| Facial canal | |
|---|---|
 Route offacial nerve, with facial canal labeled | |
 View of the inner wall of thetympanum. (Facial canal visible in upper left; promontory labeled at center) | |
| Details | |
| System | Skeletal |
| Nerve | Facial nerve (CN VII) |
| Identifiers | |
| Latin | canalis nervi facialis, canalis facialis |
| TA98 | A02.1.06.009 |
| TA2 | 688 |
| FMA | 54952 |
| Anatomical terminology | |
Thefacial canal (also known as theFallopian canal) is a Z-shaped canal in thetemporal bone of theskull. It extends between theinternal acoustic meatus andstylomastoid foramen. It transmits thefacial nerve (CN VII) (after which it is named).
The facial canal gives passage to thefacial nerve (CN VII) (hence the name).[1][verification needed][better source needed] Its proximal opening is at theinternal auditory meatus; its distal opening is thestylomastoid foramen. In humans, the canal is approximately 3 cm long, making it the longest bony canal of a nerve in the human body.[2][verification needed][better source needed] It is located within the middle ear region.[verification needed][better source needed]
The facial nerve gives rise to three nerves while passing through the canal: thegreater petrosal nerve,nerve to stapedius, and thechorda tympani.[3]
The proximal portion of the facial canal is termed thehorizontal part. It commences at theintroitus of facial canal at the distal end of the internal auditory meatus. The horizontal part is further subdivided into two crura: the proximal/medial[4] anterolaterally[5] directedmedial crus (orlabyrinthine segment[5]), and the distal/lateral[4] posterolaterally[5] directedlateral crus (ortympanic segment[5]); the two crura meet at a sharp angle at thegenu of facial canal (geniculum canalis facialis[6]) where thegeniculate ganglion is situated (at the genu, thegreater petrosal nerve leaves the facial canal through the hiatus of the facial canal).[4]
The lateral crus of horizontal part ends by turning sharply inferior-ward, commencing the distal-mostdescending part (ormastoid segment[5]) of facial canal which passes vertically inferior-ward, ending distally at thestylomastoid foramen. The descending part presents two openings through each of which a branch of the facial nerve passes: thenerve to stapedius enters thecanaliculus for nerve to stapedius, and thechorda tympani enters theposterior canaliculus of chorda tympani (canaliculus chordae tympani, oriter chordae posterius[7]).[8]
The labyrinthine segment is situated superior tocochlea.[5]
The canal traverses themedial wall of thetympanic cavity superior to theoval window;[citation needed] here, theprominence of the facial canal (orprominence of the aqueduct of Fallopius) upon the medial wall indicates the position of the superior portion of the facial canal.[9]: 745 The canal then curves nearly vertically inferior-ward along theposterior wall.[citation needed] The tympanic segment is closely related to the posterior and medial walls of thetympanic cavity; it passes superior to theoval window and inferior to thelateral semicircular canal.[5]
The facial canal may be interrupted in some people. This may lead to thefacial nerve being split into 2 or 3 fibres, or it may be poorly formed or congenitally absent on one side.[2]
The facial canal was first described byGabriele Falloppio.[10] This is why it may also be known as the Fallopian canal.[10]
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