Upload
others
View
11
Download
0
Embed Size (px)
Citation preview
02/11/2020
1
Cranial nerves: normal anatomy and imaging
Head&Neck Neuroradiology 1st Cycle Module 1
4th‐6th November 2020
Sofie Van Cauter, MD PhD
12 pairs of cranial nerves
Motor and sensory functions of the head and neck
Purely sensory (afferent):I: olfaction II: visionVIII: hearing ‐ balance
Purely motor (efferent):III: Rectus muscles (exc. lateral) and inferior oblique mucles
IV: Superior oblique muscle
VI: Lateral rectus muscle
XI: Sternocleidomastoid, trapezius muscles
XII: Intrinsic and extrinsic tongue muscles (exc. palatoglossus, mylohyoid and digastric (ant belly))
Mixed V: Sensory facial region ‐Motor masticator muscles, tensor palatini/tympani m, mylohyoid and digastric (ant
belly) m.
VII: Taste ant 2/3 tongue ‐ Parasympathic lacrimal glands submandibular sublingual glands ‐Motor facial muscles
IX: Taste post 1/3 tongue ‐ Sensory middle ear pharynx ‐ Parasympathic parotid ‐Motor m. stylopharyngeus ‐ Viscerosensory carotid body
X: Taste epiglottis ‐ Sensory external ear/ auditory canal/eardrum ‐ Parasympathic H&N and ThorAbd ‐Motor palatoglossus, constrictor pharynx, larynx, uvula ‐ Viscerosensory larynx, oesophagus, trachea, ThorAbd organs
Cavernous sinus
Jugular foramen
Nuclei not in the brainstemDerivatives of the forebrain
Myelination not by Schwann cells
MRI
High contrast and spatial resolution
3D GE sequences!
End organ muscles!
CT Inferior to MRI
Trauma
Intraosseous segments of cranial nervesBony foramina
Romano et al. Insights into Imaging 2019
1 2
3 4
02/11/2020
2
• Sensitive nerve /extension of the brain – olfactory stimuli
• Shortest cranial nerve – enveloped by ensheating glia
: Olfactory fossa
Nasal epithelium (2,5 cm2 in roof of the nose/septum)Bipolar olfactory receptor cells (first order neurons) Not visible on MRI or CTTransethmoidal segment
O’Brien WT et al. Radiology, 2016
True olfactory nerves : receptor cellsAnterior cranial fossa
Olfactory nerve
OLFACTORY BULB AREA
CRISTA GALLI
In the olfactory fossa
Suzuki et al. AJNR 1989 – Held et al. J. Neuroradiol. 2000 – Burmeister et al. Acad Radiol 2011
Bulb Tract
length 6‐14 mm
25 mm
width 3‐7 mm 3 mmPhysiological variants: unilateral absence
Olfactory nerve
Combination of CT and MRI exam is recommended for complex cases of anosmia
Olfactory bulb Olfactory tract
Orbital gyrus Olfactory sulcus
Gyrus rectus
Olfactory nerve
In the olfactory fossa
Posterior tractus and Primary olfactory cortex Primitive cortical areas – no thalamus
Statdx
• Sensitive nerve /extension of the brain – visual stimuli
• Enveloped by oligodendrocytes
4 segments:Intra‐ocular: 1mm lamina cribrosaIntra‐orbital: 20‐30 mm: 3 meningeal layers (subarachnoid CSF in continuum intracranial compartiment‐Central retinal arteries and veins: (a. ophtalmica)Intra‐canalicular: 4‐9 mm in bony canal + ophtalmic arteryIntra‐cranial/prechiasmatic: 10‐16 mm proximal of chiasma.
Optic nerve
Intra‐ocular
Intra‐orbital
Intra‐canalicular
Intracranial
CHIASM
OPTIC TRACT
5 6
7 8
02/11/2020
3
Optic nerve
N N + S
Diameter 2,5 +/‐0,4 mm
4,2 +/‐0,6 mm
Intra‐orbital
Intracranial
CHIASM
Intracranial
Optic nerve – Posterior visual pathway
OPTIC TRACT
LATERAL GENICULATE NUCLEUS
Oculomotor nerve
Intra‐axial segment
Cisternal segment
Cavernous segment
Intra‐ocular segment
Oculomotor nuclear complexLevel superior colliculiPartly in peri‐aqueductal grey matter
Between posterior cerebellar arteryAnd superior cerebellar artery
Along free edge of the tentorium
Crosses petroclinoid ligament
Trochlear nerve
Caudal from ONCCROSSES in the brainstem –leaves DORSALLYLevel inferior colliculiPartly in peri‐aqueductal grey matter
Ambient cistern , under tentoriumInferolateral n. III
Choi et al. AJNR 2010
High resolution imaging!3D‐bTFE ( 0,3 x 0,3 x 0,25 mm)
Intra‐axial segment
Cisternal segment
Cavernous segment
Intra‐ocular segment
9 10
11 12
02/11/2020
4
Abducent nerve
Pontine tegmentum
Pontomedullary junctionUpwardsLongest cisternal course!
Interdural segment
Dorello’s canalPetroclival venous confluens: basilary venous plexus
Intra‐axial segment
Cisternal segment
Cavernous segment
Intra‐ocular segment
Trigeminal nerve
Lateral Midpons3 sensory nuclei1 motor nuclei
Anterior courseSeparate motor root!
Interdural segmentPorus trigeminusTrigeminal cistern/Meckel’s cave
Intra‐axial segment
Cisternal segment
Cavernous segment (V1/V2)
Extracranial segment
Motor root anterosuperiorlyVisible on MRI
1 51,2%
2 37,5%
3 11,2%
Largest CN
Trigeminal nerve
Lateral Midpons3 sensory nuclei1 motor nuclei
Anterior courseSeparate motor root!
Interdural segmentPorus trigeminusTrigeminal cistern/Meckel’s cave
Intra‐axial segment
Cisternal segment
Cavernous segment (V1/V2)
Extracranial segment
Sensory RootSensory Root
CN V Motor RootCN V Motor Root
CN V CN V Meckel’s CaveMeckel’s Cave
Cavernous sinus
13 14
15 16
02/11/2020
5
Cavernous sinus
CN III
CN IV
CN V1
CN V2
CN VI
Extracranial segment CN III‐VISkull base
III – IV –VI – V1 V2 V3
Superior orbital fissure – optic canal Oval foramenRound for/can – vidian for/can
Infratemporal fossa
Extracranial segment CN III‐VI
III – IV –VI – V1 V2 V3
Soft Tissue
Orbital apex
Infraorbital canal
Facial and vestibulocohlear nerve
3 nuclei pontine tegmentum
Pontomedullary junctionCerebellopontine angle
Intratemporal segmentInternal auditory canalLabyrinthine segmentTympanic segmentMastoidal segment
Intra‐axial segment
Cisternal segment
Extracranial segment
Nuclei lateral side inferior cerebellar peduncle
Intratemporal segmentInternal auditory canal
Intra‐axial segment
Cisternal segmentCerebellopontine anglePontomedullary junction (POST from VII)
Facial nerve
Superior vestibularnerve
Cochlear nerve
Inferior vestibularnerve
17 18
19 20
02/11/2020
6
Facial and vestibulocohlear nerve
Cochlear nerve
Inferior vestibularnerve
Internal auditory canal
Facial nerveSuperior vestibular
nerve
Exit internal auditory canal – CP angle Near brainstem
Inferior vestibularnerve
Facial nerve
vestibulocochlear nerve
vestibulocochlear nerve
Facial nerve (motor root)
Intermediary nerve
Facial nerve
Anterior courseSeparate motor root!
Intratemporal segmentInternal auditory canalLabyrinthine segmentTympanic segmentMastoidal segment
Intra‐axial segment
Cisternal segment
Extracranial segment
3 nuclei pontine tegmentum
Mastoidal segment
Mastoidal segment
Labyrinthine segment
Tympanic segment
Anterior genu
Tympanic segment
Glossopharyngeal ‐ Vagus nerves
Medulla Oblongata
Postolivary sulcus
Skull BaseJugular ForamenX: Ganglion vagale superior in foramen
Intra‐axial segment
Cisternal segment
Extracranial segment
X:Neck spacen. laryngeus recurrens (left:aortopulmonary / right: subclacianartery)
IX:Carotid spaceMiddle ear (Jacobson’s nerve)
Vagus nerve
Glossopharyngeal nervePostolivary sulcus
Preolivary sulcus
Jugular foramen
Olive
Acessory nerve
Nc ambiguus BULBAR PORTIONSpinal C1‐C5 SPINAL PORTION
Postolivary sulcus
Skull BaseJugular Foramen
Intra‐axial segment
Cisternal segment
Extracranial segment
Carotid spacem. SCM ‐m. trapezius
n.X
n. IX
n.XI –bulbar portion
N.XI –spinal portion
21 22
23 24
02/11/2020
7
Jugular ForamenOpening on the skull base between the occipital and the temporal bone
CE –CISS sequences
Linn et al, AJNR 30: 34-41, 2009
Jugular spine
Pars nervosa n. IX
Pars vascularis n. X and n. XI
jugular foramen
1. ICA2. Inferior petrosal sinus3. Sigmoid sinus
N. IX
N. X ‐ XIN. X ‐ XI
N. IXJugular spine
Hypoglossal nerve
Medulal Oblongata
Preolivary sulcusMultiple rootlets
Skull BaseHypoglossal canal
Intra‐axial segment
Cisternal segment
Extracranial segment
Carotid space – posterior aspectExtrinsic tongue muscles
Hypoglossal nerve
Hypoglossal canalJugular foramen
Jugular tubercle
coronal transversal
“ Dans les champs de l’observation, le hasard ne favorise ques les esprits préparés”“ Where observation is concerned, chance favours only the prepared mind”
Louis Pasteur
25 26
27