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Head

Nasal Bones

Anatomy

Students should be able to identify the following structures on radiographic images:

Nasal bones, Anterior nasal spine, Frontonasal suture, Nasal septum, perpendicular plate of the ethmoid, vomer,  acanthion, frontal sinus, maxillary sinuses, orbits, zygomatic arches (malar bones), and occasionally the mandible

Routine Projections (ARRT Required)

Lateral Nasal Bones – Right and Left

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Erect or prone, side of interest closest to IR
  • Adjustments:
    • MSP ∥ IR
    • IPL ⟂ IR
    • IOML ⟂ front edge of IR
  • CR: Perpendicular, centered ½ inch inferior to nasion
  • Pt. Instructions: Suspend respiration
  • Exposure: Low kV (50–60 analog, 60–70 digital), nongrid

Evaluation Criteria

  • Coverage (what anatomy must be included and how you verify it’s complete): Nasal bones, anterior nasal spine, frontonasal suture, and nasal soft tissue included
  • Rotation checks (how symmetry or alignment tells you if positioning is correct): No rotation — nasal bones symmetric
  • Motion checks (how sharpness confirms patient cooperation/exposure timing): Sharp bony and soft tissue margins
  • Technique checks (what contrast, density, soft tissue visibility, and artifacts to look for): Soft tissue density sufficient to show nasal cartilage and outline of nose
  • Clinical aim (when applicable, e.g., reflux, obstruction, displacement, etc.): Detect displacement and comparison between sides

Parietoacanthial Nasal Bones (Waters Method)

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Erect preferred (or prone)
  • Adjustments: Chin on IR; MML ⟂ IR; OML forms ~37° with IR; MSP ⟂ IR
  • CR: Perpendicular, exiting acanthion
  • Pt. Instructions: Suspend respiration
  • Exposure:  75–85 kV digital

Evaluation Criteria

  • Coverage: IOMs, maxillae, nasal septum, zygomas, anterior nasal spine
  • Rotation checks: Equal orbital margins, nasal septum midline
  • Motion checks: Sharp margins of maxillae and sinuses
  • Technique checks: Petrous ridges just below maxillary sinuses
  • Clinical aim: Demonstrates bony nasal septum deviation and midface fractures

Supplemental Projections

Superoinferior Tangential (Axial)

Clinical Indications:

  • Nasal bone fractures with medial-lateral displacement

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Seated erect or prone; chin on IR
  • Adjustments: IR angled so GAL ⟂ IR; MSP ⟂ IR; extend chin to rest on IR
  • CR: Parallel to GAL, centered to nasion (skims glabella and anterior upper teeth)
  • Pt. Instructions: Suspend respiration
  • Exposure: 60–70 kV digital, nongrid

Evaluation Criteria

  • Coverage: Mid- and distal nasal bones with soft tissue profile; minimal superimposition of glabella/alveolar ridge
  • Rotation checks: Symmetry of anterior nasal spine to outer soft tissue borders
  • Motion checks: Sharp nasal margins
  • Technique checks: Correct extension/flexion — too much chin = alveolar ridge in view; too little = excess glabella in view
  • Clinical aim: Assess displacement in the axial plane

Hows & Whys of Nasal Bone Radiography

Anatomy / Clinical Aim

  • What anatomy is best demonstrated on the lateral nasal bones?
    The nasal bones, anterior nasal spine, frontonasal suture, and nasal soft tissues.
  • What anatomy is best demonstrated on the Waters view?
    The bony nasal septum, maxillae, zygomas, and anterior nasal spine.
  • What anatomy is best demonstrated on the superoinferior tangential view?
    The mid- and distal nasal bones and the soft tissue nose without significant superimposition.

Positioning

  • In the lateral projection, why must the interpupillary line (IPL) be perpendicular to the IR?
    To prevent tilt, ensuring the orbital roofs and nasal bones are superimposed.
  • In the lateral projection, why should the infraorbitomeatal line (IOML) be parallel to the transverse axis of the IR?
    To keep the head from tipping forward or backward, which would distort nasal bone detail.
  • Why are both lateral projections taken for nasal bones?
    Because each side is positioned closest to the IR in turn, ensuring maximum detail for comparison.
  • For the Waters projection, why is the OML adjusted to form a 37° angle with the IR?
    To bring the mentomeatal line (MML) perpendicular, projecting the petrous ridges below the maxillary sinuses and opening the midface.
  • Why is a horizontal beam lateral important in trauma cases involving the nasal bones?
    It allows evaluation without manipulating the head or neck and demonstrates air–fluid levels if associated sinus fractures are present.
  • Why must cervical spine injury be ruled out before positioning for nasal bone studies?
    Head or neck movement could worsen an undiagnosed spinal injury.
  • Why are two laterals especially important in trauma cases?
    They allow comparison of displacement or depression between the right and left nasal bones.

Technique & Image Evaluation

  • How do you know the interpupillary line (IPL) was perpendicular on a lateral projection?
    The orbital roofs and nasal bones are superimposed without vertical separation.
  • How do you know the IOML was parallel to the IR on a lateral projection?
    The frontal sinuses and orbital roofs appear in proper vertical alignment without slanting.
  • How do you know the OML was angled correctly for the Waters projection?
    The petrous ridges are seen just below the maxillary sinuses, and the nasal septum is clearly visible.
  • How do you know there was no rotation on a lateral nasal bones projection?
    The anterior nasal spine and soft tissue outline are aligned without anterior/posterior separation of bilateral structures.
  • How do you know there was no rotation on a Waters projection?
    The orbital margins and nasal septum are symmetrical side to side.
  • Why must close collimation be used for nasal bone studies?
    To reduce scatter and improve recorded detail of the thin nasal bones and adjacent soft tissue.
  • How do you know the exposure factors were appropriate for nasal bones?
    Bony detail of the nasal bones is visible along with surrounding soft tissues without overexposure.
  • Which structures should be included on a properly collimated Waters projection for nasal bones?
    Nasal bones, orbits, maxillae, and anterior nasal spine.

 

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Radiographic Procedures Review Guide Copyright © 2025 by Carla M. Allen and Taylor M. Otto is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, except where otherwise noted.

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