The Auditory System Flashcards
What is the external ear made up of
Pinna (auricle)
External auditory meatus
Tympanic membrane
What does the external ear do
Conducts sound waves to middle ear
What is the middle ear made up of
Tympanic cavity
Ossicles (malleus, incus, stapes) -small bones
What does the middle ear do
Conducts sound waves to inner ear
What is the inner ear made up of
Cochlear and vestibular system
Vestibulocochlear nerve
What does the inner ear do
Hearing and equilibrium (balance)
How is the pinna Innervated
Mandibular trivision of the trigeminal nerve and cervical nerve 2+3
What is the pinna
External ear
Elastic cartilage covered with skin
Sound waves pass into the eternal auditory meatus
What 3 parts of the external ear helps to funnel sounds into the ear canal
Tragus, helix and concha
How is the external auditory meatus (ear canal) Innervated
Auriculotemporal nerve and the vagus nerve
External auditory meatus
-canal that conducts sounds to the tympanic membrane
-2-3cm long
-cartilaginous lateral third
-skin continuous with skin of pinna
-skin is continuous with external layer of tympanic membrane which is at the distal end of external auditory meatus
Does the external auditory meatus have a slight s bend true or false
True and it needs to be straightened in order to use an otoscope
What produces cérumen (earwax)
Sebaceous and ceruminous glands
What is the tympanic membrane
External ear
Ear drum
What is the tympanic membrane (eardrum)
-oval thin and semi transparent membrane
-1cm diameter
-mucous membrane internally (columnar epithelium)
-laterally concave
What does the tympanic membrane seperate
External auditory meatus form the tympanic cavity
Where does the tympanic membrane conduct sound waves to
Auditory ossicles
The tympanic membrane is covered with skin externally. What kind of tissue is this
Stratified squamous epithelium
How is the central Umbro formed
Handle of malleus
What kinds of fibres does the Tense part inferior to lateral handle of malleus have
Has radial and circular fibres
What kind of fibres does the flaccid part superior to handle of malleus (eardrum) have
Thin and lacks fibres
How is the tympanic membrane Innervated
Glossopharyngeal nerve
What are the two parts of the tympanic cavity
- tympanic cavity proper medial to the tympanic membrane
-epitympanic recess supero- medial to the tympanic membrane
What does the tympanic cavity contain
-the auditory ossicles (malleus, incus, stapes)
-tensor tympani and stapedius muscles
-chords tympani (branch of the facial nerve)
-tympanic nerve plexus
What is the tympanic cavity in communication with
The nasopharynx via the Eustachian tube
The mastoid air cells vis the aditus and mastoid antrum
What part of the ear is the tympanic cavity
Middle ear
Tympanic cavity walls
-tegmetal wall
-jugular wall
-membranous wall
-labryinthine wall
-mastoid wall
-carotid wall
Tegmetal wall
Roof
-formed by Tegan tympani, a thin plate of bone
-seperates tympanic cavity from middle cranial fossa and brain
Jugular wall
Floor
-formed from bone
-seperates tympanic cavity from superior bulb of internal jugular vein
Membranous wall
Lateral wall
-formed from tympanic membrane and lateral bony wall of epitympanic recess
-seperates tymapnic cavity from external ear
Labryinthine wall
Medial wall
-formed from lateral wall of vestibule (including oval window) and initial turn (including round window) of the cochlear
-seperates tympanic cavity from inner ear
Mastoid wall
Posterior wall
-aditus links tympanic cavity to the antrum which in turn communicates with the mastoid air cells
-facial nerve canal is between the antrum and the posterior wall of the tympanic cavity
-mastoid antrum and air cells are within the mastoid process
-lined with mucous membrane that is continuous with lining of tympanic cavity
-tegmen tympani seperates antrum from middle cranial fossa
Carotid wall
Anterior wall
-contains openings of the pharyngotympanic tube and the canal for the tensor tympani
-seperates tympanic cavity from the carotid canal (and internal carotid artery)
Ossicles
-middle ear
-three bones, incus, malleus and stapes
-transmit sounds from the tympanic membrane to the cochlear
-increase the force of sound waves
-maintain the frequency of the sound waves