Pars flaccida of tympanic membrane

Pars Flaccida of Tympanic Membrane

The pars flaccida is a small, slack, superior section of the tympanic membrane (eardrum). It is also known as Shrapnell's membrane. Unlike the larger, taut part of the tympanic membrane known as the pars tensa, the pars flaccida is more flexible and less structured.

Anatomy

The pars flaccida is located in the upper region of the tympanic membrane, above the lateral process of the malleus. It is bordered by the anterior malleolar fold and the posterior malleolar fold. The pars flaccida is composed of two layers: an outer layer of epidermis and an inner layer of mucosa. Unlike the pars tensa, it lacks the intermediate fibrous layer, which contributes to its flaccid nature.

Function

The primary function of the pars flaccida is to accommodate pressure changes within the middle ear. Due to its flexibility, it can absorb and dissipate pressure fluctuations, helping to protect the more rigid pars tensa and the delicate structures of the middle ear, such as the ossicles.

Clinical Significance

The pars flaccida is a common site for the formation of cholesteatoma, a type of non-cancerous skin growth that can develop in the middle ear. Cholesteatomas can lead to chronic infections and damage to the ear structures, potentially causing hearing loss. The pars flaccida's susceptibility to such conditions is due to its thin and flexible nature, which can allow for the retraction and accumulation of skin cells.

See Also

• Tympanic membrane
• Middle ear
• Cholesteatoma
• Ossicles
• Hearing loss