Download Mastoids and - El Camino College

Mastoids and
Organs of Hearing
Fall 2009
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
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
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 45-degree 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