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Skull Positioning DMI 55 Basic Skull Positioning- Parts 1 and 2 6/5/2014 2 types of Skull bones 8 Cranial 14 Facial -form protective housing of brain (cranial vault) -provides structure, shape & support for face -protective housing for upper ends of respiratory & digestive tracts - with cranial-forms eye sockets The Cranium • The Brain • Of Jane • Stays mainly • In her Cran(ium) 8Cranial Bones are: • 1 Frontal • 2 Parietal • 1 Occipital • 1 Ethmoid • 1 Sphenoid • 2 Temporal Top of skull = skull cap Made up of 4 bones: Frontal L & R Parietal Occipital = Calvarium Frontal bone 2 parietal bones Occipital Floor of Cranium Floor of Cranium is made of 4 bones (The four on the floor!) • Ethmoid • Sphenoid • Left & Right Temporal bones 1 Ethmoid Bone 1 Sphenoid bone 2 Temporal bones Temporal Bones PETROUS RIDGE LATERAL AP Temporal bones contain the organs of hearing and balance! 14 Facial Bones • • • • • • • • 2 2 2 2 2 2 1 1 maxillary bones nasal lacrimal Zygoma (malar) palatine inferior nasal conchae vomer mandible 2 Maxillary bones 2 nasal bones 2 lacrimal bones 2 Zygomas 2 Palatine bones 2 inferior nasal conchae 1 Vomer 1 Mandible At approximately what age does the human eyeball reach maturity? What are fontanels? Six areas of incomplete ossification in newborn Sphenoidal fontanel (pterion) Mastoid fontanel (asterion) At what age do the fontanels close? • Posterior and sphenoidal fontanels close during first 1-3 months after birth • Anterior and mastoid fontanels close during 2nd year of life Radiographic Landmarks Radiographic Landmarks Landmarks Radiographic baselines All skull positions are based on 3 factors • Rotation • Tilt • Flexion- Extension 3 types of Skull Position change • 1st type • Rotation -your head is rotating on an axis-your neck • The “NO” position 2nd type of skull position change • Flexion-extension • Also called “Yes” position Flexion Extension 3rd type of skull position change • Tilt • Or “Maybe” position Skull Morphology Mesocephalic Brachycephalic Dolichocephalic Average Skull Skull Morphology Brachycephalic(Broad) Mesocephalic(middle-average) Dolichocephalic(thin) Review • A-Vomer • B-Perp.plate ethmoid • C-Nasion • D- inferior nasal conchae • E- Anterior nasal spine Lateral Skull b (suture) bc aA a i d e h h g f • a-sphenoid • b-squamous suture • c-temporal • d-occipital • e-EAM • f-mastoid process • g-styloid process • h-TMJ • i-zygoma Landmarks Midsagittal plane a b Outer Canthus Infraorbitlal margin j Glabella c Interpupillary line d Inner Canthus i Gonion h eNasion f Acanthion g Mentum Generally 5 basic positions in “Skull Series” • • • • • PA PA Axial (Caldwell) Lateral AP Axial (Towne) SMV (Submentovertical) • All use 40” SID and 10X12 IR PA projection PA projection O degrees • Forehead and nose touch IR • CR perpendicular to IR (0 deg. Angle) • Exit at nasion • Cassette 10x12 lengthwise Alternate PA skull projections Decub style AP PA Skull- Evaluation Criteria R • Entire Cranium included • Equal distance from lateral border of skull to lateral border of orbit on both sides • Symmetric petrous pyramids filling orbits! At approximately what age does human skull reach full size? ___ years old? PA Axial –Caldwell method PA Axial-Caldwell • Exactly same as PA, except CR angled 15 degrees down! PA Axial- Caldwell Evaluation Criteria • Same as PA except petrous ridges fill the lower 1/3 of orbits! Which PA Axial projection is best? A B Compare the difference! PA PA Axial What is TREPANATION? • Intentional drilling of holes through skull • to improve mental functions • open up cranial vault so brain can once again bathe directly in cosmic energy that it has been sealed off from since fontanels closed up Lateral projection of Skull Lateral projection of Skull • 10x12 CW • CR 2” superior to EAM • Midsagittal plane parallel to IR • Interpupillary line perpendicular to IR • (IOML parallel to long axis of IR) Lateral Skull- Evaluation Criteria • Entire cranium without tilt or rotation • Superimposed orbital roofs, and EAMs, TMJs • Sella Turcica in profile • No overlap of C-spine by mandible What is wrong with this lateral? Other ways to perform Lateral Semiprone Dorsal Decubitus Erect What projection and what is wrong? R AP Axial- (Towne Method) AP Axial- Towne method • CR 30 deg. Cauduad to OML (37 deg to IOML) • CR enters 2 ½” above glabella, passing through level EAM AP Axial (Towne Method) - Evaluation Criteria • No rotation (equal distance from lateral border of skull to lateral margin of foramen magnum) • Symmetric petrous ridges • Dorsum sellae and posterior clinoids visible in foramen Alternate ways to perform Towne Lateral Decubitus Erect Submentovertical projection (SMV) SMV • CR-through Sella turcica (3/4” anterior to EAM) Perpendicular to IOML • IOML parallel to IR • 10x12 cassette lengthwise SMV- alternate position SMV- Evaluation Criteria • Equal distance from lateral border of skull to mandibular condyles on both sides (no tilt) • Superimposition of mental protuberance over frontal bone • Mandibular condyles anterior to petrous pyramids What’s wrong with this SMV projection? Which is best SMV projection? A B Which SMV projection is the best? A B ? ?