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EE 137: MR Imaging Review
of the Skull Base Foramina
and Their Lesions
Brandon W. Sur MD, MSE
Department of Imaging Sciences
University of Rochester Medical Center
Disclaimer
The author has no financial disclosure or
conflicts of interest with the presented
material in this presentation.
Objectives
 Review anatomical location of the skull base
foramina with CT images
 Review contents of each foramen
 Learn various lesions affecting each foramen with
exemplary MR images.
Cribriform Plate
Anatomy
 Thin, horizontal bony plate
with numerous foramina
transmitting nerves
 Part of the ethmoid bone
 Bounded laterally by the
lateral lamella
Contents
 Olfactory bulbs/nerves
 Anterior ethmoidal artery
(extradural)
Cribriform Plate
A
C
B
Lesions
Esthesioneuroblastoma: Axial (A),
coronal (B), and sagittal (C) T1+C images
show a heterogeneously enhancing mass
in the nasal cavity destroying the cribriform
plate and extending intracranially
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Meningioma
Esthesioneuroblastoma
Squamous cell carcinoma
Lymphoma
Melanoma
Olfactory schwannoma
Bony lesions: fibrous dysplasia,
metastases
Cribriform Plate
D
E
F
Lesions
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Meningioma
Esthesioneuroblastoma
Squamous cell carcinoma
Lymphoma
Melanoma
Olfactory schwannoma
Bony lesions: fibrous dysplasia,
metastases
Olfactory groove meningioma: Sagittal
(D), axial (E) , and coronal (F) T1+C images
show an intensely enhancing dural based
mass within the olfactory groove.
Optic Canal
Anatomy
Contents
 Located in the posterior portion of the
orbital roof
 Situated within the base of the lesser
wing of the sphenoid bone
 Optic nerve and its
meninges
 Ophthalmic artery
 Central retinal vein
 Sympathetic nerve fibers
Optic Canal
A
Optic Glioma: Axial T2 (A) shows
diffusely thickened right optic nerve in a
patient with neurofibromatosis type I.
Axial T1+C (B) shows no significant
enhancement.
Lesions
B


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Optic nerve glioma
Meningioma
Schwannoma
Lymphomatous/leukemic
infiltration
 Hemangioblastoma
 Cavernous hemangioma
 Sarcoidosis
Optic Canal
C
Optic nerve sheath meningioma:
Coronal (C) and axial (D) T1+C images
show enhancement along the left optic
nerve and extending into the optic canal.
Lesions
D
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Optic nerve glioma
Meningioma
Schwannoma
Lymphomatous/leukemic
Hemangioblastoma
Cavernous hemangioma
Sarcoidosis
Superior Orbital Fissure
Anatomy
 Located between the
lesser and greater
wings of the sphenoid
bone
 Pathway between the
cavernous sinus and
the apex of the orbit
Contents


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Oculomotor nerve
Trochlear nerve
Abducens nerve
Ophthalamic (V-1) nerve
Ophthalmic veins
Sympathetic nerve plexus
Orbital branch of middle
meningeal artery
 Recurrent branch of
lacrimal artery
Lesions




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Aneurysm
Meningioma
Pituitary tumors
Craniopharyngioma
Perineural spread of
tumor
 Lymphoma
 Orbital varix
Inferior Orbital Fissure
Contents
 Maxillary nerve
 Zygomatic nerve
 Orbital branches of
pterygopalatine ganglion
 Infraorbital vessels;
inferior ophthalmic veins
Anatomy
 Located inferior to the
superior orbital fissure
 Bounded superiorly by the
greater wing of sphenoid,
inferiorly by maxilla and orbital
process of palatine bone, and
laterally by the zygomatic
bone.
Lesions
 Meningioma
 Schwannoma
 Perineural spread of
tumor
Foramen Rotundum
Anatomy
 Located at the anterior
base of the greater wing of
the sphenoid bone
 Runs laterally obliquely
downward
Contents
 Maxillary (V-2) nerve
 Artery of the foramen
rotundum
 Emissary veins
Foramen Rotundum
A
B
Lesions
Nasopharyngeal Carcinoma: Coronal (A)
and axial (B) T1+C images show an ill-defined,
enhancing sinonasal mass extending through the
right foramen rotundum.
 Schwannoma
 Meningioma
 Nasopharyngeal
carcinoma
 Metastasis
 Perineural spread
Foramen Rotundum
C
D
Lesions
Skin Squamous Cell Carcinoma
Metastasis: Coronal (C) and axial (D)
T1+C images show enhancement along
the left foramen rotundum.
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
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Schwannoma
Meningioma
Nasopharyngeal carcinoma
Metastasis
Perineural spread
Foramen Ovale
Anatomy
 Located at the posterior base of the
greater wing of the sphenoid bone;
posterolateral to the foramen
rotundum
 Extracranial opening at the lateral
pterygoid plate
Contents
 Mandibular (V-3) nerve
 Accessory meningeal
artery
 Emissary veins
Foramen Ovale
A
B
Lesions
Meningioma: Sagittal (A) and axial (B)
T1+C images show a dural based
enhancing mass extending through the
right foramen ovale.
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Schwannoma
Meningioma
Neurofibroma
Hemangiopericytoma
Perineural spread of
tumor
Foramen Spinosum
Contents
 Meningeal branch of
mandibular (V-3) nerve
 Middle meningeal artery
Lesions
Anatomy
 Situated in the greater
wing of the sphenoid bone
 Located posterolateral to
the foramen ovale
 Perineural spread of
tumor
 Metastasis
Foramen Lacerum
Anatomy
 Situated in the occipital
bone
 Located between the
occipital condyle and
jugular tubercle
 Runs anterolaterally
Contents
 Greater petrosal nerve
 Internal carotid artery
overlies
Lesions
 Perineural spread of
tumor
 Metastasis
Stylomastoid Foramen
Anatomy
 Located in the temporal bone
 Termination of the facial canal
Contents
 Facial nerve
 Styloidmastoid artery
Stylomastoid Foramen
A
C
B
Adenoid cystic carcinoma: Coronal T1+C
(C) image shows an enhancing right parotid
gland mass extending intracranially through the
stylomastoid foramen and destroying the
temporal bone.
Schwannoma: Axial (A) and
coronal (B) T1+C images show
enhancement along the facial canal
and the stylomastoid foramen.
Lesions
 Schwannoma
 Neurofibroma
 Perineural spread of tumor
Internal Auditory Canal
Contents
Anatomy
 Located in the petrous part of the
temporal bone
 Runs laterally
 Facial nerve
 Vestibulocochlear nerves
 Labyrinthine artery
Internal Auditory Canal
A
B
Lesions
Schwannoma: Axial (A) and
coronal (B) T1+C images show a
heterogeneous, enhancing mass in
the left cerebellopontine angle
involving the left internal auditory
canal.
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
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Schwannoma
Meningioma
Epidermoid
Arachnoid cyst
Internal Auditory Canal
D
C
Bilateral Acoustic Neuromas: Axial
(C) and coronal (D) T1+C images of
neurofibromatosis type II patient show
bilateral enhancing masses in the
bilateral internal auditory canals.
Lesions
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Schwannoma
Meningioma
Epidermoid
Arachnoid cyst
Jugular Foramen
Anatomy
 Formed by the petrous part of the
temporal bone and the occipital bone
 Two compartments divided by the
jugular spine:smaller, anteromedial,
“pars nervosa” and larger,
posterolateral, “pars vascularis”
Contents
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Glossopharyngeal nerve
Inferior petrosal sinus
Vagus nerve
Spinal accessory nerves
Internal jugular vein
Ascending pharyngeal& occipital
artery branches
Jugular Foramen
B
A
Lesions
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Schwannoma
Meningioma
Glomus tumor
Metastases
Perineural spread of tumor
Glomus Tumor: Coronal (A) and axial
(B) T1+C images show a heterogeneous,
enhancing mass within the left jugular
foramen.
Jugular Foramen
C
E
Chondrosarcoma: Axial (C) and coronal (D)
D
T2 images demonstrate a T2 hyperintense lesion
in the left jugular foramen. Axial T1+C image (E)
shows heterogeneous enhancement.
Lesions
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
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Schwannoma
Meningioma
Glomus tumor
Metastases
Hypoglossal Canal
Anatomy
 Situated in the occipital
bone
 Located between the
occipital condyle and
jugular tubercle
 Runs anterolaterally
Contents
 Hypoglossal nerve
 Meningeal branch of
ascending pharyngeal
artery
 Emissary vein
Hypoglossal Canal
A
C
Meningioma: Coronal T1+C
(A) and axial T1+C (B) images
show an enhancing, dural based
mass occupying the foramen
magnum and extending into the
right hypoglossal canal.
Schwannoma: Coronal T1+C
B
D
(C) and axial T1+C (D) images
show a dumbell-shpaed (not fully
seen in these two images),
enhancing mass within the right
hypoglossal canal.
Lesions
 Meningioma
 Schwannoma
 Persistent hypoglossal
artery
Hypoglossal Canal
E
Persistent
Hypoglossal
Artery: Axial (E) and
G
coronal (F) images of CT
angiogram of the head
show persistent
hypoglossal artery within
expanded left
hypoglossal canal.
F
Dissection of Persistent
Hypoglossal Artery: Axial
Lesions
 Meningioma
 Schwannoma
 Persistent hypoglossal artery
image of CT angiogram of the
head/neck (G) shows dissection of
the persistent hypoglossal artery
within the left hypoglossal canal.
Foramen Magnum
Anatomy
 Situated in the occipital
bone
 A line drawn between the
basion and opisthion
defines the opening
Contents
 Spinal cord; medulla
oblongata and meninges
 Vertebral arteries
 Spinal arteries and nerves
Foramen Magnum
A
C
B
D
Schwannoma: Coronal T1+C (D)
Meningioma
Coronal (A), sagittal
(B) and axial T1+C
(C) images show an
intensely enhancing,
dural based mass
occupying the
foramen magnum.
image of a patient with NF2 shows
an enhancing mass within the
foramen magnum extending down to
the spinal canal.
Lesions
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Meningioma
Schwannoma
Chordoma
Neurofibroma
Conclusion
Understanding of the anatomy of the skull base foramina,
knowledge of the characteristic and differential imaging
findings of disorders affecting them, and reviewing pertinent
clinical history will allow radiologists to formulate accurate
diagnoses and present appropriate differential diagnostic
considerations.
References
Boulton MR, Cusimano MD. Foramen magnum meningiomas: concepts, classifications,
and nuances. Neurosurg Focus. 2006;14 (6): e10.
Fujita N, Shimada N, Takimoto H et-al. MR appearance of the persistent hypoglossal
artery. AJNR Am J Neuroradiol. 1995;16 (4): 990-2.
Snyder WE, Shah MV, Weisberger EC et-al. Presentation and patterns of late recurrence
of olfactory groove meningiomas. Skull Base Surg. 2011;10 (3): 131-9.
Vogl T, Brüning R, Schedel H et-al. Paragangliomas of the jugular bulb and carotid body:
MR imaging with short sequences and Gd-DTPA enhancement. AJR Am J Roentgenol.
1989;153 (3): 583-7.
Vogl TJ. Differential Diagnosis in Head and Neck Imaging. Thieme. 1999