Download The cerebello-pontine angle

Anatomy Primer
The cerebello-pontine angle
T he basics. The cerebello-pontine angle is the space bound by the cerebellum, pons and temporal bone
and contains the short intracranial courses of the fifth, seventh and eighth cranial nerves. By far the most
comm on pathology in this area is the acoustic neurom a (or, m ore correctly, schw annoma) which
classically gives rise to sensorineural deafness, ipsilateral facial palsy, ipsilateral cerebellar signs and
trigeminal sensory loss.
Coronal MRI of the pons
Five nerves enter the internal auditory canal:
• Facial
• Intermediate (usually enters with the facial
nerve, but som etim es travels with the
superior vestibular nerve)
• Cochlear
• Superior & inferior vestibular nerves
V
VI
VII
Basal vein of Rosenthal
VIII
Trigeminal Nerve
Internal Auditory Canal
Pons
This image demonstrates the relationship
betw een the nerves running in the
internal auditory canal and the trigem inal
nerve.
Nerves VII and VIII
Intermediate nerve
Facial nerve
Superior
Sagittal MRI of the internal auditory meatus
Vertical crest
(Bill’s bar)
Superior
vestibular nerve
Anterior
Transverse bar
Facial Nerve
Posterior
Cochlear nerve
Inferior
Inferior
vestibular
nerve
Acoustic neuromas usually (85%) arise from the
inferior vestibular nerve, less often (10%) the superior
vestibular nerve and never the cochlear nerve. The
facial and cochlear nerves are pushed forward by a
tum our of the inferior vestibular nerve.
Cochlear Nerve
Vestibular Nerves Unresolved
superior and
inferior nerves
“Suppliers of advanced neuro embolisation coils”
16
ACNR • VOLUME 2 NUMBER 3 JULY/AUGUST 2002
Section
Anatomy
Primer
Justin Cross and Alasdair Coles
Large cerebello-pontine angle lesions may compress the
pons, the ipsilateral cerebellar hemisphere, the trigem inal
nerve anteriorly and superiorly, and the IX, X and XI nerves
posteriorly. Although the sixth cranial nerve emerges from
the anterior pons betw een the fifth and seventh nerves, it
imm ediately runs upwards into the subarachnoid space
around the basilar and so usually avoids compression from
cerebello-pontine angle lesions.
Axial section of the pons
Basilar Artery
Cochlear Nerve
Cochlear
Lateral Semicircular Canal
Posterior Semicircular Canal
Middle
Cerebellar
Peduncle
Facial Colliculus
Vestibular Nerve
Flocculus
Cerebello-pontine angle lesions
•
•
•
•
75% acoustic schwannoma
10% meningioma
5% epidermoid
Rare:
• Metastases
• Paraganglioma (glomus
jugulare tumours)
• Other schwannomas (facial
and trigeminal)
• Vascular lesions
V
Internal
auditory
canal
VI
VII, VIII
References
IX, X, XI
University of California Acoustic Neuroma team
http://itsa .ucsf .edu/~rkj /IndexAN .html
Johns Hopkins Acoustic Neuroma Textbook
http://www.med. jhu. edu/radiosurgery /braintumors /ac
oustic/textbook/
Relationships of the
cranial nerves of the
cerebello-pontine angle
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ACNR • VOLUME 2 NUMBER 3 JULY/AUGUST 2002
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