CN5 Trigeminal nerve Flashcards
What is cranial nerve 5?
Trigeminal nerve
What is the route of the CN5 trigeminal nerve from its origin to its innervation?
Trigeminal ganglion lateral to cavernous sinus
divides into branches
How many branches of the CN5 trigeminal nerve are there?
Three
What are the branches of the CN5 trigeminal nerve?
Opthalmic
Maxillary
Mandibular
What is the route of the opthalmic division of the CN5 trigeminal nerve from its origin to its innervation?
Passes through cavernous sinus
through superior orbital fissure
into orbit
What is the route of the maxillary division of the CN5 trigeminal nerve from its origin to its innervation?
Passes through cavernous sinus
through foramen rotundum
into the pterygopalatine fossa
What is the route of the mandibular division of the CN5 trigeminal nerve from its origin to its innervation?
Passes through foramen ovale
into the infratemporal fossa
What are the functions of the CN5 trigeminal nerve?
General sensory - opthalmic, maxillary and mandibular branches supply corresponding regions of face
Motor - mandibular branch supplies muscles of mastication
What are the causes of damage to the cutaneous branches of the CN5 trigeminal nerve?
Facial trauma
Orbital trauma
How are the functions of the CN5 trigeminal nerve tested?
General sensory - test sensation in dermatomal areas relating to opthalmic, maxillary and mandibular branches, corneal reflex
Motor - test muscles of mastication
What is the corneal reflex?
Gently touching the cornea
should cause blinking of both eyes
Whar are the nerves involved in the corneal reflex?
General sensory - trigeminal nerve, opthalmic branch on same side
Motor - facial nerve, temporal and zygomatic branches supplying orbicularis oculi on both sides
What is an important branch of the maxillary branch of the CN5 trigeminal nerve?
Infraorbital nerve
What is the function of the infra-orbital nerve?
General sensory - lateral nose, lower eyelid, upper lip
What is the route of the infra-orbital nerve from its origin to its innervation?
Passes over floor of orbit
then through the infra-orbital foramen
What are the causes of damage to the infra-orbital nerve?
Fracture of floor of orbit
How does damage to the infra-orbital nerve present?
Loss of sensation over lower eyelid, lateral nose and upper lip
What are the most important branches of the mandibular branch of the CN5 trigeminal nerve?
Inferior alveolar nerve
Lingual nerve
What is the route of the inferior alveolar nerve?
Enters mandibular foramen
travels through the mandible bone
emerges from the mental foramen
What is the continuation of the inferior alveolar nerve?
Mental nerve
Where does the inferior alveolar nerve become the mental nerve?
When it emerges from the mental foramen
What are the functions of the mental nerve?
General sensory - chin, lower lip
What is the route of the lingual nerve?
Runs medially to inferior alveolar nerve
to tongue
What is the function of the lingual nerve?
General sensory - anterior two thirds of tongue
What are the causes of damage to the inferior alveolar nerve, mental nerve?
Fracture of mandible
How does damage to the inferior alveolar nerve, mental nerve present?
Loss of sensation over chin and lower lip
What are the effects of damage to the ophthalmic branch of the CN5 trigeminal nerve on the eye?
Loss of sensation over conjunctiva and cornea
loss of corneal reflex
What are the consequences of loss of the corneal reflex?
Particles in eye not felt, no blinking to remove them
damage to cornea, may lead inflammation and scarring, loss of vision
