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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.

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Mastoids and Organs of Hearing

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  1. Mastoids and Organs of Hearing Fall 2011 FINAL

  2. Ear

  3. http://www.squidoo.com/otosclerosis

  4. Temporal Bone

  5. 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

  6. Temporal Bones • Consist of • Squamous portion • Tympanic portion • Styloid process • Zygomatic process • Petromastoid portion a) contains the organs for ___________________

  7. 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

  8. 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

  9. 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

  10. Temporal Bones • Auditory ossicles = bones of middle ear 1. 2. 3. • Temporal bone articulates with the parietal, occipital, sphenoid, zygoma, and mandible

  11. Temporal Bone Pathology • Mastoiditis • Neoplasms • Acoustic neuroma • Cholesteatoma • Polyp • Otosclerosis

  12. Mastoiditis

  13. Acoustic neuroma

  14. Cholesteatoma

  15. Essential Projections: Temporal Bone • Axiolateral oblique (Modified Law) • Axiolateral oblique (Stenvers) • Axiolateral oblique (Arcelin)

  16. Axiolateral Oblique (Modified Law) • IOML ______with IR • IPL _________ to IR • MSP angled 15 degrees toward IR

  17. 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

  18. 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

  19. Axiolateral Oblique (Stenvers) • IOML ________with transverse axis of IR • MSP at ________angle from IR

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

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