Skull Base Overview

Orbitosphenoid (LWS)
Presphenoid (planum sphenoidale)
Alisphenoid (GWS)
Petrous ridge
Exocciput (condylar occipital bone)
Foramen cecum
Olivary eminence
Craniopharyngeal canal
Intersphenoidal synchondrosis
Sphenooccipital synchondrosis
Median basal canal
Graphic of the skull base shows many ossification centers. Between the ossification centers of presphenoid is a cartilaginous gap called the olivary eminence, which is obliterated shortly after birth. In the midline, note the craniopharyngeal canal, sphenooccipital synchondrosis, and median basal canal. The sphenooccipital synchondrosis fuses over the first 20 years of life while the craniopharyngeal and median basal canals are rarely persistent into childhood. When persistent, these two canals can rarely be the source of meningitis.

Foramen lacerum
Pharyngeal mucosal space/surface
Carotid canal
Hypoglossal canal/CNXII
Jugular foramen/CNIX-XI
Masticator space
Foramen ovale/CNV3
Foramen spinosum/middle meningeal artery
Parotid space
Stylomastoid foramen/CNVII
Carotid space
Graphic of the skull base viewed from below shows the relationship of spaces of the suprahyoid neck to the skull base. Four spaces have key interactions with skull base: Masticator, parotid, carotid, and pharyngeal mucosal spaces. Parotid space (green) malignancy can follow CNVII into the stylomastoid foramen. Masticator space (purple) receives CNV3 while CNIX-XII enter the carotid space (red). The pharyngeal mucosal space abuts the foramen lacerum, which is covered by fibrocartilage in life.

Anterior ethmoid foramen
Olfactory bulb
Olfactory nerve (CNI)
Line dividing anterior and central skull base
Optic nerve (CNII)
Central skull base
Foramen cecum
Crista galli
Cribriform plate of ethmoid
Posterior ethmoid foramen
Lesser wing, sphenoid bone
Anterior clinoid process
Planum sphenoidale
Tuberculum sellae
Graphic of the anterior skull base seen from above shows the olfactory bulb of CNI lying on the cribriform plate. Neural structures have been removed on right, allowing visualization of numerous perforations in the cribriform plate, through which afferent fibers from olfactory mucosa pass to form the olfactory bulb. The posterior margin of the anterior skull base is formed by the lesser wing of sphenoid and planum sphenoidale. Note the foramen cecum, a small pit anterior to the crista galli, bounded anteriorly by frontal bone and posteriorly by ethmoid bone. If the anterior neuropore persists, an enlarged foramen cecum, bifid crista galli, and epidermoid along the neuropore tract are possible.

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Nov 17, 2017 | Posted by in HEAD & NECK IMAGING | Comments Off on Skull Base Overview

Full access? Get Clinical Tree

Get Clinical Tree app for offline access