Home › Human Anatomy › Canals of the Temporal Bone

Canals of the Temporal Bone

Canales ossis temporalis

For medical students2 min readUpdated 2026-10-10

The temporal bone contains 7 canals in total: three major canals and four minor canals (canaliculi). Knowing their openings, trajectories, and transmitted neurovascular structures is essential for understanding head and neck topography.

Total Count7 canals (3 major, 4 minor)

NervesFacial nerve, intermediate nerve, vagus nerve branch, etc.

VesselsInternal carotid artery and accompanying veins

ConnectionsWith the middle ear cavity (tympanic cavity)

Major Canals

The temporal bone features three primary (major) canals.

Carotid Canal (Canalis caroticus)
Beginning: External aperture on the inferior surface of the petrous part.
Course: Runs anteriorly and medially, then bends (genu) and ascends vertically.
End: Internal aperture at the apex of the petrous part.
Contents: Internal carotid artery, carotid plexus of veins, and sympathetic nerves.

Facial Canal (Canalis nervi facialis)
Beginning: Fundus of the internal acoustic meatus.
Course: Follows a complex trajectory. Initially runs perpendicularly to the axis of the petrous part to the genu (Geniculum), then turns and runs parallel to the axis posteriorly (forming a bulge in the tympanic cavity), before descending vertically.
End: Stylomastoid foramen (Foramen stylomastoideum).
Contents: Facial nerve, intermediate nerve, and blood vessels.
Musculotubular Canal (Canalis musculotubarius)
Beginning: Lateral to the carotid canal, near the apex of the petrous part.
Course: Penetrates the petrous bone, divided by a bony septum into two semicanals (the semicanal for the tensor tympani muscle and the semicanal for the pharyngotympanic / auditory tube).
End: Opens into the anterior wall of the tympanic cavity.

Minor Canals (Canaliculi)

In addition to the major canals, four smaller canaliculi pass through the temporal bone.

Caroticotympanic Canaliculi (Canaliculi caroticotympanici). Originate from the posterior wall of the carotid canal (usually 2–4 openings) and end on the anterior wall of the tympanic cavity. They transmit the corresponding nerves and vessels.
Canalicular for Chorda Tympani (Canaliculus chordae tympani). Begins from the descending part of the facial canal (near the stylomastoid foramen), passes through the middle ear cavity in transit, and exits via the petrotympanic fissure (Fissura petrotympanica). It transmits the chorda tympani, a branch of the intermediate nerve.
Tympanic Canaliculus (Canaliculus tympanicus). Begins in the petrous fossa (Fossula petrosa) on the inferior surface of the petrous part, ascends, and opens via the hiatus for the lesser petrosal nerve on the anterior surface of the petrous part.
Mastoid Canaliculus (Canaliculus mastoideus). Starts from the floor of the jugular fossa (Fossa jugularis) and ends in the tympanomastoid fissure. It transmits the auricular branch of the vagus nerve.

Topographic Landmarks

To rapidly locate the canals on a skull specimen, key anatomical landmarks are used:

Jugular fossa, external carotid aperture, and the aperture of the cochlear canaliculus form a triangle, inside of which lies the entrance to the tympanic canaliculus.
Stylomastoid foramen is the primary landmark for locating the exit of the facial canal and the origin of the chorda tympani canaliculus.
Hiatuses and openings on the anterior surface of the petrous part (hiatuses for the greater and lesser petrosal nerves) indicate the level of the facial nerve genu.

Frequently asked questions

Which specific nerves and vessels pass through the caroticotympanic canaliculi?

The caroticotympanic canaliculi transmit the caroticotympanic nerves and unnamed vascular branches.

Caroticotympanic nerves serve as landmarks helping to quickly locate connections between the carotid canal and the middle ear cavity.
Vascular branches accompany the nerves, though their precise individual names are not detailed in the source texts.

The canaliculi themselves begin at the posterior wall of the carotid canal and open onto the anterior wall of the tympanic cavity.

Which exact blood vessels accompany the facial nerve within its canal?

Arteries and veins pass within the facial canal itself, though their exact names are not fully detailed inside the canal; however, a specific vessel accompanies the nerve upon its exit.

Stylomastoid vein (v. stylomastoidea) accompanies the facial nerve as it exits the stylomastoid foramen.
Arteries and veins are mentioned generally as contents of the facial canal without specific individual names.

The stylomastoid artery (a. stylomastoidea) is also noted in texts, though its direct course strictly inside the canal alongside the nerve is not described.

Is the internal acoustic meatus considered a canal of the temporal bone?

No, according to international anatomical nomenclature, the internal and external acoustic meatuses, as well as the vestibular and cochlear aqueducts, are not classified as true canals of the temporal bone.

What structures pass through the carotid canal?

It transmits the internal carotid artery, accompanying veins, and a plexus of sympathetic nerve fibers.

What are the parts of the facial canal?

The facial canal consists of three parts: labyrinthine (running perpendicular to the petrous axis), tympanic (parallel to the axis), and mastoid (descending vertical).

Where does the musculotubular canal open?

The musculotubular canal and both of its semicanals open into the anterior wall of the tympanic cavity (middle ear cavity).

Go deeper

Detailed course of the facial nerve within the petrous part
Walls of the tympanic cavity and canals opening into it
Topography of fissures on the external cranial base (petrotympanic, petrosquamous)
Relationship between inner ear structures and temporal bone canals