Positioning II Merrill's CH 20 Facial Bones & Orbits
for an SMV projection of the zygomatic arches, which line is parallel with the IR?
IOML
What line is perpendicular to the IR for a PA axial projection of the facial bones
OML
What projections can be used to view the lacrimal bones?
PA & Lateral projections of the skull
CR for SMV of the zygomatic arches
Perpendicular to the IOML, entering midsagittal plane of the throat 1 inch posterior to outer canthi
Which body position should be used for patients with depressed fractures or flat cheekbones?
Tangential projection supine instead of upright
Which bones lie between the maxillae & the pterygoid processes of the sphenoid bone in the posterior nasal cavity?
The vertical portions of the palatine bones
What is the orbit composed of?
a roof, a medial wall, a lateral wall, and a floor
What bones articulate with the maxillary bones?
all facial bones excluding the mandible & frontal and ethmoid bones of the cranium
Where are the lacrimal bones situated?
at the anterior part of the medial wall of the orbits, between the labyrinth of the ethmoid bone and the maxilla
Where are the petrous ridges projected below for a modified parietoacanthial projection of the facial bones?
below inferior border of the orbits , midway through maxillary sinuses
Where are the petrous portions projected for the reverse waters method for facial bones?
below maxillary sinuses
Where are the petrous portions located on a Waters method radiograph for facial bones?
below the maxillary sinuses
Le fort
bilateral horizontal fractures of the maxillae
How can the reverse waters projection be achieved in trauma patients?
by adjusting the CR (30 degree angulation cephalad) to enter acanthion while remaining parallel to the MML. No hyperextension of the neck.
CR for Modified Townes method when neck is flexed sufficiently
directed to enter the glabella 1 inch above the nasion at an angle of 30 degrees caudad
CR for lateral projection of the facial bones
entering the lateral surface of the zygomatic bone, halfway between the outer canthus and the EAM
What can you do to show orbital rims and orbital floors ?
exaggerated caldwell, 30 degree angulation of CR will place petrous portions below the inferior margins of the orbits
depressed fracture
fracture causing a portion of the skull to be pushed into the cranial cavity
Blowout fracture
fracture of the floor of the orbit
tripod fracture
fracture of the zygomatic arch and orbital floor or rim and dislocation of the frontozygomatic suture
contre-coup
fracture to one side of a structure caused by trauma to the other side
What bones articulate with the lacrimal bones?
frontal and ethmoid cranial bones & maxilla and inferior concha facial bones
Which cranial bones form part of the orbit?
frontal, sphenoid, and ethmoid
Which bones form the outer rim of the orbit?
frontal, zygoma, & maxilla
Polyp
growth or mass protruding from a mucous membrane
Which facial bones are long, narrow, extremely thin, curl laterally and have a scroll like appearance?
inferior nasal conchae
mastoiditis
inflammation of the mastoid antrum and air cells
What is the infraorbital foramen?
it serves as a passage through which the infraorbital nerve & artery reach the nose
What does the lacrimal fossa accommodate?
lacrimal sacs
Where are the petrous portions located for a PA axial projection of the facial bones
lower third of the orbits
which facial bones form part of the orbit?
maxilla, zygoma, lacrimal, and palatine
the apex
optic foramen
What structures are shown in the Parietoacanthial projection of the facial bones?
orbits, maxillae & zygomatic arches
Modified waters method is which projection
parietoacanthial projection
For a lateral projection of facial bones, the MSP is _______________ to the IR
perpendicular
For a lateral projection of the facial bones, the IPL is ____________________ to the IR
perpendicular
In a parietoacanthial projection of the orbits, the midsagittal plane should be _________________ to the IR
perpendicular
Which bone do the nasal bones articulate with at their posterosuperior surface?
perpendicular plate of the ethmoid bone
CR for Modified waters for orbits
perpendicular through mid-orbits
CR for Acanthioparietal projection of the facial bones
perpendicular to enter the acanthion
CR for lateral nasal bones
perpendicular to the bridge of the nose at a point 1/2 inch distal to the nasion
Which line is perpendicular to the IR in an AP Axial projection of the zygomatic arches when the patient is unable to flex the neck sufficiently?
place IOML perpendicular with IR
What's the purpose of the alveolar process of the maxilla?
supports the roots of the teeth
Which line is perpendicular to IR for reverse waters method of the facial bones
the MML
Which line is perpendicular to the plane of the IR for Waters Method for facial bones?
the MML
For SMV projection of the zygomatic arches, which plane is perpendicular to the IR
the MSP
Which plane do the nasal bones articulate with?
the MSP
which plane is perpendicular to the IR for the reverse waters method for facial bones?
the MSP
Which bones form part of the lateral walls & most of the floor of the nasal cavity, part of the floor of the orbital cavities and 3/4 of the roof of the mouth?
the Maxillary bones
Which line is perpendicular to the IR in an AP Axial projection of the zygomatic arches?
the OML when neck is flexed
quadrilateral shaped anterior circumference of the orbit
the base
Which part of the head is touching the IR for a modified waters for orbits?
the chin
Which bone do the nasal bones articulate with superiorly?
the frontal bone
What bones lie inferiorly and diagonally from the lateral walls of the nasal cavity at approximately its lower third?
the inferior nasal conchae
Which is the narrow cleft extending from the lower anterolateral aspect of the sphenoid body anteriorly and laterally between the floor & lateral wall of the orbit
the inferior orbital fissure
What forms the lacrimal fossae?
the lacrimal bones & the maxillae
Which are the smallest bones of the skull?
the lacrimal bones (2)
Which bone do the nasal bones articulate with at the sides?
the maxillae
Which are the largest immovable bones of the face?
the maxillary bones (2)
Which projection is good for showing blowout fractures?
the modified waters method
What forms the superior bony wall (bridge of the nose) of the nasal cavity?
the nasal bones (2)
What is the pointed forward process formed at the anterior MSP of the junction of the maxillae?
the nasal spine (acanthion)
What is in between the sphenoid strut and the lesser wing
the optic foramen
Which facial bone is composed of vertical and horizontal plates?
the palatine bones (2)
The horizontal plate of the palatine bones articulate with the maxillae to complete the posterior fourth of the bone palate, which is also known as?
the roof of the mouth
What cleft is between the greater and lesser wings of the sphenoid bone?
the superior orbital fissure
What bone assists in the formation of the posteromedial bony orbit?
the superior tips of the vertical portions of the palatine bones
Why should you rotate and tilt head for the tangential projection?
the tilt and rotation ensure that the CR is tangent to the lateral surface of the skull, to skim across lateral portion of mandibular angle
Which bone is situated in the midsagittal plane of the floor of the nasal cavity, and forms the inferior part of the nasal septum?
the vomer
which bone forms the inferior part of the nasal septum?
the vomer
Which thin bone is situated in the MSP of the floor of the nasal cavity?
the vomer bone
which part of the orbits are subject to fracture?
the walls of the orbit due to thinness
Why is the modified waters method good to show blowout fractures?
this method places the orbital floor perpendicular to the IR and parallel to the central ray, showing inferior displacement of orbital floor
For a tangential projection of the zygomatic arches, you should ________ the top of the head 15 degrees ___________ from the affected side
tilt, away
Where is the infraorbital foramen located?
under each orbit, on the maxillary bones
Where can a sponge be placed when dealing with a hypersthenic patient for the caldwell method?
underneath forehead
What bones do the zygomatic bones articulate with?
-superiorly with the frontal bone -zygomatic process of temporal bone at the side -anteriorly with the maxilla -posteriorly with the sphenoid bone
For a tangential projection of the zygomatic arches, you should rotate the midsagittal plane of head ____ degrees toward the affected side
15 degrees
CR for Caldwell Method for facial bones
15 degrees caudad to exit nasion
For a supine tangential projection of the zygomatic arches rotate & tilt the head ____ degrees _____________ the side being examed
15, towardsA
For a Waters Method (Parietoacanthial projection) for facial bones the OML forms a _____ degree angle with the IR
37
For a reverse waters method for facial bones, the OML forms a ___ degree angle with the IR
37
The long axis of each orbit is directed obliquely, posteriorly, and medially at an average angle of _____ degrees to the midsagittal plane of the head and superiorly at an angle of about _____ degrees from the OML
37 30
CR for Modified Townes method when the IOML is perpendicular to the IR
37 degrees caudad
For the modified waters method of the orbits, the OML forms an angle of ____ degrees with the plane of the IR
50
MML forms _____ degrees with the IR for a parietoacanthial projection of the facial bones
53
In a modified waters method for facial bones, the OML forms a ____ degree angle with the IR
55
How many bones is each orbit composed of?
7 bones
What is another name for the modified towne method?
AP axial projection
In a parietoacanthial projection for the orbits, where do the petrous pyramids lie?
Below the orbital shadows
What is another name for a PA axial projection for facial bones?
Caldwell Method
Which bones divide the lateral portion of the nasal cavity into superior, middle and inferior meatus?
The inferior nasal conchae
