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Rad 270 Skull Lecture.

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Presentation on theme: "Rad 270 Skull Lecture."— Presentation transcript:

1 Rad 270 Skull Lecture

2 Skull Anatomy Comprised of 22 separate bones divided into two groups:
Cranial bones – 8 Facial bones – 14 Cranial bones further subdivided into Calvaria Floor

3 Cranial Bones Calvaria Floor Frontal Occipital R. parietal L. parietal
Ethmoid Sphenoid R. temporal L. temporal

4 Skull Anatomy Sutures = fibrous joints that connect the bones of the skull Coronal = between frontal and parietal bones Sagittal = on top of head between two parietal bones Squamosal = between temporal bone and the parietal bones Lambdoidal = between occipital and the parietal bones

5 Skull Morphology Typical skull = mesocephalic Brachycephalic skull
Petrous pyramids project anteriorly and medially at angle of 47 degrees from MSP Brachycephalic skull Petrous pyramids project anteriorly and medially at angle of 54 degrees from MSP Short from front to back, broad from side to side, and shallow from vertex to base


7 Skull Morphology Dolichocephalic skull
Petrous pyramids project anteriorly and medially at angle of 40 degrees from MSP Long from front to back, narrow from side to side, and deep from vertex to base Asymmetry of outer features should be noted while positioning; for example, the nose may not always be in the midline


9 Frontal Bone Landmarks to note Frontal eminences Supraorbital margins
Supraciliary arches Supraorbital foramina Glabella



12 Ethmoid Bone Consists of Horizontal plate Vertical plate
Two light, spongy masses = labyrinths



15 Parietal Bones Somewhat square-shaped
Have a convex external surface and concave internal surface Parietal eminence = prominent bulge near center of external surface of each bone This is the point where the width of the skull should be measured to set technique


17 Sphenoid Bone Irregular, wedge-shaped bone that resembles a bat (somewhat) Located in base of cranium anterior to temporal bones and basilar portion of occipital




21 Occipital Bone Situated at posteroinferior part of cranium
Forms posterior half of cranial base and greater portion of posterior cranial fossa Has four parts Squama Two occipital condyles Basilar portion



24 Temporal Bones Consist of Squamous portion Tympanic portion
Styloid process Zygomatic process Petromastoid portion which contain the organs for hearing and equilibrium



27 Skull Topography Be able to locate the following landmarks: Gonion
Mental point External auditory meatus (EAM) Auricular point Top of ear attachment (TEA) Glabella Inner canthus Outer canthus Nasion Infraorbital margin Acanthion



30 Hyposthenic/Asthenic Patients

31 Hypersthenic Patients

32 Essential Projections: Cranium
Lateral PA PA axial (Caldwell method) AP AP axial AP axial (Towne method) PA axial (Haas method) Submentovertical (SMV) For cranial base


34 Lateral Projection Patient position Part position CR
Seated upright or semiprone Part position MSP of head parallel to IR IPL perpendicular IOML parallel to transverse axis of cassette CR Perpendicular to center of IR Enters 2 superior to EAM

35 Lateral Projections Entire cranium without rotation or tilt
Superimposed orbital roofs and greater wings of sphenoid Superimposed mastoid regions and EAMs Superimposed TMJs Sella turcica in profile Penetration of parietal region No overlap of C-spine by mandible


37 PA/PA Axial (Caldwell)
Patient position Seated erect or prone MSP centered to midline Forehead and nose resting on table or upright Bucky Part position OML perpendicular to IR plane MSP perpendicular to IR IR centered to nasion

38 PA/PA Axial (Caldwell)
CR for PA projection Perpendicular Exits nasion CR for PA axial (Caldwell) Angled 15 degrees caudad





43 PA Projection Entire cranial perimeter showing three tables of squamous bone No rotation Equal distance from lateral borders of skull to lateral border of orbits Symmetric petrous ridges Petrous ridges fill orbits Penetration of frontal bone without excessive density at lateral borders of skull


45 PA Axial (Caldwell Method)
Same as for PA projection, except Petrous ridges demonstrated in lower one third of orbit


47 AP/AP Axial Projection
Same as PA and PA axial projections Anatomy more magnified in AP and AP axial projections

48 AP Axial (Towne Method)
Patient and part position Supine or seated erect MSP centered to midline MSP perpendicular OML or IOML perpendicular IR top border level with skull vertex IR center at or near foramen magnum CR Directed through foramen magnum OML – 30 degrees caudal IOML – 37 degrees caudal


50 AP Axial (Towne Method)
No rotation Equal distance from lateral border of skull to lateral margin or foramen magnum Symmetric petrous ridges Dorsum sellae and posterior clinoid processes visible within foramen magnum Penetration of occipital bone without excessive density at parietals


52 PA Axial (Haas) Projection of dorsum sellae and posterior clinoid processes within foramen magnum Equal distance from lateral border of skull to lateral margin of foramen magnum Symmetric petrous pyramids Entire cranium


54 SMV Projection (Schüller)
Patient position Seated upright or supine Torso elevated if supine Part position MSP centered to midline IOML parallel with IR MSP perpendicular to IR

55 SMV Projection (Schüller)
CR Through sella turcica perpendicular to IOML Enters MSP of throat between angles of mandible Passes through a point ¾ (1.9 cm) anterior to level of EAM Center IR to CR


57 SMV Projection (Schüller)
No rotation or tilt Equal distance from lateral border of skull to mandibular condyles Symmetric petrous pyramids Penetration sufficient to demonstrate structures of cranial base Superimposition of mental protuberance over anterior frontal bone, indicating full neck extension Mandibular condyles anterior to petrous pyramids

58 SMV Projection (Schüller)
Superimposition of mental protuberance over frontal bone – indicates full neck extension Condyles of mandible anterior to petrous pyramids





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