External Ear Flashcards
how can the external ear be divided?
auricle/pinna
external acoustic meatus
where does the external acoustic meatus end?
tympanic membrane
what is the auricle and what is its function?
- paired struture that is found on either side of the head
- functions to capture and direct sound waves towards EAM
what is the concha?
hollow depression in the middle of the auricle that continues into the skull as the external acoustic meatus
what is the role of the concha?
directs sound into the EAM
auricular haematoma
a collection of blood between the cartilage of the ear and the overlying perichondrium, usually as a result of trauma
how can auricular haematoma result in cauliflower ear?
- accumulation of clood can disrupt blood suplly to the cartilage
- if untreated, avascular necrosis of cartilage can occur
where does the external acoustic meatus extend?
from the deep part of the concha to the tympanic membrane
the walls of the external 1/3 of the external acoustic meatus are formed from what? what about the inner 2/3?
external 1/3 - cartilage
inner 2/3 - temporal bone
describe the path of the external acoustic meatus:
s-shaped curve:
* superoanterior direction
* turns and travels superoposteriorly
* ends by running inferoanterior
what lies at the distal end of the external acoustic meatus?
tympanic membrane
what is on the outside of the tympanic membrane? what is on the inside?
outside - skin
inside - mucous membrane
how is the tympanic membrane connected to the surrounding temporal bone?
fibrocartilaginous ring
how can the structures of the middle ear be observed during otoscopy, if the tympanic membrane sits in front of them?
tympanic membrane is translucent
what occurs at the umbo of the tympanic membrane?
handle of the malleus attaches to the tympanic membrane
what branches of the external carotid artery supply the external ear?
there are 4
- posterior auricular artery
- superficial temproal artery
- occipital artery
- maxillary artery - deep EAM and tympanic membrane only
describe the sensory innervation of the external ear:
list 4
- greater auricular nerve - skin of auricle
- lesser occipital nerve - skin of auricle
- auriculotemporal nerve - skin of auricle and EAM
- branches of facial and vagus nerves - deeper aspects
why do some people complain of an involuntary cough when cleaning their ears?
- auricular branch of vagus nerve is stimulated
- responsible for the cough refex
what is the lymphatic drainage of the external ear?
superficial parotid, mastoid, upper deep cervical and superficial cervical nodes
Label the auricle
Label the tympanic membrane
