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Mastoid & Ear
Mastoid, Outer, Middle & Inner Ear
| Question | Answer |
|---|---|
| What are the 3 aspects of the Temporal bone? Which aspect of the Temporal bone is considered the densest? | Squamous portion, Mastoid portion & Petrous portion. The Petrous portion is the densest. |
| Which structure makes up the cartilaginous, external ear? | The Auricle or Pinna |
| How long is the average External Acoustic Meatus (EAM)? | 2.5 cm (1") |
| Which small membrane marks the beginning of the middle ear? | Tympanic membrane (eardrum) |
| What is the collective term for the small bones of the inner ear? | Auditory Ossicles |
| Which structure allows for communication between the nasopharynx & middle ear? What is the major function of this structure? | Eustachian tube (auditory tube. To equalize atmospheric pressure within the middle ear. |
| What are the 3 auditory ossicles? | Malleus (hammer), Incus (anvil), Stapes (stirrups) |
| What is the name of the thin plate of bone that separates the mastoid air cells from the brain? | Tegman Tympani |
| Which one of the auditory ossicles pick up sound vibrations from the tympanic membrane? | Malleus (hammer) |
| Which structure serves as an opening between the mastoid portion of the temporal bone & the middle ear? | Aditus |
| Which one of the auditory ossicles is considered to be the smallest? | Stapes (stirrups) |
| Which one of the auditory ossicles resembles a pre-molar tooth? | Incus (anvil) |
| What is the name of the small membrane that connects the middle to the inner ear? What is it located between? | Oval Window (Vestibular window). Between the Stapes & Vestibule (central portion of bony labyrinth. |
| Which two sensory functions occur within the inner ear? | Hearing & equilibrium |
| What is the name of the small membrane that will move outward to transmit impulses to the auditory nerve, thus creating the sense of hearing? Where is structure. | Round window (Cochlear window). At the base of the cochlea. |
| Is the cochlea a closed system relating to the sense of hearing? Why? | Yes. Because of its connection to the stapes through the oval window. |
| How will the doctor diagnose a cholesteatoma, or neuroma? | If the height of the Internal Auditory Canal (IAC) isn't consistent. A neuroma will erode the bone in the IAC. |
| What are the 3 semi circular canals? What portion of the bony labyrinth do they come off? What senses do the semi circular canals relate to? | The posterior semi circular canal, lateral semi circular canal & superior semi circular canal. Off the Vestibule. To a sense of direction or equilibrium (balance). |
| What are the 3 parts of the Osseous (bony) labyrinth? | The cochlea, vestibule & Semi circular canals. |
| What are the 2 main parts that the internal ear is divided into? | Osseous (bony labyrinth) & Membranous labyrinth. |
| Where is the Membranous labyrinth located? What is it lined with? Where does the fluid come from? | Inside the osseous labyrinth (in the cochlea). With fluid & membranous lining that transmit sound. from the endolymph duct. |
| What passes through the Internal Acoustic Meatus (IAM)? | Auditory nerve & blood vessels. |
| Which of the middle ear structures is most lateral? | The Malleus (hammer). |
| What is the opening between the Epitympanic recess & the Mastoid portion of the temporal bone? | The aditus. |
| Which auditory ossicle attaches to the oval window? | Stapes (stirrups) |
| What is a benign, cyst-like mass of the middle ear? | Cholesteatoma |
| What are the 3 main parts of the middle ear? | Tympanic membrane (eardrum), Auditory ossicles & the Tympanic cavity. |
| What are the 2 parts of the tympanic cavity divided into? Where are they. | Tympanic cavity proper is inferior & epitympanic recess (attic) is superior. They are located in the middle ear. |
| Where is the Drum Crest or Spur located? | Attached to the tympanic membrane that separates the external acoustic meatus from epitympanic recess (attic) |
| For Stenver's view, what will semi circular canals appear as? Which 3 points should be on the IR? How is patient's head rotated? How much & which direction is CR angled? Where is CR centered? How does the affected petrous ridge position relate to the IR? | As a star. The forehead, nose & cheek. IOML perpendicular to front of IR, skull rotated 45 degrees from lateral. CR angled 12 degrees cephalic. Along the IOML & on the anterior aspect of the sideburns. The affected petrous ridge will be parallel to IR. |
| What is the Schuller method for the demonstrating Mastoids? | Patient skull positioned in a true lateral (affected side on IR) with CR angled 25 degrees caudad centered 1" posterior to the EAM. |
| What is the Law method for demonstrating the Mastoids? What does it do to the ossicles & mastoid air cells? | Patients skull rotated 15 degrees from lateral nose down, with the CR centered 1" posterior to EAM on side down. It elongates the ossicles & mastoid air cells. |
| Which projection puts the Mastoid tip (process) in profile? | Stenver's projection. |
| What is the Owen method? | Head is rotated 30 degrees (nose up) from lateral & a 30 degree caudad CR angle exiting at the Mastoid side down. |
| What is the Meyer method? What does it demonstrate? | head rotated 45 degrees with a 45 degree CR angle. Demonstrates the chain of connection between the ossicles. |
| Which projection will demonstrate petrous ridges at to the mid-orbital level? How much CR angle is used? | Modified PA caldwell with a 10 degree caudad angle to OML. |
| What is the large chamber within the mastoid portion that connects to the aditus? | The antrum |
| What is an Arcelin method for the petromastoid region? | A reverse Stenver's. Patient's head rotated 45 degrees, CR 12 degrees caudad centered 1" anterior & superior to TEA on side up |