Temporal Bone X-Ray Positioning: 5 Views for Mastoid & Petrous Imaging
An order arrives: "mastoids — rule out mastoiditis." Your textbook calls it one of the hardest exams in radiography — dense petrous bone, tiny air cells, and superimposing skull structures all fighting you for contrast. Getting an order for mastoids is rare these days, but it still happens, and the named methods (Law-type lateral oblique, Stenver's, Schuller's) remain classic ARRT content.
This guide covers the commonly taught, protocol-dependent projections for the temporal bone and mastoid region — AP axial 35° caudad, mastoid lateral oblique, mastoid profile, Stenver's anterior oblique, and the submento-vertical alternative — with centering points from Clark's Positioning in Radiography and US-oriented teaching labeled separately where they differ. There is no universal five-view series: obtain only the projections in the imaging order and validated facility protocol.
Why Temporal Bone Radiography Is Hard
The temporal bone is the most complex bone in the skull. It houses the external, middle, and inner ear — the external auditory meatus (EAM), the tympanic cavity, the ossicles, the cochlea, and the semicircular canals — plus the mastoid air cell system, a honeycomb of air-filled spaces that extends from the mastoid antrum into the mastoid process behind the ear.
Three things make it difficult to radiograph:
- Superimposition — the dense petrous pyramids are buried inside the skull base, overlapped by the occiput, the facial skeleton, and the opposite temporal bone on most projections
- Low subject contrast — the air cells are small; the surrounding bone is dense; tiny differences in density carry the diagnostic information
- Patient cooperation — the exact skull angles (25°, 35°, 45°) must be held precisely, and the positions are often uncomfortable
💡 Why It Matters
The mastoid air cell system is a direct continuation of the middle ear lining. In acute otitis media, infection spreads into the air cells — this is how acute mastoiditis develops. Plain-film evaluation answers: are the mastoids cellular or acellular? Is the cortical bone thin or thick? Are both sides symmetric? Is there bone destruction or cholesteatoma formation?
Modern context: CT of the temporal bones is now the standard imaging study for mastoid pathology, and MRI is the study of choice for complications of acute otitis media such as sinus thrombosis and intracranial extension. As Clark's notes, the plain-film temporal bone projections are "traditionally difficult to perform" and many are now "more or less redundant" because CT affords exquisite demonstration of temporal bone detail. But the classical methods remain part of radiography curricula and registry content — know them, and know when CT is the better answer.
Anatomy and Landmarks You Must Know
| Structure | What it is | Why it matters |
|---|---|---|
| External auditory meatus (EAM) | The opening of the ear canal | The primary centering landmark for every temporal bone projection |
| Mastoid process | Bony projection behind the ear, palpable | Target for the lateral oblique and profile views; the mastoid air cells live within it |
| Mastoid air cells | Honeycomb of air spaces extending from the antrum | The diagnostic target in mastoiditis; size varies greatly between individuals |
| Petrous part (petrous pyramid) | Dense pyramid of the temporal bone in the skull base | Contains the inner ear; target of Stenver's anterior oblique |
| External occipital protuberance (inion) | Bony prominence at the back of the skull | Centering reference for Stenver's |
| Sella turcica | Depression in the sphenoid bone | Its position within the foramen magnum verifies correct AP axial angulation |
Baselines used in temporal bone positioning:
- Orbito-meatal baseline (OMBL/OML) — from the outer canthus of the eye to the external auditory meatus (the radiographic baseline)
- Median sagittal plane (MSP) — divides the head into right and left halves
- Inter-orbital (interpupillary) line — joins the centers of the two orbits
Routine Views Overview
The table compares projections that may appear in textbooks or local protocols. It is not a universal exam recipe. SID, detector, grid use, exposure, and the exact projection set must come from the department's validated protocol and technique chart.
| Projection | View | Key Angulation | Key Centering |
|---|---|---|---|
| AP axial (frontal-occipital) 35° caudad | AP | CR 35° to the OMBL | Midway between the EAMs |
| Mastoid lateral oblique 25° caudad | Lateral oblique | CR 25° caudad (Clark's) | 5 cm above, 2.5 cm behind the far EAM |
| Mastoid profile | Axiolateral | Head rotated 35° away; CR 25° to OMBL | Middle of the mastoid process |
| Petrous bone anterior oblique (Stenver's) | PA oblique | MSP 45° to table; CR 12° cephalad (Clark's) | Midway between inion and far EAM |
| Submento-vertical (SMV) | Base (axial) | CR perpendicular to OMBL | Midway between the EAMs |
View 1: AP Axial — Frontal-Occipital 35° Caudad
Clark's describes this as the frontal-occipital 35 degrees caudad projection for the temporal bones — an AP axial view that projects the mastoid and petrous parts of the temporal bone clear of the foramen magnum region.
Patient Positioning
- Position: Supine in the midline of the table, or erect with the back against an erect Bucky
- Head: EAMs equidistant from the table — the median sagittal plane at right-angles to, and in the midline of, the table
- Chin: Depressed so the orbito-meatal line is at right-angles to the table
- IR: Small (24 × 30-cm) cassette placed transversely, centred to coincide with the angled central ray
Technical Factors
| Parameter | AP Axial Temporal Bones |
|---|---|
| CR angle | 35° caudad to the orbito-meatal plane |
| Centering point | Midway between the external auditory meatuses |
| Collimation | Laterally to the lateral skull margins; supra-inferiorly to include the mastoid and petrous parts |
| Respiration | Suspended |
Evaluation Criteria
- Sella turcica projected within the foramen magnum
- No rotation — the sella turcica appears in the middle of the foramen magnum
- Mastoid and petrous parts of the temporal bone included
📌 Exam Tip
Under-angulation is the most common fault — the foramen magnum won't demonstrate clearly above the petrous ridges. Patients struggle to keep the baseline perpendicular. If the chin can't be depressed enough, increase the tube angle more than 35° to the vertical while maintaining 35° to the orbito-meatal plane. Also remember: the standard Towne's projection uses 30° to the OMBL; the temporal bone AP axial uses 35° — a classic exam distinction.
View 2: Mastoid — Lateral Oblique 25° Caudad
Clark's mastoid lateral oblique is the primary lateral oblique for the mastoid air cells. In US/ARRT-oriented texts the same family of view is taught as the Law method — but with a different angle (15° caudad). Both are described below; follow your program's text and facility protocol.
Patient Positioning (Clark's)
- Position: Seated facing the erect Bucky
- Head: Rotated so the MSP is parallel to the Bucky and the inter-orbital line is perpendicular to the Bucky
- Shoulders: May be rotated slightly; the patient may grip the Bucky for stability
- Ear: The auricle of the ear adjacent to the table is folded forward — this prevents its soft-tissue outline from superimposing over the region of interest
- Part: Mastoid process positioned in the middle of the Bucky
- IR: 18 × 24-cm cassette longitudinal, centred to coincide with the central ray and the mastoid process
Technical Factors
| Parameter | Mastoid Lateral Oblique |
|---|---|
| CR angle | 25° caudad (Clark's) |
| Centering point | 5 cm above and 2.5 cm behind the EAM remote from the cassette |
| Collimation | To the area under examination |
Evaluation Criteria
- All mastoid air cells included within the image — their size varies greatly between individuals
- No soft-tissue artefact from the auricle
- Both sides imaged for comparison (Clark's note)
📌 Exam Tip
Centering too far anteriorly is the classic error — well-developed posterior air cells get cut off. And check the auricle is folded forward immediately before exposure: patients shift, and the ear flops back, producing a soft-tissue artefact right over the region of interest.
The Law Method (US/ARRT-oriented teaching)
- CR directed at a 15° oblique plane cephalocaudally with the skull's sagittal plane parallel to the film (CE4RT)
- Same lateral-oblique geometry family as Clark's 25° version — the angle differs between texts (15° vs 25°); label your source and follow the validated protocol
- The Schuller method is similar to Law's but uses 30° angulation, which superimposes the internal and external acoustic meatuses to separate the two mastoids and visualizes the upper attic and antrum
View 3: Mastoid — Profile
The mastoid profile (axiolateral) places the mastoid process and air cells in true profile, free of the skull vault.
Patient Positioning
- Position: Supine on the table, OMBL perpendicular to the tabletop
- Rotation: From the MSP perpendicular to the table, the head is rotated through 35° away from the side under examination — the MSP now makes an angle of 55° to the table
- Check: The vertical tangent to the skull should be at the level of the middle of the mastoid process under examination (mastoid in profile)
- Shift: The head is moved transversely so the mastoid process under examination is in the midline of the table
Technical Factors
| Parameter | Mastoid Profile |
|---|---|
| CR angle | Angled caudally, making an angle of 25° to the OMBL |
| Centering point | Middle of the mastoid process on the side under examination |
| Collimation | Tightly around the mastoid process |
| Marker | Small lead side-marker within the collimation field |
Evaluation Criteria
- Mastoid process and air cells in true profile
- No rotation — the profile relationship is confirmed by the vertical-tangent check
- Both sides often imaged for comparison
View 4: Petrous Bone — Anterior Oblique (Stenver's)
Stenver's (spelled Stenver's or Stenvers) demonstrates the petrous part of the temporal bone in profile — the petrous pyramid, internal auditory meatus, arcuate eminence, and semicircular canals.
Patient Positioning (Clark's)
- Position: Prone, or erect facing a vertical Bucky
- Part: The middle of the supra-orbital margin on the side being examined is centred to the middle of the Bucky
- Neck flexion: Nose and forehead in contact with the table, orbito-meatal line perpendicular to the table
- Rotation: From the MSP perpendicular to the table, the head is rotated toward the side under examination so the MSP is at 45° to the table — this brings the petrous part of the temporal bone parallel to the cassette
- Neck extension: The neck is extended so the orbito-meatal line is raised 5° from horizontal
- IR: 18 × 24-cm cassette transverse, centred at a level to coincide with the central ray
Technical Factors
| Parameter | Stenver's (Petrous Anterior Oblique) |
|---|---|
| CR angle | 12° cephalad (i.e., 7° to the OMBL) to separate the occiput from the petrous bone |
| Centering point | Midway between the external occipital protuberance and the EAM furthest from the cassette |
| Collimation | To the mastoid and petrous parts under examination |
Evaluation Criteria
- Petrous part of the temporal bone in profile, separated from the occiput
- Internal auditory meatus, arcuate eminence, and semicircular canal region demonstrated
- No rotation — MSP at 45° to the table confirmed
📌 Exam Tip
Stenver's is the view that shows the petrous pyramid in profile — the internal auditory meatus and arcuate eminence hang off it like landmarks on a map. Two numbers to memorize: MSP at 45° to the table (rotation toward the side under examination) and CR 12° cephalad (Clark's). CE4RT/US teaching describes ~14° angulation with the head rotated to the opposite side — the same named view, described differently by source.
View 5: Submento-Vertical (SMV) — Alternative
Clark's lists the submento-vertical as an alternative for the temporal bones, collimated down to include only the petrous and mastoid parts. In US-oriented teaching the "full axial" SMV is also listed among mastoid positions.
Patient Positioning
- Position: Erect or supine. Supine is advisable if the patient is unsteady
- Supine: Shoulders raised, neck hyperextended to bring the vertex of the skull in contact with the grid cassette
- Head: EAMs equidistant from the cassette; MSP at right-angles to the cassette along its midline; OMBL as near parallel to the cassette as possible
Technical Factors
| Parameter | Submento-Vertical |
|---|---|
| CR angle | At right-angles to the OMBL |
| Centering point | Midway between the EAMs |
| Collimation | Down to the petrous and mastoid parts for temporal bone work |
Evaluation Criteria
- Angles of the mandible clear of the petrous portions of the temporal bone
- Foramina of the middle cranial fossa seen symmetrically on either side of the midline
📌 Exam Tip
The SMV is an uncomfortable position — prepare all equipment before you start so the patient holds it for the minimum time. Erosion of the skull-base foramen margins is an important indicator of destruction by tumour, and under-tilt, over-tilt, or rotation all reduce foramina visibility. A skull unit makes this position much easier by minimizing neck hyperextension.
When CT Is the Better Answer
Plain-film temporal bone radiography has largely been replaced by cross-sectional imaging:
- CT of the temporal bones is the standard study for mastoid pathology — it diagnoses mastoiditis in the large majority of cases and shows opacification of the air cell system, mucosal swelling, tegmen defects, and periosteal changes
- MRI is the study of choice for complications of acute otitis media: sinus thrombosis, intracranial extension, and abscess formation
- Clark's: the isocentric skull technique and CT "afford exquisite demonstration of temporal bone detail" — the plain projections are "more or less redundant" for the petrous bone
Understand the classical methods for the registry and for the occasional order — but when mastoid pathology is the clinical question, CT is the answer.
Internal Linking — Build Your Knowledge
This temporal bone positioning guide is part of the complete head and facial positioning library:
- Skull X-Ray Positioning — Lateral, PA, AP, Towne, and Caldwell skull projections, including the standard 30° Towne's
- TMJ X-Ray Positioning — open and closed mouth views of the adjacent temporomandibular joint
- Mandible X-Ray Positioning — the axiolateral oblique family for the mandible
- Facial Bones X-Ray Positioning — Waters, Caldwell, lateral, and SMV for the facial skeleton
- CT vs MRI Comparison — why cross-sectional imaging has replaced plain-film temporal bone radiography
- X-Ray Modality Overview — general radiography technique and physics
- CT Scan Modality Overview — the current standard for temporal bone imaging
Test Your Knowledge — Educational Practice Questions
📝 Practice Questions
Question 1: For the AP axial temporal bones projection, what angulation does Clark's specify for the central ray?
Question 2: Where does Clark's center the mastoid lateral oblique projection?
Question 3: In the mastoid profile projection, the head is rotated through what angle away from the side under examination?
Question 4: What rotation brings the petrous part of the temporal bone parallel to the cassette for Stenver's?
Question 5: Which evaluation criterion confirms correct angulation on the AP axial temporal bones projection?
Quick Reference — Temporal Bone Positioning Checklist
Use this checklist before every temporal bone X-ray exam:
- ✅ Ordered projection set checked against the local protocol; no automatic extra views
- ✅ Correct radiopaque side marker placed for every projection
- ✅ AP axial temporal bones — OMBL perpendicular, CR 35° caudad to OMBL, centred midway between EAMs, sella in foramen magnum
- ✅ Mastoid lateral oblique — MSP parallel to Bucky, auricle folded forward, CR 25° caudad (Clark's), centred 5 cm above / 2.5 cm behind the far EAM
- ✅ Mastoid profile — head rotated 35° away (MSP 55° to table), CR 25° to OMBL, centred to middle of mastoid process
- ✅ Stenver's — MSP 45° to table, OML raised 5°, CR 12° cephalad, centred midway between inion and far EAM
- ✅ SMV — neck hyperextended, vertex on the cassette, OMBL parallel, CR perpendicular centred between EAMs
- ✅ Both sides imaged for comparison where indicated
- ✅ No motion — sharp bony margins confirmed
- ✅ CT recommended and communicated when mastoid pathology is the clinical question
Authoritative Sources
- Clark's Positioning in Radiography, 12th edition (Whitley, Sloane, Hoadley, Moore, Alsop — Hodder Arnold, 2005): temporal bones pp. 249–254; Towne's projection p. 243; submento-vertical p. 246.
- CE4RT: Radiography of the Mastoid Process — Law 15°, Stenver's 14°, Schuller 30°, transorbital, and full-axial mastoid positions; pathology and modern-imaging context (accessed 2026-08-05).
- ARRT Examination Content Specifications — official exam scope; not a facility protocol.
Radiography 101
Educational resource for radiologic technology students and professionals. This guide is for educational purposes and does not replace the imaging order, clinical assessment, or institutional protocol.