Ear Flashcards
Inner ear made up of
Bony labyrinth
Membranous labyrinth
Filled with a fluid perilymph, series of canals and cavities within the temporal bone
Bony labyrinth
Floats in perilymph, filled with fluid called endolymph
Membranous labyrinth
Utriculus and sacculus
- membranous sacs suspended in perilymph and filled with endolymph
- contain maculae, equilibrium receptors, that are hair like cells covered with a jelly like ,Ayer where crystals called otoliths are ambedded
Semi circular canals
Three canals at right angles to each other with a swelling called an ampulla
- ampullae contain equilibrium receptors called crista; patch of hair cells covered with a jelly like cap called a capula
Crista
Equilibrium receptors contained within ampullae, hair cells covered in a jelly like cap called a capula
Maculae
Contained in utriculus and sacculus, equilibrium receptors, hair cells covered in a jelly like layer where cristals called otoliths are embedded
What structural and functional region are utriculus and sacculus, and semi circular canals classifies under
Vestibular apparatus
Function of vestibular apparatus
Maintaining balance
Able to determine changes of position of the head (orientation). When head moves, otoliths are stimulated and respond to forces of gravity
Function of utriculus and sacculus
Register movem. of head in any direction, detect acceleration due to flow of endolymph which stimulate crista
Function of semi circular canals
Found on the basilar membrane partly covered by the tectorial membrane. Hairs from the hair cells of _ are embedded in the overhanging tectorial membrane.
Organ of corti
Function of the organ of corti
Sound waves cause vibration in the oval window
These vibrations cause vibrations in the perilymph of the scala vestibule which gives rise to vibrations in the endolymph of scala media.
The hair cells of the organ of corti are stimulated, and translate these vibrations into a nerve impulse which is moved through the auditory nerve to the cerebrum.
The round window absorbs the vibrations
What is the cochleas main function
Hearing
HEARING DEFECTS
Middle ear infections
Inflammation in middle of ear = otitis media
Bacterial or viral infection resulting in symptoms
Possible symptoms of middle ear infection
- swelling of the lining of the middle ear, blocks Eustachian tube, causes build up of fluid in normally air filled cavity. Often results in a discharge.
- conductive hearing loss as the eardrum and ossicles are unable to move freely and prevents transmission of sound waves
- tearing of the eardrum as a pressure builds up
- severe pain
Deafness
Partial or total loss of hearing results in inability to hear sound
Reasons deafness can occur
- genetics: genes for deafness can be inherited
- meningitis
- trauma or disease
TREATMENT FOR HEARING LOSS
- Grommets
- Hearing aids
- Cochlear implants
If middle ear infections persist after treatment with antibiotics then small ventilation tubes are inserted throu eardrum - allows air to the middle ear and reduces build up of fluid
Grommets
Electronic device, restores hearing to people with severe or profound deafness. Compensates for damaged hair cells on the organ of corti by artificially stimulating the auditory nerve
Cochlear implants
Small electronic device that amplifies incoming sound, fitted to patients who are not totally deaf. Consists of a tiny microphone, amplifier, and speaker
Hearing aid
