Disorders Of The Outer Ear

Front 1

helix

Back 1

outer, distal ridge of the pinna

Front 2

scaphoid fossa

Back 2

trough between the helix and antihelix

Front 3

antihelix

Back 3

second ridge in, moving proximally

Front 4

tragus

Back 4

cartilaginous projection extending posteriorly from the middle of the anterior margin of the pinna. Extends over the entrance to the EAM, can shut the eam with it.

Front 5

antitragus

Back 5

projection of cartilage, posterior and inferior to the tragus.

Front 6

lobule (lobe)

Back 6

no cartilage, just fat and connective tissue. serves no purpose.

Front 7

crura

Back 7

fork or extension. antihelix has two with the triangular fossa in between.

Front 8

crus of helix

Back 8

separates the concha into two sections.

Front 9

conch cymba

Back 9

part of concha, superior to crus of helix

Front 10

concha cava

Back 10

part of concha, inferior to crus, entryway to EAM

Front 11

microtia and anotia

Back 11

small underdeveloped pinna/ no pinna (can also indicate problem in EAM). often seen with stenosis or atresia of the ear canal, which does affect hearing.

Front 12

protrusion

Back 12

ears that stick out. can be fixed with otoplasty, but seldom done in children because scar tissue does not grow in the same way that normal tissue does.

Front 13

auricular deformities

Back 13

pinna is deformed due to failure to develop at various stages of gestation

Front 14

EAM

Back 14

(ear canal) 7 mm in diameter, 25-35 mm in length. elongated S on it's side that provides insulation and protection.

Front 15

lateral 1/3 of EAM

Back 15

lateral 1/3 cartilaginous, covered with epithelial cells, many having cilia. sabecous glands produce oil and ceruminous glands produce cerumen. innervated by CN V: trigeminal.

Front 16

medial 2/3 of EAM

Back 16

osseus portion, surrounded by temporal bone, canal narrows at juncture of cartilagious and osseus portions
no cilia, or glands
innervated by CN X (vagus) also controls cough reflex.
no lining btw epithelium and bone. skin is thin 1/10mm, and has many pain sensors and blood vessels.

Front 17

cerumen

Back 17

production is normal, natural and necessary. traps insects and dirt, which is swept outward by cilia to entrance of EAM where it dries and falls out. impacted cerumen occurs when you produce it faster than cilia can sweep it out.

Front 18

tympanic membrane

Back 18

concave medial boundary of the outer ear. converts acoustic to mechanical energy.
55mm2 in area, 10mm in diameter, 55 degree angle to floor of EAM
three layers:external (continuation of epithelial lining of the EAM), middle (fibrous and tough, circular and radial fibers), inner (continuation of mucous membrane lining of the middle ear). very rich in blood supply, size of pinky nail

Front 19

TM landmarks

Back 19

pars tensa: 4/5 of TM, held taut and pulled medially by manubrium of malleus (points to left in left ear, and right in right ear)
umbo: inferior end of the manubrium, most medial pt.
cone of light: always in anterior/inferior quadrant in normal TM
pars flaccida: sup/ant 1/5 of TM, no fibrous layer. inferior border is the lateral process of malleus and the ant/post malleolar folds

Front 20

atresia

Back 20

lack of EAM. Treacher-Collins syndrome. not always treatable with surgery, requires a bc hearing aid or a bone anchored hearing aid (BAHA)

Front 21

stenosis

Back 21

narrowing of the EAM. does not cause HL by itself, but can cause ear wax build up and is common in down syndrome.

Front 22

foreign bodies

Back 22

disorder of EAM. canal narrows at the osseocartilaginous junction. HL is not the main problem, infection is.

Front 23

external otitis

Back 23

swimmer's ear. may be bacterial or fungal. can cause extreme pain and foul smelling discharge. can spread to the TM (myringitis) causing some HL.

Front 24

osteomas

Back 24

bony tumors that grow in the medial, osseus portion of the EAM. may be benign or malignant. cause hearing problems only is they completely close the canal.

Front 25

exostoses

Back 25

grow in the EAM. look like osteomas but are bony projections, not tumors. surfer's ear-swimming in cold water. completely benign.

Front 26

cerumen occlusion

Back 26

overactive cerumenous glands and/or incorrect removal techniques that push the wax into the bony portion (o.c. junction) of the canal where cilia can't remove it.

Front 27

ways to remove ear wax

Back 27

cerumenolytic, such as peroxide, dissolves it.
irrigation
suction
curettage
degree of HL depends on the amount of occlusion.

Front 28

manubrium

Back 28

the handle of the malleus is imbedded in the fibrous middle layer of the TM, inclining toward the front of the head.

Front 29

TM perforation

Back 29

caused by pressure build up (from fluid in the ME bulging the TM out), infection eating through TM, insertion of objects into ear canal, sudden pressure change. when healed can leave a weak spot in the firous layer. almost always causes HL but HL is not proportional to the size of the perforation.

Front 30

tympanoslerosis

Back 30

thickening of TM, calcium plaques. result of frequent perforations or ear surgeries and may or may not cause HL.