Basis Cranii Externa

An external surface of the skull base that extends from the maxillary alveolar arch to the occiput's external protuberance. Laterally the base of the skull is bordered by the temporal and infratemporal fossa.

Icon of crossfade image Comments for the borders and components of external surface of the base of skull
Basis cranii externa
The bottom view, demonstrating an external surface of the base of the skull
Click on image to switch on comments focused on the borders and the bony components that build up the basis cranii. Note that the base of the skull includes some facial skeleton bones, like the maxilla and palatine.
The list of terms: Basis cranii externa – External base of cranium
Fossa temporalis – Temporal fossa
Fossa infratemporalis – Infratemporal fossa
Cavitas nasi – Nasal cavity
Arcus alveolaris maxillae – Maxillary alveolar arch
Palatum osseum – Bony (hard) palate
Choana – Posterior aperture of the nose
Processus pterygoideus – Pterygoid process (of the sphenoid bone)
Pars petrosa – Petrous part (of temporal bone)
Pars tympanica – Tympanic part (of temporal bone)
Processus mastoideus – Mastoid process (of temporal bone)
Pars lateralis ossis occipitalis – Lateral part of the occipital bone
Squama occipitalis – Squamous part of occipital bone
Foramen magnum

Icon of crossfade image Basis cranii externa with the terminology markup
Inferior and medal communications with pterygopalatine fossa
Basis cranii externa.
The list of terms: Arcus alveolaris – Alveolar arch
Juga alveolaria – Alveolar juga (eminences)
Foramen incisivum – Incisive foramen
Canalis incisivus – Incisive canal
Palatum osseum – Bony (hard) palate
Processus palatinus maxillae – Palatine process of maxilla
Lamina horizontalis ossis palatini – Horizontal plate of palatine bone
Sutura palatina mediana – Median palatine suture
Sutura palatina transversa – Transversal palatine suture
Canalis palatinus major – Greater palatine canal
Canalis palatinus minor – Lesser palatine canal
Processus pyramidalis ossis palatini – Pyramidal process of palatine bone
Cavitas nasi – Nasal cavity
Choana – Posterior aperture of the nose
Processus pterygoideus – Pterygoid process
Lamina lateralis processus pterygoidei – Lateral plate of the pterygoid process
Lamina medialis processus pterygoidei – Medial plate of the pterygoid process
Fossa pterygoidea – Pterygoid fossa
Foramen ovale
Foramen spinosum
Tuberculum pharyngeum – Pharyngeal tubercle
Foramen lacerum
Tuberculum articulare – Articular tubercle
Fossa mandibularis – Mandibular fossa
Fissura petrotympanica – Petrotympanic (glasserian) fissure
Canalis caroticus – Carotid canal
Fossula petrosa – Petrosal fossula
Canaliculus tympanicus – Tympanic canaliculus
Foramen jugulare – Jugular foramen
Fossa jugularis – Jugular fossa
Foramen stylomastoideum – Stylomastoid foramen
Canalis n. facialis – Canal for the facial nerve
Processus styloideus – Styloid process
Processus mastoideus – Mastoid process
Incisura mastoidea – Mastoid notch
Sulcus a. occipitalis – Groove for occipital artery
Protuberantia occipitalis externa – External occipital protuberance
Linea nuchalis superior – Superior nuchal line
Linea nuchalis inferior – Inferior nuchal line
Crista occipitalis externa – External occipital crest
Foramen magnum

Icon of crossfade image Cranial base to and the canalis musculotubarius
Cranial base. Bottom and slightly dorsal view
That illustration shows canals of the base of the skull, which usually is more challenging to localize. To find canalis musculotubarius and canalis pterygoideus it is recommended to first localize the scaphoid fossa on the pterygoid process's medial plate. After escaping from the canalis musculotubarius, the cartilage of the pharyngotympanic tube attaches to the fossa scaphoidea. Follow fossa in the direction toward temporal bone, and you will find the entrance to the musculotubal canal.
Canalis pterygoideus also opens into the basis cranii externa. However, this opening settles deep in the foramen lacerum, at the base of the fossa scaphoidea mentioned above.
The list of terms: Fossa scaphoidea – Scaphoid fossa
Canalis musculotubarius – Musculotubal canal
Canalis pterygoideus – Pterygoid canal
Canalis condylaris – Condylar canal
Canalis hypoglossalis – Hypoglossal canals
First published: Jan/2020
Last update: 17/Jan/2022