Wednesday, 4-6-Ear (Stephens) Flashcards
(36 cards)
What are the functions of the external ear/externa auditory meatus?
- collect and conduct sound and protect the eardrum
- air transmission
The pinna consists of a plate of elastic cartilage covered by skin. It is innervated by GSA sensory fibers from the ___ nerves.
- Auriculotemporal (V3)
- Lesser occipital (C2-3)
- Great auricular (C2-3)
-Skin of the concha probably receives contributions from VII, IX, and X
Blood supply to the auricle is via the ___ arteries
Superficial temporal and posterior auricular
Trauma to the pinna may cause hemorrhaging in the subQ tissue resulting in a ___.
Auricular hematoma
If hematoma is not evacuated and bandaged, the subsequent scar tissue may grossly deform the auricle and become a CAULIFLOWER EAR
The skin lining the outer 1/3 of the external auditory meatus contains numerous ___ which secrete cerumen.
Sebaceous and ceruminous glands
Accumulation of cerumen may be firmly adherent to the epithelia of the ext auditory meatus and/or tympanic membrane. Casual removal of a mass of ear wax may lead to avulsion of what?
The tympanic membrane and ossicles
__ is located at the medial end of the EAM, is tilted forward, lateral and downward in the canal and divides the external ear from middle ear
Tympanic membrane
The outer portion or skin of the tympanic membrane is innervated by GSA fibers from the ___ nerves.
A middle fibrous layer is present in most of the tympanic membrane and forms the ___.
The inner mucous layer of the tympanic membrane is innervated by GVA fibers of the ___
- V and X
- Pars tensa
- IX n. Via the tympanic plexus
The absence of the middle fibrous layer in the antero-superior quadrant of the tympanic membrane forms the ___
Pars flaccida
The central concavity of the tympanic membrane is called the ___. The anterior and posterior mallear folds are V-shaped folds formed by the inner mucous membrane on the borders of the pars flaccida. The __ n. Courses through these folds.
Umbo
Chorda tympani
Describe the location of the tympanic membrane to the following structures of the middle ear cavity:
___: long process of incus, stapes, fenestra vestibuli
___: fenestra cochleae
___: auditory tube
___: carotid canal
Supero-posterior
Infero-posterior
Supero-anterior
Infero-anterior
The __ cavity is a small hour-glass shaped air space in the petrous temporal bone where the energy of sound waves are transformed into mechanical energy through a chain of bony ossicles
Middle ear
The __ is that portion of the middle ear cavity which is located above the level of the tympanic membrane and contained the head of the malleus, and body and short crus of the incus. It communicates with the mastoid ear cells via the mastoid aditus and antrum
Epitympanic space
___ is an inflammation of the middle ear cavity that is relatively common in infants and children. It may result in an accumulation of fluid and mucous and a decrease in hearing. It is more common in infants because their auditory tubes are oriented horizontally, thereby impeding drainage from the tympanic cavity. The tubes are directed downward in the adult
Otitis media
Otorrhea, otorrhagia, vestibular disturbances, deafness, or Bell’s palsy may result from fractures of the ___ bone. These fractures are often associated with some degree of brain trauma and have a considerable mortality and morbidity
Petrous temporal
The roof of the tympanic cavity is formed by the ___
The floor of the tympanic cavity is formed by the ___
The anterior (carotid) wall of the tympanic cavity contains ___
The posterior (mastoid) wall of the tympanic cavity contains ___
- tegmen tympani
- superior bulb of the IJV
- semicanal for tensor tympani m. & opening for auditory tube
- stapedius m.
After leaving the brainstem, the facial nerve travels laterally in the ___ before entering the facial canal. Within the canal, the geniculate ganglion is located just above and medial to the promontory of the middle ear cavity. At the level of the ganglion, the nerve turns sharply posteriorly as it forms the ___. After about 1.0 cm the nerve courses downward, sends a branch to the stapedius muscle and exits the __ foramen
- internal auditory meatus
- external genu
- stylomastoid
Where is the cochlea relative to the facial n.?
Anterior
Where does the chorda tympani nerve cross relative to the malleus?
It crosses the neck of the malleus
__ is an ossification or scarring of the small ossicular joints that prevents the transmission of sound from the tympanic membrane to the fenestra vestibuli. It may result in significant hearing impairment. Typically, tests for bone conduction are normal but nerve conduction is reduced
Otosclerosis
The ___ tightens the tympanic membrane and attenuates its vibrations. It is located in a semicanal above the auditory tube, from which it arises and its tendon loops laterally around the processus cochleariformis and inserts on the handle of malleus
Tensor tympani muscle
What is the innervation of the tensor tympani m.?
V3
The ___ pulls the stapes out of the fenestra vestibuli which is a protective mechanism to prevent excessive movement of the stapes due to loud sound. It is located in the pyramid on the posterior wall of the middle ear cavity
Stapedius
What is the innervation of the stapedius m.?
Facial n.
