See mnemonic for the position of the nerves in the IAC. Inferior: cochlear nerve and inferior vestibular nerve (IVN) the cochlear nerve is situated anteriorly 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 IAM: 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. S2CID 12712839.The opening of the IAM, the porus acusticus internus, is located within the cranial cavity, near the posterior surface of the temporal bone. European Archives of Oto-Rhino-Laryngology. "Fetal development of the tympanic part of the facial canal". "Three-dimensional study of the facial canal using microcomputed tomography for improved anatomical comprehension". ^ a b Shin KJ, Gil YC, Lee JY, Kim JN, Song WC, Koh KS (October 2014).Otolaryngologic Clinics of North America. "Anatomie Variations and Anomalies Involving the Facial Canal". "Imaging of the facial canal by means of multiplanar angulated 2-D-high-resolution CT-reconstruction". ^ Weiglein AH, Anderhuber W, Jakse R, Einspieler R (1994).An investigation based on cadaver dissections and computed tomography". "Postnatal development of the facial canal. This is why it may also be known as the Fallopian canal. The facial canal was first described by Gabriele Falloppio. This may lead to the facial nerve being split into 2 or 3 fibres, or it may be poorly formed or congenitally absent on one side. The facial canal may be interrupted in some people. At the internal auditory meatus, the facial nerve together with its intermediate nerve, enters through the anterosuperior part, and the vestibulocochlear nerve enters through the posteroinferior part into the facial canal. The facial canal contains the facial nerve (CN VII), after which it is named. The prominence of the facial canal (or prominence of the aqueduct of Fallopius) indicates the position of the bony facial canal in which the facial nerve is contained this canal traverses the medial wall of the tympanic cavity above the oval window, and behind this it curves nearly vertically downward along the posterior wall. The narrowest part is located at the beginning of the labyrinthine segment and midpoint of tympanic segment. The mastoid segment starts from the second bend of the facial canal, going downwards, towards the stylomastoid foramen. It lies superior to the oval window and inferior to the lateral semicircular canal. It is closely related to the posterior and medial walls of the tympanic cavity. The tympanic segment starts from the geniculate ganglion and until the second bend of the facial canal. Initially, it runs anterolaterally before turning sharply posterolaterally at the geniculate ganglion (first bend of the facial canal). The labyrinthine segment runs from the internal auditory meatus to the geniculate ganglion, superior to cochlea. It contains the facial nerve (CN VII), after which it is named. It is located within the middle ear region, according to its shape it is divided into three main segments: the labyrinthine, the tympanic, and the mastoidal segment. In humans it is approximately 3 cm long, which makes it the longest human osseous canal of a nerve. The facial canal runs from the internal auditory meatus to the stylomastoid foramen. It runs from the internal acoustic meatus to the stylomastoid foramen. The facial canal ( canalis nervi facialis), also known as the Fallopian canal, is a Z-shaped canal running through the temporal bone of the skull.
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