Transcript Trigeminal nerve & innervation of the tongue

Katerina Kyprianou
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Major general sensory nerve of the head
Innervates muscles of mastication
It carries somatic sensory & motor fibres
Has 3 terminal divisions:
◦ Ophthalmic nerve (V1)
◦ Maxillary nerve (V2)
◦ Mandibular nerve(V3)
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Exits from the
anterolateral surface
of the pons
◦ Large sensory root
◦ Small motor root
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Leaves the posterior
cranial fossa &
continues forward
Enters the middle
cranial fossa
◦ Passes over the medial
surface of the
temporal bone
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In the medial cranial
fossa
◦ Sensory root expands into
trigeminal ganglion
◦ Contains cell bodies of
sensory neurons
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Trigeminal depression:
where the ganglion of
CNV is found
◦ on anterior surface of
petrous part of temporal
bone
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The motor root
◦ found below & completely
separate from the sensory
root
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Arising from the
anterior border of
trigeminal ganglion are
the 3 terminal divisions
of the trigeminal nerve
in descending order:
Ophthalmic nerve/
division (V1)
Maxillary nerve/ division
(V2)
Mandibular nerve/
division (V3)
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Ophthalmic nerve
◦ Superior orbital
fissure
Maxillary nerve
◦ Foramen
rotundum
Mandibular nerve
◦ Foramen ovale
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Course:
◦ Passes forward in the dura
matter of the lateral wall of
the cavernous sinus
◦ Leaves the cranial cavity
◦ Enters the orbit
 Through the superior orbital
fissure
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Carries sensory branches
from:
◦ Eyes, conjuctiva, orbital
contents, anterior part of
scalp, lacrimal gland
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Passes forward in the dura
matter of the lateral wall of
the cavernous sinus
Leaves the cranial cavity
◦ Just inferior to opthalmic
nerve
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Enters the pterygopalatine
fossa
Carries sensory branches
from:
◦ Dura in middle cranial fossa,
teeth of upper jaw, palate,
nasopharynx
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Course
◦ Leaves the inferior margin of
trigeminal ganglion
◦ Leaves skull through foramen
ovale
◦ Motor root of trigeminal nerve
 Also passes through foramen
ovale
 Unites with the sensory
component of the mandibular
nerve outside the skull
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NOTE
◦ Mandibular nerve is the only
division of trigeminal nerve
that contains a motor
component
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Motor innervation to:
◦ 4 muscles of mastication
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Temporalis
Masseter
Medial pterygoid
Lateral pterygoid
Tensor tympani
Tensor veli palatini
Anterior belly of digastric
Mylohyoid muscles
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Sensory innervation:
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Skin of lower face
Cheek
Lower lip
Anterior part of external ear
Part of external acoustic
meatus & temporal region
Anterior 2/3 of tongue
Teeth of lower jaw
Mandible
Dura in middle cranial fossa
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Auriculotemporal nerve
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Buccal nerve
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Mental nerve
◦ Passes through
temporomandibular joint &
parotid gland
◦ Supplies the external acoustic
meatus, surface of the
tympanic membrane & temple
◦ On the surface of buccinator
◦ Supplies the cheek
◦ Exits the mandible through the
mental foramen
◦ Supplies:
 skin & mucous membrane of
the lower lip
 skin of the chin
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Attachments:
◦ Origin: (broad attachment)
 Floor of temporal fossa
 Deep surface of temporal fascia
◦ Insertion: (narrow attachment)
 Tip of medial surface of coronoid
process
 Anterior border of ramus of
mandible
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Action on mandible
◦ Elevates mandible
 Closing jaws
◦ More horizontal fibres are
retractors of jaw
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Attachments
◦ Origin:
 Inferior border & medial
surface of maxillary
process of zygomatic bone
◦ Insertion:
 Angle of mandible
 Lateral surface of
mandible
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Action on mandible
◦ Elevates mandible
◦ Superficial fibres make
limited contribution to
protrusion of mandible
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Attachments:
◦ Origin:
 Deep head: medial surface
of lateral plate of pterygoid
process and pyramidal
process of palatine bone
 Superficial head: tuberosity
& pyramidal process of
maxilla
◦ Insertion
 Medial surface of mandible
near angle
◦ Action on mandible
 Elevation
 side to side movements of
mandible
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Attachments
◦ Origin
 Upper head: roof of
infratemporal fossa
 Lower head: lateral surface of
lateral plate of pterygoid process
◦ Insertion
 Capsule of temporomandibular
joint in the region of attachment
to the articular disc and to the
pterygoid fovea on the neck of
the mandible
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Action on mandible
◦ Protrusion
◦ Side to side movements of the
mandible
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Neuralgia: sudden sharp pain in one or more
nerves that occurs without stimulation of the
pain receptor usually as a result of change in
neurological structure/ function
Sensory disorder of the sensory root of CN V
Characterized by sudden attacks of
excruciating pain
Maxillary nerve is most frequently involved
(ophthalmic nerve is least frequently involved)
Pain is initiated by: touching a sensitive
trigger zone of the skin
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Cause: Unknown
◦ Possible cause: anomalous blood vessel that
compresses the sensory root of CN V
 E.g. enlarged vessel in the foramen ovale impinging on
the mandibular division
◦ When the artery is moved away from the root the
symptoms disappear
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Treatment:
◦ Appropriate nerve roots may be sectioned or
destroyed to relieve neuralgia
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Can cause widespread anesthesia (loss of
sensation) involving:
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Corresponding anterior half of scalp
Face
Cornea & conjunctiva
Mucous membranes of nose & paranasal sinus,
mouth & anterior part of the tongue
Paralysis of muscles of mastication can also
occur