Question

The is attached to the tympanic membrane and the oval window of the cochlea. (a) Malleus, Incus (b) Incus, Stapes (c) Malleus, Stapes (d) Stapes, Malleus

Short answer

(c) Malleus, Stapes

Step-by-step solution

Analyze the Structure of the Ear

In the human ear, there are three small bones, known as ossicles, that participate in the conduction of sound waves from the air to the inner ear. These are the Malleus (Hammer), Incus (Anvil) and the Stapes (Stirrup).

Identify the Ossicles' Positions

The Malleus is the first ossicle and it is attached to the tympanic membrane. The second ossicle is the Incus which is connected to the Malleus. The third ossicle is the Stapes which is connected to the Incus and the oval window of the cochlea.

Choose the Correct Answer

Now knowing the positions of the ossicles, the correct answer is the option where the first element is the one attached to the tympanic membrane (Malleus) and the second one is the ossicle attached to the oval window of the cochlea (Stapes). Thus, the correct answer is (c) Malleus, Stapes.

Key concepts

Tympanic Membrane

The tympanic membrane, commonly known as the eardrum, is an essential part of the human ear. It acts like a drum skin by capturing sound waves from the environment and transmitting them to the ossicles of the middle ear.
It is a delicate membrane that separates the outer ear from the middle ear.
The role of the tympanic membrane is crucial as it serves as the initial stage of converting sound waves into mechanical movements.

• When sound waves hit the tympanic membrane, it vibrates accordingly to the frequency and amplitude of those waves.
• These vibrations then travel to the ear ossicles, starting with the malleus.

The strength and condition of the tympanic membrane are vital for maintaining good hearing health, as any perforation or damage can lead to hearing loss.

Cochlea

The cochlea is a spiral-shaped organ located in the inner ear.
It is primarily responsible for converting mechanical vibrations into electrical signals that the brain interprets as sound.
The cochlea is filled with a fluid which plays a key role in the hearing process, helping to conduct sound vibrations.

• Inside the cochlea, there are tiny hair cells that move as fluid vibrations pass by them.
• These movements are translated into nerve impulses that travel through the auditory nerve to the brain.

The spiral shape of the cochlea is essential for processing different sound frequencies, with higher frequencies detected at the base and lower frequencies detected at the top. Proper functioning of the cochlea is critical for accurate sound perception.

Sound Waves Conduction

Sound wave conduction in the ear involves the seamless transfer of sound energy from the outer ear to the inner ear.
This process begins when sound waves enter the ear canal and strike the tympanic membrane.
The tympanic membrane's vibrations are handed over to the ossicles of the middle ear.

• The ossicles – malleus, incus, and stapes – work together to amplify the vibrations.
• The stapes, being the last in this chain, transfers these vibrations to the oval window of the cochlea.

This process is incredibly efficient, ensuring that sound waves are converted into nerve impulses for the brain to analyze. Impairments in any part of this chain can affect hearing.

Malleus

Malleus, also referred to as the hammer, is the first of the three ossicles in the middle ear.
It connects directly to the tympanic membrane, making it a critical part of the sound conduction chain.
The shape of the malleus resembles a hammer, which is where it gets its name.

• When the tympanic membrane vibrates due to sound waves, these vibrations are transmitted to the malleus.
• The malleus then acts as an intermediary, passing on these vibrations to the incus.

The precise movement of the malleus is vital for accurate sound transmission, and any hinderance in its motion can disrupt hearing.

Stapes

The stapes is the smallest bone in the human body and the third ossicle in the middle ear.
Shaped like a stirrup, it is also known as the stirrup bone.
The stapes plays a key role in the transition from middle-ear vibrations to fluid waves within the cochlea.

• It receives vibrations from the incus and transmits them to the oval window of the cochlea.
• This transition is crucial as it begins the process of converting mechanical sound waves into electrical signals that the brain can interpret.

As with other ossicles, any dysfunction of the stapes can severely impact hearing, highlighting its importance in the auditory process.