Inner ear structure
The Structure of Inner Ear
The inner ear is the essential part of the organ of hearing, receiving the ultimate distribution of the auditory nerve. It also called the labyrinth.
Inner ear consists of two parts: the osseous labyrinth, a series of cavities within the petrous part of the temporal bone, and the membranous labyrinth, a series of communicating membranous sacs and ducts, contained within the bony cavities.
The osseous (or bony) labyrinth:
Bony labyrinth is the rigid outer wall of the inner ear. It consists of three parts: vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a clear fluid called "perilymph".
The vestibule and semicircular canals are concerned with vestibular function (balance), whereas the cochlea is concerned with hearing.
Within the bony labyrinth is a membranous labyrinth (filled with endolymph), which is also divided into three parts:
1) Three semicircular ducts
2) Two saclike structures, the saccule and utricle, located in the vestibule.
3) The cochlear duct
Cochlea:
The cochlea is the medial portion of the inner ear that looks remarkably like a snail shell, it forms the anterior part of the labyrinth, it is conical in form, and placed almost horizontally in front of the vestibule.
The cochlea's hollow tube is about 35 mm in length and 2 mm in diameter, it consists of 2.75 turns. The start of the cochlea, where the oval and round windows are located is known as the basal end, while the other end, the inner tip is known as the apical end (or apex).
The tube of the cochlea is divided into three chambers:
1) The scala vestibuli: forms the upper chamber and at the base of this chamber is the oval window.
2) The scala tympani: forms the lowermost of the three chambers. It too has a basal aperture, the round window, which is closed by an elastic membrane.
A thin bony shelf called osseous spiral lamina divides Scala
The inner ear is the essential part of the organ of hearing, receiving the ultimate distribution of the auditory nerve. It also called the labyrinth.
Inner ear consists of two parts: the osseous labyrinth, a series of cavities within the petrous part of the temporal bone, and the membranous labyrinth, a series of communicating membranous sacs and ducts, contained within the bony cavities.
The osseous (or bony) labyrinth:
Bony labyrinth is the rigid outer wall of the inner ear. It consists of three parts: vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a clear fluid called "perilymph".
The vestibule and semicircular canals are concerned with vestibular function (balance), whereas the cochlea is concerned with hearing.
Within the bony labyrinth is a membranous labyrinth (filled with endolymph), which is also divided into three parts:
1) Three semicircular ducts
2) Two saclike structures, the saccule and utricle, located in the vestibule.
3) The cochlear duct
Cochlea:
The cochlea is the medial portion of the inner ear that looks remarkably like a snail shell, it forms the anterior part of the labyrinth, it is conical in form, and placed almost horizontally in front of the vestibule.
The cochlea's hollow tube is about 35 mm in length and 2 mm in diameter, it consists of 2.75 turns. The start of the cochlea, where the oval and round windows are located is known as the basal end, while the other end, the inner tip is known as the apical end (or apex).
The tube of the cochlea is divided into three chambers:
1) The scala vestibuli: forms the upper chamber and at the base of this chamber is the oval window.
2) The scala tympani: forms the lowermost of the three chambers. It too has a basal aperture, the round window, which is closed by an elastic membrane.
A thin bony shelf called osseous spiral lamina divides Scala