HNNS Anatomy - Ear Flashcards
Blood supply, Nerve and Lymphatic supply of External ear.
Blood = Posterior auricular a. + Superficial temporal a./ External jugular vein
Nerve = Auriculotemporal nerve (v3) + CN7 + CN10
Lymph = superficial cervical LN (along EJV)
Structure of external ear.
Outer 1/3 = cartilage
Innfer 2/3 = Temporal bone
Anterior and posterior connection of the middle ear. Medial and lateral connection?
Anterior = Auditory tube and nasopharynx
Posterior = mastoid antrum + mastoid air cells
Medial = inner ear (cochlea + semicircular canal)
Lateral = external acoustic meatus
List ossicle bones and connection for impedance matching.
Malleus
Incus
Stapes
Malleus = attached to tympanic membrane Stapes = attached to Small fenestra vestibuli
List the vital structures on the medial wall of the tympanic cavity?
- Promontory + tympanic plexus + Lesser petrosal nerve
- Geniculate ganglion + facial nerve + Chorda tympani
- Fenestra cochleae + Fenestra vestibuli
Name the muscle that attaches to the malleus.
Tensor tympani muscle at anterior wall of tympanic cavity
List 2 muscles that open the eustachian tube.
Tensor veli palatini and Levator veli palatini
Describe the opening of the auditory tube at the anterior wall of the tympanic cavity.
Cartilage superiorly and posteriorly = Tubal Eminence
Muscle at the posterior wall of tympanic cavity?
Stapedius: attached to pyramid (bony spike) at posterior wall»_space; neck of stapes ossicle bone
Define location of Mastoid antrum
Petrous part of temporal bone
Below posterior cranial fossa
Clinical significance of stylomastoid foramen at posterior wall of tympanic cavity?
Facial nerve exits here, very superficial at birth
Prone to damage in Assisted Forceps Delivery
2 muscles for middle ear reflex.
Stapedius (CN7) Tensor tympani (V3)
Name and location of roof of tympanic cavity?
Name = tegmen tympani
Location = Below middle cranial fossa and temporal bone
List 2 important features beneath the floor of tympanic cavity.
Carotid canal (anterior to floor) + Internal carotid artery Jugular foramen ( postero-inferior) + Internal Jugular vein
Landmark for surgical drainage of mastoid antrum by drilling.
Suprameatal triangle
Above and posterior to external acoustic meatus
Structure of Auditory tube.
Anteromedial 2/3 = cartilage, mucosa = respiratory epithelium, lots of mucous glands
Postero-lateral 1/3 = Petrous temporal bone
Arterial supply of auditory tube?
Ascending pharyngeal arteries + Middle meningeal arteries (through foramen spinosum)
Venous drainage of auditory tube.
Pterygoid venous plexus
Function of eustachian tube opening?
Air inside always absorbed by blood vessels
Soft palate elevation = open tube = air in pharynx replace absorbed air
Middle ear A/V/N Lymph supply?
CN9»_space; tympanic plexus
ECA
Perygoid plexus
Superior cervical LN
Function of mastoid antrum.
Regulate temp. and pressure of middle ear
Route of spread of otitis media to cranial fossa?
Through thin roof - Tegmen tympani
Erode through bone to middle cranial fossa
Trace the course of CN9 through tympanic cavity to supply parotid gland.
Enter at floor via Tympanic canaliculus >> Tympanic plexus at medial wall >> Lesser petrosal nerve to Anterior wall >> Foramen ovale >> Otic ganglion >> Auriculotemporal nerve >> Parotid gland
Trace the course of CN7 through tympanic cavity to supply Ant. 2/3 tongue sepcial sensory.
Facial nerve through Internal acoustic meatus
» Geniculate ganglion at medial wall
» Chorda tympani route through Posterior + Anterior wall
» Lingual nerve (V3)
» Ant 2/ tongue
Trace the course of CN7 to form vidian nerve at pterygoid canal.
Medial wall of tympanic cavity >> CN7 >> Greater petrosal nerve >> Foramen lacerum* >> Join with Deep petrosal nerve >> vidian nerve
