Anatomy
What does the outer ear consist of? Describe briefly what thy look like (or draw)?
Pinna(or auricle)- visible part of ear
External auditory meatus(ear canal)- Sigmoid canal, 7mm in diameter, ~25mm long, running from auricle to tympanum. First ⅓ surrounded by cartilage, remaining ⅔ surrounded by bone.Hair, sebaceous and ceruminous glands in cartilaginous portion.
Tympanum (eardrum)- Collagenous membrane separating outer from middle ear. Concave externally, umbo is most depressed part of concavity. Malleus is firmly attached to medial tympanic surface
Describe function of outer ear
Converts acoustic energy to kinetic energy
Sound waves external to body are funnelled into the ear canal via the pinna, and are converted to vibrations of the eardrum.
TRUE OR FALSE?
The middle ear contains two small bones
False
What are the two types of hearing loss?
Conductive and sensorineural hearing loss
THe name of the inferior window and its function
Round window and allows lymph fluids to expand outward. This is the only expansion space inside the boney labyrinth
Describe the anatomy of the middle ear
Air-filled chamber between eardrum and inner ear. Three smallest bones in body (ossicles) connect eardrum to oval window- Malleus(hammer), incus(anvil) and stapes (stirrup)
Describe the function of the middle ear
Converts kinetic energy of tympanic membrane to hydraulic energy in inner ear, via oscillations of the ossicles.
Name the middle ossicle (both names)
incus or the anvil
Describe the two types of hearing losses
Conductive- Problem conducting sound waves through outer ear, eardrum or middle ear.
Sensorineural- Problem in cochlea (Organ of Corti), vestibulocochlearnerve or auditory cortex of the brain.
What is the function of the semicircular canals?
Help brain understand body's position in space, balance and equilibrium
What are the middle ear ossicles?
malleus, incus and stapes
What is the purpose of the ossicles?
Eardrum area is 17x that of stapedial foot plate. Ossicles act like a lever (malleus= long arm; incus= short arm) with an average lever arm factor of 1.3. Thus, sound pressure is concentrated with a pressure gain of 20 or more.
Which bone is connected to the oval window and what does it resemble?
Stapes and a stirrup
3 causes of conductive hearing loss
Earwax, Otitis externa, perforated ear drum, embrane tension, Otitis media, damage to small bones within the middle ear, infection, fluid in the middle ear
What is the role of the cochlea?
Contains the organ of corti and is the sensory location for hearing
What are the two nerves that serve the inner ear?
vestibular and choclear nerves
What occurs if you have arthritis of the ossicles?
Arthritis hinders the ossicles ability to move and conduct sound vibrations to the inner ear.
Which structure help equalize air pressure and drain the middle ear if necessary?
the auditory tube
3 causes of sensorineural hearing loss
Congenital, Presbycusis(age-related) inflammatory disease e.g. measles, mumps, meningitis, syphilis, Ménière’s disease, ototoxic drugs, physical trauma, noise-induced, benign tumours on the auditory nerve
Name the area between the semicircular canals and the cochlea
the vestibule
Describe the anatomy of the inner ear and its contents. (Draw if easier)
Labyrinth made up of vestibular system (dedicated to balance) Bony labyrinth = surrounding petrous part of the temporal bone. Membranous labyrinth = system of tubes and chambers within bony labyrinth, filled with endolymph.
Cochlea (for hearing)-
Cochlea is a coil that makes 2¾ turns around a bony column (modiolus).Three sections: Scalamediaor cochlear duct, filled with endolymph. Scala vestibuli and Scala tympani both filled with perilymph.
What is the function of the inner ear?
Converts kinetic energy of ossicles into hydraulic energy of fluid in inner ear, and then into electrochemical signals in the vestibulocochlear nerve (VIII).Vestibular part of labyrinth uses movement of fluid to sense rotational and translational accelerations. Cochlea uses movement of fluid to sense external pressure changes (sound)
Describe what can happen if the auditory tube becomes chronically blocked due to infection?
ear infections can cause the ear drum to burst and also cause damage to the ossicles leading to permanent hearing loss
Can ear buds cause hearing loss
yes!
Which window is superior and attached to the stapes?
oval window