Ear Flashcards
(29 cards)
Ear pinna is formed of…..while outer part of EAM is formed of…..
Yellow elastic fibro-cartialge
Yellow elastic cartilage
Ceruminous glands are……, the function of their secretion is……
Modified apocrine sweat glands
Ear wax prevents objects from penetrating deep into the meatus
The inner surface of tympanic membrane & the middle ear are lined by…..which transitions into…..in the Eustachian tube.
Simple cuboidal epithelial
Respiratory epithelium
The function of tympanic membrane is…..
While function of bony ossicles is……., mention their lining
Transmits sound waves to the bony ossicles of the middle ear
Act as a lever, as they maginfy the vibration received from tympanic membrane to the oval window then to the inner ear. Lined by simple squamous epithelium.
Action of tensor tympani is…..(1)while stapedius……(2)
- Makes ear drum tense
- Pukks stapes out to protect the organ of Corti from high vibrations
Membranous labyrinth is filled with……while bony labyrinth is filled with…..
Endolymph
Perilymph
The vestibule contains…….which are connected by……..and lined by……, their receptor areas are called……
Utricle & saccule
Utriculosaccular duct
Simple squamous epithelium
Maculae
Compare type I & II hair cells
Type I: flask-shaped cells with rounded base & narrow apex, have rounded basal nuclei, they are completely surrounded. By afferent nerve terminal calyx.
Type II: They are more numerous, cylindrical, with button endings from afferent nerves
Both types contact many afferent & efferent nerve endings
Hair cells have a single…..and many….. which are connected to……
Kinocilium
Stereoclia
Actin-rich apical cytoplasm (cuticular plate) which returns these rigid stereocilia to a normal upright position after bending.
Tips of stereocilia are embedded in……., which is……
Otolithic membrane
It is a gelatinous proteoclycans layer with calcium carbonate crystals on its surface (otolith or otoconia)
Dilated part of semicircular canals is…….and contains neuroepitheial area called……
Ampulla
Crista ampullaris
Function of supporting cells & connections
- Support & nutrition of hair cells
- Production of otolithic membrane
Junctional complex
Mention differences between crista ampullaris & macula
Crista ampullaris is characterized by:
1. The proteoglycans kayer is called cupula, thicker & conically shaped with no otolith
2. The cupula extends across the ampulla establishing contact with the opposite wall
The cochlea turns around……,…..times.
Modioulus
2 and 3/4
In cochlea, a shelf extends laterally from modiolus called…..
Osseous spiral lamina
The roof of cochlear duct is formed by ……separated from……. White its floor is formed by……separated from……. . Both these chambers communicate by…….
Vestibular membrane, scala vestibuli
Basilar membrane, sacala tympani
Helicotrema
Structure & function of vestibular membrane
It is formed of 2 layers of simple squamous epithelium separated by their basement membranes, with extensive tight junctions, that help maintain the high ionic gradients between the 2 compartments.
Structure & function of basilar membrane
Formed of amorphous material containing keratin-like fibers. Extending from osseous spiral lamina to spiral ligament on lateral wall. It supports organ of Corti.
Structure & function of stria vascularis
Area of stratified epithelium covering the spiral ligament on lateral wall of cochlear duct. Contains intraepithelial capillary plexus. They are ion transporting cells responsible for secretion & maintenance of endolymph of entire membranous labyrinth.
Compare inner hair cells & outer hair cells
Inner: single row of cells supported by outer phalyngeal cells, short, flask-shaped with central nuclei, apical surface contain stereocilia arranged in linear array. More richly innervated.
Outer: 3-5 rows of cells supported by inner phalyngeal cells, long, columnar cells with basal nuclei, apical surface contains stereocilia arranged as V-shaped bundles, less innervated.
Structure & function of tectorial membrane
It is an acellular membrane that extends over Organ of Corti from vonnective tissue of modiolus. It consists of fine bundles of CT (types II, V, IX, XI) associated with proteoglycans. It is secreted bt the cells covering the spiral limbus.
Stereocilia of the hair cells are embedded in this membrane.
Pillar cells rest on……, separated by…..
Basilar membrane
Inner tunnel of Corti
Compare outer and inner phalangeal cells
O, they support the base of outer hair cells by their cup shaped apices
I, they surround and support the inner hair cells completely, apical ends joined by tight junctions.
Describe extension on medial longitudinal fasciculus
It extends upwards till interstitial nucleus of Cajal in posterior commissure and below continues in spinal cord as medial vestibulospinal tract
It connects vestibular and cochlear nuclei with motor nuclei of cranial nerves that move the eye (III, IV, VI) and with the spinal nucleus of accessory nerve that moves the neck.
