Final Exam- Unit VIII-- Ears Flashcards
What does the ear embryologically develop from?
ectodermal thickening on later “head” called the placode
What is the ectodermal thickening on the lateral “head” that the ear develops from called?
placode
What will the placode do and what will it give rise to?
it invaginates–> gives rise to auditory pit, and then the auditory vesicle
What does the Auditory Vesicle give rise to most of?
the membranous inner ear
What are the auditory tube and tympanic cavity derived from?
first pharyngeal pouch
What is the malleus derived from?
the dorsal end of the ventral mandibular carilage
What is the incus derived from?
dorsal end of the first pharyngeal arch
What is the stapes derived from?
dorsal end of the second pharyngeal arch
What does the tympanic membrane develop from?
interstitial mesoderm
What does the external acoustic canal develop from?
first pharyngeal groove
What does the auricle develop from?
a groove next to the first pharyngeal groove
What three areas does the ear consists of?
- external portion
- middle portion
- inner portion
What two things does the external ear include?
- auricle
2. external acoustic meatus
What is another name for auricle? What does it serve to do?
pinna
a horn-like structure that serves to funnel sound waves into the external acoustic meatus
What is the auricle composed of?
cartilage
What are the landmarks of the Auricle?
- helix
- antihelix
- scaphoid fossa
- triangular fossa
- concha of the auricle
- tragus
- antitragus
- intertragic notch
- lobule
What are the three extrinsic muscles that position the auricle? Which is the smallest? Which is the largest?
- anterior auricular muscle–> smallest
- superior auricular muscle–> largest
- posterior auricular muscle
(if have “auricular” in name = extrinsic muscle)
Is the anterior auricular muscle an extrinsic or intrinsic muscle?
extrinsic muscle
Is the superior auricular muscle an extrinsic or intrinsic muscle?
extrinsic muscle
Is the posterior auricular muscle an extrinsic or intrinsic muscle?
extrinsic muscle
What are the 6 intrinsic muscle of the ear?
- helicis major
- helicis minor
- tragicus
- antitragicus
- transverse muscle of the auricle
- oblique muscle of the auricle
How long is the external acoustic meatus? What is it shaped like? What is the medial 2/3 within?
about 1 inch in length; “S” shaped; medial 2/3 is w/in temporal bone
What is the external acoustic meatus covered in? What type of glands does it contain and what do they produce?
covered by skin
contains Modified sweat glands that produce cerumen (ear wax) = ceruminous glands
Where does the external acoustic meatus terminate?
at the tympanic membrane
Since the external acoustic canal is not straight (it is shaped like an “S”) how is otoscopic examination made possible?
gently pulling out, down, and forward on the lobule
What three vessels provide the blood supply to the external ear? What are they branches of?
- Posterior auricular branch of the external carotid artery
- Anterior auricular branch of the superficial temporal artery
- Auricular branch from the occipital artery
What types of nerve supply does the external ear receive?
- Sensory
- Motor
- Sympathetic
(no parasympathetic)