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