The dorsal utricular portion gives rise to the vestibular system, including the utricle, semicircular canals, and endolymphatic tube. The ventral saccular portion gives rise to internal ear structures involved in hearing, including the cochlear ducts and saccules. The otic vesicle forms two visible regions: a ventral saccular portion and a dorsal utricular portion. The statoacoustic, or vestibulocochlear, ganglion arises as neurons delaminate during the formation of the otic vesicle and, later, the ganglion splits into cochlear and vestibular portions. Rapidly, the otic vesicle moves deep to the surface ectoderm and is instead enveloped in mesenchyme to form the otic capsule. The sides of the otic pit fold together and fuse to form a hollow piriform structure lined with columnar epithelium, called the otic vesicle. The otic placode invaginates into the mesenchyme adjacent to the rhombencephalon to form an otic pit. The otic placode is one of the first sensory placodes involved in the formation of special sensory organs to develop. Development begins as a pair of short-lived thickenings of the surface ectoderm, the otic placode or otic disc, appear dorsolateral to the hindbrain around the fourth week of development-the otic placode forms due to the induction of surface ectoderm by the nearby notochord and paraxial mesoderm. The internal ear is derived from ectoderm, and it is the first of the three anatomic parts of the ear to form. Notably, several anatomic variants and congenital conditions can arise from deviations in the typical developmental processes. While the development of the ear continues post-birth, a fetus can functionally hear by about 26 weeks of development. Each anatomic division of the ear has a distinct origin and unique developmental processes resulting in their typical form. The development of the ear requires contributions from all three germ layers and involves a sophisticated process with intricate embryologic patterning. The cochlea's organ of Corti functions to transduce auditory signals into neuronal impulses that reach the brain via the vestibulocochlear nerve. The delicate structures of the internal, middle, and external ear must function in concert to transmit sound and sense movement. The internal ear is composed of the vestibule, semicircular canals, and cochlea. The vestibule functions to sense linear acceleration, while the semicircular canals sense rotational movements.
The internal ear, or labyrinth of the ear, houses the organs of hearing and balance. The ossicles transmit sound vibrations from the tympanic membrane to the internal or inner ear. The middle ear's tympanic membrane converts energy from sound waves into mechanical energy as vibrations. The middle ear is essentially an air-filled cavity that houses three auditory ossicles: the malleus, incus, and stapes. The external ear resonates and amplifies sound, and it directs sound towards the tympanic membrane. The external ear, or outer ear, consists of the auricle or pinna, and the tubular external auditory canal ending at the tympanic cavity. The ear is an incredible organ of hearing and equilibrium divided into three anatomic parts: the external, middle, and internal ear.
0 kommentar(er)
