[Biology Class Notes] on Stapes Pdf for Exam

The ossicular chain in our body is made up of three bones; malleus, incus stapes which are ingrained deep inside the temporal bone within the tympanic cavity. All the three are joined together by two synovial joints called the incudostapedial and incudomalleolar joints. Malleus, incus stapes together form the sound-conduction apparatus in our system which transmits vibrations.

For sound to be recognized by the brain, sound waves need to enter the auditory canal and then go through the tympanic membrane (or eardrum), and finally enter the middle ear compartment. Once the sound waves reach the middle ear compartment, they vibrate the ossicular chain i.e. the three bones malleus, incus, and stapes. Out of these three bones, the stapes bone is the tiniest one which is also the smallest bone in the body.

Here we will find out what exactly stapes bone is, what is the stapes location, stapes function, and stapes superstructure.

Stapes Bone in Human Body

With a dimension of 3 mm X 2 mm, stapes (plural stapedes) is the smallest known bone in the human body. Since the shape of stapes bone is like a stirrup it is also referred to as stirrup ear bone.

Stapes Function

If for some reason (like severe head trauma) our stapes get damaged, we can lose some or all of our hearing abilities. Such is the importance of stapes functions in the human hearing system.

• Stapes is the last bone in the ossicular chain so when it hits the oval window, a wave is generated in our inner ear’s fluid.

• This fluid wave initiates the process in the inner ear which is responsible for the conversion of sound waves to electrical signals.

• Our brain then interprets these electrical signals.

What is Otosclerosis? 

Sometimes an abnormal growth of extra bone can occur around the stapes bone. Due to this growth, the stapes bone is frozen in its place and unable to vibrate, which is its usual function. This condition is known as Otosclerosis. This results in hearing loss. Otosclerosis is a slow growth and generally happens in both ears. It is mostly a genetic trait that runs in the family. This condition can be corrected through a surgery called stapedectomy.

Conclusion

Stape bone is a vital bone in the human hearing system. They are the smallest bone known in the human body and are responsible for the translation of movement from the outer eardrums to the fluid in the inner ear which transforms sound waves into nerve impulses. These nerve impulses get interpreted by the brain.