Ear Anatomy Flashcards
Pinna (Auricle)
outer ear structure that is visible. Made out of elastic cartilage. Funnels sound into the external auditory canal.
External Auditory Canal
funnels sound further into the ear.
What produces ear wax? What is another name for ear wax>
Ceruminous Glands secrete Cerumen.
Tympanic Membrane (Tympanum)
thin connective tissue sheet that separates the external ear from the middle ear. This structure converts sound waves into mechanical movement that cause the ossicles to vibrate.
Auditory Ossicles
small bones that act as levers that transfer sound vibrations from the tympanum to the fluid-filled chamber within the inner ear
Malleus
connects to the tympanic membrane
Incus
connects to the malleus
Stapes
connects to the stapes
Tensor Tympani (Innervation)
muscle that is directly attached to the malleus.
Innervation: Motor Fibers of the Mandibular Branch of the Trigeminal Nerve (CN V)
Stapedius
muscle directly attached to the stapes.
Innervation: Facial Nerve CN (VII)
What is this?
Protection of the tympanic membrane from rupturing in response to very loud sounds. The muscles Tensor Tympani and Stapedius are going to contract to reduce the vibrations and wave frequencies.
Attenuation Flex
Auditory Tube (Eustachian Tube)
connects the middle ear to the nasopharynx. Role is to equalize the pressure in the middle ear cavity with the external atmospheric pressure.
What is the Bony Labyrinth (Osseous Labyrinth) filled with?
Perilymph
Which closely resembles CSF.
Semicircular Canals
responsible for dynamic movement
Anterior Semicircular Canal
sense of nodding “yes”
Posterior Semicircular Canal
sense of nodding side to side
Lateral Semicircular Canal
sense of nodding “no”
Ampullae
an enlargement that contains sensory receptors located at the junction between the semicircular canal and the vestibule
Vestibule
large main structure where the semicircular canals connect to.
Cochlea
coiled, snail-like bone structure used for hearing
What is the Membraneous Labyrinth filled with?
Endolymph
Filled with high K+ concentration.
Semicircular Ducts
structures within the semicircular canals
Utricle
superior bump on the vestibule. Responsible for sensing static movement for linear acceleration.
Saccule
inferior bump on the vestibule. Responsible for sensing static movement for vertical acceleration/ gravity
Scala Vestibuli (Vestibular Duct)
this structure is continuous with the bony labyrinth and it contains perilymph
Scala Media (Cochlear Duct)
this structure is continuous with the membranous labyrinth and it contains endolymph. The Origin of Corti and the Hair Cells are located here.
Scala Tympani (Tympanic Duct)
this structure is continuous with the bony labyrinth and it contains perilymph
Round Window
a round membrane that releases pressure that is created at the oval window
Oval Window
an oval membrane that the stapes sits directly on top of
What are the two branches of the vestibulocochlear nerve?
Vestibular Branch and Cochlear Branch
What is the clinical?
an infection of the middle ear, frequently of bacterial origin. It commonly occurs in infants and children and occasionally seen in adults.
Otitis Media (Middle Ear Infection)
What is the clinical?
if the symptoms get worse and bacteria is involved, pus can accumulate in the middle ear cavity, the tympanic membrane becomes painfully distorted, and in untreated cases it will often rupture, producing a characteristic of drainage from the external auditory canal. The infection may also spread to the mastoid air cells.
Mastoiditis
What is this procedure?
drainage of the middle ear through a surgical opening in the tympanic membrane
Myringotomy
What is the clinical?
a condition where the eye make sudden short, rhythmic, jerky movements even when the individual is stationary
Nystagmus
What is the clinical?
a condition in which the middle ear is blocked from the normal transfer of vibration from the tympanic membrane to the oval window. A plugged external auditory canal from accumulated wax or trapped water may cause temporary hearing loss. Scarring or tear on the tympanic membrane, fluid in the middle ear cavity, are more serious examples of conductive deafness.
Conductive Deafness
What is the clinical?
a problem that lies within the cochlea or somewhere along the auditory pathway. The vibration are still occurring, but either the receptors cannot respond or their response cannot reach its central destination.
Nerve Deafness
What is the pathway of sound?
- Pinna (sound waves funnel)
- External Auditory Canal
- Tympanic Membrane
- Malleus
- Incus
- Stapes
- Oval Window
- Displacement of Lymph in Scala Vestibuli
- Vibration in the Vestibular Membrane
- Displacement of Endolymph in Scala Media
- Vibration of Basilar Membrane
- Causes Hair Cells to Bend against the TECTORIAL MEMBRANE
- Stimulates a Nerve Impulse through the Cochlear Branch of the Vestibulocochlear Nerve.
Describe tonotopic organization.
Close to the Oval Window = High Pitch
Farther Away from the Oval Window -> Low Pitch
What determine pitch?
How frequent the vibrations occur.
What determines amplitude?
Size of the vibration.
