MRI ANATOMY OF THE CRANIAL NERVES

Alexandra Borges

Radiology Dpt.

Instituto Português de Oncologia de Lisboa

SENR 2014

CRANIAL NERVES

• Olfactory: I

• Optic: II

• Oculomotor nerves: III, IV, VI

• Trigeminal nerve: (V1, V2, V3)

• Facial nerve (VII)

• Vestibulochoclear (VIII)

• Glossopharyngeal (IX)

• Vagus (X)

• Spinal accessory (XI)

• Hypoglossal nerve (XII)

CRANIAL NERVES: Anatomy

• Segments:

– Brainstem/ fascicular

– Cisternal

(cavernous sinus CNs III, IV, VI)

– Skull base

– Exocranial

Borges A, Casselman J. "Imaging the cranial nerves Part I”. Eur Radiol 17(8):2112-2125, 2007

3DFT CISS

MR FSE T2W 3DFT-CISS SE T1W pre- and post gad

3DFT-MPRAGE

TR 4000 12.25 684 11.6

TE 99 5.9 20 4.9

FA 180º 70º 90º 12º

Acq. time 3 7.14 5.31 10.51

Thick 4 0.7 2 1

Matrix 242x512 192x256 160x256 192x256

FOV 300 95 230 240

Pixel size 0.62x0.59 0.49x0.37 0.90x0.90 0.94x0.94

CNs MR IMAGING TECHNIQUE

FACIAL NERVE (CN VII)

Brainstem segment (lower pons)

Cisternal segment (CPA cistern)

Temporal bone segment:

Intracanalicular

Labyrinthine

Tympanic

Mastoid

Parotid segment

BRAINSTEM SEGMENT

Mn

CN VIn

Gn

Ln

Axial TSE T2W 3T

T2* 7T Axial CISS

Courtesy from Dr. Teresa Ferreira Courtesy from Prof. Francis Veillon

TEMPORAL BONE AND PAROTID SEGMENTS

From Ric Harnsberger Imaging anatomy

CN VII

• Facial nerve supplies:

– Motor fibers to: stapedius muscle, stylohyoid, occipitalis, posterior digastric, muscles of facial expression, buccinator and platysma

– PS fibers to lacrimal and salivary glands via the GPSN

– Taste fibers to 2 anterior thirds of the tongue via chorda tympani

VESTIBULO-COCLEAR NERVE

VII

VIIIc VIIIvi

VIIIvs

Bill’s bar

Crista falciformis

VESTIBULO-COCLEAR NERVE

Courtesy from Prof. Francis Veillon

ANT. POST.

MIP CISS

VESTIBULO-COCLEAR NERVE

Courtesy from Dr. Jan Casselman

Scarpa ganglion

Spiral ganglion

Organ of Corti

LOWER CRANIAL NERVES (IX, X, XI)

Solitary Spinal V

Ambiguous

Inf. salivatory

LOWER CRANIAL NERVES

Inf. petrous sinus

Jacobson nerve

Jugular vein

Meningeal branches

Carotid artery

EAC

Petrous bone

JUGULAR FORAMEN

JF

Pars vascularis

CN IX (GLOSSOPHARYNGEAL NERVE)

• Provides:

– Motor fibers to the palatoparyngeus

– Sensory fibers to the pharyngeal plexus (CNX)

– Sensory fibers to middle ear and PS fibers to parotid gland (via tympanic branch or Jacobson’s nerve)

– Taste fibers to the posterior third of the tongue (via lingual branch)

CN X (VAGUS NERVE)

• Longest course along the carotid space

• Contributes to pharyngeal plexus

• Gives off two major branches

– Superior laryngeal nerve

– Inferior or recurrent laryngeal nerve

CN X (VAGUS NERVE)

Superior laryngeal branch Recurrent laryngeal branch

• It also provides:

– Motor innervation to the pharyngeal muscles

– Visceral sensation from the larynx, trachea, esophagus, thoracic and abdominal viscera

– Sensory fibers to the external ear and tympanic membrane (via the auricular nerve or Arnold’s nerve)

CN X (VAGUS NERVE)

CN XI (SPINAL ACCESSORY NERVE

CN XII (HYPOGLOSSAL NERVE)

CN XII

• Major technical advances on MR hardware and software led to a dramatic increase on MR imaging resolution

• The intracranial course of CNs can now be nicely imaged: – Detailed knowledge of CN anatomy – Mastering MR technique – Adequate tailoring of imaging to the diffent segments

of the nerves

• Increase the diagnostic yield in patients presenting with CN deficits

CONCLUSIONS

Thank you very much for your attention!