Reverse Towne’s View
Dental Radiology · Extraoral Skull Projections
TL;DR
The Reverse Towne’s view is the dedicated plain film projection for bilateral assessment of the mandibular condyles, widely used in trauma and oral and maxillofacial surgery settings.
- The Reverse Towne’s projection (also called the Reverse Towne view or Reverse Towne’s occipital view) is an extraoral radiograph in which the X-ray beam is directed in a posteroanterior (PA) direction at a downward angle of 30–35° through the occipital bone to the receptor placed against the patient’s forehead
- It is primarily used to visualise the condylar heads and necks of the mandible, especially to assess condylar fractures — the most common indication
- The name “Reverse” refers to the fact that the beam direction is opposite to the original Towne’s projection (in Towne’s, the beam passes anteroposterior from in front of the patient; in Reverse Towne’s, the beam passes posteroanterior from behind)
- The projection shows both condylar heads in the same image and is particularly valuable for detecting condylar neck fractures and medially displaced condylar head fractures that may not be visible on a panoramic radiograph
- It is a simple, low-cost radiograph requiring standard equipment and remains widely used in oral and maxillofacial surgery and emergency settings despite increasing availability of CT
Key Facts
What Is It?
The Reverse Towne’s view is an extraoral plain radiographic projection of the skull designed to bring the mandibular condyles into clear view without superimposition from the dense base of skull. By directing the X-ray beam posteroanteriorly (from behind the patient’s head, downward at approximately 30–35° to the orbitomeatal line), the beam passes through the occipital bone and projects the condylar heads clear of the petrous temporal bones and mastoid processes — structures that otherwise obscure the condyles on many standard skull views.
The original Towne’s projection — described by Elias H. Towne in 1926 — directs the beam anteroposteriorly (from in front of the patient), tilted 30–35° caudally. The Reverse Towne’s directs the beam from behind the patient (PA direction), which in practice means the patient faces the receptor, the back of the head faces the tube, and the beam travels through the occiput. This reversed geometry is what provides the unobstructed view of the condyles.
Why It Matters
The mandibular condyle is among the most frequently fractured structures in the facial skeleton, and condylar fractures are commonly missed or inadequately characterised on panoramic radiographs alone. The Reverse Towne’s view fills a critical gap in the plain film imaging of mandibular trauma by providing a dedicated bilateral condylar projection that is fast, inexpensive, and widely available.
Clinical Relevance
- Condylar fractures: the mandibular condyle is the most frequently fractured part of the mandible (accounting for approximately 30–36% of all mandibular fractures). In trauma, condylar fractures can be missed on a panoramic radiograph — especially when the condylar head is displaced medially or when overlying structures cause confusion. The Reverse Towne’s view is the dedicated projection for condylar assessment in trauma.
- Bilateral visualisation: both condylar heads and necks are visible in a single image, allowing side-by-side comparison of position, height, and angulation — essential for symmetric condylar assessment.
- Subcondylar and condylar neck fractures: the subcondylar region is particularly well-demonstrated. Medial displacement of the condylar head (a common fracture pattern) is clearly visible.
- Pre- and post-operative monitoring: used to document condylar position before and after trauma, surgical repair, or mandibular advancement.
- Low-cost alternative to CT: in settings where CT is not available, the Reverse Towne’s view combined with a panoramic and lateral skull provides comprehensive initial mandibular trauma assessment.
Technique and Positioning
Correct positioning is the single most important determinant of diagnostic quality on the Reverse Towne’s view. The following steps outline the standard technique.
- The patient stands or sits facing the upright receptor (image receptor positioned against the patient’s forehead/frontal bone)
- The patient’s head is positioned with the orbitomeatal line (OML — from outer canthus of eye to centre of external auditory meatus) perpendicular to the receptor surface
- The chin is depressed slightly (approximately 15–20° from the OML-horizontal relationship) — this helps clear the petrous ridges from the condylar region
- The midsagittal plane must be centred to the receptor — both sides must be equidistant to avoid asymmetric magnification
- The X-ray tube is positioned behind the patient’s head; the central ray is directed posteroanteriorly at a downward (caudal) angle of approximately 30–35° to the OML — aimed at the centre of the receptor
- The central ray passes through the occipital bone, through the foramen magnum region, and exits through the condylar regions toward the receptor
- Collimate to include the TMJ regions bilaterally
- Expose; typical settings: 70–80 kVp; mAs as appropriate for skull penetration
What Is Visible
- Condylar heads (bilaterally) — projected free of the petrous bones
- Condylar necks and subcondylar regions
- Glenoid fossae and articular eminences
- Mandibular rami (partially)
- Lower part of the occiput and foramen magnum region
What Is NOT Well Visualised
- Teeth and alveolar bone
- Anterior mandible (symphysis, body)
- Maxillary sinuses
- Fine intra-articular detail (disc, joint space — MRI needed)
Radiographic Anatomy Visible on the Reverse Towne’s View
Familiarity with the expected radiographic anatomy is essential for both identifying normal landmarks and recognising pathological changes.
| Structure | Radiographic Appearance | Clinical Significance |
|---|---|---|
| Condylar head (bilateral) | Rounded radiopaque structures projected in the supraglenoid region | Bilateral comparison; fracture detection; condylar hyperplasia/hypoplasia |
| Condylar neck | Short radiopaque column connecting condylar head to ramus | Condylar neck fractures — most common fracture type visible |
| Subcondylar region | Broader area of ramus below condylar neck | Subcondylar fractures; ramus fractures |
| Glenoid fossa | Concave radiolucent region above condylar head | Erosion, widened joint space, dislocation |
| Articular eminence | Radiopaque tubercle anterior to glenoid fossa | Visible in some patients; dislocation assessment |
| Mandibular rami | Broad flat bones connecting condyles to mandibular body | Ramus fractures; asymmetric ramus height |
| Foramen magnum | Central oval radiolucency | Normal landmark; confirms correct positioning |
| Mastoid processes | Dense radiopaque processes lateral to condyles | Positioning reference; mastoiditis in appropriate clinical context |
| Petrous temporal ridges | Dense horizontal radiopaque lines | Should NOT overlap condyles in a well-positioned Reverse Towne’s |
Clinical Applications and Interpretation
The Reverse Towne’s view is most frequently used in the context of mandibular trauma and condylar pathology. Understanding the condylar fracture classification system is essential for interpreting this projection.
Condylar Fracture Classification
- Condylar head fracture (intracapsular): fracture within the joint capsule; condylar head may be comminuted. May be difficult to assess even on Reverse Towne’s — CBCT preferred.
- Condylar neck fracture (most common): fracture through the thin neck below the head. Classic sign: medial displacement of the condylar head with lateral deviation of the chin at rest. Well-visualised on Reverse Towne’s.
- Subcondylar fracture: fracture through the ramus above the sigmoid notch. Well-visualised on Reverse Towne’s.
- Diacapitular fracture: fracture line passes through the condylar head. Requires CBCT for accurate assessment.
Signs of Condylar Fracture on Reverse Towne’s
- Loss of normal condylar head contour
- Medial or lateral displacement of condylar head
- Shortening of condylar neck height on affected side
- Angulation of condylar fragment
- Difference in condylar head height between left and right
Comparison with Other Condylar Views
| View | Shows Condyles? | Best For | Limitation vs Reverse Towne’s |
|---|---|---|---|
| Panoramic (OPG) | Yes (but may miss displaced fractures) | Screening; overall mandible | Condylar head may be cut off; medial displacement hard to see |
| Reverse Towne’s | Yes (primary view) | Condylar neck/subcondylar fractures; bilateral comparison | Limited to condylar region; no teeth visible |
| Transcranial | Yes (lateral view) | TMJ joint space; lateral open/closed position | Only shows lateral pole; medial pathology missed |
| PA skull | Yes (limited) | Facial symmetry; midline | Condyles not primary focus; superimposed on petrous bone in standard PA |
| CBCT | Yes (3D) | Intracapsular fractures; complex pathology | Higher dose; not always available in emergency |
Clinical Considerations
- Trauma protocol: in suspected mandibular condylar fracture, the recommended imaging sequence is: panoramic radiograph (broad survey) + Reverse Towne’s view (condyle-specific) as the initial plain film combination. CT or CBCT is added when fracture is confirmed or clinical findings are incongruent with plain film findings.
- Patient positioning: the most critical positioning variable is the midsagittal plane alignment. A tilted head produces asymmetric condylar height that mimics pathology. Always confirm patient position before exposure.
- Paediatric patients: condylar fractures are the most common mandibular fractures in children. However, in young children, positioning for Reverse Towne’s may be challenging. Panoramic + OPG is often the preferred initial approach in the paediatric setting; CBCT reserved for complex cases.
- Dose: the Reverse Towne’s delivers a moderate skull radiation dose (approximately 15–25 μSv effective dose). Thyroid collar use is appropriate; lead apron over the gonads is standard.
Common Mistakes & Misconceptions
INBDE candidates and clinicians alike can fall into predictable errors when reasoning about the Reverse Towne’s view. Understanding these pitfalls is the first step to avoiding them.
-
Misconception: “A panoramic radiograph is sufficient to exclude a condylar fracture.”
Correction: Panoramic radiographs can miss condylar fractures, especially medially displaced condylar head fractures or subcondylar fractures. The Reverse Towne’s view is the dedicated adjunct for condylar assessment and should always accompany the panoramic in suspected condylar trauma. -
Misconception: “Asymmetric condylar height on the Reverse Towne’s always means pathology.”
Correction: If the patient’s midsagittal plane is not centred perfectly on the receptor (i.e., the head is tilted), one condyle will appear higher than the other — a positioning artefact. Confirm head positioning before interpreting condylar height asymmetry as pathological. -
Misconception: “The Reverse Towne’s and the standard Towne’s view are the same projection.”
Correction: In the standard Towne’s projection, the beam passes anteroposteriorly (from in front of the patient, aimed posteriorly). In the Reverse Towne’s, the beam passes posteroanteriorly (from behind the patient, aimed anteriorly). The patient faces the receptor in the Reverse Towne’s — opposite to the standard Towne’s. -
Misconception: “A normal Reverse Towne’s view rules out all condylar pathology.”
Correction: The Reverse Towne’s shows condylar necks and heads on a 2D projection. Intracapsular fractures, fine diacapitular fractures, disc displacement, and articular surface erosions require CBCT or MRI for detection. -
Misconception: “The beam angle in the Reverse Towne’s is the same as in the submentovertex view.”
Correction: In the Reverse Towne’s, the beam is directed posteroanteriorly, angled approximately 30–35° caudally (downward). In the submentovertex (SMV) view, the beam is directed nearly vertically upward from below the chin. These are fundamentally different projections with different clinical purposes.
Related Topics
The Reverse Towne’s view sits within the broader family of extraoral skull projections and TMJ imaging modalities.
References & Sources
The following foundational texts and peer-reviewed sources inform this article.
- White SC & Pharoah MJ, 2014. Oral Radiology: Principles and Interpretation. 7th ed. Elsevier Mosby.
- Whaites E & Drage N, 2013. Essentials of Dental Radiography and Radiology. 5th ed. Churchill Livingstone.
- Nair MK & Nair UP, 2010. Digital and advanced imaging in endodontics: a review. Journal of Endodontics, 36(2):216–237.
- Ellis E & Zide MF, 2006. Surgical Approaches to the Facial Skeleton. 2nd ed. Lippincott Williams & Wilkins.
- Laskin DM, 2004. Oral and Maxillofacial Surgery. Saunders.
Summary
The Reverse Towne’s view is the dedicated plain film projection for bilateral assessment of the mandibular condyles. Its posteroanterior geometry — with the patient facing the receptor and the X-ray tube positioned behind the head at a 30–35° caudal angle — causes the beam to traverse the occipital bone and project the condylar heads free of the petrous temporal bones. This provides a clear, bilateral view of the condylar heads and necks in a single image, making it an essential adjunct to the panoramic radiograph in any suspected mandibular condylar fracture.
While the Reverse Towne’s is highly effective for condylar neck and subcondylar fractures — including medially displaced condylar head fractures that are frequently missed on panoramic imaging — it cannot exclude intracapsular pathology. CBCT or MRI is required for complete assessment of complex condylar injuries, disc pathology, and articular surface disease. Correct head positioning, with the midsagittal plane strictly centred on the receptor, is the single most important technical variable for diagnostic image quality.
Key Takeaways
- Primary plain film projection for the condyles: The Reverse Towne’s view is the standard dedicated projection for assessing the mandibular condyles — both condylar heads and necks are visible in a single bilateral image.
- Posteroanterior beam at 30–35° caudal angle: The patient faces the receptor, the tube is behind the head — opposite geometry to the standard Towne’s projection.
- Primary indication is condylar and subcondylar fractures: Especially medially displaced fractures that may be missed on panoramic radiographs; always use in combination with an OPG in suspected condylar trauma.
- Head positioning is critical: A tilted midsagittal plane produces false condylar height asymmetry that can mimic or obscure pathology — confirm position before exposure.
- A normal Reverse Towne’s does not exclude intracapsular pathology: CBCT or MRI is needed for complete joint assessment in complex cases involving intracapsular fractures or disc pathology.
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