What Bones are in the Ear?
The human ear does more than just make it possible for you to hear well. Each ear is part of a complex system that also plays a role in balance and stability. While men typically have slightly larger ears than women, they come in all shapes and sizes but still serve the same functions. Today, though, we’re going to specifically focus on one question – what bones are in the ear?
While often referred to as the “hammer,” the malleus actually looks more like a club. It’s one of three bones that collectively make up the ear bone (auditory ossicle), in the middle ear. It’s attached to the inner surface of the eardrum and links to another ear bone called the incus. It’s also:
• The largest of the three middle ear bones
• About eight millimeters in length in most adults
• Responsible for transmitting sound vibrations from the eardrum to the other two middle ear bones
• Not likely to be the reason for hearing loss since it directly connects to the eardrum
Also called the anvil, the incus is the second of the three middle ear bones. It’s sometimes said to resemble a premolar tooth with roots. The body of this bone is held together with a joint located in the upper part of the eardrum cavity (attic).
This anvil-shaped bone receives sound vibrations once they are passed along from the malleus. The surface of the incus pairs with the malleus to form the joint that supports it. Additional features of the incus include:
• Long and short structures called crus
• A hooked-shaped part that forms a joint with the next bone (stapes)
• An extension (short crus) that attaches to the back part of the middle ear
• A bent part that carries a small knoblike bone that links loosely to the stapes
This bone is sometimes referred to as the stirrup because of its shape and appearance. It sits in a horizontal position in the ear next to the incus, and it’s the smallest of the three middle ear bones. The wall of the ear cavity where these bones are located has a bony labyrinth with two openings. These openings are the perfect size for the footplate of the stapes. It’s then held in place by the annular ligament. After sound vibrations make it to the stapes, the hearing process is completed with the following steps:
• Sound vibrations are sent to another part of the ear called the cochlea
• Vibrations are then turned into nerve signals
• Nerve signals are sent along their way to the brain
As you read this article discussing what bones are in the ear, you may be thinking that the outer ear “bone” was overlooked. However, this part of your ear is actually made up of flexible cartilage, not bone tissue. Your ears also contain soft tissues and sensitive membranes like the tympanic membrane (eardrum). The eighth cranial nerve (vestibulocochlear nerve) also helps with the hearing process by transmitting sound and balance-related signals to the brain.