5. TMJ

normal joint- posterior band is positioned _______

11-12o clock to condylar head

superior joint space- ____mm anterior and posterior: ___mm space between condyle and eminence condylar eccentricity seen in _____ to ____ of asx individuals

2.5mm 1.5mm 1/3-1/2

cortical borders of condyle complete at _____ condyles in children will show little or no evidence of _____

20 yoa cortical borer

Transpharyngeal view •Advantages:

Visualizing erosive change of condyle Good for condylar fracture Okay for gross disease of condyle

most inferior aspect of articular eminence is called _____

apex or crest

soft tissue imaging

arthrography mri

anterior to condylar head are_______ and _____

articular eminence and tubercle

interarticular disk: _______ tissue ______ shape 3 portions and thickness of each divides in to __ and ____

avascular fibrous CT biconcave anterior band, intermediate zone (thin), posterior band (Thickest) superior and inferior spaces

panoramic (pantomograph) adv

broad overview of TMJ and surr structures rule out gross osseous dz symmetry analysis okay for gross dz of condyle

arthrography adv

can see disk position and configuration can see disk perforations can see relationships of tmj

submentovertex (basal) disadv

can't see TMJ in detail

conventional tomography disadv

can't see early dz easily can't see the disk

transorbital view disadv

can't see relationship b/w condyle and glenoid fossa

towne 30o (AP) view disadv

can't see relationshipo b/w condyle and glenoid fossa must open mouth wide

transcranial view disadv

cna't see accurate relationship between condyle and glenoid fossa medial and central aspects projected inferiorly can't see early dz

conventional tomography adv

depict true condylar position and reveal osseous changes see earlier gross dz

interaticular disc

disc itself has thick component in the anterior but thicker in the posterior component retrodiscal tissue (posterior attachment) is highly vascularized and innervated, responsible for pain pt feels disc itself is avascular- so it gets nutrietns from surrounding synovial fluids

condyle: shape ____mm mediolaterally ___mm anteriorposteriorly

ellipsoide 20mm 8-10mm

purpose of tmj dx imaging

evaluate the integrity and relationshiops of hard and soft tissues confirm the extent or stage of progression of known disease evaluate the effects of treatment

condyle is covered by thin layer of _____.

fibrocartilage

posteriorly to condylar head is ______, which is the squamous part of the temporal bone. also has a thin layer of ______

glenoid (mandibular) fossa fibrocartilage

shape of articular eminence i

has a "s" shap to it, when the person has osteoarthritis, this shape will be flattened

condylar movement: at max opening, the head is at _____ ____mm posterior and ____mmm anterior to the crest

head at apex 2-5mm, 5-8mm

mdct disadv

higher radiation dose than cbct articular disk not adequately visualized

condylar mvmt: anterior translation greater than 5mm to eminence results in

hypermobility

condylar movement: opening

inferior and anterior translation of condyle extent of translation varies

soft tissue components of TMJ

interarticular disk and retrodiscal tissue

arthrograph disadv

invasive procedure somewhat painful cannot use if allergies to contrast or iodine

condylar mvmt: superior movement past the eminence results in

locking and dislocation

retrodiscal tissue- has superior and inferior lamellae which is ____ tissue

loose vascular tissue so restrodiscal tissue is well vascularized and innervated

transorbital view adv

modified AP view of condyle okay for gross dz good for condylar fractures like Transpharyngeal view

towne 30o (AP) view adv

modified AP view of condyle ok for gross dz good for condylar dz (like transphryangeal and transorbital)

panoramic (pantomograph) disadv

no info about condylar position or function mild osseous changes obscured pan is very sensitive to position of the pt, so asymmetry on pan may be due to technique error, if you see a condyle larger than the other one, don't jump to say there is hyperplasia of the condyle

MRI adv

no radiation dose best for articular disk and soft tissue can detect joint effusinos

cbct adv

no superimposition reconstruction in multiple views and planes corrected coronal and sagittal least distortion 3D imging good for skeletal asymmetries reduced radiation dose good visualization for osseous dz and tmj relationshipo, mandibular/condylar fractures , ankyloses, and neoplasms

MRI mechanism

nuses magnietic field and radiofrequency so no radiation dose is needed sagittal and coronal planes acquired: open and closed TMJ

transcranial view

open and close mouth positions through cranium and above petrous ridge

MRI disadv

osseous structures not in details thick slices cannot do for cluastrophobics orthodontic wires--> appear as artifact but not a contraindicatio

contraindication for MRI

pacemakers intracranial vascular clips

common tmj img modalities

pantomograph computed tomography (MDCT and CBCT) MRI

articular eminence may be ____ with air cells from mastoid air complex

pneumatized

condylar mvmt: reduced translation results in

reduced mouth opening

Transpharyngeal view •disadvantages:

relationship b/w condyle and glenoid fossa NOT visible

source of pain when trapped bewteen condyle and eminence in anterior disk displacement of TMJ

retrodiscal tissue as it is well innervated

submentovertex (basal) adv

see condyle in axial direction see relationship of condyle to glenoid fossa

transcranial view adv

see distorted relationship of condyle and glenoid fossa okay for gross dz of condyle

multidetector CT (MDCT) adv

similar to cbct allows visualization of soft tissue (neoplasms) can see relationships of tmj components

cbct disadv

soft tissue components (disk) not visualized, also muscles not seen streak of artifacts from metallic implants can obscure structures

img techniques

specialized tmj views pantomograph computed tomography (MDCT and CBCT) arthrography mri

Diagnostic TMJ Imaging Indications- Goal: supplement information from clinical exam

•History of trauma •Suspected osseous abnormality •Significant dysfunction •Worsening symptoms •Alteration in range of motion •Sensory / Motor abnormalities •Changes in occlusion (apertognathia, midline shifts etc.)

transpharyngeal view

•Maximal open mouth

specialized tmj views

•Transcranial •Transpharyngeal •Transorbital •Towne (30o AP) Projection •Submentovertex (basal) projection •Conventional Tomography