Temporal Bone

Front 1

5 bony parts that make the Temporal Bone

Back 1

Squamous
Mastoid
Petrous
Tympanic
Styloid

Front 2

Mastoid Portion of temporal bone
(name three important anatomic landmarks)

Back 2

Mastoid Antrum
Adidis ad antrum
Korner's Septum

Front 3

Adidus ad antrum is latin for

Back 3

Entrance to the cavity

Front 4

What does the adidis ad antrum do?

Back 4

Connects the epitympanum of the middle ear cavity to the mastoid antrum

Front 5

What is Korner's Septum?

Back 5

Part of the petrosquamosal suture that runs posterolaterally through the mastoid air cells.

Front 6

What is function of Korner's Septum?

Back 6

- Services as barrier to the extension of infection from the lateral mastoid air cells to the medial mastoid air cells
- Also serves an an important surgical landmark within the mastoid air cells

Front 7

Which portion of the temporal bone is the inner ear(otic capsule)?

Back 7

Petrous portion - often referred to as the petrous pyramid because it is shaped like a pyramid with anterior, posterior, and inferior structures

Front 8

Two important structures on the anterior surface of anterior surface of the petrous pyramid?

Back 8

Tegman tympani - roof or cover of the tympanic cavity
Arcuate eminence - the bone prominence over the superior semicircular canal(its a surgical landmark as the surgeon cuts along the floor of the middle cranial fossa)

Front 9

Posterior surface of the petrous portion of the temporal bones contain _____?

Back 9

Porus acusticus
Vestibular aqueducts
Cochlea aqueducts

Front 10

What is the porus acusticus?

Back 10

Opening or mouth of the internal auditory canal

Front 11

What is the modiolus?

Back 11

The entrance to the cochlea through which the cochlear nerve passes

Front 12

What is the crista falciformis?

Back 12

The horizontal bony septum in the lateral 3 mm of the internal auditory canal fundus

Front 13

Vestibular Aqueduct transmit endolymphatic duct or perilymphatic duct?

Back 13

Endolymphatic duct and runs parallel to the petrous ridge

Front 14

Cochlear Aqueduct transmits endolympatic duct or perilympatic duct?

Back 14

Perilymphatic duct and is located vertically below the IAC running parallel to it.

Front 15

What is the petrous apx separated from the clivus by?

Back 15

Petrooccipital fissure and foramen lacerum.

Front 16

What forms the medial border of the EAC?

Back 16

Tympanic Membrane

Front 17

Where does the tympanic membrane attach superiorly and inferiorly?

Back 17

Superiorly - at the scutum
Inferiorly - at the tympanic annulus
(see coronal figure 12-2 p 430 in Handbook of head and neck imaging)

Front 18

The tympanic annulus serves as an important coronal CT landmark to determine if the lesion is _______?

Back 18

In the external or middle ear.

Front 19

Where does the external auditory canal and adjacent scalp drain and why is it important?

Back 19

Parotid lymp nodes, because when evaluating a parotid mass, it may represent nodal mets from an EAC squamous cell carcinoma or melanoma

Front 20

Three distinct regions of the middle ear are?

Back 20

Epitympanum
Mesotympanum(or tympanic cavity proper)
Hypotympanum

Front 21

The posterior wall of the mesotympanum has three important structures, what are they (Figure 17-1 p 429 Head and Neck)

Back 21

1. Pyramidal eminence
2. Sinus Tympani
3. Facial nerve Recess

Front 22

What does the Pyramidal eminence contain?

Back 22

The belly and tendon of the Stapedius muscle.

Front 23

What is significant about the sinus tympani?

Back 23

It's a clinical blind spot during a standard mastoid surgical approach to the temporal bone.
Cholesteatoma can hide hear as a result.

Front 24

What does the facial nerve recess contain?

Back 24

The descending facial nerve, either dehiscent or with a bony cover.

Front 25

The Superior wall of the middle ear cavity is also known as?

Back 25

Tegman tympani

Front 26

Clinical significance of tegman tympani?

Back 26

Loss of this bony separation can lead to leptomeningeal or brain parenchymal involvement with infection or tumor

Front 27

Inferior wall of the middle ear cavity is also known as ____?

Back 27

"jugular wall"

Front 28

Inferior wall(jugular wall), what is it and describe the normal variant a surgeon must know?

Back 28

- The bony plate that separates the middle ear cavity from the jugular bulb and be normally dehiscent(ie dehicent jugular bulb)
- Should be noted so that surgeon can ovoid a protuberent vein

Front 29

The lateral wall of the middle ear cavity is also known as?

Back 29

"membranous wall"

Front 30

What forms the lateral wall of the middle ear cavity?

Back 30

The tympanic membrane, slopes inferomedially from the scutum attachment to the tympanic annulus

Front 31

Definittion of epitympanum?

Back 31

The tympanic cavity above the line drawn between the inferior tip of the scutum and the tympanic portion of the facial nerve

Front 32

Contents of the epitympanum?

Back 32

malleus head
body and short process of the incus
Prussak's space

Front 33

What is the most common site for the pars flaccida cholesteatoma?

Back 33

Prussak's space - in area beween the incus and lateral side wall of the epitympanum

Front 34

What are the remainder of the ossicles in the mesotympanum?

Back 34

manubrium of malleus
long process of the incus
entire stapes

Front 35

What two muscle s of middle ear are in the mesotympanum?

Back 35

Tensor tympani
Stapedius

Front 36

Tensor tympani is innervated by?

Back 36

Cranial nerve V3

Front 37

Where is the tensor tympani located?

Back 37

in an anterior bony canal above the osseus eustachian tube

Front 38

Stapedius muscle is innervated by?

Back 38

Facial nerve

Front 39

Where is the stapedius muscle?

Back 39

It is contained within the pyramidal eminence, with its tendon reaching from the tip of the pyramidal eminence to the posterior surface of the head of the stapes

Front 40

What is the central bony axis that the entire cochlea encircles?

Back 40

Modiolus

Front 41

Subunits of the vestibule

Back 41

Utricle and saccule

Front 42

Utricle vs. saccule

Back 42

Utricle - more cephalad portion of the vestibule
Saccule - inferior part of the vestibule

Front 43

The vestibule is separated laterally from the middle ear by ____?

Back 43

The oval window niche.

Front 44

What is the arcuate eminence?

Back 44

The upper bony margin of the superior semicircular canal that forms a convexity on the petrous pyramid roof

Front 45

The lateral semicircular canal is also known as ?

Back 45

Horizontal

Front 46

What is significant about the lateral semicircular canal and a typical epitympanic cholesteatoma?

Back 46

the canal just into the epitympanum and as a result a cholesteatoma has a propensity to fistulize the membranous labyrinth by eroding the lateral cortex of the lateral semicircular canal

Front 47

Where is the midtympanic portion of the facial nerve related to the lateral semicircular canal?

Back 47

Pass along the undersurface of the lateral semicircular canal.

Front 48

What does the cochlear aqueduct(perilymphatic) run parallel to?

Back 48

The IAC, it can be mistaken for that.

Front 49

Three segments of the facial nerve within the tympanic bone?

Back 49

Labyrinthine segment
Tympanic segment
Mastoid segment

Front 50

Where does the labyrinthine segment of the facial nerve terminate?

Back 50

in the anterior genu (ie geniculate ganglion)

Front 51

Describe the tympanic segment of the facial nerve?

Back 51

The facial nerve from the anterior genu(geniculate ganglion) to the posterior genu

Front 52

Describe the mastoid segment of the facial nerve?

Back 52

The facial nerve from the posteior genu to the stylomastoid foramen

Front 53

Function of the facial nerve in the parotid segment?

Back 53

The extracranial segment of the facial nerve that divides the parotid gland into superficial and deep lobes

Front 54

Four functions of the facial nerve that may be used to localize a lesion along its course?

Back 54

1. Lacrimation
2. Stapedius reflex
3. Taste, anterior 2/3 of tongue
4. Facial expression

Front 55

What branch of facial nerve is responsible for lacrimation?

Back 55

The greater superficial petrosal nerve

Front 56

What does the stapedius reflex do?

Back 56

Sound dampening

Front 57

What branch of facial nerve provides taste?

Back 57

via chorda tympani nerve to lingual nerve to oral tongue

Front 58

If cranial nerve VI is also involved with VII, where is lesion?

Back 58

brainstem - VII circles the VI nerve nucles on its way out of the brainstem

Front 59

The external and middle ear are derived from embryologically?

Back 59

From the first and second branchial cleft apparatus(usually develop separate from inner ear)

Front 60

What is associated in EAC atresia that is critical to mention before surgery?

Back 60

Ectopic nerve VII, it is usually out of place and includes the posterior tympanic and mastoid semgents, need to know because surgical creation of a new EAC will result in facial nerve paralysis

Front 61

Conductive hearing loss in a child with no history of inflammatory ear disease suggests a ___________?

Back 61

Congenital cholesteatoma

Front 62

Where do congenital cholesteatomas arise from?

Back 62

aberrant epithelial rests

Front 63

An aberrant ICA may be mistaken by the surgery as a?

Back 63

paraganglioma, surgeon may want to biopsy this and it is disastrous!

Front 64

Describe the pathogenesis of an acquired cholesteatoma?

Back 64

- Occurs within the middle ear cavity and results from ingrowth of squamous epithelium through the eardrum
- the accumulation of squamous and keratin debris within the middle ear prduces a mass efect that erodes the bony walls and ossicles.

Front 65

Two typical locations for cholesteatomas?

Back 65

1. Pars flaccida (prussak's space)
2. Pars tensa

Front 66

All complications of cholesteatomas are related to ___________?

Back 66

Bony erosion

Front 67

Otoscopic examination reveals a "blue (vascular) tympanic membrane" in the absence of a pulsatile tinnitus when the lesion is in the middle ear>

Back 67

Cholesterol granuloma

Front 68

Mondini malformation?

Back 68

When the primary lesion on CT shows the lss of the normal two and one-half turns of the cochlea

Front 69

What part of the ossicles is most weakest and most susceptible to injury?

Back 69

Incudostapedial joint