In this post we shall discuss about Submentovertex – Extraoral View
Radiograph of the base of the skull is taken by Submentovertex – Extraoral View (SMV).
Indications
Lesions affecting palate or pterygoid region or base of skull or sphenoidal sinus.
Exposure
0.4 Seconds
50 kVp
20-30 mA
Structures Visible in this view
Carotid canals
Nasal septum
Odontoid process or atlas
Mandible
Projection of petrosa
Mastoid process
Foramen Ovale
Spinosum canal
Sphenoidal sinus
Maxillary sinus
Axial inclination of Mandibular condyles
Film Placement
Perpendicular to the floor
Long axis of film/cassette should be placed vertically
Patient Position
Head of the patient is centered on the casette
Head and neck should be tipped back as far as possible
Vertex of skull should touch cassette
Mid sagittal plane should be perpendicular to the film
Radiographic base line is parallel to film
Central Ray
It is directed perpendicular to the film passing through mid sagittal plane.
Central ray should be perpendicular to an imaginary line joining mandibular first molars
For viewing petroud portion, central ray should be at right angles to film midway between the external auditory meatus.
