CT IMAGING OF TEMPORAL BONE
Dr. Adila iqbal
PGR-1
CT PROTOCOL
Axial supine 1mm
Coronal Prone 1mm
120 kv@200mA :1sec
512x512 @140mmFOV
Squamous
Mastoid
Petrous
Tympanic
Styloid
SquamousMastoid
Petrous
Tympanic
Styloid
Squamous
MastoidPetrous
Tympanic
Styloid
Petrous and its subsegments
•Pyramid and otic capsule
•Subsegments
1. Anterior
2. Posterior
3. Inferior
4. Apical
Anterior petrous subsegment
Tegmen tympani
Arcuate eminenceProminence
over upper
SCC
Posterior petrous subsegment
Inner acoustic pore;Inner ear canal joins SAS
Modiolus;entrance to chochlea for
chochlear nerve
7up
coke
SV
IV
Posterior petrous aqueducts
Vestibular (endolymphatic):
parallel to petrous ridge
Cochlear (perilymphatic):
Verticaly below and parallel to
inner ear canal
VESTIBULAR AQUEDUCT
10 mm long endolymphatic duct
From common crus to post wall of petrous
pyramid
Joins endolymphatic sac nestled in leaves of
dura
Equilibration of endolymphatic fluid pressure
subdural
COCHLEAR AQUEDUCT
8 mm long perilymphatic aqueduct
From basal turn of cochlea to medial border
of jugular foramen
Regulation of CSF and perilymphatic fluid
pressure
Subarachnoid
Inferior petrous subsegment
•Carotid canal
•Jugular foramen
Squamous
Mastoid
Petrous
TympanicStyloid
Segments of the
ear
•Outer acoustic meatus
•Outer(externa)
•Middle(media)
•Inner (interna)
•Inner acoustic pore
Pinna attachment
Outer ear canal
•Epitympanum(attic)
•Mesotympanum(cavity)
•Hypotympanum(basement
)
Middle ear cleft
WALLS OF MIDDLE EAR CLEFT
Anterior: carotid
Posterior:mastoid
Upper: aditus ad antrum
Lower: •Pyramidal eminence
•Sinus tympani
•Facial recess
EPITYMPANUM
Above plane from lower scutum to tympanic VII
Malleus capitis and short process of incus
Prussak epitympanum recess
EPITYMPANUM
MESOTYMANUM
Tympanic cleft proper dampens sounds
Manubrium of malleus
Long process of incus
Superstructure and foot plate of stapes
MESOTYMANUM
Tensor tympani
Cochleariform process
Stapedius muscle
Stapedius tendon
HYPOTYMPANUM
Shallow trough in floor ofmiddle ear cleft
No vital structures
Squamous
Mastoid
Petrous
Tympanic
Styloid
STYLOID SEGMENT
Styloid process develops after birth(like
mastoid)
Stylomastoid canal
INNER EAR
Membranous labyrinth
Osseus labyrinth
MEMBRANOUS LABYRINTH
Vestibule: utricle and saccule
Semicircular canals
OSSEUS(COCHLEAR) LABYRINTH
Osseus edifice for cochlea,vestibule and
semicircular canals
Vestibular and cochlear aqueducts
COCHLEA
More than 2.5 turns
Basal and intermediate spirals readily seen
Basal turn opens post into round window
Cochlea encircles central osseus axis of
modiolus
SEMI CIRCULAR CANALS
Project off superior,posterior and lateral
aspects of vestibule
Upper margin of superior SCC forms
superior convexity on petrous pyramidal
roof(Arcuate eminence)
SEMI CIRCULAR CANALS
Posterior SCC points
posteriorly along
petrous ridge
Lateral SCC juts
lateraly into
epitympanum
(cholesteatoma here
erodes lateral
cortex:fistulization)
FACIAL NERVE
SEGMENTAL
TEMPORAL BONE ANALYSIS
Ear or anterior cerebellopontine sulcus Ear :outer,middle,inner
ACPA masses
Osseus destruction
Anatomic extent
OUTER AND MIDDLE EAR DISEASE
Malignant otitis externa
Chronic otitis media
Cholesteatoma
Post surgical ear COM/CS
Middle ear
effusion
Cholesteatoma
ACPA masses
1. Neoplastic
•Schwanommas
•Meningeomas
•Epidermoid
2. Vascular• Vertebrobasilar dolichoectesias
• Glomus tumor
Symmetry
Patency
Outer ear canal
Middle ear cleft
Inner ear structures
Ossicular erosion
Aeration(mastoids,bones
Labyrinths
Nerves
Segmental Analysis
SEGMENTAL ANALYSIS
Outer ear canal
Middle ear cleft
Inner ear structures
Focal mass
•Destructive changes
•Ossicular inteagrity
•Focal enhancement
•Outer ear canal,Middle ear cleft,Inner
ear
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