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Head And Neck Imaging > Temporal Bone > Flashcards

Temporal Bone Flashcards

1
Q

The adult temporal bone is made up of five bony parts. What are these parts?

A

Squamous, mastoid, petrous, tympanic, and styloid portions

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2
Q

What is the function of the squamous portion?

A

This functions as the bony floor of the adult suprazygomatic masticator space (i.e., temporal fossa) and the lateral wall of the middle cranial fossa

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3
Q

What are the three important landmarks of the mastoid portion?

A

Mastoid antrum

Aditus ad antrum (Latin for “entrance to cavity”)

Korner septum

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4
Q

What is the purpose of the aditus ad antrum?

A

It connects the epitympanum (i.e., attic) of the middle ear cavity to the mastoid antrum.

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5
Q

What is the Korner’s septum?

A

It is a part of the petrosquamosal suture that runs posterolaterally through the mastoid air cells.

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6
Q

What is the function of the Korner’s septum?

A

It acts as a barrier to extension of infection from the lateral mastoid air cells to the medial mastoid air cells.

It also functions as an important surgical landmark within the mastoid air cells.

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7
Q

The inner ear is contained within what portion of the temporal bone?

A

Petrous portion

It is often referred to as the petrous pyramid

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8
Q

What are the two important structures on the anteior surface of the petrous pyramid?

A

The tegmen tympani - roof or cover of the tympanic cavity

The arcuate eminence - bone prominence over the superior semicircular canal. This is a surgical landmark as the surgeon cuts along the floor of the middle cranial fossa.

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9
Q

The posterior surface of of the petrous portion of the temporal bone contains what structures?

A

The porus acusticus - opening (or “mouth”) of the internal auditory canal

Modiolus (Latin for “hub”) - which is the entrance to the cochlea through which the cochlear nerve passes, and the crista falciformis, which is the horizontal bony septum in the lateral 3 mm of the internal auditory canal

Vestibular aqueduct - transmits the endolymphatic duct and runs parallel to the line of the petrous ridge

Cochlear aqueduct - transmits the perilymphatic duct and located vertically below the internal auditory canal running parallel to it

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10
Q

What is the function of the inferior surface of the petrous temporal bone?

A

It helps to form the carotid canal and jugular foramen

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11
Q

The petrous apex is seperated from the clivus by what structures?

A

By the petrooccipital fissure and the foramen lacerum

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12
Q

This portion of the temporal bone is a U-shaped bone forming the majority of the adult bony external auditory canal.

A

Tympanic portion

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13
Q

This portion of the temporal bone forms the styloid process.

A

Styloid portion

Like the mastoid process, the styloid process develops after birth.

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14
Q

The medial border of the external auditory canal is form by what structure?

A

Tympanic membrane

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15
Q

This is the bony projection to which the tympanic membrane attaches superiorly; it attaches to the tympanic annulus inferiorly.

A

Scutum

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16
Q

This is an important landmark to determine if a lesion is in the external or middle ear.

A

Tympanic annulus

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17
Q

Where is the nodal drainage of the external auditory canal and adjacent scalp?

A

Parotid lymph nodes

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18
Q

What are the three distinct regions of the middle ear?

A

Epitympanum or attic

Mesotympanum or tympanic cavity proper

Hypotympanum

19
Q

What are the six important walls of the normal middle ear cavity?

A 
A. Anterior wall, or "carotid wall"
B. Posterior wall. or "mastoid wall"
C. Superior wall or tegment tympani
D. Inferior wall or "jugular wall
E. Lateral wall, or "membranous wal"
20
Q

The upper part of the posterior wall of the middle ear is absent. What connects the epitympanum to the mastoid antrum?

A

Aditus ad antrum

21
Q

The lower part of the mesotympanic portion of the posterior wall is comprised of three important structures. What are these structures?

A

Pyramidal eminice
Sinus tympani
Facial nerve recess

22
Q

This is the tympanic cavity above the line drawn between the inferior tip of the scutum and the tympanic portion of the facial nerve.

A

Epitympanum

23
Q

What are the contents of the epitympanum?

A

The malleus head and the body and short process of the incus.

24
Q

This is the area between the incus and the lateral, side wall of the epitymopanum.

A

Prussak’s space

25
Q

This is the tympanic cavity or cleft proper. It extends from the inferior tip of the scutum above the line drawn parallel to the inferior aspect of the bony external auditory canal.

A

Mesotympanum

26
Q

What are contents of the mesotympanum?

A

Remainder of the osscicles
- Manubrium of malleus, the long process of the incus, and the entire stapes

Two muscles of the middle ear
- Tensor tympani and stapedius muscle

27
Q

This is a shallow trough in the floor of the middle ear.

A

Hypotympanum

28
Q

What are the contents of the hypotympanum?

A

The hypotympanum contains no vital structure

29
Q

This region of the ear contains the membranous labyrinth, which is set within the bony labyrinth (i.e., otic capsule)

A

Inner ear

30
Q

The membranous labyrinth consists of what structures?

A 
Vestibule (i.e., utricle and saccule)
Semicircular channels
Endolymphatic duct
Cochlear duct
Multiple communicating channels
31
Q

The bony labyrinth forms what structures?

A

The cochlea, vestibule, semicircular canals, and both the vestibular and cochlear aqueducts

32
Q

The cochlea has approximately how many turns?

A

Two and one-half turns

The basal first turn and the apical second turn are readily visible on routine CT scansof the temporal bone.

The basal first turns opens posteriorly into the round window niche.

The entire cochlea encircles a central bony axis, also called the modiolus. The cochlear nerve enters the cochlea through the modiolus on its way to the multiple spiral ganglia.

33
Q

This is the largest part of the membranous labyrinth.

A

The vestibule

34
Q

It is the more cephalad portion of the vestibule.

A

The utricle

The saccule is the inferior part.

35
Q

The vestibule is separated laterally from the middle ear by what structure?

A

Oval window niche

36
Q

Superiorly, the vestibule leads to where?

A

Superior semicircular canal

37
Q

Medially, this structure separates the vestibule from the fundus of the internal auditory canal.

A

Lamina cribrosa

38
Q

The upper bony margin of the superior semicircular canal forms a convexity on the petrous pyramid roof, called what?

A

Arcuate eminence

39
Q

The midtympanic portion of the facial nerve passes along the undersurface of the what part of the semicircular canal?

A

Lateral semicircular canal

40
Q

The cochlear aqueduct contains what?

A

The perilymphatic duct

41
Q

This structure encompasses the endolymphatic duct.

A

The vestibular adqueduct

42
Q

What are the segments of the facial nerve within the temporal bone?

A

Cisternal segment: Facial nerve from brain stem to porus acusticus

Internal auditory canal segment: Facial nerve in the anterosuperior portion of the canal

Labyrinthine segment Short segment of facial nerve curling anteriorly over the top of the cochlea.

Tympanic segment Facial nerve from anterior genu to posterio genu.

Mastoid segment: Facial nerve from posterior genu to stylomastoid foramen

Parotid segment: Extracranial segment of the facial nerve

43
Q

What are the four major functions of the facial nerve that may be used to localized topographically a lesion along its course?

A

From central to peripheral:

  1. Lacrimation (via greater superficial petrosal nerve)
  2. Stapedius reflex - sound dampening
  3. Taste, anterior two thirds of the tongue (via chorda tympani to lingual nerve to oral tongue)
  4. Facial expression

Head And Neck Imaging (10 decks)

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