LEC 18 - Olfaction vision and hearing part 2 Flashcards
(39 cards)
Describe the primary functions of the ear as a whole.
The ear functions to protect, absorb, and transform air pressure waves into mechanical vibratory energy (external and middle ear) and to absorb and transform mechanical energy into neural impulses (inner ear).
Identify the structures that comprise the external ear and their functions.
The external ear includes:
Auricle (Pinna): Protects the canal, captures sound, and provides directional sensitivity.
External Auditory Canal (Meatus): Channels sound waves to the tympanic membrane (eardrum).
How does the auricle enhance sound directionality?
The auricle captures sound waves and enhances directional sensitivity, allowing for better localization of sound sources.
Define the external acoustic canal’s structure.
its lateral portion being cartilaginous and the medial portion being osseous, directed slightly downward to prevent foreign particle accumulation.
What is the function of ceruminous glands?
Ceruminous glands secrete cerumen (earwax), which helps keep foreign objects and insects out of the tympanic membrane and slows the growth of microorganisms.
How can excessive cerumen buildup affect hearing?
Excessive wax can block sound transmission to the tympanic membrane, leading to temporary hearing loss.
Describe the role of the tympanic membrane in hearing.
The tympanic membrane separates the external and middle ear and conducts vibrations from the external ear to the middle ear.
Describe the layers that compose the tympanic membrane.
The tympanic membrane consists of a thin layer of connective tissue sandwiched between two layers of epithelium.
How does the middle ear function in sound transmission?
The middle ear conducts vibrations from the tympanic membrane to the oval window and amplifies these vibrations.
Explain the structure of the middle ear (tympanic cavity).
The middle ear is an irregular space within the temporal bone, and contains the ossicles.
Define the ossicles and their function and where it is
The ossicles are three bones: the malleus, incus, and stapes, which conduct and amplify vibrations from the tympanic membrane to the oval window. In middle ear (tympanic cavity)
How does the external ear contribute to sound processing?
The auricle captures sound waves, while the S-shaped external acoustic canal directs these waves toward the tympanic membrane for mechanical transformation.
Describe mechanical transduction in the inner ear.
Mechanical transduction in the inner ear involves absorbing mechanical energy from vibrations and transforming it into neural impulses sent to the brain for auditory processing.
What is the role of the middle ear in amplifying sound?
The middle ear amplifies sound vibrations received from the tympanic membrane before transmitting them to the oval window.
Describe the medial wall of the middle ear.
The medial wall features the oval window, occupied by the foot plate of the stapes, which transmits vibrations into the inner ear, and the round window, which helps diffuse returning vibrations from the cochlea.
Define the auditory tube and its alternate names.
The auditory tube, also known as the Eustachian tube or pharyngotympanic tube, is a passageway between the middle ear and the nasopharynx.
Explain the primary functions of the auditory tube.
The auditory tube equalizes pressure in the middle ear, provides a passage for microorganisms (which can lead to otitis media), and allows drainage of fluid from the middle ear.
How does pressure difference affect the auditory tube?
An air pressure difference between the ear canal and middle ear can build up, and the Eustachian tube can open via palatine muscle activation to equalize pressures, often experienced as ‘popping’ the ears through swallowing, yawning, or chewing.
Identify the muscles responsible for opening the Eustachian tube.
The main muscles responsible for opening the Eustachian tube are the levator veli palatini and tensor veli palatini.
Explain the method to equalize pressure while scuba diving.
While scuba diving, pressure is equalized by ‘pushing’ air (positive pressure) into the middle ear while pinching the nose closed with fingers, which can cause the eardrums to pop the opposite direction.
How does pressure buildup differ when ascending into the air versus descending underwater?
When ascending into the air, there is a pressure buildup in the middle, whereas when descending underwater, the pressure difference builds in the opposite direction.
Define the ossicular chain and the bones it includes.
The ossicular chain connects the tympanic membrane to the oval window and includes the malleus (hammer), incus (anvil), andapes (stirrup).
Describe how the ossicular chain amplifies sound vibrations.
The ossicular chain amplifies sound by transferring force from the eardrum to the oval window.
What does the Eustachian tube play in ear health?
The Eustachian tube helps equal air pressure in the middle ear and facilitates drainage, which is essential for preventing infections and maintaining ear health.
