Central Lect1

8/4/2019 Central Lect1

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Central radiographic positioning


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Introduction

Radiography of the skull requires a goodunderstanding of the related anatomy

The anatomy of the skull is very complexand requires careful and detailed study


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Cranial bones

Cranial bones are divided into two mainparts:

Clavarium,4 bones, (skull cap)

Floor of the skul, 4 bones.


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Floor

Right temporal

Left temporal

Sphenoid Ethmoid


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Frontal bone

Forms the forehead (the squamous orvertical portion) and the superior part ofeach orbit (orbital or horizontal portion)


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Landmarks of frontal bone (frontaland lateral views)

Glabella: is the smooth raised prominencebetween the eyebrows just above thebridge of the nose

Supraorbital groove (SOG): is the slightdepression above each eyebrow

Supraorbital margin (SOM): the superiorrim of each orbit


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Skull landmarks (frontal and lateralviews)

Supraorbital notch (foramen): is a smallhole or opening within the supraorbitalmargin slightly medial to its midpoint

Sperciliary ridge (arch): the ridge of bonebeneath each eyebrow (the glabella islocated between the superciliary arches)

Frontal tuberosity (eminence): is a largerounded prominence above thesupraorbital grooves


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Skull landmarks (inferior view)

Orbital plate: forms the superior part ofeach orbit

The nasal spine: found at the anterior endof the ethmoidal notch

Each orbital plate is separated from theother by the ethmoidal notch


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Articulations of frontal bone

The frontal bone articulates with fourcranial bones: right and left parietals, thesphenoid, and the ethmoid

The frontal bone articulates with eightfacial bones


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Parietal bones

Is roughly square in shape

It has a concave internal surface

Forms the lateral walls of the cranium and part

of the roof The widest portion of the entire skull is located

between the parietal tubercles

The frontal bone is primarily anterior to the

parietals, the occipital is posterior, the temporalsare inferior, and the greater wings of thesphenoid are inferior and anterior.


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Articulation

Each parietal bone articulates with fivecranial bones:

1. The frontal

2. The occipital

3. A temporal

4. The sphenoid5. The opposite parietal


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Occipital bone

Forms the inferoposterior portion of theclavarium

Squamous portion: a rounded part which

forms the external surface of the occipitalbone (superior to the external occipitalprotuberance)

external occipital protuberance or

inion: the prominent bump orprotuberance at the inferoposterior portionof the skull


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Occipital bone

Foramen magnum: the large opening atthe base of the occipital bone throughwhich the spinal cord passes

Occipital condyles: oval processes withconvex surfaces on each side of theforamen magnum

Occipito-atlantal joint: two-partarticulation between the skull and thecervical spine


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Articulations

The occipital articulates with six bones:

1. The two parietals

2. The two temporals3. The sphenoid

4. And the atlas


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Thank you

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Central Lect1