Sulcus spiralis internus

Sulcus spiralis internus is a structure found in the cochlea of the inner ear. It is a groove that separates the scala media and the scala tympani, two of the three fluid-filled spaces in the cochlea. The sulcus spiralis internus is an important part of the auditory system, as it helps to facilitate the transmission of sound waves from the outer ear to the inner ear.

Anatomy

The sulcus spiralis internus is located in the cochlea, a spiral-shaped structure in the inner ear. The cochlea is divided into three fluid-filled spaces: the scala vestibuli, the scala media, and the scala tympani. The sulcus spiralis internus separates the scala media from the scala tympani.

The scala media, also known as the cochlear duct, contains the organ of Corti, which is responsible for converting sound vibrations into electrical signals that can be interpreted by the brain. The scala tympani, on the other hand, is filled with perilymph, a fluid that plays a crucial role in the transmission of sound waves through the inner ear.

Function

The primary function of the sulcus spiralis internus is to separate the scala media and the scala tympani. This separation is crucial for the proper functioning of the auditory system. By keeping these two spaces distinct, the sulcus spiralis internus helps to ensure that sound waves are transmitted efficiently and accurately from the outer ear to the inner ear.

In addition to this, the sulcus spiralis internus also plays a role in maintaining the balance of fluids in the cochlea. It helps to prevent the mixing of endolymph, the fluid in the scala media, with perilymph, the fluid in the scala tympani. This is important because the different chemical compositions of these fluids are essential for the functioning of the organ of Corti.

Clinical significance

Abnormalities or damage to the sulcus spiralis internus can lead to hearing loss or other auditory disorders. For example, a condition known as Meniere's disease is associated with an excess of endolymph in the scala media, which can be caused by a breakdown in the barrier formed by the sulcus spiralis internus.