This auditory tube maintains the middle ear’s air pressure equal to atmospheric pressure as the other side of air is exposed to the atmosphere. The eustachian tube helps to have a painless hearing. Hence, you will notice that during cold or infection of the respiratory system, your ears may become less audible. It is the only vent to the otherwise closed middle ear. This eustachian tube is a few millimeter-long tubes that connect the middle ear with the pharynx. Stapedius is, no doubt, the smallest muscle of the human body. Two muscles are also attached to these bones, called tensor tympani and stapedius. Moreover, they amplify the sound many times as it reaches the round window. They can temporarily shut down hearing if a sound of large amplitude hits the tympanic membrane by losing the annular ligament of stapes. Not only this, but they also act as a safety valve. The ear ossicles transfer the vibrations they receive from the tympanic membrane to the round window. It is attached with incus on one side, with the annular ligament on the attic of the middle ear, and on the other side, it is attached to the oval window.Įar ossicles play a critical role in hearing. This is the last ossicle and the smallest bone of the human body. IncusĪs seen in the image, it is the next ossicle, which is attached with malleus on one side and with the stapes on the other side. And the other end is attached to the next ossicle called the incus. This is a hammer-shaped bone, which is attached to the tympanic membrane (pars tensa part). Three bones of the middle ear ( Anatomy and Physiology by Ross and Wilson) Malleus Three ear ossicles are found in a human, namely. It has three small bones called ear ossicles. The middle ear is a densely packed portion of the ear. A closed room, with the tympanic membrane on one side and oval and round windows on another side, the only aperture of this chamber is situated at its base, called the Eustachian tube. In the above image, the region with a blue shade is in the middle ear.Īs we can see, it is the continuation of the tympanic membrane. These vibrations are transmitted to the inner ear ossicles that, in the course, help in hearing. It converts sound energy into mechanical energy in the form of oscillations. It is loose, reddish, and has malleal folds. The tympanic membrane has two basic partsĪ) Pars tensa: It is quite stretched with an attachment of the head of the malleus bone.ī) Pars flaccida. It is 9-10mm in height, 8-9mm in width, and 0.1mm in thickness, placed obliquely. The tympanic membrane acts as the barrier between the middle ear and the external ear. Ii) It also helps to avoid the entry of insects and keep the infections and dust away from the inner ear.Įar structure showing External, middle, and inner ear ( Anatomy and Physiology by Ross and Wilson) C. I) It helps to carry the sound waves to the tympanic membrane. But cerumen secreted in the outer part can be seen here too. It is devoid of glands and hair follicles. It has skin with hair follicles.Ĭerumen and pilosebaceous glands are also seen in this part and are a seat for Staphylococcus bacterial infections too.ī) The inner two-thirds of the canal is made of bone. The structure of the auditory canal has two parts.Ī) The outer one-third of the canal is made up of cartilage. One needs to pull the pinna upward, backward, and laterally to have a look at the tympanic membrane. The outer part is directed upward, backward, and medially and the inner part is directed downward, forward, and medially. The concha of pinna leads to an ‘S-shaped canal that ends at the tympanic membrane. The cartilage is used in reconstruction surgery of the middle ear or nasal bridge.ī. A perfect condensation of sound is achieved through this pinna.įurther, the skin of pinna is used for grafting like nasal ala or of hands. It’s an astonishing piece of art of nature that shows perfect engineering. It is a single piece of yellow cartilage tissue, except for the lower lobule part, which is barely a piece of flesh and skin.įunctions of the pinna: Pinna acts as a condenser it collects the sound waves from distant sources and channels them onto the tympanic membrane. The structure of the pinna has cartilage covered up with skin. It cannot be moved in humans, but in lower animals, it can be moved, like in rabbits, dogs, cows, etc. Pinna is the outer helical structure that we can see on each side of the head. Structures: External, although it may seem devoid of many structures, also has a lot. The external ear starts from the part of the ear we see, that protruding part, and is limited in the inner side by the tympanic membrane.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |