Ear Flashcards
2 main functions of ear
equilibrium (balance) - vestibular system
hearing - cochlear system
external ear (pinna/auricle) structures
helix antihelix antitragus lobule (no cartilage) external acoustic meatus
external ear injury
Bleeding within the auricle resulting from trauma –> auricular hematoma
compromises blood supply to the cartilage. If untreated (by aspiration of blood) –> fibrosis –> deformed auricle (the cauliflower ear)
sensory innervation of external ear
auriculotemporal n. (V3): anterior helix, tragus
lesser occipital n. (C2)
greater auricular n. (C2, C3)
also CN VII and X (small contribution, overlap)
Arnold’s reflex
cough reflex initiated by stimulating CN X around external ear
auricular m.
superior auricular m.
anterior auricular m.
posterior auricular m.
supplied by motor br. CN VII (temporal br., posterior auricular br.)
blood supply to external ear
superficial temporal a.
posterior auricular a.
deep auricular a. –> pt of external acoustic meatus
venous drainage of external ear
superficial temporal v. –> __________
superficial temporal v. –> RETROMANDIBULAR V.
venous drainage of external ear
posterior auricular v. –> __________
posterior auricular v. –> EJV
posterior auricular + posterior retromandibular –> EJV
lymphatic drainage of lateral top half of external ear
to superficial parotid nodes
lymphatic drainage of medial top half of external ear
to mastoid nodes
lymphatic drainage of bottom of external ear
to superficial cervical nodes
external acoustic meatus has both a _____ and _____ portion
lined with skin containing which types of glands?
external acoustic meatus has both a CARTILAGINOUS and BONY portion
lined with skin containing SUBACEOUS and CERUMINOUS glands
tympanic membrane
separates external and middle ear
set in sulcus of temporal bone
oriented laterally, anteriorly, and inferiorly
captures changes in air pressure (sound) and transfers to bones of middle ear
otoscopic examination
Pull helix posterosuperiorly to straighten external acoustic meatus to view …
- tympanic membrane
- lateral process of malleus
- umbo (handle/manubrium of the malleus poking into the pars tensa)
- pars flaccida
- light reflex triangle radiates anteroinferiorly.
sensory innervation to lateral (external) surface of tympanic membrane
CN V3, VII, X
sensory innervation to medial surface of tympanic membrane
CN IX
sensory fibers from CN IX get to inner surface of ear via the
tympanic n. of Jacobsen
tegmen tympani
roof over middle ear
separates cranial and tympanic cavities
arcuate eminence
elevated area on petrous portion of temporal bone
overlays semicircular canals
middle ear bones (ossicles)
malleus
incus
stapes
(all 3 function in conduction of sound thru middle ear)
posterior process on head of malleus articulates w/ body of ____
posterior process on head of malleus articulates w/ body of INCUS
(ice cream scoop + cone)
tensor tympani m.
innervation/origin/insertion
V3
tendon inserts onto handle of malleus
originates off cartilaginous portion of pharyngotympanic tube and part of the sphenoid GW
lenticular process of incus articulates w/ ____
lenticular process of incus articulates w/ STAPES M.
stapedius
innervation/origin/insertion
CN VII
tendon inserts onto neck of stapes
originates off walls of pyramidal eminence
paralysis of stapes
xs acuteness of hearing (hyperacusis)
poss due to CN VII lesion
middle ear blood supply
anterior tympanic a. (off 1st pt. maxillary a.)
middle ear lymphatic drainage
superior deep cervical nodes
middle ear innervation
CN IX (sensory to INNER surface tympanic membrane)
some CN V, IX, X (rest of middle ear)
parasympathetic (CN VII)
membranous wall of middle ear
lateral
- tympanic membrane
- chorda tympani, passes over tensor tympani m.
segmental wall of middle ear
superior
- tegmen tympani
- epitympanic area
labyrinthine wall of middle ear
medial
- lateral semi-circular canal
- facial canal
- processus cochleariformis
- oval window (fenestra vestibuli)
- promontory
- round window (fenestra cochlea)
oval window
communication between middle and inner ear (into scala vestibuli of the cochlea)
base of stapes inserts onto here
on labyrinthine wall
promontory
right below oval window, on labyrinthine wall
1st basal turn of cochlea that bulges out into middle ear
has tympanic plexus (where tympanic n. of Jacobsen comes thru)
round window
secondary tympanic membrane, on labyrinthine wall
(blocked from scala tympani by a membrane)
alleviates pressure from oval window and stapes (oval membrane moves in –> round window moves out –> fluid moves into cochlea –> moves inner hair cells –> hearing)
jugular wall of middle ear
inferior
- jugular fossa (IJV runs past)
mastoid wall of middle ear
posterior
- facial n. runs thru
- aditus
- pyramidal eminence (encloses stapedius m.)