CrystaCRANIAL TOPOGRAPHY SURFACE LANDMARKS & SKULL POSITIONING LINES

Vocabulary flashcards covering cranial surface landmarks, skull positioning lines, and related projections used in radiographic topography and imaging.

Midsagittal Plane (MSP)

Symmetrically divides the body into left and right halves.

Interpupillary Line (IPL)

Connects the centers of the pupils (or outer canthi) of the eyes.

Supraorbital Groove (SOG)

A slight depression above each eyebrow; corresponds to the anterior fossa of the cranial vault.

Supraorbital Margin (SOM)

Superior rim of each orbit.

Glabella

Smooth prominence between the eyebrows, above the bridge of the nose.

Nasion

Junction of the frontal bone and nasal bones.

Acanthion

Junction of the upper lip and nasal septum.

Mental Point

Midpoint of the triangular area of the chin as it appears from the front.

Gonion (Angle of the Mandible)

Lower posterior angle on each side of the jaw (mandible).

Canthus (Canthi)

Junction of the upper and lower eyelids.

Pinna (Auricle)

Large flap of cartilage at the external portion of the ear.

Tragus

Small cartilaginous flap covering the ear.

Top of Ear Attachment (TEA)

Superior attachment of the auricle; at the same level as the petrous ridge.

Superciliary ridge (arch)

Ridge of bone above the eyebrow.

Acanthomeatal Line (AML)

Line between the acanthion and the external auditory meatus (EAM).

Orbitomeatal Line (OML)

Line from the inferior orbital margin to the external auditory meatus.

Infraorbitomeatal Line (IOML)

Reid's base line; line through the infraorbital margin and EAM.

Glabelloalveolar Line (GAL)

Line from the glabella to the anterior osseous alveolar process of the maxilla.

Glabellomeatal Line (GML)

Line from the glabella to the EAM.

Mentomeatal Line (MML)

Line from the mental point (chin) to the EAM.

Lips-meatal Line (LML)

Line from the junction of the lips to the EAM.

External Acoustic Meatus (EAM)

External opening of the ear canal.

Inion

External occipital protuberance (posterior skull landmark).

Sella Turcica

Turkish saddle; bony depression in the sphenoid bone housing the pituitary.

Dorsum Sellae

Posterior part of the sella turcica.

Petrous Ridge (Pyramids)

Ridge of dense bone forming part of the temporal bone; used in positioning references.

EAM (External Auditory Meatus)

External opening of the ear canal (landmark for many radiographic lines).

Paranasal Sinuses

Air-filled cavities (frontal, ethmoid, maxillary, sphenoid) shown in radiographs; often imaged erect to demonstrate air-fluid levels.

Glabella-Alveolar Line (GAL)

Line from the glabella to the anterior alveolar process of the maxilla.

IOML in TOwnes/Haas context

Infraorbitomeatal line; used to orient CR angles for skull base projections like Towne, Haas.

Rhese Method (Orbitoparietal Oblique)

Parieto-orbital oblique projection used to visualize the optic foramen; head rotated to place MSP at a 53° angle to the plane of the film.

Rheese (Orbitorparietal Oblique) CR

Central ray perpendicular to enter the affected orbit’s lower outer quadrant; used in Rhese projections.

Bertel Method

PA axial projection used to demonstrate inferior orbital fissures; uses a specific CR angle and forehead resting on grid.

Kemp Harper Method

SMV axial projection used to demonstrate jugular foramina; patient supine or upright with specific CR angulation.

Eraso Modification

Modification of Kemp Harper SMV projection for jugular foramina; different cranial angulation.

SMV (Submentovertex) Projection

Full basal projection; head resting on vertex; OML parallel to IR; IOML parallel to IR; demonstrates basal skull and petrous portions.

Mayer Method

Axiolateral oblique projection of the mastoid region; 45° Midsagittal rotation with 45° IOML alignment.

Fuchs Method

An axiolateral projection to delineate the styloid process; patient in prone position with AML perpendicular to IR.

Galeazzi/Wigby-Taylor Method

AP oblique projection to demonstrate the styloid process; patient supine with mouth opened for exposure.

Towne's Method

AP axial skull projection used to demonstrate occipital bones and dorsum sellae; CR angled caudad.

Haas Method

AP axial projection of the skull with specific cranial angulation to project dorsum sellae and posterior skull structures.

Caldwell Method

PA or PA axial projection often used to demonstrate frontal sinuses and anterior ethmoid sinuses; petrous ridges project into lower thirds of orbits at 15° caudad.

Waters Method

Parietoacanthial projection used to visualize orbital rims, maxillae, and zygomatic arches; chin support to extend orbitomeatal line to 37°.

Modified Waters Projection

A variation of Waters with less axial angulation; petrous ridges projected lower in maxillary sinuses.

Lateral Skull Projection

Lateral view with MSP parallel to IR; IPL perpendicular to IR; demonstrates parietal bones; sella turcica and clivus in profile.