiopaque borders, superior to maxillary sinus

Mandibular Condyle

Rounded radiopaque structure from posterior ramus

Sigmoid Notch

Radiopaque curved depression between condyle and coronoid process

Lingula

Small radiopaque projection near mandibular foramen

Angle of the Mandible

Radiopaque angle formed where the body and ramus meet

Hyoid Bone

Radiopaque curved structure below the mandible

Palatoglossal Air Space

Radiolucent band between the palate and tongue

Nasopharyngeal Air Space

Radiolucent area posterior to nasal cavity

Glossopharyngeal Air Space

Radiolucent area behind the tongue and oral cavity

Tongue

Slight radiopacity filling the oral cavity

Soft Palate and Uvula

Slightly radiopaque outline posterior to the oral cavity

Lip line

Faint radiopaque or radiolucent shadow across the anterior teeth

Ear

Radiopaque structure seen in the posterior portion of the image