Chapter 127: Anatomy of the Temporal Bone, External Ear, and Middle Ear

Question 1

Temporal bone articulates with

Answer 1

1. sphenoid
2. parietal
3. occipital
4. zygomatic

Question 2

Temporal bone consists of four embryologically distinct components

Answer 2

1. squamous
2. mastoid
3. petrous
4. tympanic

Question 3

Forms the lateral wall of the middle fossa

Answer 3

Squamous

Question 4

It consists of a plate of bone with an anterior extension known as the zygomatic process

Answer 4

Squamous

Question 5

Formed along the most inferior insertion by the temporalis muscle; it is aligned with the zygomatic process and is used as
a surface landmark to estimate the location of the middle fossa
floor

Answer 5

Horizontal ridge/temporal line

Question 6

Average offset of temporal line

Answer 6

4.7 mm

Question 7

Bulbous bony structure shaped by the expansion of air-filled spaces within

Answer 7

Mastoid

Question 8

Constant pull by the sternocleidomastoid (SCM) and posterior belly of the digastric muscles elongates the mastoid inferiorly to form the

Answer 8

Mastoid tip/mastoid process

Question 9

A funnel-shaped cartilaginous structure that is continuous with the meatus and the EAC

Answer 9

Auricle

Question 10

The blood supply of the external ear originates from the

Answer 10

External division of the carotid artery via the posterior auricular and superficial temporal vessels

Question 11

External auditory canal is about

Answer 11

2.5 cm in length

Comprises a lateral cartilaginous (lateral 3rd) portion and a medial bony (medial 2/3) portion

Question 12

Skin that lines the membranous canal

Answer 12

Thicker and more mobile

Endowed with sebaceous and apocrine (ceruminous) glands and hair follicles

Question 13

Bony portion of the canal is lined by

Answer 13

Thin, immobile skin that lacks hair and glands and is continuous with the epithelium of the tympanic membrane

Question 14

Narrowest portion of EAC

Answer 14

Bony-cartilaginous junction/isthmus

Question 15

Site at which underlying osteomyelitis will manifest as mounds
of granulation tissue in the EAC, a finding pathognomonic for
malignant otitis externa

Answer 15

Bony-cartilaginous junction

Question 16

Incomplete ossification of the anterior bony canal produces an opening into the infratemporal region

Answer 16

Foramen of Huschke

Question 17

Serve as a means for extension of malignant tumors from the

EAC to the deep lobe of the parotid gland

Answer 17

Foramen of Huschke

Question 18

Naturally occurring defects in the cartilaginous portion of the EAC

Answer 18

Fissures of Santorini

Question 19

Provide avenues of spread to the superficial lobe of the gland

Answer 19

Fissures of Santorini

Question 20

True of False
The external ear is developed from ectodermal and mesodermal components of the first and second branchial arches and the intervening first branchial groove

Answer 20

True

Question 21

Distinct condensations of tissue that give rise to the tragus and most of the helix, antihelix, antitragus, and lobule and the inferior helix

Answer 21

Hillocks of His

Question 22

Ttragus and most of the helix

Answer 22

First branchial arch

Question 23

Antihelix, antitragus, and lobule and the inferior helix

Answer 23

Second branchial arch

Question 24

Sensory innervation to the external ear is provided by

Answer 24

1. first branchial nerve
2. auriculotemporal branch of the trigeminal nerve
3. cutaneous branch of the facial nerve

Question 25

True or False
EAC develops from the dorsal portion of the first branchial cleft, which extends toward and eventually makes contact with endoderm of the expanding tubotympanic recess

Answer 25

True