Perilymph: Fluid surrounding the membranous labyrinth

The membranous labyrinth is a series of fluid-filled tubes and chambers located within the bony labyrinth of the inner ear. It is responsible for detecting sound waves and maintaining balance. The fluid that surrounds the membranous labyrinth is called perilymph.

Perilymph vs. Endolymph

It is important to understand the difference between perilymph and endolymph, as both are fluids present in the inner ear.

- Perilymph: Perilymph is the fluid that fills the space between the membranous labyrinth and the bony labyrinth. It is similar in composition to cerebrospinal fluid (CSF) and has a high concentration of sodium ions and a low concentration of potassium ions. Perilymph helps to protect and support the delicate structures of the inner ear.

- Endolymph: Endolymph, on the other hand, is the fluid that fills the membranous labyrinth itself. It has a high concentration of potassium ions and a low concentration of sodium ions. Endolymph is important for the function of sensory cells in the inner ear, as it helps to transmit sound and balance information to the brain.

Functions of Perilymph

1. Mechanical Support: Perilymph provides mechanical support and cushioning to the delicate structures of the inner ear, including the sensory hair cells. It helps to protect these cells from damage caused by the movement of the head or exposure to loud noises.

2. Conducting Sound Waves: Perilymph plays a crucial role in transmitting sound waves from the outer ear to the sensory cells in the cochlea. Sound waves cause vibrations in the bony labyrinth, which are then transmitted to the perilymph and ultimately to the sensory hair cells.

3. Maintaining Ionic Balance: Perilymph helps to maintain the appropriate ionic balance in the inner ear. The high concentration of sodium ions in perilymph is essential for the proper function of sensory cells and their ability to transmit signals to the brain.

In conclusion, the fluid surrounding the membranous labyrinth of a rabbit is called perilymph. It provides mechanical support, conducts sound waves, and helps maintain the ionic balance necessary for proper auditory and vestibular function.