7. External ear (lecture) Flashcards
function of ear?
organ of hearing and balance (equilibrium)
what are the different parts of the ear?
external, middle and inner ear
what can symptoms of ear disease include?
pain (otalgia) discharge hearing loss (conductive VS sensorineural) tinnitus vertigo facial palsy
which bone of the skull is the ear in?
temporal
what does the external ear consist of?
pinna (auricle)
external auditory (acoustic) meatus
lateral surface of tympanic membrane
what happens if the antihelix is damaged?
the ear becomes more protrude (ears stick out more)
what is the lobule of the ear?
no cartilage, full of fat
which sections of the ear contains least fat?
sections of most curvature - skin closest to cartilage
why is the auricle shaped the way it is?
to help funnel sound to EAM
what are the different types of abnormalities of the pinna?
congenital
inflammatory
traumatic
infective
what is an infective cause of abnormality of pinna of ear?
virus affecting sensory ganglion of the facial nerve - gives rise to vesicles around the external ear
(facial nerve palsy)
aside from facial nerve palsy, what is another infective cause of abnormality of pinna of ear?
Ramsay-Hunt syndrome
shingles of the facial nerve (VII)
how does pinna haematoma arise?
secondary to blunt injury to the pinna
common in contact sports
what happens during pinna haematoma?
accumulation of blood between cartilage and perichondrium
what does accumulation of blood between cartilage and perichondrium lead to?
deprives cartilage of its blood supply –> pressure necrosis of tissue
what is the treatment for pinna haematoma?
prompt drainage,
measures to prevent re-accumulation and re-apposition of two layers
what happens in pinna haematoma? (pathophysiology)
shearing of skin over elastic cartilage
skin pulls with it the perichondrium (away from underlying cartilage)
blood accumulates between perichondrium and cartilage
what does untreated or poorly treated pinna haematoma lead to?
fibrosis and new asymmetrical cartilage development - ‘cauliflower ear’
what is the external acoustic meatus?
ear canal
a skin-lined cul-de-sac
what shape is the external acoustic meatus?
sigmoid shape
need to pull ear up and back to straighten EAM when examining
what is the composition of the EAM?
cartilaginous (outer 1/3) bony part (inner 2/3)
what function does the EAM have?
self-cleaning function, to keep ‘pathway’ clear
how does EAM carry out self-cleaning function?
the arrangement of hairs and production of wax (within cartilaginous part):
- prevents objects entering deeper into ear canal
- aid in desquamation (shed skin) and skin migration out of canal
what is wax?
old and dying epithelial cells that have shed (desquamation) with the sticky secretions from skin cells within EAM
