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Ear is one of the most important sense organs present in the body of a living being which is responsible for hearing and taking care of equilibrium. As sensitive as it is, it plays an important role in detecting different kinds of sound, transmitting, and transducing them. Even when we are asleep, our ears are at work. There are three most essential parts of the ear, known as the outer ear, the inner ear, and the middle ear. Each of them is associated with important and unique functions to work together. They are situated in different places inside the ear.
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Key Terms: Ear, Sense Organs, Hearing, Sounds, Pinna, Tympanic Cavity, Auditory Meatus, Ear Ossicles, Hammer, Vestibule
What is Ear?
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The ear is a sensitive sense organ that is responsible for hearing and maintaining body balance. We are highly dependent on this sensitive organ for getting our work done on time, storing important information, understanding people, and more importantly, keeping a good balance! The ear holds the most control of our auditory system. The primary function of our ears is to catch the sound waves and work on converting them into electric waves for the brain to perceive, and maintain balance.
Most of the animals present have an external ear. The external ear is also present in humans, which goes by the name pinna. It is the fleshy part that is visible to the naked eyes. Pinna or auricle is made of yellow elastic cartilages and opens into the ear canal. Our ears may be affected due to many diseases or conditions which will ultimately lead to permanent hearing loss or disorders in balance. It is crucial we be vigilant and remain on the lookout for these signs so as to treat them immediately.
Human Ear
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Structure of Ear
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The human ear consists of 3 primary parts which are essential for hearing. These are the outer ear, inner ear, and inner year. These are situated in different places. The ear canal belonging to the outer region of the ear is separated from the air-filled tympanic cavity of the middle ear.
Structure of Ear
External Ear/Outer Ear
Pinna: Also known as the auricle, this is a fleshy part and is situated at the external side of the ear. There are two sets of muscles located here, intrinsic and extrinsic. It has been found that some mammals have the ability to adjust the direction of the pinna, whereas, in humans, pinna almost has a negligible effect. The auricle holds a thin plate of elastic cartilage which is masked by a dermal layer. There are funnel-like curves present which are responsible for collecting sound waves and sending them to the ear. The ear lobe is also present here. The lobule is made of adipose and fibrous tissues which are fueled by blood capillaries.
External Auditory Meatus: Held together by a bone in the interior part, and by the cartilage in the outer region, the external auditory meatus is a slightly curvy canal. It is associated with the function of equalising air pressure which is present inside the middle ear with the external air pressure. The meatus is lined along with the stratified epithelium and wax glands.
Tympanic Membrane: This membrane separates the middle ear from the external ear. The external auditory canal provides a medium for the sound to flow to the tympanic membrane. After receiving the sound waves, it enhances and magnifies them. The tympanic membrane or the eardrum is thin and semi-transparent by nature. Its central part is known as the umbo.
Outer Ear
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Middle Ear
This is present between the outer ear and the inner ear. It consists of three important parts which are known as the tympanic cavity, the eustachian tube, and the ear ossicles.
Tympanic Cavity: The tympanic cavity is filled with air and has been separated from the external ear by the tympanic membrane. It is also separated from the inner wall because of the bony wall. The membrane consists of 3 ossicles and the ligaments which are attached to them. These ossicles are named malleus, incus, and stapes. Their job is to receive the sound, amplify it, and transmit it to the inner ear, all the way from the eardrum. Stapes are known as the smallest bone in the body. This cavity has an auditory tube called the eustachian tube.
Eustachian Tube: Associated with equalising air pressure, on either side of the membrane, this tube joins the tympanic cavity with the nasopharynx. The tube has a size of 4 cm.
Ear Ossicles: The ossicles are responsible for transmitting sound waves from the eardrum to the middle ear. The three main ossicles present are:
- Malleus- This is present in the shape of a hammer which is attached to the tympanic membrane. It is joined to the membrane by the help of the handle, and to the incuse because of the head. It is the largest ear ossicle present inside the human body.
- Incus- It is connected with the stapes, and has an anvil-like shape.
- Stapes- It is the smallest ossicle as well as the smallest bone in the human body. When it vibrates, the frequency of the vibration is transferred through the oval window, and the fluid within the cochlea starts moving.
Middle Ear
Inner Ear
The inner ear is present inside a cavity, which is called a bony labyrinth. This compartment consists of the membranous labyrinth, which is contained inside the temporal bone.
Bony Labyrinth: It consists of a vestibule, three semicircular canals, and a spiral cochlea. Apart from this, two reverses filled with fluid are also present and go by the names utricle and saccule. The cochlea serves its purpose by defining the sense of hearing. It is filled with perilymph fluid.
Membranous Labyrinth: It includes sensory receptors which help us hear. These receptors are cristae, the organ of Corti, and ampullary macula. The receptors also assist the human body in maintaining an optimal balance. The labyrinth is filled with endolymph. This organ of Corti is responsible for converting the mechanical form of energy of the sound, into nervous energy, with the help of electric impulses.
Inner Ear
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Functions of Ear
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All the living beings present on the face of Earth, require an ear to hear. But, hearing is not the only speciality ears have. Hearing and balance are two foremost important functions of the ear. Let us see how it helps us achieve these actions.
- Hearing
The ear assists our body in hearing by letting the sound waves pass all the way through the auditory canal, into the eardrum. The vibrations which are produced in the process, make way through the tympanic membrane into the tympanic cavity. The three ear ossicles present within the cavity grab these vibrations, as the smallest ossicle, the stapes pushes the oval window in and out, or pumps it up. As a result, it is passed onto the Organ of the Corti. Tiny hair cells present inside this, absorb this vibration and transform them into an electrical impulse, which the brain finally perceives as sound through the sensory nerves.
- Balance
You may be stationary, or in motion, it is necessary that our bodies remain balanced. Static balance is achieved with the help of utricle and saccule, the three semicircular canals provide a dynamic balance. The eustachian tube and the vestibular complex are crucial to help maintain a pepper balance in your body. The elongated tube works towards equalising the air pressure in the middle ear and actively contributes to maintaining a suitable posture. Meanwhile, the vestibular complex contains sensory receptors, which help balance the overall body.
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Things to Remember
- Ear is a sense organ that is responsible for hearing and body balance.
- There are parts of the ear namely the outer ear, the inner ear, and the middle ear.
- The external or outer ear consists of the pinna that collects all sounds to the tympanic membrane and provides an idea about the source of the sound, present in its vertical plane.
- The cochlea gets into work in the inner ear and helps maintain a balance of the body, both static and dynamic.
- The ear ossicles transmit the sound waves to the inner ear and are as important as other organs in the body.
- Hammer, anvil, and stirrup are associated with the function of amplifying the sound waves.
- Ears have the ability to self-clean with the presence of earwax.
- Earwax is responsible for trapping all the dust, and debris stuck inside, thereby creating a barrier to the ear canal, to help in the cleaning process.
Sample Questions
Ques. Why is the inner ear known as a labyrinth? Can labyrinthitis in humans be cured? (3 Marks)
Ans. The name “Labyrinth” comes from the labyrinths that hold the vestibular system together. Labyrinthitis is a condition that can lead to balance disorders in the body. However, it can be cured without treatment. The most important aspect is to realise and recognize the symptoms, which will prevent any future complications. Antibiotics may be prescribed for this.
Ques. What are the factors that may affect hearing? (3 Marks)
Ans. Constant exposure to loud noise from speakers, industrial or occupational noises from factories, or construction, noise from firecrackers, or some diseases like meningitis may rupture the eardrum, leading to hearing loss. Sometimes, hearing can also be lost due to age factors, or wax build-up. Medications like viagra and chemotherapy may also hamper the inner ear.
Ques. What is the importance of hearing? (3 Marks)
Ans. To be able to connect with the world, form relationships, understand one another, and listen to others' problems, the ability of hearing is imperative. It is an indispensable part of our lives. Lack of hearing prevents us from participating in important life events. Studies have shown that loss of hearing has often led to conditions like the desire to remain isolated, depression, and other chronic diseases. Hearing loss may be partial, or total in a human being.
Ques. Name some types of hearing loss. (3 Marks)
Ans. Conductive hearing loss, mixed hearing loss, and sudden sensorineural hearing loss are some common types of conditions that affect people. It is crucial that you get treated as soon as you notice symptoms, for if you delay, it might reduce the chances of getting better through medication. Later people can depend upon hearing aids for this.
Ques. What happens to a person in vertigo? (3 Marks)
Ans. Vertigo is a condition when a person cannot understand or perceive motion correctly. This happens due to failure of the vestibular system when an otolith gets displaced from the ventricles and travels all the way to the semicircular canal. This lost otolith comes to rest over the cupola, which makes us feel like there is slight movement, even when there is none. Many congenital diseases like labyrinthitis may result because of this.
Ques. What disease affects the ears? (3 Marks)
Ans. Acoustic neuroma is a common condition that affects the ears a great deal. In this condition, a tumour starts to grow in the vestibulocochlear nerve. People may also experience ringing of the ears. There is still no knowledge about the cause of this condition. Apart from this some other diseases like ear infections, fluid flowing out of the ears, or glued ear, are some other common diseases that affect hearing.
Ques. What happens in glue ears? (3 Marks)
Ans. When the liquid present inside our ears starts to adapt to a very thick consistency, people start to face problems like difficulty in balancing, needing to hear high volumes, difficulty in sleeping, painful earaches, etc. which is especially common in children and can continue till months. This condition is caused when the eustachian tube is blocked.
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