Glossary of Procedures Test 3-Skull

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Skull rests on...
superior aspect of spine
How many bones make up the skull?
Skull bones are divided into 2 groups: __ cranial bones + __ facial bones
8; 14
Cranial bones are divided into ______ and ______
calvaria; floor
Function of cranial bones
Protective housing for brain
Functions of facial bones
-Provide structure, shape, and support for face
-Protective housing for upper ends of respiratory and digestive tracts
-Along with several cranial bones, form orbital sockets for protection of eyes

Names of cranial bones
Calvaria: Frontal, occipital, R/L parietals
Floor: Ethmoid, sphenoid, R/L temporals
Names of facial bones
Nasal 2, lacrimal 2, maxillary 2, zygomatic 2, palatine 2, inferior nasal conchae (turbinate) 2, mandible 1, vomer 1
Bones of cranial vault are 2 plates of _______ tissue separated by _______ (inner layer of _______ tissue)
compact; diploe; spongy
Except for ________, the bones of the cranium and face are joined by _______ joints called _______
mandible; fibrous; sutures
4 main sutures
Coronal, sagittal, squamosal, lambdoidal
Suture between frontal and parietal bones
Suture on top of head between the 2 parietal bones and just behind coronal suture line
Junction of coronal and sagittal sutures
Sutures between temporal bones and parietal bones
Suture between occipital bone and parietal bones
Junction of lambdoidal and sagittal sutures
Junction of occipital and both parietal bones
Junction of parietal bone, squamosal suture, and greater wing of sphenoid
Where is pterion found?
Lateral aspect of skull
What does the pterion overlie?
Middle meningeal artery
Junction of occipital bone, parietal bone, and mastoid portion of temporal bone
Superior aspect of cranium; where parietal bones join together
Newborn skull has __ areas of incomplete ossification called ________
6; fontanels
What are the 6 fontanels?
Anterior, posterior, R/L sphenoidal, R/L mastoid
Fontanel at junction of the 2 parietal bones and the 1 frontal bone at the bregma
Fontanel posterior in MSP, at lambda
Fontanel at pterion
Fontanel at asterion
When does the posterior fontanel close?
1 month
When do the sphenoidal fontanels close?
3 months
When does the anterior fontanel close?
During 2nd year of life
When do the mastoid fontanels close?
During 2nd year of life
Cranium develops rapidly in size and density from __ to __
5; 6
At what age does the skull reach adult size, shape, and density?
Internally, cranial floor is divided into __ parts: _____________________________
3; anterior, middle, and posterior cranial fossae
Posterior cranial fossa is posterior to ___________ and protects ___________________
petrous ridges; cerebellum, pons, and medulla oblongata
Average cranium is ____-shaped and wider in ______ than in _______
oval; back; front
Skull is __" from side to side at its widest point
Skull is __" at its longest point from front to back
Skull is __" at its deepest point from the vertex to the submental region
The length and width of the normally shaped head vary by __"
If deviation in skull size/shape involves more than a __ degree change, it must be compensated for by a change in either __________ or ____________
5; part rotation; CR angulation
Rounded elevation on each side of MSP of superior part of squama
Frontal eminence
Arched ridges that correspond in position to eyebrows and are located below frontal eminences and above supraorbital margins
Superciliary arches
Opening for nerves and blood vessels in the center of each supraorbital margin
Supraorbital foramen
Smooth elevation between superciliary arches
Frontal bone articulates with...
parietals, sphenoid, and ethmoid cranial bones
Frontal squama articulates with parietal bones at...
coronal suture
Midpoint of frontonasal suture
Junction of frontal and nasal bones in midline
Receives the cribriform plate of the ethmoid bone
Ethmoidal notch
Small inferior projection of bone which is the most superior component of bony nasal septum
Nasal spine
Superciliary arches bone
Frontal bone
Glabella bone
Frontal bone
Nasion bone
Frontal bone
Ethmoidal notch bone
Frontal bone
Nasal spine bone
Frontal bone
Which bone is small and cube-shaped?
Ethmoid bone consists of...
vertical plate, horizontal plate, and 2 labyrinths
Spongy lateral masses of ethmoid bone
Where is ethmoid bone situated?
Between the orbits
What does the ethmoid bone form part of?
Anterior cranial fossa, orbital walls, nasal cavity, and bony nasal septum
Horizontal portion of ethmoid bone
Cribriform plate
What receives the cribriform plate of the ethmoid bone?
Ethmoidal notch of frontal bone
The cribriform plate is perforated by many _____________ for the transmission of _____________
olfactory foramina; olfactory nerves
Thick, conical process on cribriform plate which projects superiorly from its anterior midline and serves as the anterior attachment for the falx cerebri (meninges)
Crista galli
The crista galli serves as the anterior attachment for the...
falx cerebri (meninges)
Vertical portion of ethmoid bone
Perpendicular plate
Thin, flat bone that projects inferiorly from inferior surface of cribriform plate and, with nasal spine, forms superior portion of bony septum of nose
Perpendicular plate
Labyrinths contain...
ethmoidal sinuses (air cells)
What do the walls of the labyrinths form?
Part of the medial walls of the orbits and part of the lateral walls of the nasal cavity
2 thin, scroll-shaped processes that project inferiorly from each medial wall of the labyrinths
Superior and middle nasal conchae
Ethmoid bone cleanses _____ before it goes into _______
air; lungs
Ethmoid bone articulates with...
frontal and sphenoid bones of cranium and 11 facial bones
Square bones with a convex external surface and a concave internal surface
Parietal bones
What bones form a large portion of the sides of the cranium?
Frontal bones
Parietal bones form posterior portion of __________ by articulating with each other at _________ suture in MSP
cranial roof; sagittal
Prominent bulge on each parietal bone, near the central portion of its external surface
Parietal eminence
What is the widest point of the head, where the width of the head should be measured?
Parietal eminences
Each parietal bone articulates with...
frontal, temporal, occipital, sphenoid, and the opposite parietal bone of the cranium
Irregularly wedge-shaped bone that somewhat resembles a butterfly/bat with wings extended
Sphenoid bone
Cribriform plate bone
Ethmoid bone
Crista galli bone
Ethmoid bone
Perpendicular plate bone
Ethmoid bone
Labyrinths bone
Ethmoid bone
Superior and middle nasal conchae bone
Ethmoid bone
What bone forms the anchor for all other cranial bones to articulate with?
Sphenoid bone
Bone situated in base of cranium anterior to temporal bones and basilar part of occipital bone
Sphenoid consists of ________, ___________, and ___________
body; 2 lesser wings and 2 greater wings that project laterally from sides of body; 2 pterygoid processes which project inferiorly from each side of inferior surface of body
Body of sphenoid has 2...
sphenoidal sinuses
Anterior surface of body of sphenoid bone forms posterior bony wall of...
nasal cavity
Depression on superior surface of body of sphenoid bone that contains pituitary gland
Sella turcica
Where does sella turcica lie?
In MSP at a point 3/4" anterior to and 3/4" superior to level of EAM
Sella turcica is bounded anteriorly by ___________ and posteriorly by ___________, which bears the _________________
tuberculum sellae; dorsum sellae; posterior clinoid processes
Slanted area of bone posterior to and inferior to dorsum sellae
Clivus is continuous with...
basilar portion of occipital bone
What does the clivus support?
Groove on either side of sella turcica that contains the internal carotid artery and cavernous sinus
Carotid sulcus
What extends across anterior portion of tuberculum sellae?
Optic groove
Optic groove ends on each side at...
optic canal
Opening into the apex of the orbit for transmission of optic nerve and opthalmic artery
Optic canal
What is the actual opening for the optic canal?
Optic foramen
The lesser wings of the sphenoid bone are ________ in shape and nearly __________
triangular; horizontal
Medial ends of posterior borders of sphenoid bone
Anterior clinoid processes
Greater wings of sphenoid bone arise from __________ and curve __________, _________, and ________
sides of body; laterally; posteriorly; superiorly
Where are foramina ovale, rotundum, and spinosum found?
Greater wings of sphenoid
What foramina are paired and found in greater wings of sphenoid?
Ovale, spinosum, rotundum
Foramina ovale, rotundum, and spinosum transmit...
nerves and blood vessels
Pterygoid processes arise from...
lateral portions of inferior surface of body of sphenoid bone and medial portions of inferior surfaces of greater wings
Pterygoid processes project _________ and curve ___________
inferiorly; laterally
Elongated, hook-shaped process on inferior extremity of medial lamina of pterygoid process
Pterygoid hamulus
Sphenoid bone articulates with...
each of the 7 other bones of the cranium
Sella turcica bone
Sphenoid bone
Tuberculum sellae bone
Sphenoid bone
Dorsum sellae bone
Sphenoid bone
Anterior and posterior clinoid processes bone
Sphenoid bone
Clivus bone
Sphenoid bone
Carotid sulcus bone
Sphenoid bone
Optic groove bone
Sphenoid bone
Optic canal bone
Sphenoid bone
Foramina ovale, rotundum, and spinosum bone
Sphenoid bone
Pterygoid processes bone
Sphenoid bone
Where is the occipital bone located?
Posteroinferior part of cranium
Occipital bone forms posterior half of _____________ and greater part of _______________
base of cranium; posterior cranial fossa
Occipital bone has __ parts: _____________________
4; squama, 2 occipital condyles, and basilar portion
Parts of occipital bone that extend anteriorly, 1 on each side of foramen magnum
Occipital condyles
Saucer-shaped part of occipital bone, convex externally
Large aperture through which inferior portion of medulla oblongata passes as it exits cranial cavity and joins spinal cord
Foramen magnum
Occipital squama articulates with parietal bones at ________________ and with mastoid portions of temporal bones at ________________
lambdoidal suture; occipitomastoid sutures
Prominent process on external surface of squama midway between its summit and the foramen magnum
External occipital protuberance (inion)
Posterior surface of occipital bone
External occipital protuberance (inion)
What does inion correspond in position to?
Internal occipital protuberance
Occipital condyles project ___________ and articulate with __________
anteriorly; atlas of C-spine
Part of each lateral portion of the occipital condyles curves __________ to fuse with _________ to complete the ___________
medially; basilar portion; foramen magnum
What are the only bony articulations between skull and neck?
Occipitoatlantal joints
What are found at anterior ends of occipital condyles, and what do they transmit?
Hypoglossal canals. Hypoglossal nerves
Anterior part of occipital bone contains a deep notch that forms part of...
jugular foramen
What allows blood to drain from brain via internal jugular vein?
Jugular foramen
What part of occipital bone joins body of sphenoid?
Basilar portoin
In adult, basilar part of occipital bone fuses with body of sphenoid, resulting in...
formation of a continuous bone
Sloping surface of junction between dorsum sellae of sphenoid and basilar portion of occipital bone
Occipital bone articulates with...
the 2 parietals, 2 temporals, and sphenoid of cranium, and C1
Foramen magnum bone
Occipital bone
Inion bone
Occipital bone
Hypoglossal canals bone
Occipital bone
Jugular foramen bone
Occipital bone
Where are temporal bones located?
On each side of base of cranium between greater wings of sphenoid bone and occipital bone
Temporal bones form a large part of the ___________ and a small part of the ___________
middle fossa of the cranium; posterior fossa
Temporal bones consists of a __________, __________, _________, __________, and a __________
squamous portion; tympanic portion; styloid process; zygomatic process; petromastoid portion (mastoid and petrous portions)
Petromastoid portion of temporal bones contain...
organs of hearing and balance
Thin upper part of temporal bone
Squamous portion
Squamous portion of temporal bone has prominent arched ______________, which articulates with _______________ and completes _____________
zygomatic process; zygomatic bone of face; zygomatic arch
Rounded eminence on inferior border of zygomatic process
Anterior tubercle
____________ receives condyle of mandible to form _____________
Mandibular fossa; TMJ (temporomandibular joint)
What part of the temporal bone is below the squama and in front of the petromastoid portion?
Tympanic portion
Which part of temporal bone has styloid process?
Tympanic portion
Which part of temporal bone has EAM?
Tympanic portion
How long is EAM?
Petrous portion is _________ and __________ to EAM
posterior; inferior
What is the thickest, densest bone in the cranium?
Petrous pyramid
What contains the organs of hearing and balance?
Petrous portion of temporal bones
Upper border of petrous portion
Petrous ridge
Top of petrous ridge lies at level of...
top of ear attachment (TEA)
Temporal bone articulates with...
parietals, occipital, and sphenoid bones of cranium and 8 facial bones
Organ of hearing and balance (equilibrium)
3 main divisions of ear
External ear, middle ear, internal ear
2 parts of external ear
Auricle and EAM
EAM is not 1/2" long. Grr.
Book claims it is 1/2" long in one section, then says it is 1" long in another section.
Oval-shaped, fibrocartilaginous sound-collecting organ on side of head
Sound-conducting canal
EAM ends at...
tympanic membrane of middle ear
Middle ear consists of...
tympanic membrane (eardrum), tympanic cavity (containing air), and 3 auditory ossicles
What are the 3 auditory ossicles?
Malleus (hammer), incus (anvil), stapes (stirrup)
Middle ear communicates with _________ and _____________
mastoid antrum; auditory (eustachian) tube
Tympanic membrane transmits...
sound vibrations
Tympanic cavity communicates with nasopharynx through...
auditory (eustachian) tube
Passage by which air pressure in middle ear is equalized with pressure in outside air passages
Auditory (eustachian) tube
How long is auditory tube?
Auditory ossicles articulate to permit _________________. They bridge middle ear cavity for transmission of _____________ from _________ to __________
vibratory motion; sound vibrations; tympanic membrane; internal ear
What does the stapes fit into?
Oval window of inner ear
What contains the essential sensory apparatus of hearing and equilibrium?
Inner ear
Internal ear is housed within...
bony labyrinth
3 parts of bony labyrinth:
Cochlea, vestibule, semicircular canals
What communicates with middle ear through round window?
What communicates with middle ear through oval window?
What are the 3 semicircular canals?
Anterior, posterior, lateral
What is cochlea used for?
What are vestibule and semicircular canals used for?
Internal ear is an intercommunicating system of ducts and sacs known as the...
membranous labyrinth
Cochlear and vestibular nerves pass from membranous labyrinth through _____ to brain
Sutures of skull are connected by __________ projections of bone interlocked with a layer of _______ tissue
toothlike; fibrous
Movement of sutures
Sutures are ______ joints of ______ type
fibrous; suture
Articulations of facial bones (except TMJ), including joints between roots of teeth and jawbones, are _______________. What type of movement do these joints have?
fibrous gomphoses; immovable
Atlanto-occipital joint is a ________________ joint. What type of movement does this joint have?
synovial ellipsoidal; freely movable
Line extending across the front of both eyes
Interpupillary line (IP)
Lateral aspect of each orbit; where the two eyelids originate
Outer canthus
Plane dividing the skull into equal right and left halves
Extends from EAM to outer canthus
Orbitomeatal line (OML)
Line extending from glabella to anterior aspect of maxilla
Glabelloalveolar line
Line extending from EAM to midpoint of anterior nasal spine
Acanthiomeatal line (AML)
Line extending from EAM to the smooth elevation between the superciliary arches
Glabellomeatal line (GML)
__ degree angle between OML and IOML
__ degree angle between OML and GML
__ degree angle between GML and IOML
A typical skull is called...
Mesocephalic skull: Petrous pyramids project anteriorly and medially at angle of __ degrees from MSP
Brachycephalic skull: Petrous pyramids project anteriorly and medially at angle of __ degrees from MSP
Dolichocephalic skull: Petrous pyramids project anteriorly and medially at angle of __ degrees from MSP
Whether patient is examined in upright or recumbent position depends on:
-Age and condition of patient
-Equipment available
-Preference of radiographer and/or radiologist
-Whether upright images would increase diagnostic value, such as showing air-fluid levels in paranasal sinuses

What part of the head should always be radiographed with the patient upright?
Paranasal sinuses
Should head projections be done with patient upright or recumbent?
Either way (except for sinuses, which should be done upright)
What is responsible for most repeat exams?
Uncomfortable body position resulting in rotation or other motion
For exams of hyposthenic or asthenic patients, _____________________ to raise C-spine to correct level for lateral, PA, and oblique projections when patient is recumbent
elevate chest on small pillow
For exams of obese or hypersthenic patients, ___________________ to obtain correct part-IR relationship if needed when patient is recumbent
elevate head on a radiolucent pad
What simplifies handling of obese or hypersthenic patients for exams of the head?
Head unit
For supine exams of hypersthenic or round-shouldered patients and prone exams of hypersthenic patients, you may need to ____________________ to adjust OML to vertical position
elevate head on radiolucent pad
For prone exams of hyposthenic patients, you may need to ________________ to adjust OML to vertical position
elevate chest on a support
When body is correctly placed and adjusted so _____________________________, the final position of the head requires only minor adjustments
long axis of C-spine is supported at level of foramen magnum
When area to be exposed, how should head be immobilized?
With sandbags placed against sides or vertex
What SID is used for skull?
What technique is used for most of skull?
80 kVp, center cell
What are the breathing instructions for all headwork?
Suspend respiration
Skull routine
AP axial (Towne), PA axial (Caldwell), both laterals
General body position for AP axial skull (Towne)
Seated or supine (upright recommended for hypersthenic/obese patients)
How can you bring the skull closer to the IR for an AP axial skull (Towne method)?
Lean back lordotically and rest shoulders against vertical grid device
Both AP axial (Towne) and PA axial (Haas) show a comparable image of the ___________ region
What projection is the reverse of the AP axial (Towne method) and produces a comparable image?
PA axial (Haas method)
What is the baseline positioning for AP axial (Towne method) skull?
OML and MSP perp to IR
IR for AP axial (Towne method) skull
10x12 LW
IR centering for AP axial (Towne method) skull
Top of IR at vertex (highest point of skull). Center IR at foramen magnum
CR for AP axial (Towne method) skull
30 degrees caudad, entering 2.5" above glabella
For a localized image of dorsum sellae and petrous pyramids using AP axial (Towne method) skull projection...
Center IR at or slightly below level of occlusal plane
AP axial (Towne method) skull projection is also used for tomographic studies of...
ears, facial canal, jugular foramina, and rotundum foramina
AP axial (Towne method) skull shows _________ bone and posterior aspects of ________ bones
occipital; parietal
AP axial (Towne method) skull shows _______ part of foramen magnum
Baseline positioning for AP skull
OML and MSP perp to IR
CR for AP skull
Perp, entering nasion
Where will petrous pyramids be for AP skull?
Filling orbit
Where will petrous pyramids be for AP axial skull?
Lower 1/3 of orbit
Baseline positioning for AP axial skull
OML and MSP perp to IR
CR for AP axial skull
15 degrees cephalic, entering nasion
For PA or PA axial skull, _________ and _________ will be on table or against upright Bucky
forehead; nose
Baseline positioning for PA skull
OML and MSP perp to IR; IP parallel to IR
Baseline positioning for PA axial (Caldwell) skull
OML and MSP perp to IR; IP parallel to IR
IR for PA or PA axial skull
10x12 LW
IR for PA skull is centered to...
IR for PA axial skull (Caldwell) is centered to...
CR for PA axial (Caldwell) skull
15 degrees caudad, exiting nasion
What do you do a PA projection of the skull for?
Frontal bone
CR for PA axial skull to show superior orbital fissures
20-25 degrees caudad through midorbits
CR for PA axial skull to show rotundum foramina
25-30 degrees caudad, directed to nasion
PA axial (Caldwell) skull shows __________, ________ and ___________ sinuses, and ________ and ________ walls of cranium
crista galli; frontal; anterior ethmoid; anterior; side
Eval criteria for PA or PA axial (Caldwell) skull:
-Entire cranial vertex demonstrated
-Entire cranial perimeter showing 3 distinct tables of squamous bone
-Equal distance from lateral border of skull to lateral border of orbit on both sides
-Symmetric petrous ridges
-Properly penetrated frontal bone without excessive density at lateral borders of skull
-Petrous ridges in lower 1/3 of orbit if 15 degree angle used; filling orbits if no angle used; at or below inferior orbital rim if 25-30 degree angle used
-Caldwell method demonstrates anterior ethmoid air cells

Baseline positioning for PA axial (Haas) cranium
OML and MSP perp to IR
IR for PA axial (Haas) cranium
10x12 LW
CR for PA axial (Haas) cranium
25 cephalic to OML, entering 1.5" below inion and exiting 1.5" above nasion
Eval criteria for PA axial (Haas) cranium
-Symmetric petrous pyramids
-Dorsum sellae and posterior clinoid processes within foramen magnum
-Equal distance from lateral border of skull to lateral margin of foramen magnum on both sides (no rotation)
-Entire cranium
-Occipital bone and posterior aspects of parietal bones

General body position for lateral skull
Seated upright or semiprone, about a 45 degree body oblique
What side of the skull is closest to IR for lateral skull?
Side of interest
Baseline positioning for lateral skull
IP perp to IR; IOML and MSP parallel to IR (IOML perp to front edge of IR)
IR for lateral skull
10x12 CW
CR for lateral skull
Perp, entering 2" above EAM
Cross-table lateral skull is used to demonstrate ___________________ and may be the only evidence of a ______________
traumatic sphenoid sinus effusion; basilar skull fracture
Lateral skull shows...
-Superimposed cranial halves with detail of side closest to film
-All 4 sets of sinuses
-Lateral of sella turcica
-Anterior clinoid processes, dorsum sellae, posterior clinoid processes

Eval criteria for lateral skull
-Entire cranium without rotation or tilt
-No rotation as demonstrated by superimposed mandibular rami, orbital roofs, greater wings of sphenoid, EAMs, mastoid regions, and TMJs
-Properly penetrated parietal bone
-Sella turcica in profile
-No overlap of C-spine by mandible

Submentovertical (SMV) projection of cranial base is aka...
Schuller method; full basal
What is the preferred general body position for SMV?
Seated upright
When patient is supine for SMV, ______________ to allow head to rest on vertex with neck in hyperextension
elevate torso on supports
Baseline positioning for SMV skull
Vertex on IR. IOML parallel with IR (vertical). MSP perp to IR
IR for SMV skull
10x12 LW
CR for SMV skull
Perp to IOML, entering MSP of throat between angles of mandible and passing through a point 3/4" anterior to level of EAMs, directed through sella turcica
(May have to angle tube cephalad to be perp to IOML)
SMV skull shows...
-SMV images floor of base of skull
-Symmetric petrosae and mastoid processes
-Foramina ovale and spinosum (are best shown in SMV projection)
-Carotid canals
-Maxillary sinuses superimposed over mandible
-Bony nasal septum
-Occipital bone
-Odontoid in foramen magnum
-Ethmoid and sphenoid sinuses free of superimposition
-SMV projection is also used for axial tomography of orbits, optic canals, ethmoid bone, maxillary sinuses, and mastoid processes
-If exposure factors are decreased, SMV projection demonstrates zygomatic arches well

Eval criteria for SMV skull:
-No rotation
-Equal distance from lateral border of skull to mandibular condyles on both sides (no tilt)
-Mandibular symphysis (protuberance) superimposed over anterior frontal bone (full extension of neck)
-Mandibular condyles anterior to petrous pyramids
-Symmetric petrosae
-Adequate penetration indicated by clearly visible structures of cranial base

When patient can’t be positioned for a PA or PA axial projection, a similar but somewhat ____________ image can be obtained with an ______________ projection
magnified; AP or AP axial
Eval criteria for AP or AP axial skull
-Petrous pyramids filling orbit if CR is perp; petrous pyramids in lower 1/3 of orbit if CR is angled 15 cephalic
-Entire cranial perimeter showing 3 distinct areas of squamous bone
-Equal distance from lateral border of skull to lateral border of orbit on both sides
-Symmetric petrous ridges
-Penetration of frontal bone without excessive density at lateral borders of skull

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