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226 terms

RAD-255 Positioning 3 Ch.12 - Skull & Cranium

Bontrager 7th Edition workbook
STUDY
PLAY
Number of bones in the cranium
8
Number of facial bones
14
Alternate term for the skull cap
Calvaria
Four cranial bones which form the calvaria
1.Frontal 2.Right Parietal 3.Left Parietal 4.Occipital
Four cranial bones which form the floor of the cranium
1.Right Temporal 2.Left Temporal 3.Sphenoid 4.Ethmoid
Name of the small horizontal plate of the ethmoid bone
Cribriform Plate
Name of the vertical plate of the ethmoid bone which forms the upper portion of the bony nasal septum
Perpendicular Plate
Term for the structure found in the middle of the sphenoid bone that surrounds the pituitary gland
Sella Turcica
Name of the posterior aspect of the Sella Turcica
Dorsum Sellae
Name of the structure of the sphenoid bone which allows for the passage of the optic nerve and is the actual opening into the orbit
Optic Foramen
Two structures of the sphenoid bone which help form part of the lateral walls of the nasal cavities
Medial and Lateral Pterygoid Processes
Radiographic cranial position which best demonstrates the Sella Turcica
Lateral
Aspect of the frontal bone which forms the superior aspect of the orbit
Orbital or horizontal portion
Four major sutures of the cranium
1.Coronal 2.Squamosal 3.Lambdoidal 4.Sagittal
Six Asterions of the cranium
1.Bregma 2.Lambda 3.Right Pterion 4.Left Pterion 5.Right Asterion 6.Left Asterion
Adult Asterion which is associated with the Anterior Fontanel of an infant
Bregma
Adult Asterion which is associated with the Posterior Fontanel of an infant
Lambda
Adult Asterion which is associated with the Right and Left Sphenoid Fontanels of an infant
Right and Left Pterions
Adult Asterion which is associated with the Right and Left Mastoid Fontanels of an infant
Right and Left Asterions
Joint classification for cranial sutures
Fibrous or synarthrodial
Name of the small irregular bones that sometimes develop in adult skull sutures
Sutural or Wormian bones
Location in the skull where sutural or wormian bones are most frequently found
The Lambdoidal Suture
Term which best describes the superior rim of the orbit
Supraorbital Margin (SOM)
Name of the notch that separates the orbital plates from each other
Ethmoidal Notch
Cranial bones which form the upper lateral walls of the calvarium
Right and Left Parietal bones
Cranial bone which contains the foramen magnum
Occipital bone
Name of the small prominence located on the squamous portion of the occipital bone
External Occipital Protuberance or Inion
Name of the oval processes found on the occipital bone that help form the occipito-atlantal joint
Occipital Condyles or Lateral Condylar Portions
Three aspects of the Temporal bones
1.Squamous 2.Mastoid 3.Petrous
Densest of the three portions of the temporal bone
Petrous
External landmark which corresponds with the level of the petrous ridge
Top of the Ear Attachment (TEA)
Opening in the temporal bone which serves as a passageway for nerves of hearing and equillibrium
Internal Acoustic Meatus
Structure which makes up the cartilaginous, external ear
Auricle or Pinna
Length of the average External Acoustic Meatus (EAM)
1 inch
Small membrane that marks the beginning of the middle ear
Tympanic Membrane (ear drum)
Collective term for the small bones of the middle ear
Auditory Ossicles
Structure which allows for communication between the nasopharynx and the middle ear
Eustachian or Auditory Tube
Major function of the Eustachian or Auditory Tube
To equalize the atmospheric pressure within the middle ear
Structure that serves as an opening between the mastoid portion of the temporal bone and the middle ear
Aditus
Name of the thin plate of bone that separates the mastoid air cells and from the brain
Tegmen Tympani
Name of the auditory ossicle that picks up sound vibrations from the tympanic membrane
Malleus
Smallest of the auditory ossicles
Stapes
Auditory ossicle that resembles a premolar tooth
Incus
Name of the small membrane that connects the middle ear to the inner ear
Oval or Vestibular Window
Two sensory functions which occur within the inner ear
1.Hearing 2.Equillibrium
Name of the small membrane that will move outward to transmit impulses to the auditory nerve, thus creating the sense of hearing
Round or Cochlear Window
Name of the closed system related to the sense of hearing
Cochlea
Bacterial infection of the mastoid process
Mastoiditis
Growth arising from a mucous membrane
Polyp
Hereditary disease involving excessive bone formation of the middle and inner ear
Otosclerosis
Benign, cystlike mass or tumor of the middle ear
Cholesteatoma
New and abnormal growth
Neoplasia
Benign tumor of the auditory nerve sheath
Acoustic Neuroma
Radiographic appearance of acoustic neuroma
Expansion of the internal acoustic canal
Imaging modality which best demonstrates otosclerosis
CT
Term for skull shape described by width as less than 75% of the length
Dolichocephalic
Term for skull shape described by width as 80% or more than the length
Brachycephalic
Term for skull shape described by width between 75% and 80% of the length
Mesocephalic
Skull shape which CR angles, rotations, and basic positions are based on
Mesocephalic
Angle between the MSP and the long axis of the petrous bone for a mesocephalic skull
47°
Angle between the MSP and long axis of the petrous bone for a dolichocephalic skull
±40°
Two older terms for the Infraorbitomeatal line (IOML)
1.Reid's base line 2.Anthropological base line
Difference in degrees between the orbitomeatal line (OML) and infraorbitomeatal line (IML)
7°-8°
Difference in degrees between the orbitomeatal line (OML) and the glabellomeatalline (GML)
7°-8°
Term for the lateral junction of the eyelid
Outer Canthus
Term for the posterior angle of the jaw
Gonion
Name for the line between the infraorbital margin and EAM
Infraorbitomeatal line (IOML)
Structure which corresponds to the highest "nuchal" line of the occipital bone
Inion
Name of line between the glabella and the alveolar process of the maxilla
Glabelloalveolar line
Name of the line between the mental point and EAM
Mentomeatal line (MML)
Structure located at the junction of the two nasal bones and the frontal bone
Nasion
Name of the small cartilaginous flap covering the ear opening
Tragus
Structure which corresponds with the highest level of the facial bone mass
Supraorbital Groove
Name of the line between the midlateral orbital margin and the EAM
Orbitomeatal Line (OML)
Name for the center point of the EAM
Auricular Point
Name for the positioning line that is primarily used for the modified Waters position
Lips-meatal line
Name for the line used in positioning to ensure that the skull is in a true lateral position
Interpupillary line
External landmark which corresponds to the level of the petrous ridge
Top of the Ear Attachment (TEA)
Name for the smooth slightly depressed area between the eyebrows
Glabella
Average Kilovolt range for skull radiography
70-85kV
Name of the report which states that the patient receives no detectable gonadal exposure during skull radiography when accurate collimation is used
HEW Report 76-8031
Difference in thyroid dose between AP Axial skull (Towne) and PA Axial skull (Haas) projections
Towne is 10 times higher thyroid dose
Thyroid dose range for a submentovertex (SMV) projection of the skull
200-300 mRad
Skull projection which results in the highest thyroid dose of any skull radiograph
Submentovertex (SMV) skull projection
Five common errors made during skull radiography
1.Excessive flexion 2.Excessive extension 3.Rotation 4.Incorrect CR angle 5.Tilt
Two most common errors made during skull radiography
Rotation and Tilt
Percentage of reduction in mAs required for patients with osteoporosis
25%-30% reduction in mAs
Most common neuroimaging modality procedure performed for the cranium
Computed Tomography (CT)
Imaging modality which is usually performed on neonates with a possible intercranial hemorrhage
Ultrasound
Imaging modality which is most commonly performed to evaluate patients with Alzheimer's disease
Nuclear Medicine
Fracture that may produce an air-fluid level in the sphenoid sinus
Basal Skull Fracture
Destructive lesion with irregular margins
Osteolytic neoplasm
Medical term for a "ping-pong" fracture
Depressed skull fracture
Proliferative bony lesion of increased density
Osteoblastic neoplasm
A tumor that may produce erosion of the sella turcica
Pituitary adenoma
Also known as osteitis deformans
Paget's disease
A bone tumor that originates in the bone marrow
Multiple myeloma
Pathological indication which may require an increase in manual exposure factors
Paget's disease
Cranial bone which is best demonstrated with an AP Axial (Towne method) projection of the skull
Occipital
Positioning line which should be perpendicular to the IR when performing the AP Axial (towne) skull projection
Orbitomeatal line (OML)
CR angle which should be used for the Towne method (AP Axial) skull projection
30° Caudal angle
Projection in which the dorsum sellae is shown in the middle aspect of the foramen magnum when properly positioned
AP Axial Skull (Towne method)
Positioning error shown by a lack of symmetry in the petrous ridges during the AP Axial (Towne) skull projection
Rotation
Correction which can be made during an AP Axial Skull (Towne) if the patient cannot adequately flex the head
Place the IOML perpendicular to the IR and change the CR angle to 37° Caudal
Evidence on the AP Axial (Towne) skull x-ray which indicates whether the correct CR angle and head flexion were used
Dorsum Sellae and Posterior Clinoids should be projected into the middle of the foramen magnum
CR angle which should be used for the PA Axial (Haas method) projection of the cranium
25° Cephalad
Proper CR centering location for a lateral projection of the skull
2 inches superior to the EAM
Specific positioning error which is present if the mandibular rami are not superimposed on a lateral skull radiograph
Rotation
Location where the petrous ridges will be projected with a 15° PA Axial (Caldwell) projection of the cranium
In the lower 1/3 of the orbits
Specific positioning error which is present if the petrous ridges are projected higher in the orbits than expected for a 15° PA Axial (Caldwell) projection
Excessive flexion or insufficient CR angle
Projection of the cranium which produces an image of the frontal bone with little or no distortion
0° PA
Condition which must ruled out for a trauma patient before performing the SMV (submentovertex) projection of the skull
Rule out any possible cervical fractures or subluxation
Proper CR centering for a lateral projection of the sella turcica
3/4" anterior and 3/4" superior to the EAM
Skull positioning line which is placed parallel to the plane of the IR for the SMV (submentovertex) projection
IOML (infraorbitomeatal line)
Best angle of the AP Axial projection for the sella turcica to visualize the anterior clinoid processes
30° Caudal to IOML
Skull projection which best demonstrates the sella turcica in profile
Lateral
Projection which best demonstrates the foramen rotundum
25°-30° PA Axial
Projection which best demonstrates the clivus in profile
Lateral
Exit point of the CR for a PA Axial (Haas method) projection of the skull
1.5 inches superior to the nasion
CR angle used with the AP Axial projection for the sella turcica if the dorsum sellae and posterior clinoid processes are of primary interest
37° Caudal
Imaging modality which is best to differentiate between an epidural and subdural hemorrhage
CT
Positioning error shown during Towne method if the right petrous ridge is wider than the the left
Over-rotation of the skull to the left
Positioning error during Caldewell (15° PA Axial) when the petrous ridges are projected at the inferior margin
Excessive extension or excessive caudal CR angle (petrous ridges should be in the lower third of the orbit)
Positioning error during the Caldwell (15° PA Axial) which shows unequal distances between the midlateral borders of the orbit and lateral margin of the skull
Rotation of the skull
Positioning error during an SMV projection which reveals the mandibular condyles within the petrous bone
Insufficient extension of the skull or the CR was not perpendicular to the IOML
Positioning error during a lateral skull projection which reveals that the orbital plates are not superimposed (one orbital plate is slightly superior to the other)
Skull tilt
Positioning error during a lateral skull which demonstrates one mandibular ramus about 0.5cm more anterior than the other
Skull rotation
Positioning error shown during a Towne projection which shows the dorsum sellae projected superior to, rather than within, the foramen magnum
CR angle is greater than 37° to IOML or greater than 30° to the OML (would be caused by 30° angle to IOML)
Projection which best demonstrates any bony involvement of the sella turcica for a Pt with a possible pituitary gland tumor
Collimated, lateral projection of the sella turcica
Single skull projection to demonstrate a possible linear fracture of the right parietal bone for a Pt in the ER
Right lateral projection of the skull
Projection which can be performed for a Pt who needs a skull series but cannot assume correct positions for the Towne due to very short neck and severe kyphosis
Perform the PA Axial projection (Haas method)
Specific projection which can best demonstrate evidence of a possible basal skull fracture for a Pt in the ER
Horizontal beam (dorsal decubitus) lateral position will best demonstrate a possible air/fluid level in the sphenoid sinus
Best imaging modality for a neonate with a clinical history of craniosynostosis
Ultrasound - a non-invasive means of evaluating the newborn's cranium
Best imaging modality for a Pt with a clinical history of acoustic neuroma
Either MRI or CT
Positioning error shown during a Towne projection which reveals that the anterior arch of C1 is projected within the foramen magnum
Overangulation of the CR
Correction to be made after a Towne projection which reveals that the mid to lower mandible is cut off
No repeat required - Elongation of the facial mass cutting off the mandible is acceptable
Three bones that make up the floor of the cranium
1.Temporal 2.Ethmoid 3.Sphenoid
Aspect of the frontal bone which is thin-walled and forms the forehead
Squamous
Four cranial bones which articulate with the frontal bone
1.Right parietal 2.Left parietal 3.Sphenoid 4.Ethmoid
Structures which are found at the widest aspect of the skull
Parietal Tubercles or eminences
Name of a prominent landmark (or "bump") found on the external surface of the occipital bone
External occipital protuberance or Inion
Number of bones that articulate with the parietal bone
Five
Number of bones that articulate with the occipital bone
Six
Number of bones that articulate with the temporal bone
Three
Number of bones that articulate with the sphenoid bone
Seven
Number of bones that articulate with the ethmoid bone
Two
Thickest and densest structure in the cranium
Petrous Portion (Petrous Pyramids)
Alternate term for the pituitary gland
Hypophysis
Name of the bone which articulates with all the other cranial bones
Sphenoid bone
Name of the shallow depression just posterior to the base of the dorsum sellae and anterior to the foramen magnum
Clivus
Name of the paired collections of bone found inferior to the cribiform plate that contain numerous air cells and help form the lateral walls of the nasal cavity
Lateral Labrynth or masses
Small section of bone which is located superior to the cribiform plate
Crista Galli
Formal term for the left sphenoid fontanel in the adult
Left Pterion
Name of the cranial suture formed by the inferior junction of the parietals to the temporal bones
Squamosal suture
Two terms for the small, irregular bones found in the adult skull sutures
Sutural or Wormian bones
Cranial bone containing the Pterygoid Hamulus
Sphenoid bone
Cranial bone containing the Anterior clinoid process
Sphenoid bone
Cranial bone containing the Glabella
Frontal bone
Cranial bone containing the Foramen Ovale
Sphenoid bone
Cranial bone containing the Perpendicular plate
Ethmoid bone
Cranial bone containing the Superior nasal conchae
Ethmoid bone
Cranial bone containing the Foramen magnum
Occipital bone
Cranial bone containing the Cribiform plate
Ethmoid bone
Cranial bone containing the Zygomatic process
Temporal bone
Cranial bone containing the Lateral condylar portions
Occipital bone
Cranial bone containing the Superciliary arch
Frontal bone
Cranial bone containing the EAM
Temporal bone
Cranial bone containing the Inion
Occipital bone
Cranial bone containing the Sella turcica
Sphenoid bone
Cranial bone containing the Petrous ridge
Temporal bone
Skull classification which applies to a skull with an angle of 54° between the MSP and the long axis of the pars petrosa
Brachycephalic
Classification of the average shaped skull
Mesocephalic
Name for the tip of the chin
Mentum (mental point)
Name of the landmark line from the glabella to the EAM
Glabellomeatal line (GML)
Name of the line from the lateral posterior portion of the orbit to the EAM
Orbitomeatal line (OML)
Name of the line from the most inferior portion of the orbit to the EAM
Infraorbitomeatal line (IOML)
Name of the line from the acanthion to the EAM
Acanthomeatal line (AML)
Name of the line from the lips to the EAM
Lips-meatal line (LML)
Name of the line from the mentum to the EAM
Mentomeatal line (MML)
External landmark which pertains to the highest level of the petrous ridge
Top of the Ear Attachment (TEA)
Term for the large cartilaginous aspect of the external ear
Pinna
Newer term for Reid's base line
IOML
Difference in degrees between the OML and IOML
7°-8°
Positioning error which most frequently results in a repeat exposure of a cranial position
Rotation
Name for a bone tumor that originates in the bone marrow
Multiple myeloma
Fracture which is evident by sphenoid sinus effusion
Basal fracture
Condition that begins with bony destruction followed by bony repair
Paget's disease
Destructive lesion with irregular margins
Osteolytic neoplasm
Fracture of the skull with jagged or irregular lucent line which lies at right angle to the axis of the bone
Linear fracture
Fracture which is best visualized with a tangential view to determine extent
Depressed fracture
Pathologic indication that requires a decrease in manual exposure factors
Multiple myeloma
Imaging modality that may be used to examine a possible cranial bleed caused by trauma
CT
Imaging modality that provides an excellent distinction between normal and abnormal brain tissue
MRI
Aspect of the temporal bone that is considered to be the thinnest
Squamous portion
Aspect of the temporal bone that contains the organs of hearing and balance
Petrous portion
Correct term for the eardrum
Tympanic membrane
Middle ear structure which is considered to be the most lateral
Malleus
Structure that helps to equalize atmospheric pressure in the middle ear
Eustachian or Auditory tube
Two structures that passs through the internal acoustic meatus
Auditory nerve and blood vessels
Name for the opening between the epitympanic recess and the mastoid portion of the temporal bone
Aditus
Infection of the mastoid air cells, which if untreated can lead to a serious infection of the brain
Encephalitis
Name for the auditory ossicle which attaches to the oval window
Stapes
Names of the two labrynths that comprise the inner ear
Osseous (bony) labrynth and Membranous labrynth
Three divisions of the bony labrynth of the inner ear
1.Cochlea 2.Vestibule 3.Semicircular canals
Term for a benign, cystlike mass of the middle ear
Cholesteatoma
Ear disease which is hereditary
Otosclerosis
Two projections of the cranium which project the dorsum sellae within the foramen magnum
AP Axial (Towne) and PA Axial (Haas)
CR angle which is used during the Towne method for a skull which has the IOML perpendicular to the IR
37° Caudal
CR angle during the Towne method for a skull which has the OML perpendicular to the IR
30° Caudal
Proper CR centering for a lateral projection of the cranium
2" superior to the EAM
Line which is placed perpendicular to the IR during a lateral cranium projection to prevent skull tilt
Interpupillary line
Proper location of the petrous ridges for a well-positioned 25° Caudal Hass projection
Symmetrically superior to the mastoid processes
Proper CR centering for an SMV projection of the skull
1.5" inferior to the mandibular symphysis midway between the gonions
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CR angle to the IOML during an AP Axial projection of the sella turcica when the posterior clinoid processes are of primary interest
37° Caudal
CR angle to the IOML when the anterior clinoid processes are of primary interest
30° Caudal
Correction to be made during an AP Axial projection of the skull which reveals the dorsum sellae just above rather than into the foramen magnum
Increase CR angle approximately 7° Caudal
Positioning error shown during a lateral skull when the greater wings of the sphenoid are not superimposed
Rotation
Correction to be made during a 15° caudal PA Axial skull when the petrous ridges are at the level of the supraorbital margin
Increase extension of skull to place OML perpendicular to the IR which will place the petrous ridges into the lower third of the orbits
Best projection for an ER patient with a possible basilar skull fracture to demonstrate possible sphenoid sinus effusion
Horizontal beam (dorsal decub) lateral skull for air/fluid levels in the sphenoid sinus
Best projection for an ER Pt with possible basilar fracture when the MD also orders a frontal skull x-ray and C-spine fracture has not been ruled out
AP with CR 15° cephalad to the IOML
Best projection for a skull series when the Pt cannot flex neck enough to place OML perpendicular to the IR for the AP Axial, and head cannot be raised due to possible C-spine trauma
Use the IOML instead of the OML and increase CR angle an additional 7° caudal for a total of 37°
Correction to be made during a Towne which shows the anterior arch of C1 within the foramen magnum
Decrease CR based on skull line used (OML-30° and IOML-37°)
Positioning error shown during a lateral skull which shows the orbital plates (roof) of the frontal bone NOT superimposed
Skull tilt
Positioning error shown during a Towne which shows the left petrous portion of the temporal bone wider than the right
Rotation of the patient's skull to the right
Correction to be made during an SMV exam which shows the mandibular condyles projected into the petrous portion of the temporal bone
Extend the skull further to place the IOML parallel to the IR