The Structure of the Ear Lecture Notes

This set of flashcards covers the key concepts and details related to the structure and function of the ear, including the roles of various components in hearing and balance.

What are the three main parts of the ear?

Outer ear, middle ear, inner ear.

What does the outer ear consist of?

The pinna and the auditory canal.

What role does the tympanic membrane play in hearing?

It converts soundwaves into physical vibrations.

What are the names of the three small bones in the middle ear?

Malleus, incus, and stapes.

What is the function of the ossicles?

They amplify and transmit vibrations from the eardrum to the inner ear.

How does the Eustachian tube function?

It equalizes pressure between the middle ear and the external atmosphere.

What does the cochlea resemble?

A coiled tube resembling a snail's shell.

What is the organ responsible for hearing called?

The organ of Corti.

What is the role of the vestibular system?

It provides balance and spatial awareness.

What fluid fills the semi-circular canals?

Endolymph.

What are the two otolith organs?

Utricle and saccule.

What is the function of the utricle?

It detects horizontal movement.

What is the function of the saccule?

It detects vertical acceleration.

What do otoliths do in the otolith organs?

They trigger activation of hair cells by pulling on the gelatinous layer due to gravity.

What separates the scala media from the scala vestibuli?

The vestibular membrane or Reissner's membrane.

What structure is located on the basilar membrane?

The organ of Corti.

How many rows of internal hair cells are in the organ of Corti?

One row of 3,500 internal hair cells.

What triggers the release of the neurotransmitter glutamate?

Bending of the stereocilia.

What type of movement does the vestibular system detect?

Rotational and linear movement.

Where is the crista ampullaris located?

Within the ampula of the semi-circular canals.

What happens when the head turns in relation to the endolymph and cupula?

Endolymph lags behind, pushing the cupula and triggering hair cell depolarization.

What are the names of the three semi-circular canals?

Lateral, anterior, and posterior.

How does the basilar membrane contribute to sound frequency perception?

Its varying stiffness and length allow for detection of different frequencies.

What issue can arise if the tympanic membrane is ruptured?

Hearing loss.

How does sound wave pressure vary from the eardrum to the oval window?

Low-pressure to high-pressure movement.

What must occur for the cochlear nerve to send signals to the brain?

Activation of postsynaptic cochlear nerves via neurotransmitter release.

What is the function of the basilar fibres in the basilar membrane?

They help to vibrate and transmit sound waves.

What characterizes the structure of the scala tympani?

Connected to the round window of the middle ear.

How does the inner ear convert physical vibrations into nerve signals?

Through the organ of Corti and hair cells.

What condition can excessive triggering of the vestibular system cause?

Motion sickness.

What is the function of the macula in otolith organs?

To detect linear acceleration.

What is the significance of the helicotrema?

It connects the scala tympani to the scala vestibuli.

What does the term 'perilymph' refer to?

The fluid that separates the bony labyrinth from the membranous labyrinth.

What kind of membrane lies free in the scala media?

The tectorial membrane.

How many rows of external hair cells are in the organ of Corti?

Three or four rows of 20,000 external hair cells.

What anatomical feature allows the hair cells to detect sound?

They are embedded in the tectorial membrane.

What happens to the ion channels of hair cells during depolarization?

Potassium and calcium enter the cell.

How does pressure in the scala vestibuli affect the basilar membrane?

It causes the membrane to vibrate.

What is the role of cochlear nerve endings?

To transmit auditory signals to the brain.

What is the key function of the inner ear?

To translate sound vibrations into nerve signals.

How does head tilting affect hair cells in otolith organs?

It causes gravity to pull otoliths and activate hair cells.

What typically happens to small perforations of the tympanic membrane?

They heal spontaneously.

What are the main learning outcomes of the lecture?

Describe ear structure, explain vestibular role, and function of cochlea and organ of Corti.

How many semi-circular canals are there?

Three.

What is the auditory nerve's role concerning hair cells?

Transmits signals generated by hair cell activation to the brain.

What does the term 'angular acceleration' refer to?

Change in rotational speed detected by the vestibular system.