![]() Superior: facial nerve and superior vestibular nerve (SVN) the facial nerve is anterior to the SVN and is separated from it laterally by Bill's bar, a vertical ridge of bone This horizontal ridge divides the canal into superior and inferior portions: Their position is most constant in the lateral portion of the meatus which is anatomically divided by the falciform crest. Superior vestibular nerve (component of CN VIII) Inferior vestibular nerve (component of CN VIII) Nervus intermedius (sensory component of CN VII)įacial motor root (motor component of CN VII) There are five nerves that run through the IAC: Labyrinthine artery (usually a branch of the AICA or basilar artery) The canal narrows laterally, and the lateral boundary is the fundus, where the canal splits into three distinct openings, one of which is the facial nerve canal. The margins of the opening are smooth and rounded, and the canal is short (1 cm), running laterally to the bone. Two ears are needed for complex hearing and brain function.The opening of the IAC, the porus acusticus internus, is located within the cranial cavity, near the posterior surface of the temporal bone. Complex hearing and brain functions are needed in noisy situations – like classrooms, at work and in social settings. Complex brain functions develop up to 10 to 12 years of age. Even a small hearing loss during these first 5 years can lead to reduced vocabulary, sentence structure and language development. From ages 1-5 expressive language begins and is defined as our vocabulary and sentence structure. ![]() Children will understand what is said to them before they can speak well. Receptive language is understanding what is being said. In general, receptive language develops first over the first three years. It is for this reason we recommend hearing reconstruction earlier than any other group. For auditory and brain development early sound stimulation is best for maximum results. In the human auditory system, the first five years of life are particularly important with the great majority of auditory brain development occurring during that time period. Developmental specialists know that this means if sound input is not received early in life, the system will not develop at a later date. Hearing is a system that has a critical period of development. ![]() Hearing Explained from CEI Medical Group on Vimeo. In the inner ear, the cochlea contains hearing nerve cells that turn the vibrational energy of sound into electrical signals to be carried by the brain via the hearing nerve. Normally, the outer ear, ear canal, eardrum and middle ear bones work together to conduct the small vibrations of sound to the inner ear. Testing during the evaluation process is used to confirm normal inner ear function. In the high majority of cases of AM, the inner ear (including the hearing nerve) is normal. Ear canal development starts 2 or 3 weeks after conception, is complete by 6 weeks and the outer ear is formed by 10 weeks after conception. The inner ear begins formation just days after conception – even before a mom knows she is pregnant. The inner ear contains the three vestibular (or balance) canals and the snail shaped cochlea where the hearing nerve is located that will carry sound signals to the brain. The middle ear includes the eardrum and three middle ear bones. The outer ear includes the pinna (also called the auricle), and ear canal. Three components are needed for normal function: the outer, middle and inner ear. Balance and hearing functions are both produced in the ear. The human auditory system begins development very early after conception. Read Atresia Microtia and Your Child Book.Atresia Microtia Overview and Treatment.
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