Trigeminal nerve Flashcards
describe the osteological landmarks, components, course and branches and supply of the trigeminal nerve CNV
what are the divisions of the trigeminal nerve CNV?
- opthalmic CNV1
- maxillary CNV2
- mandibular CNV3
where do the divisions arise from? where is this positioned?
trigeminal ganglion located in Meckel’s cave on the apex of the petrous temporal bone
where does the opthalmic V1 branch exit the skull to the face?
supra-orbital notch (foramen)
where does the maxillary V2 branch exit the skull to the face?
infra-orbital foramen
where does the mandibular V3 branch exit the skull to the face?
mental foramen
what is each arrow of the diagram pointing to?
what are the key anatomical features of the mandible?
- site for muscle attachments (masticatory and facial expression)
- foramina for passage of neurovascular structures - mental foramen, mandibular foramen
- alveolar processes which house teeth and supports the periodontium
what are the different parts of the mandible?
identify where the CNV motor and sensory roots exit the base of the brain and skull? what is this structure called?
CNV exits the brain at the pons
where does the motor nucleus of CNV arise and exit from? what kind of fibres are these?
arises and exits via the pons - special visceral efferent fibres
where do the three sensory nuclei of CNV arise and exit from? what are their names? what kind of fibres are these?
- mesencephalic nucleus of V - midbrain
- chief sensory nucleus of V - pons
- spinal nucleus of V - medulla oblongata
- all exit from the pons
- general somatic afferent fibres
what is the function of each of the sensory nuclei?
- mesencephalic - proprioception
- chief sensory - discriminative touch
- spinal - pain and temperature, and general conscious sensation for the viscera
which branch of the trigeminal nerve CNV is a mixed nerve and which are sensory only?
- CNV1 opthalmic - sensory
- CNV2 maxillary - sensory
- CNV3 mandibular - mixed
where does the opthalmic division CNV1 exit the intercranial cavity?
superior orbital fissure
where does the maxillary division CNV2 exit the intercranial cavity?
foramen rotundum
where does the mandibular division CNV3 exit the intercranial cavity?
foramen ovale
if all three divisions of CNV are affected, what does that suggest?
there is a lesion in the pons (stroke) or at the cranial base (trauma/tumour)
what may happen if the divisions of the CNV are affected in the cavernous sinus?
there is usually evidence of an effect on other nerves (CNVIII and CNIV)
what are the main branches of the opthalmic division CNV1? what does it innervate?
- frontal, lacrimal, nasociliary
- innervates scalp, forehead, conjunctiva, cornea, upper eyelid
describe the course of the opthalmic division CNV1
- pons
- trigeminal ganglion in Meckel’s cave
- lateral wall of cavernous sinus
- superior orbital fissure
- divides into frontal nerve, nasocillary nerve and lacrimal nerve
- supraorbital notch
what does the frontal nerve of CNV1 divide into? where does it innervate?
- supraorbital nerve
- supratrochlear nerve
- innervates skin of vertex, upper eyelid and forehead
what does the lactrimal nerve of CNV1 innervate?
the lacrimal gland, upper eyelid and forehead
what does the nasocillary nerve of CNV1 branch into? where does it innervate?
- long cilliary nerves
- anterior and posterior ethmoidal nerves
- infratrochlear nerve
- innervates skin of medial upper eyelid and root of nose
describe the corneal blink reflex
- eye is poked (stimulus)
- opthalmic nerve (nasociliary branch) carries stimulus to trigeminal sensory nucleus
- signal is relayed to facial motor nucleus
- sends impulses via facial nerve CNVII to the ocularis oculi muscle which closes the eye
what are the main branches of the maxillary division CNV2? what does it innervate?
- zygomatic
- infraorbital
- nasopalatine
- greater and lesser palatine
- alveolar
- innervates the lower eyelid, cheek, side of nose, upper lip, hard palate, maxillary teeth and maxillary sinus
describe the course of the maxillary division CNV2
- pons
- trigeminal nerve ganglion in Meckel’s cave
- foramen rotundum
- pterygopalatine fossa
- branches to zygomatic, infraorbital nerves, nasopalatine, greater and lesser palatine, alveolar nerves
- infraorbital foramen
where is the pterygopalatine fossa? what leads to this fossa?
- lateral to the upper aspect of the nasal cavity and nasopharynx, behind the orbit and above the hard/soft palate
- sphenopalatine foramen is in the medial wall of the pterygopalatine fossa
- pterygomaxillary fissure leads to pterygopalatine fossa
what does the zygomatic nerve of CV2 divide into? what do they innervate?
- zygomaticotemporal - skin of the temple
- zygomaticofacial - skin of the cheekbone area
what does the infraorbital nerve of CV2 innervate?
innervates midface, upper lips and lower eyelid
what does the nasopalatine nerve innervate? what is its route?
- innervates the anterior hard palate
- nasopalatine nerve enters the nasal cavity via the sphenopalatine foramen and passes through the incisive foramen
what do the greater and lesser palatine nerves innervate? what is its route?
- innervates the hard (greater palatine) and soft (lesser palatine) palate
- palatine nerves leave the pterygopalatine fossa via the palatine canal to branch into the greater and lesser palatine nerves which leave the skull via the greater and lesser palatine foramen
what do the alveolar branches divide into? what do they innervate? where do they exit the pterygopalatine fossa?
- anterior superior nerve - incisors and canines - exits via inferior orbital fissure
- middle superior nerve - premolars and 1st molar - exits via inferior orbital fissure (60% have)
- posterior superior nerve - molars - exits via pterygomandibular fissure
what happens if someone does not have the middle superior alveolar nerve (MSAN)?
the anterior superior alveolar nerve provides sensation to the premolars adn first molar instead
what nerves supply sensory innervation to the teeth on the maxilla?
- anterior superior alveolar nerve CNV2 - incisors and canine
- middle superior alveolar nerve CNV2 - premolars and first molar
- posterior superior alveolar nerve CNV2 - molars
what nerves supply sensory innervation to the gingivae and soft tissues of the maxilla?
- nasopalatine nerve CNV2 - anterior hard palate and labial gingivae of incisors and canine
- greater palatine nerve CNV2 - posterior hard palate and palatal gingivae of premolars and molars
- lesser palatine nerve CNV2 - soft palate
- anterior superior alveolar nerve CNV2 - buccal gingivae of incisors and canine
- middle superior alveolar nerve CNV2 - buccal gingivae of premolars and first molar
- posterior superior alveolar nerve CNV2 - buccal gingivae of molars
what are the main branches of the mandibular division of CNV3? what does it innervate?
- auriculotemporal
- buccal
- mental
- lingual
- muscular
- sensory innervation: anterior 2/3 of tongue, tempoauricural skin, lower lip, chin, mandibular teeth
- motor innervation: muscles of mastication
describe the course of the mandibular division of CNV3
- pons
- trigeminal ganglion in Meckel’s cave - motor fibres do not pass through ganglion and joins CNV3 directly
- foramen ovale
- infratemporal fossa
- branches into main trunk, anterior trunk and posterior trunk
- mental foramen
what are the boundaries of the infratemporal fossa?
- laterally: ramus of mandible
- medially: lateral pterygoid plate of sphenoid bone
- anteriorly: posterior aspect of maxilla
- posteriorly: tympanic plate, mastoid and styloid process
- superiorly: infratemporal crest of sphenoid bone
- inferiorly: angle of mandible
what does the main trunk of the mandibular division of CNV3 divide into? what do they innervate? do they have motor or sensory fibres?
- meningeal branch - meninges of middle cranial fossa - sensory
- branch to tesor tempani - muscle in middlde ear - motor
- branch to tensor veli palatini - muscle in soft palate - motor
- nerve to medial pterygoid - motor
what does the anterior trunk of the mandibular division of CNV3 divide into? what do they innervate? do they have motor or sensory fibres?
- masseteric nerve - masseter muscle - motor
- nerve to lateral pterygoid - lateral pterygoid muscle - motor
- deep temporal nerves - temporalis muscle - motor
- buccal nerve - cheek, gums, molars - sensory (not to be confused with buccal branch of facial nerve CNVII)
what does the posterior trunk of the mandibular division of CNV3 divide into? what do they innervate? do they have motor or sensory fibres?
- auriculotemporal nerve - ear, scalpl, TMJ - sensory
- inferior alveolar nerve - mandibular teeth, gums, chin - mixed
- lingual nerve - anterior 2/3 tongue - sensory
what does the inferior alveolar nerve divide into and when? what do they supply?
divides into the mylohyloid nerve and dental nerves (incisive and mental) before the mandibular foramen
* mylohyoid nerve - mylohyoid muscle - motor
* incisive nerve - mandibular incisal teeth - sensory
* mental nerve - gingiva and chin - sensory
which muscle(s) of mastication are innervated by the main trunk?
medial pterygoid muscle (nerve to medial pterygoid)
which muscle(s) of mastication are innervated by the anterior trunk?
- masseter muscle (masseteric nerve)
- lateral pterygoid muscle (nerve to lateral pterygoid)
- temporalis muscle (deep temporal nerves)
what nerves supply sensory innervation to the teeth of the mandible?
- inferior alveolar nerve CNV3 - molars and second premolar
- incisive nerve CNV3 - first molar, canine and incisors
what nerves supply sensory innervation to the gingivae of the mandible?
- lingual nerve CNV3 - lingual gingivae from molars to incisors
- buccal nerve CNV3 - buccal gingivae of molars
- mental nerve CNV3 - labial gingivae of premolars, canines and incisors
what other nerve does the lingual nerve carry? what other nerve is it a branch of? what does it innervate?
carries the chorda tympani nerve which is a branch of the facial nerve CNVII tjhat innervates taste receptors on the anterior 2/3 of the tongue - sensory
describe the innervation of the tongue
- general sensation to anterior 2/3 via lingual nerve of CNV3
- special sensation (taste) to anterior 2/3 via chorda tempani nerve of CNVII
- general and special sensation (taste) to posterior 1/3 via glossopharyngeal nerve CNIX
- motor innervation to intrinsic muscles, genioglossus, hyoglossus, styloglossus via hypoglossal nerve CNXII
what nerve innervates the angle of the mandible?
the cervical plexus with the great auricular nerve (C2 & C3)
apart from the muscles of mastication, what other muscles does the mandibular branch of CNV3 supply?
- tensor tympani muscles in the middle ear
- tensor palati via the branch to the medial pterygoid
- mylohyoid and anterior belly of digastric via inferior alveolar branch
describe the jaw jerk reflex
- gently tap semi-open mandible (stimuli)
- stretches muscle spindles and mechanoreceptors detect
- sensory impulse travels via CNV3 to the mesecephalic nucleus of the CNV in the pons
- the motor nucleus of CNV sends signals back via CNV3 to the masseter muscle to contract and close the jaw
