Review the structures of the ear external ear middle

• Review the structures of the ear:
• External ear
• Middle ear
• Outer ear (Refer to Figure 35-7 and 35-8 and PowerPoint Slides 35 – 41 .)
• Discussion Points
• Point out that the ear is commonly discussed from the most external structures to the most
internal structures. Ask students to name the primary structures within each section. (External—
auricle, or pinna, and external auditory canal; middle— tympanic membrane, ear ossicles, and
Eustachian tube; inner—oval window, semicircular canals, vestibule, and cochlea, which
contains the organ of Corti.)
• Discuss with students the two fluids that are found in the inner ear—perilymph and
endolymph. Explain that these fluids move to activate hearing and equilibrium receptors.
• Ask your students: What nerves are responsible for delivering sound to the brain for
interpretation? (Auditory nerves, also called the vestibulocochlear nerves.)
• Remind students that sound information is interpreted by the auditory cortex, which is
found in the temporal lobe of the cerebrum.
• Learning Activities
• Ask an audiologist, audiology assistant, or hearing aid specialist to come speak to the
class regarding hearing loss and the treatments available for the varying causes of hearing

loss (Specifically, conductive and sensorineural hearing loss). Students should be
prepared prior to the speaker's arrival with appropriate questions regarding hearing loss,
treatments, and how patients with hearing loss cope in our "hearing-based" society. If the
speaker does not bring up the connection between noise pollution and hearing loss, be
sure that you or the students ask about it.
Learning Outcome 35.7: Explain how sounds travel through the ear and are interpreted in the brain.
• Lecture Topics
• Teach your students that sound consists of waves of different frequencies that move through the
air. (Refer to PowerPoint Slides 43 – 48 .)
• Discussion Points
• Discuss the following steps in the way sound travels through the ear and is interpreted in
the brain:
• The external ear initiates sound conduction when it collects these waves and channels them to the
tympanic membrane.
• The waves make the tympanic membrane vibrate.
• The vibrations, in turn, are amplified by the middle ear’s ossicles.
• The amplified waves enter the inner ear and the cochlea.
• These waves cause tiny hairs that line the cochlea to bend.
• Movements of the hairs trigger nerve impulses.
• The auditory nerve transmits these impulses to the brain, where they are perceived as sound.
• Point out that sound waves are also conducted through the bones of the skull directly to
the inner ear—a process called bone conduction. This alternative pathway for sound
bypasses the external and middle ears.
• Learning Activities
• Ask your students to research the instruments used to assess hearing ability (tuning fork,
audiometer). Ask them if they have ever had a hearing evaluation in school (many will
probably remember being tested in grammar school with an audiometer). Inform the
class that hearing ability is measured in decibels