Ear Flashcards
What are the 3 areas of the ear?
- External ear
- Middle ear
- Internal ear
What is another name for the middle ear?
Tympanic cavity
What is another name for the internal ear?
Labyrinth
What are the 3 areas of the external ear?
- Auricle
- External auditory meatus
- Tympanic membrane
What is the function of the auricle?
Assist in capturing sound waves into external acoustic meatus
What type of gland produce ear wax?
Modified sweat gland called ceruminous gland
What 2 tissues make up the external acoustic meatus?
- Outer 1/3 is elastic cartilage
2. Inner 2/3 is bone
What is the function of the external acoustic meatus?
Conduct sound waves towards tympanic membrane
Describe the lining of the external acoustic meatus
Thin sin containing hair follicles, sebaceous glands and ceruminous glands
What are the 3 layers of the tympanic membrane?
- Outer - Cutaneous
- Intermediate - Fibrous
- Inner - Mucous
Describe the circumference of the tympanic membrane
Has thickened fibrocartilaginous ring which is fixed to tympanic sulcus
What bone is attached to the inner surface of the tympanic membrane?
Handle of the malleus
What is found above the site of the handle of the malleus?
Anterior and posterior malleolar folds
What is the area between the two malleolar folds called?
Pars flaccida
What is found in the anteroinferior quadrant of the tympanic membrane?
Cone of light
What is the function of the tympanic membrane?
Transmits sound vibrations of ossicles of middle ear
What 2 things connects the middle ear to the nasopharynx?
- Eustachian tube
2. Mastoid antrum
What 3 bones are found in the middle ear?
- Incus
- Malleus
- Stapes
What 2 muscles are found in the middle ear?
- Tensor tympani
2. Stapedius
What is the function of the eustachian tube?
Allows air to enter middle ear to balance pressure and allow free movement of tympanic membrane
What forms the roof of the middle ear?
Tegmen tympani of petrous temporal bone
What forms the floor of the middle ear?
Plate of bone separating middle ear from internal jugular vein
What 3 things are found forming the anterior wall of the middle ear?
- Plate of bone which separates middle ear from internal carotid artery
- Opening for eustachian tube
- Canal for tensor tympani muscle
What 3 things are found in the posterior wall of the middle ear?
- Aditus to mastoid antrum
- Pyramid containing stapedius
- Posterior canaliculus for chorda tympani nerve
What forms lateral wall of the middle ear?
Tympanic membrane
What are 4 presenting features of the medial wall of the middle ear?
- Facial canal
- Promontory
- Fenestra vestibuli
- Fenestra cochleae
What is the promontory found on the medial wall of the middle ear?
Rounded eminence formed by 1st turn of cochlea
What is the fenestra vestibuli of the medial wall of the middle ear?
Opening above and behind promontory
What is the function of the fenestra vestibuli of the medial wall of the middle ear?
Transmit vibrations of ossicles to perilymph in scala vestibuli
What is the fenestra cochleae of the medial wall of the middle ear?
Opening below and behind the promontory closed by secondary tympanic membrane
What is the innervation of the tensor tympani muscle?
Mandibular nerve of trigeminal
What is the action of the tensor tympani muscle?
Dampens down vibrations of tympanic membrane
What is the innervation of the stapedius muscle?
Facial nerve
What is the action of the stapedius muscle?
Dampens down vibrations of stapes by pulling on neck of the bone
What is the point in the stapedius?
Prevents excess movement of stapes helping to control amplitude in inner ear
Describe the transmission of sound waves in the cochlea
6 steps
- Vibrations of stapes footplate at fenestra vestibuli create waves in perilymph of scala vestibuli
- Waves move into scala tympani and dissipate at fenestra cochleae
- Wave is transmitted to endolymph inside cochlear duct
- Basilar membrane vibrates
- Organ of Corti moves against tectoral membrane
- Stimulates generation of nerve impulses to brain
