The facial canal (''canalis nervi facialis''), also known as the Fallopian canal, is a Z-shaped canal running through the

temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. ...

of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

. It runs from the internal acoustic meatus to the stylomastoid foramen. It contains the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

(CN VII), after which it is named.

Structure

The facial canal runs from the internal auditory meatus to the stylomastoid foramen. In humans it is approximately 3 cm long, which makes it the longest human osseous canal of a nerve. 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. It contains the

(CN VII), after which it is named. The labyrinthine segment runs from the internal auditory meatus to the

geniculate ganglion The geniculate ganglion (from Latin ''genu'', for "knee") is a collection of pseudounipolar sensory neurons of the facial nerve located in the facial canal of the head. It receives fibers from the facial nerve. It sends fibers that supply the ...

, superior to

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory o ...

. Initially, it runs anterolaterally before turning sharply posterolaterally at the geniculate ganglion (first bend of the facial canal). The tympanic segment starts from the geniculate ganglion and until the second bend of the facial canal. It is closely related to the posterior and medial walls of the

tympanic cavity The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound. Structure On its lateral surface, it abuts the external auditor ...

. It lies superior to the

oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the in ...

and inferior to the lateral semicircular canal. The mastoid segment starts from the second bend of the facial canal, going downwards, towards the stylomastoid foramen. The narrowest part is located at the beginning of the labyrinthine segment and midpoint of tympanic segment.

Prominence

The prominence of the facial canal (or prominence of the aqueduct of Fallopius) indicates the position of the bony facial canal in which the

is contained; this canal traverses the medial wall of the

above the

, and behind this it curves nearly vertically downward along the posterior wall.

Function

The facial canal contains the

(CN VII), after which it is named. 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.

Clinical significance

The facial canal may be interrupted in some people. This may lead to the

being split into 2 or 3 fibres, or it may be poorly formed or congenitally absent on one side.

History

The facial canal was first described by

Gabriele Falloppio Gabriele Falloppio (also Gabrielle Falloppia) (1522/23 – 9 October 1562) was an Italian anatomist often known by his Latin name Fallopius. He was one of the most important anatomists and physicians of the sixteenth century, giving his name ...

. This is why it may also be known as the Fallopian canal.

Gallery

File:Slide1CAC.JPG, Lateral head anatomy detail. Facial nerve dissection. File:Occipital bone dissection.jpg, Tympanic cavity. Facial canal. Internal carotid artery. File:Gray913.png, Coronal section of right

. Prominence of the facial canal labeled at top, fourth from the left.

References

{{DEFAULTSORT:Facial Canal Foramina of the skull Ear