Special Senses hearing Flashcards
conducts soundsto tympanic memb
External acoustic meatus
collects sounds
Auricle
Consists of single elastic cartilage which is continuous w/ cartilage of ext acoustic meatusContains hair,sweat/sebaceous glands
Auricle
no cartilage, can be pierced for earring
Lobule
External acoustic meatus extend from concha to
Tympanic membrane
External Acoustic Meatus
S shape 2.5 cm long
External Acoustic Meatus
Composition
Lateral/3 = cartilage
-Medial 2/3 = bony
Infants
Pure cartilage
External Acoustic MeatusLateral partLined w/ skinContents
Hair follicles
Sebaceous gl
Ceruminous gl
•prod cerumen
External medial part
Lined w/ thin skin
Isthmus= constricted part
External Acoustic Meatus>Arterial supply
1] Post auricular branch of external carotid artery
2] Deep auricular branch ofmaxillary artery
3] Auricular br of superficial temporal artery
External acoustic meatus venous drainage
1] External jugular vein
2] Maxillary vein
3] Pterygoid plexus
External Acoustic MeatusNerve supply
1] Auriculotempral n fr CN V
2] Tympanic plexus fr CN VII
3] Auricular branch fr CN X
When doing otoscopic exam, know the
Anatomy of external acoustic meatus
Pull the ear
Superiorly
Posteriorly
Laterally
Thin, semitransparent,oval membrane
Medial end of EAM
Separates external from middle ear
Tymphanic membrane
Tympanic membrane
Oblique and slopes inferomedially
Pearly gray and shiny
Fr umbo, bright area emanates called
Cone of light
Vibrations are transmitted from TM by auditory ossicles through the
Middle ear to internal ear
Concavity toward the meatus w/ a central depression, umbo, formed by handle of malleus
Tympanic membrane
Tympanic MembraneArterial Supply
Maxillary artery
Deep auricular a -Posterior auricular a-Tympanic branch
Tympanic membrane venous drainage
External jugular vein
Tympanic membrane nerve supply
Auriculotemporal n [CN V3
Deafness-Etiology:> Foreign Bodies> Infection> Excessive Pressure as in scuba diving
Perforation of TM
During PE of tympanic membrane pull the auricle
Superiorly
Posteriorly
Laterally
Narrow cavity in petrous part of temporal bone
Middle ear
Middle ear contents
Auditory ossiscles
Stapedius
Tensor tympani
Chorda tympani n
Middle ear connections anterior
Nasopharynx
Middle ear connections, postero superior
Mastoid antrum
formed by tegmen tympani
-separates ME fr dura
Roof or tegmental
formed by bone
-sep ME fr int jugular vein
Floor or jugular
formed by tymp membr
Lateral or membranous
Semicircular ducts and cochlea
-sep ME from inner ear-2 small windows
Medial or labirynthine
closed by base of stapes
-through this window, vibrations of stapes are transmitted to inner ear
Fenestra vestibuli
closed by a secondary TM
-allows perilymph to move in response to impulses
Fenestra cochlea
leads to mastoid antrum via an opening, aditus
Posterior or mastoid
pyramidal eminence contains the stapedius mm
Posterior or mastoid
Interior or Carotid wall2 openings w/c connects
1] w/ canal occupied by tensor tympani
2] w/ nasopharynx thru auditory tube
Funnel shaped
Connects NP to middle ear
Auditory tube
Auditory tube measurement
3.5 to 4.0 cm long
1/3 bone, 2/3 cartilage
Auditory tube Equalize pressure in middle ear w/
ATM pressure
Auditory tube arterial supply
1]Ascending pharyngeal a
2]middle meningeal art
3] artery of pterygoid canal