[Biology Class Notes] on Tympanic Membrane Pdf for Exam

Define Tympanic Membrane – It is an ear membrane that vibrates in the reaction of the sound waves. In some of the higher vertebrates and humans formation of tympanic membranes is seen. It is present in between the outer and middle ear. The tympanic membrane is also called the eardrum or myringa. We can know the different parts of it by referring to the below tympanic membrane diagram. Here, we will learn about the tympanic membrane anatomy.

[Image: Tympanic membrane diagram] 

The main function of the tympanic membrane is to transmit sound from the air to the ossicles inside the middle ear and also to the oval window in the fluid-filled cochlea. People with ruptured tympanic membranes have extreme difficulty in hearing and possibly it might even result in the complete loss of hearing. 

Tympanic Membrane or Eardrum Structure 

The tympanic membrane structure is oriented obliquely in the anteroposterior, mediolateral, and superoinferior planes, consequently, its super posterior end lies lateral to its anterior inferior end. The structure of the tympanic membrane relates to the middle cranial fossa and posteriorly to the ossicles and facial nerve, inferiorly to the parotid gland and anteriorly to its anteroinferior 

Parts of Tympanic Membrane 

The tympanic membrane is divided into two membranes: pars flaccida and pars tensa. Pars flaccida lies above the lateral process of the malleus between the notch of rivinus and the anterior and posterior malleal folds and it consists of the two layers which appear slightly pinkish in hue. And the pars tensa consists of the three main layers: skin, fibrous tissue, and mucosa. The periphery of the pars tensa forms the fibrocartilaginous ring called Gerlach’s ligament. The middle fibrous layer consists of radial, circular and parabolic fibers and which encloses the handle of the malleus. Pars tensa is comparatively more robust and commonly associated with perforation. 

Layers of Tympanic Membrane

The tympanic membrane mainly consists of three layers: the outer layer, the middle layer, and the inner layer. The outer layer is continuous along with the skin on the external canal and the inner layer is continuous with the mucous membrane lining the middle ear. The middle layer is between the two, a layer of radicle and circular fiber which gives the fiber its tension and stiffness. The tympanic membrane is well supplied with the blood due to blood vessels and it is extremely sensitive to pain because of its sensory nerve fibers. 

Tympanic Membrane or Eardrum Anatomy

According to the tympanic membrane anatomy, it is the stiff, translucent, and diaphragm-like structure. It moves synchronously in response to the variations in air pressure, which constitute the sound waves. This drum vibrates through the ossicular chain to the cochlea, where the mechanical energy changes to electrochemical energy and streams through the eighth cranial nerves in the brain. The tympanic membrane with the ossicles acts as a transducer, which changes one form of energy to the other form.

Did You Know?

How thick is the tympanic membrane? The tympanic membrane is the thin and circular layer of the tissue, which makes the point between the external ear and the internal ear. The tympanic membrane is approximately 0.1mm thick and eight to ten millimeters in diameter and the mass weight is around 14mg.