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Facial anatomy
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
The facial nerve exits the pons at the level of the pontomedullary junction and projects through the cerebellopontine angle via the cerebellopontine cistern towards the internal auditory meatus within the petrous temporal bone. The internal auditory canal runs laterally through this bone for approximately 1 cm whilst it gradually narrows until it creates a fundus at its lateral boundary. The facial nerve enters the internal auditory canal via the anterosuperior quadrant and runs along this canal to the fundus, where it enters the facial canal. The facial canal is approximately 3 cm long and “Z”-shaped. Despite being small, it is divided into three sections, the labrynthine, tympanic and mastoidal segments. The facial nerve traverses the facial canal, giving off branches as it does so, such as the chorda tympani and the nerve to stapedius.
Varicella zoster virus infection
Published in Avindra Nath, Joseph R. Berger, Clinical Neurovirology, 2020
Don Gilden, Randall J. Cohrs, Dallas Jones, Maria A. Nagel
Particularly well-known is weakness or paralysis of ipsilateral facial muscles associated with vesicles in the external auditory canal, the tympanic membrane (zoster oticus), or the ipsilateral anterior two-thirds of the tongue or hard palate. The combination of peripheral facial weakness and rash in any of the aforementioned areas constitutes the Ramsay Hunt syndrome. Because the facial nerve is adjacent to the eighth cranial nerve in the facial canal, patients with this syndrome often have tinnitus, hearing loss, nausea, vomiting, vertigo, and nystagmus.
Head, neck and vertebral column
Published in David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings, McMinn’s Concise Human Anatomy, 2017
David Heylings, Stephen Carmichael, Samuel Leinster, Janak Saada, Bari M. Logan, Ralph T. Hutchings
The facial nerve leaves the brainstem at the junction of the pons and medulla to enter the internal acoustic meatus and run to the genu (bend), where the geniculate ganglion is located, before passing through the facial canal within the temporal bone, lying medial to and then behind the middle ear. It then emerges through the stylomastoid foramen without its sensory and autonomic fibres, which branch off between the dura and this skull foramen. (The sensory fibres for taste, with cell bodies in the geniculate ganglion, leave just proximal to this foramen, cross the tympanic membrane and leave through the small petrotympanic fissure before the chorda tympani crosses to join the lingual nerve, p. 66).
Clinical features and treatment of endolymphatic sac tumor
Published in Acta Oto-Laryngologica, 2020
Seong Hoon Bae, Seung-seob Kim, Sang Hyun Kwak, Jin Sei Jung, Jae Young Choi, In Seok Moon
Four out of five patients with ELST presented with facial weakness; nevertheless, 5–33% was reported in other literatures [1]. This dissociation might be due to the mean tumor size; the study which reported facial weakness in 33% of the patients documented a mean tumor size of less than 3 cm. In this study, the mean tumor size was 4.5 cm (longest distance) [8]. Nonetheless, facial nerve weakness might be a remarkable symptom distinguishing ELST from other diseases altering the inner ear fluid dynamics. Due to the destructive nature of ELST, it almost shows all-directional growing vectors, including the bony facial canal [5]. Most benign tumors in the temporal bone, including schwannoma, can also intrude the facial canal and compress the nerve trunk, rather than destruct it directly. Consequently, a thorough examination of the endolymphatic sac region using MRI or CT must be considered when the patients have hearing impairment with ipsilateral facial weakness, since ELST could be confused with Bell’s palsy superimposed on Meniere’s disease or sudden hearing loss.
Endoscopic intracanalicular vestibular schwannoma excision via middle ear approach: A surgical option
Published in Acta Oto-Laryngologica, 2021
Tengku Mohamed Izam Tengku Kamalden, Khairunnisak Misron, Puvan Arul Arumugam
The other important landmark was the inferior retrotympanum. Upon drilling, the tumor was visible and identification of modiolus by drilling the basal and mid turn of the cochlea allowed us to see the cochlear nerve exiting into the IAC. The facial nerve which located superiorly to the cochlear nerve can only be detected using intraoperative facial nerve monitoring. A visual contact of the facial nerve in the IAC is almost not possible because of two facts: (1) the facial canal was much hidden anteriorly under the first genu and (2) the tumor would have been compressed thinly the facial nerve anteriorly thus making identification of the nerve physically was a challenge, unlike the cochlear nerve where the modiolus will lead us to the nerve.
Peri-operative electrically evoked auditory brainstem response assessment of facial nerve/cochlea interaction at cochlear implantation
Published in Cochlear Implants International, 2018
Nadine Schart-Morén, Karin Hallin, Sumit K. Agrawal, Hanif M. Ladak, Per-Olof Eriksson, Hao Li, Helge Rask-Andersen
The cochlea and the labyrinthine portion (LP) of the facial canal lie anatomically near one another and have been described in both histological and radio-anatomical investigations. The mean distance is approximately 0.24 mm but ranges between 0 and 0.4 mm (Fang et al., 2016; Wadin and Wilbrand, 1987). The short distance may explain why electric currents can spread to the facial nerve from cochlear implant electrodes, especially in rare conditions of cochlear-facial dehiscence (CFD). This is also observed if the otic capsule is diseased like in malformations or after temporal bone fractures, or if unusual high stimulus levels are required, as in otospongiosis.