mandible, TMJs and nasal bones

hyoid bone

small U-shaped bone situated at the base of the tongue (about level of C3)

accessory bone of axial skeleton—not a facial or cranial bone

only bone in the body that does not articulate with another bone

muscles that attach to the hyoid bone help control the actions of the tongue, pharynx, larynx, and mandible.

what anatomy is this?

greater cornu

what anatomy is this?

lesser cornu

what anatomy is this?

body

what anatomy is this?

lesser cornu

what anatomy is this?

hyoid bone

what anatomy is this?

larynx

what anatomy is this?

trachea

nasal bone

two small, thin bones that form “bridge of nose”

form superior bony wall of nasal cavity

vary in size and shape in individuals

located anteriorly and superiorly to frontal processes of maxillae

what anatomy is this?

glabella

what anatomy is this?

nasal bone

what anatomy is this?

frontal process of maxilla

nasal bone articulations

(midsagittal plane)

superior - frontal bone

posterosuperior - perpendicular plate of ethmoid bone

on each lateral side - maxillae

what are the essential projections for the nasal bones?

parietoacanthial (waters)

PA axial (caldwell)

lateral (both left and right)

baselines for parietoacanthial (waters) nasal bones

MML perpendicular to IR

central ray for parietoacanthial (waters) nasal bones

exits nasion

structures shown/ evaluation criteria for parietoacanthial (waters) nasal bones

tangential view of mid-nasal and distal nasal bones, with little superimposition from glabella

PETROUS RIDGES INFERIOR TO MAXILLARY SINUSES

no tilt or rotation

what projection is this?

parietoacanthial (waters) nasal bone

PA axial (caldwell) nasal bone baseline

OML perpendicular to IR

central ray for PA axial (caldwell) nasal bone

15 degrees caudal; exit nasion

structures shown/ evaluation criteria for PA axial (caldwell) nasal bone

nasal septum

PETROUS RIDGES IN LOWER 1/3 OF ORBITS

no tilt or rotation

what projection is this?

PA axial (caldwell) nasal bone

lateral nasal bone baselines

IPL perpendicular to IR

adjust flexion of neck to place IOML parallel with the floor

lateral nasal bones central ray

perpendicular to bridge of nose

enters at a point 1 inch distal to nasion

what projection is this?

left lateral nasal bone

mandible

largest and densest bone of the face

single bone, but at birth to approximately 1 year of age it is 2 bones that eventually fuse

body: curved horizontal portion

what anatomy is this?

symphysis

what anatomy is this?

body

rami (ramus)

two vertical portions on each side of body; terminates in “U” shaped notch

mandibular notch

concave area at top of ramus

each have two processes

what anatomy is this?

coronoid process

what anatomy is this?

condylar process

what anatomy is this?

mandibular notch

what anatomy is this?

ramus

coronoid process

anterior process on top of ramus; serves for muscle attachment– can’t be easily felt

condylar (condyloid) process

posterior process that forms TMJ, only movable skull joint.

what anatomy is this?

neck

what anatomy is this?

coronoid process

what anatomy is this?

ramus

what anatomy is this?

neck

what anatomy is this?

condyle

what anatomy is this?

condylar process

angle of mandible (gonion)

where body and ramus meet

symphysis

most anterior and central part where left and right halves of mandible fuse

alveolar portion (process)

superior border of body; consists of spongy bone that supports roots of teeth

mental foramina

small openings on each side; transmit nerves and blood vessels (for lower teeth)

mental protuberance

anterior, triangular prominence

essential projections (mandible)

PA (for rami and body)

PA axial (for rami and body)

Axiolateral oblique

AP axial (towne)

PA (modified waters)

Submentovertex (SMV)

PA axial mandibular rami central ray

20 to 25 degrees cephalad to exit acanthion

what projection is this?

PA mandibular rami - closed mouth

what projection is this?

PA axial mandibular rami - open mouth

structures shown for PA/PA axial mandibular rami

mandibular body and rami

central part of body not well shown due to superimposed spine

shows medial or lateral displacement of fragments in fractures of the rami

PA Axial evaluation criteria

condylar processes of rami visible

PA Axial mandibular body central ray

30-degree cephalic angle midway between TMJs

what anatomy is this?

ramus

what anatomy is this?

symphysis

what anatomy is this?

body

what anatomy is this?

angle

how much should you rotate the head to see the ramus in an axiolateral oblique mandible?

true lateral - 90 degrees

how much should you rotate the head to see the body in an axiolateral oblique mandible?

30 degrees toward the IR

how much should you rotate the head to see the symphysis (mentum) in an axiolateral oblique mandible?

45 degrees toward IR

central ray for axiolateral oblique mandible

angled 25° cephalad (FOR ALL) to pass directly through the mandibular region of interest

evaluation criteria for axiolateral oblique mandible

no overlap of the ramus by opposite side of mandible

no elongation or foreshortening of ramus or body

no superimposition of the ramus by the cervical spine

what projection is this?

axiolateral oblique (body)

what projection is this?

axiolateral oblique (ramus)

what projection is this?

axiolateral oblique (symphysis)

central ray for AP axial (towne) mandible

35-40 degrees caudal

centered to glabella to pass through each rami

what projection is this?

AP Axial (towne) mandible

PA (modified waters) baseline

OML 55 degree angle with the IR

where are the petrous ridges in a PA (modified waters)

just below the inferior border of the orbits at a level midway through the maxillary sinuses

what projection is this?

PA (modified waters)

central ray for submentovertex (SMV) mandible

centered midway between mandibular angles

what projection is this?

submentovertex (SMV) mandible

what anatomy is this?

symphysis

what anatomy is this?

body

what anatomy is this?

coronoid process

what anatomy is this?

ramus

what anatomy is this?

condyle

what anatomy is this?

petrous ridge

essential projections for temporomandibular Joints (TMJs)

axiolateral (modified Shuller)

axiolateral oblique (modified Law)

AP axial (Modified Towne)

what type of joint is the TMJ?

SYNOVIAL, hinge type joint

mandibular fossa

on temporal bone; articulates with condyloid process of mandible

articular tubercle

bony prominence on temporal bone, directly anterior to mandibular fossa

central ray for axiolateral TMJs

angle 25-30 degrees caudad

enters about ½” anterior and 2” superior to EAM FURTHEST from IR

evaluation criteria for axiolateral TMJs

condyle in mandibular fossa (closed-mouth)

condyle inferior to the articular tubercle (open-mouth)

what projection is this?

closed mouth axiolateral TMJs

what projection is this?

open mouth axiolateral TMJs

AP axial TMJ baseline

OML perpendicular to IR plane

central ray for AP axial TMJs

angled 35 degrees caudad

centered midway between TMJs, entering a point 3” above nasion

what projection is this?

open and closed mouth AP axial TMJs

central ray for axiolateral oblique TMJs (modified law)

angled 15° caudad

exits through TMJ closest to IR

enters approximately 1½ inch superior to upside EAM

what projection is this?

axiolateral oblique TMJs (modified law)

structures shown for axiolateral oblique TMJs (modified law) open and closed mouth

Open-mouth – mandibular fossa and inferior and anterior portion of the condyle

Closed-mouth – fractures of the neck and condyle of the ramus