Facial Bones, Sinuses and Sinus Positioning Flashcards
14 facial bones
R and L nasal R and L lacrimal (tear ducts) R and L maxillary R and L zygomatic/zygoma (cheek) R and L palatine R and L inferior nasal conchae (superior and middle belong to ethmoid bone) Vomer Mandible
Two small, thin facial bones
Vary in size and shape in individuals
Form “bridge of nose”
Nasal bones
Superior bony wall of nasal cavity formed by nasal bones
“Bridge of nose”
4 articulations of the nasal bones
With each other in MSP
Superior/above = frontal bone
Posterosuperior surface with perpendicular plate of ethmoid bone
On each lateral side = maxillae
Two smallest bones in the skull, very thin
Located in anterior part of medial wall of orbits between labyrinth of ethmoid and maxilla
Some of the bones that make up orbit
Each contains a lacrimal foramen and form the lacrimal fossa
Lacrimal bones
Foramen in lacrimal through which the tear duct passes
Lacrimal foramen
Fossa that accommodates lacrimal sacs and is formed by the lacrimal bones and maxillae
Lacrimal fossa
4 articulations of the lacrimal bones
Frontal
Ethmoid
Maxilla
Inferior nasal concha
2 projections of the skull the lacrimal bones are seen on
PA
Lateral
Two largest, immoveable bones of the face
Maxillary bones
What do the maxillary bones articulate with?
Each articulates with all other facial bones, except for mandible; also articulate with frontal and ethmoid cranial bones
3 things the maxillary bones form
Part of lateral walls and most of floor of nasal cavity
Part of the floor of orbital cavities
3/4 of the roof of the mouth
Process of maxillary bones that articulates with zygomatic bones and assist in formation of the prominence of the cheeks
Zygomatic process
Body of maxillary bones contains large, pyramidal cavities that empty into the nasal cavity
Maxillary sinus
Foramen located in the maxillary bones under each orbit and serves as a passage through which the infraorbital nerve and artery reach the nose
Infraorbital foramen
Inferior borders of spongy bone of the maxillary bones that support roots of teeth; what upper teeth are embedded into
Alveolar process
Forward pointed process at the maxillary bone’s midline junction in the anterior MSP
Anterior nasal spine
Midpoint of junction (anterior nasal spine) of the maxillary bones
Acanthion
2 things the zygomatic bones form
Prominence of cheeks
A part of the side wall and floor of the orbital cavities
Posteriorly extending process of the zygomatic bones that unites with the zygomatic process of the temporal bone to form the zygomatic arches
Temporal process
Formed by union of temporal process of zygoma and zygomatic process of temporal bone
Zygomatic arch
4 articulations of the zygomatic bones
Frontal bone superiorly
Zygomatic process of temporal bone at lateral side
Maxilla anteriorly
Sphenoid posteriorly
Two L-shaped bones composed of vertical and horizontal plates
Palatine bones
What do the horizontal plates of the palatine bone form?
Horizontal plates articulate with maxillae to complete posterior 1/4 of bony palate (horizontal part of L makes up 1/4 roof of mouth)
Roof of mouth
Bony palate
What do the vertical plates of the palatine bone form
Vertical portions extend upward between maxillae and pterygoid processes of sphenoid bone in posterior nasal cavity
Superior tips of vertical portions assist in forming posteromedial bony orbit
Extend diagonally and inferiorly from lateral walls of nasal cavity at its lower third
Long, narrow, very thin bones with a lateral curve that gives them a scroll-like appearance
Upper two are processes of ethmoid bone
The three of these project into and divide the lateral portion of the respective sides of the nasal cavity into superior, middle and inferior meatus
Covered with a mucous membrane to warm, moisten and cleanse inhaled air
Inferior Nasal Conchae
Thin plate of bone situated in MSP of floor of nasal cavity where it forms inferior nasal septum
Posterior border is free
Vomer
2 articulations of the vomer
Anterior border slants superior and posteriorly from anterior nasal spine which its superior border articulates with body of sphenoid
Superior part of anterior border articulates with perpendicular plate of ethmoid bone
Largest and densest bone of the face
Mandible
Curved, horizontal portion of the mandible
Body
Two vertical portions on each side of the body of the mandible, unite with body at angle of mandible/gonion
Rami
Anterior, triangular prominence of the mandible; at birth mandible consists of bilateral pieces held together by fibrous symphysis that ossifies during first year of life, at site of ossification is a slight ridge
Mental protuberance
Most anterior and central part of mandible where left and right halves of mandible fuse
Symphysis
Superior border of body of mandible that consists of spongy bone which supports the roots of the teeth
Alveolar process
Small opening on each side of mandible below the second premolar tooth (approximate halfway between superior and inferior borders of the bone) that transmits nerves and blood vessels
Mental foramina
2 processes at upper extremity of rami that project superiorly at an obtuse angle to the body of the mandible and their broad surface forms an angle of approximately 110 to 120 degrees
Coronoid
Condylar process
Junction of body and ramus of mandible
Angle of mandible
Gonion
Anterior process on top of ramus of mandible, thin and tapered to a higher level than the posterior process
Coronoid process
Posterior process on top of ramus of mandible
Consists of a constricted area (neck) above which is a broad, thick, almost transversely placed condyle that articulates with mandibular fossa of temporal bone to form temporomandibular joint (TMJ) which slants posteriorly approximately 15 degrees and inferiorly and medially approximately 15 degrees & is situated immediately in front of the EAM
Condylar process
Concave area at top of ramus of mandible between coronoid and condylar process
Mandibular notch
Small U-shaped bone situated at base of tongue
Accessory bone of axial skeleton = not facial or cranial bone
Only bone in the body that does’t articulate with another bone
Hyoid Bone
7 different bones of orbits
Frontal (C) Sphenoid (C) Ethmoid (C) Maxilla (F) Zygoma (F) Lacrimal (F) Palatine (F)
Air-filled cavities located in the frontal, ethmoid and sphenoid bones of the cranium, as well as the maxillae of the face
So named because of their formation from the nasal mucosa and their continued communication with nasal fossae
Paranasal Sinuses
5 functions of the paranasal sinuses
Serve as resonating chamber for the voice
Decrease weight of skull
Aid in warming and moisturizing inhaled air
Act as shock absorbers in trauma
Possibly control the immune system
Which paranasal sinuses are usually the only ones developed enough to be demonstrated radiographically at birth?
Maxillary sinuses
By what age are the frontal and sphenoid sinuses distinguishable from ethmoidal air cells (which they resemble in size and position)?
6-7 years of age
When do the ethmoidal sinuses fully develop?
17-18 years of age
Largest and most symmetric sinuses
In maxilla, only ones within facial bone; mostly located inferior to orbits
2 pairs (one on each facial bone, R & L)
Vary in size and shape but are approximately upside-down pyramidal in shape; appear rectangular in lateral image
Apices directed inferiorly and laterally
In adults, each one is approximately 1.5 in (3.5 cm) high and 1-1 and 1/3 in (2.5-3 cm) wide
Often divided into sub-compartments by partial septa and occasionally it’s divided into two sinuses by a complete septum
Sinus floor presents several elevations that correspond to the roots of the subjacent teeth
Communicate with middle nasal meatus at superior aspect of the sinus
Maxillary sinuses
Second largest sinuses
Paired; usually see 2, never same size or shape
Normally located between the tables of the vertical plate of the frontal bone; superior to other sinus groups
Vary greatly in size and shape
Occasionally absent; patient may not have frontal sinuses
One or both may be approximately 3/4-1 in (2-2.5 cm) in the vertical or lateral dimension
Often extend beyond the frontal region of the bone, most frequently into the orbital plates
Intersinus septum usually deviated from the midline, for this reason the sinuses are rarely symmetric
Multiple septa sometimes present
Drain into the middle nasal meatus (similar to maxillary sinuses)
Frontal sinuses
Normally paired sinuses
Occupy body of sphenoid
Often only one sinus develops, but never more than two
Vary considerably in shape and size
Usually asymmetric
Located immediately below sella turcica and extend between dorsum sellae and posterior ethmoidal air cells
Open into the sphenoidal recess of the nasal cavity
Sphenoid sinuses
Two sinuses located within lateral masses of labyrinths of ethmoid
Composed of varying number of air cells
Ethmoid sinuses
3 main groups ethmoid sinuses’ varying number of air cells are divided into
Anterior: 2-8, opens into the middle nasal meatus
Middle: 2-8, opens into the middle nasal meatus
Posterior: 2-6, drain into the superior nasal meatus
5 sinuses essential projections
Lateral (demonstrates all four without distortion or superimposition the best; best detail of side closest to IR
PA axial (Caldwell method)
Parietoacathial (Waters method)
Parietoacanthial (Open-mouth Waters method) when they can’t do SMV
Submentovertical (SMV)
Part position for the lateral projection of the sinuses
MSP of head parallel with IR plane
IPL perpendicular to IR
IOML horizontal and perpendicular to front edge of IR
Central ray for lateral projection of the sinuses
Horizontal and perpendicular to IR
Enters 1/2-1 in (1.3-2.5 cm) posterior to outer canthus
Center IR to CR
5 structures shown on lateral projection of the sinuses
All four sinuses
AP and superoinferior dimensions of paranasal sinuses
Thickness of outer table of frontal bone
Detail of side closer to IR
What is the difference between the angled and vertical grid technique for the PA axial (Caldwell method) of the sinuses?
Angled grid technique: tilt vertical Bucky down 15 degrees, rest partient’s forehead and nose on device, center nasion to IR and MSP and OML perpendicular to IR plane
Vertical technique: position patient’s OML at 15-degree angle to horizontal CR, center nasion to IR and MSP perpendicular
Why is the vertical grid technique for the PA axial (Caldwell method) of the sinuses not preferred?
Because of increased OID, which results in decreased resolution
Why is a horizontal CR always used for sinus projections?
Can’t see air fluid levels with tube angle
CR for PA axial (Caldwell method) of the sinuses
Horizontal (15-degree relationship between CR and OML remains same for both techniques)
Exits nasion
Center IR and CR
4 structures shown on PA axial (Caldwell method) of the sinuses
Frontal sinuses lying superior to frontonasal suture
Anterior ethmoidal air cells lying on each side of the nasal fossae and immediately inferior to the frontal sinuses
Sphenoid sinuses projected thru nasal fossa just inferior or between ethmoidal air cells
Petrous pyramids extend from inferior third of maxillary sinus
3 evaluation criteria for PA axial (Caldwell method) of sinuses
Frontal sinuses lying above frontonasal suture and anterior ethmoidal air cells lying above petrous ridges
No rotation or tilt, demonstrated by equal distance between the lateral border of the skull and the lateral border of the orbits, petrous ridges symmetric on both sides and MSP of head aligned with long axis of collimated field
Petrous ridges lying in the lower third of the orbit
Part position for the parientocanthial (Waters method) of the sinuses
Hyperextend neck to place OML at 37-degree angle from IR plane
MSP and MML perpendicular to IR
Central ray for the parientocanthial (Waters method) of the sinuses
Horizontal and exits acanthion
3 structures shown on the parientocanthial (Waters method) of the sinuses
Maxillary sinuses
Petrous ridges lying inferior to maxillary floor
Frontal and ethmoid sinuses distorted
Part position for the parientocanthial (Waters method) of the sinuses
Hyperextend neck to place OML at 37-degree angle from IR plane
MSP and MML perpendicular to IR
Open mouth
3 structures shown on the parientocanthial (Waters method) of the sinuses
Sphenoidal sinuses projected through open mouth
Maxillary sinuses
Petrous pyramids lying inferior to maxillary floor
When is the open-mouth Waters method used?
Not routine; for patients who can’t be placed in position for SMV this and lateral may be only techniques to show sphenoidal sinuses
Enters below mental point and out back of head
Submentovertical (SMV)
Part position of SMV of sinuses
Hyperextend neck and rest vertex of head on vertical grid device
MSP perpendicular to IR
Neck extended to place IOML parallel to IR plane
CR of SMV of sinuses
Horizontal and perpendicular to IOML thru sella turcica
Enters MSP 3/4 in (1/9 cm) anterior to level of EAM
1 in below mentum
4 structures show on the SMV of the sinuses
Sphenoid and sinuses
Mandible
Bony nasal septum
Symmetric image of anterior portion of base of skull
3 evaluation criteria of the parientocanthial (Waters method) of the sinuses
Maxillary sinuses
OML in proper position (sufficient neck extension) as demonstrated by petrous pyramids lying immediately inferior to floor of maxillary sinuses
No rotation or tilt, demonstrated by equal distance between the lateral border of the skull and the lateral border of the orbits, orbits and maxillary sinuses symmetric on each side and MSP of head aligned with long axis of collimated field
4 evaluation criteria of the open-mouth Waters method of the sinuses
Sphenoidal sinus projected through open mouth
Maxillary sinuses
OML in proper position (sufficient neck extension) as demonstrated by petrous pyramids lying immediately inferior to floor of maxillary sinuses
No rotation or tilt, demonstrated by equal distance between the lateral border of the skull and the lateral border of the orbits, orbits and maxillary sinuses symmetric on each side and MSP of head aligned with long axis of collimated field
4 evaluation criteria of the SMV of the sinuses
Sphenoid and ethmoid sinuses
No tilt (MSP positioned perpendicular to IR) demonstrated by equal distance from lateral border of skull to the mandibular condyles on both sides
IOML positioned parallel to IR (sufficient neck extension) demonstrated by superimposition of anterior frontal bone by mental protuberance
Mandibular condyles anterior to petrous pyramids
