Transcript Mastoids and Organs of Hearing

Mastoids and
Organs of Hearing
Fall 2011
FINAL
Ear
 http://www.squidoo.com/otosclerosis
Temporal Bone
Temporal Bones
 Situated on each side of cranial base
between ____________and occipital bone
 Form large part of ______ cranial fossa
and a small part of ________ cranial fossa
Temporal Bones
 Consist of
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Squamous portion
Tympanic portion
Styloid process
Zygomatic process
Petromastoid portion
a) contains the organs for ___________________
Temporal Bones
 Tympanic portion = located below squama
and in front of petromastoid portion
 Forms anterior wall, inferior wall and part of
posterior walls of the EAM
 Styloid process = slender, pointed bone
projecting inferiorly, anteriorly, and slightly
medially from inferior surface of tympanic
portion
Temporal Bones
 Petromastoid portion combines petrous
and mastoid portions
 Forms the inferior, posterior part of the
temporal bone
 Articulates with parietal bone at its superior
border and with occipital bone at its posterior
border
 Usually contains air cells, which vary greatly
in size, number, and pneumatization
Temporal Bones
 Mastoid process = conical process projecting
from mastoid portion
 Petrous portion projects medially and anteriorly
between greater wing of sphenoid and occipital
bone
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Also called petrous pyramid
Conical or pyramidal in shape
Thickest and densest portion of cranium
Contains the organs of hearing and balance
Temporal Bones
 Auditory ossicles = bones of middle ear
1.
2.
3.
 Temporal bone articulates with the
parietal, occipital, sphenoid, zygoma,
and mandible
Temporal Bone Pathology
 Mastoiditis
 Neoplasms
 Acoustic neuroma
 Cholesteatoma
 Polyp
 Otosclerosis
Mastoiditis
Acoustic neuroma
Cholesteatoma
Essential Projections:
Temporal Bone
 Axiolateral oblique (Modified Law)
 Axiolateral oblique (Stenvers)
 Axiolateral oblique (Arcelin)
Axiolateral Oblique (Modified Law)
 IOML ______with IR
 IPL _________ to IR
 MSP angled 15 degrees
toward IR
Axiolateral Oblique (Modified Law)
 CR
 Angled 15 degrees caudad to midpoint of IR
 Exits mastoid tip closer to IR about 1 (2.5
cm) posterior to EAM
 Enters 2 (5 cm) posterior to and superior to
upper EAM
Axiolateral Oblique Temporal Bone
(Modified Law)
 Mastoid process closer to IR
 Air cells centered to IR
 Opposite mastoid process inferior
and anterior mastoid of interest
 Auricle of ear not superimposing
mastoid
 Superimposition of IAM and EAM
 TMJ visible anterior to mastoid
process
 Close beam restriction
Axiolateral Oblique (Stenvers)
 IOML ________with
transverse axis of IR
 MSP at
________angle from
IR
Axiolateral Oblique (Stenvers)
 CR
 Angled 12 degrees cephalad
 Enters about 3 to 4 (7.6 to 10 cm) posterior
and ½ (1.3 cm) inferior to upside EAM
 Exits 1 (2.5 cm) anterior to downside EAM
 IR and CR centered
Axiolateral Oblique Temporal
Bone (Stenvers)
 Petromastoid portion in profile
 Lateral border of skull to lateral
border of orbit
 Petrous ridge extended to a point
about two thirds up lateral border
of orbit Mastoid process in profile
below cranium
 Posterior margin of mandibular
ramus superimposing lateral
border of C-spine
 Mandibular condyle projecting
over atlas near petrosa
 Close beam restriction
Axiolateral Oblique Temporal Bone
(Arcelin)
 Rotate face away
from side of interest
to place MSP at 45degree angle with
plane of IR
 IOML perpendicular
to IR
Axiolateral Oblique Temporal Bone
(Arcelin)
 CR
 Angled 10 degrees caudad
 Enters temporal area at 1 (2.5 cm) anterior
to EAM and ¾ (1.9) cm above it
 Center IR and CR
Axiolateral Oblique Temporal Bone
(Arcelin)
 Petromastoid portion in profile
 Lateral border of skull to lateral
border of orbit
 Petrous ridge lying horizontal
about two thirds up lateral
border of orbit Mastoid process
in profile below cranium
 Posterior margin of mandibular
ramus superimposing lateral
border of C-spine
 Mandibular condyle projecting
over atlas near petrosa
 Close beam restriction