External cranial base

When looking at the cranium from underneath, the external surfaces of its bones are known as the external base (basis cranii externa).

There are numerous foramina and fissures on it, through which vessels and nerves pass. Let’s examine those in more detail.

Title	Contents
The foramen magnum	Vertebral arteries, anterior and posterior spinal arteries, the basilar plexus, spinal cord.

The condylar canal
(canalis condylaris)

Condylar emissary vein

The hypoglossal canal
(canalis nervi hypoglossi)

Hypoglossal nerve, venous plexus of hypoglossal canal

The mastoid foramen
(foramen mastoideum)

Mastoid emissary vein

The stylomastoid foramen
(foramen stylomastoideum)

Stylomastoid artery and vein, facial nerve

The jugular foramen
(foramen jugulare)

Internal jugular vein, posterior meningeal artery, lingual nerve, vagus nerve, accessory nerve, meningeal branch of vagus nerve

The tympanosquamous fissure
(fissura tympanosquamosa)

Deep auricular artery

The petrotympanic fissure
(fissura petrotympanica)

Anterior tympanic artery, chorda tympani (branch of facial nerve)

The mastoid canaliculus
(canaliculus mastoideus)

Auricular branch of the vagus nerve

The tympanic canaliculus
(canaliculus tympanicus)

Tympanic nerve

The external opening of the carotid canal
(apertura externa canalis carotidis)

Internal carotid plexus

Tympanic canaliculus (canaliculus tympanicus)

The foramen lacerum
(foramen lacerum)

Lesser petrosal nerve

The foramen spinosum
(foramen spinosum)

Middle meningeal artery and veins, meningeal branch of the mandibular nerve

The foramen ovale
(foramen ovale)

Meningeal branch of the middle meningeal artery, emissary vein, mandibular nerve

The lesser palatine foramen
(foramina palatina minora)

Lesser palatine arteries, veins, and nerves

The greater palatine foramen
(foramen palatina majus)

Greater palatine artery, vein, and nerve

The incisive foramen
(foramen incisivum)

Nasopalatine nerve

Dictionary