6. Cranial Nerves 2/ Sensory and Motor Supplies to the Face, V and VII Flashcards
Modalities and nuclei of the trigeminal nerve?
General somatic afferent: Sensory
- Mesencephalic nucleus of V (for proprioception)
- Chief sensory nucleus of V (for discriminative touch)
- Spinal nucleus of V (for pain and temp + general conscious sensation for the viscera supplied by CN IX and X)
Special visceral efferent: Motor
-Motor nucleus of V (to muscle of mastication)
Modalities and nuclei of the facial nerve?
Special visceral afferent:
-Solitarius nuclei (receives taste from ant 2/3 of tongue via the chorda tympani nerve)
General visceral efferent:
-Superior salivatory nuclei (to lacrimal gland, nasal and oral cavities, sinuses, submandibular and sublingual glands)
Special visceral efferent:
-Facial nuclei (to muscle of facial expression and stapedius, stylohyoid and post belly of digastric)
What are the 3 divisions of the trigeminal nerve?
V1- Ophthalmic
V2- Maxillary
V3- Mandibular
Where do V1,V2,V3 pass through at the end of their journey prior to innervation?
V1- Ophthalmic through the supraorbital notch/foramen
V2- Maxillary through the intraorbital foramen
V3- Mandibular through the mental foramen
What part of the face is NOT supplied by the trigeminal nerve?
The angle of the mandible.
Supplied by the carotid plexus with the great auricular nerve (C2,3)
The mandibular division (V3/Vc) carries general somatic sensation but also has the motor root for the muscles of _______ (deviation to affected side if injured)
The mandibular division (V3/Vc) carries general somatic sensation but also has the motor root for the muscles of mastication (deviation to affected side if injured)
Where is the trigeminal ganglion found?
In Meckel’s cave (a cave of dura mater) ont he apex of the petrous temporal bone
The trigeminal ganglion is equivalent to a ___ ____ ___
The trigeminal ganglion is equivalent to a dorsal root ganglion
After the trigeminal ganglion the division split off into 3 different foramen, what are they called?
CN V1 passing towards the superior orbital fissure (by passing anteriorly in the lat. wall of the cavernous sinus)
CN V2 passing through the foramen rotundum (by passing anteriorly in the lat. wall of the cavernous sinus)
CN V3 passing through the foramen ovale
In cases where all 3 of the CN V divisions are affected, what is known about the lesion?
If all 3 CN V divisions are affected, the lesion must be in the pons (i.e. stroke) or at the cranial base (i.e. trauma or tumour)
What are the 5 sensory branches of the ophthalmic division of CN V?
Lacrimal Front nerve---> Supratrochlear Frontal nerve --> Supra-orbital Nasociliary --> Infratrochlear External nasal
What is accommodation of the eye?
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies.
What are branches of the maxilary division of CN V?
Main:
Infra-orbital
Zygomatic –> Zygomatico-temporal
Zygomatic –> Zygomatico-facial
Other: Nasopalatine (to nasal cavity) Greater and lesser palatine (to palate) Pharyngeal (to nasopharnyx) Alveolar (to upper teeth)
What are branches of the mandibular division of CN V?
Buccal Mental Auriculotemporal Lingual Muscular
What PS and sympathetic supply is carried in the CN V1?
PS: Via ciliary ganglion to eye for accommodation and pupil constriction. Supply to lacrimal gland via the pterygopalatine ganglion
Sympathetic: Via the cavernous sinus for pupil dilation
What does the frontal nerve supply?
Branch of CN V1
Branches in to supraorbital and supratrochlear
Supplies: Skin to vertex and upper eyelid/forehead
What does the lacrimal gland supply?
Branch of CN V1
Supplies:
- Lacrimal gland (PS secretomotor fibres from the pterygopalatine ganglion)
- Skin of lateral upper eyelid and forehead
What nerves are given off by the nasociliary nerve?
It is a branch of CN V1
Gives off: Long ciliary nerves, anterior ethmoidal nerve, posterior ethmoidal nerve then continues as intratrochlear nerve
Anterior ethmoidal nerve continues as WHICH NERVE?
The external nasal nerve
The supratrochlear, supraorbital & lacrimal nerves supply?
The supratrochlear, supraorbital & lacrimal nerves supply the vertex, forehead & upper eyelids
The anterior ethmoidal nerve continues as the ______ nasal nerve to the skin at the ___________
The anterior ethmoidal nerve continues as the external nasal nerve to the skin at the tip of the nose
The infratrochlear nerve supplies???
The infratrochlear nerve supplies the skin at the medial angle of the eye & adjacent root of nose
Branches that leads to the external nasal nerve?
V –> V1 –> Nasociliary nerve –> anterior ethmoidal –> External nasal nerve
Shingles (herpes zoster) at the tip of the nose may be a warning that the disease will also develop on the ___
Shingles (herpes zoster) at the tip of the nose may be a warning that the disease will also develop on the cornea
Why? bc the nasociliary nerve
ALSO supplies the cornea of the eye
What is supplied by CN V1?
Skin of upper eyeiid
Underlying conjunctiva on eyelid and over the cornea
What is the first limb of the corneal reflex?
CN V1
What do the anterior and posterior ethmoid nerves supply?
Ethmoidal sinuses
lateral wall of nasal cavity
nasal septum
What PS supply is carried in the CN V1?
PS via pterygopalatine ganglion to lacrimal gland, mucous glands of nose, palate, nasopharnyx
CN V2 divides to send ____ & infraorbital branches into the orbit via the _____ orbital fissure that pass through the orbit & emerge through bony ______ to supply the skin
CN V2 divides to send zygomatic & infraorbital branches into the orbit via the inferior orbital fissure that pass through the orbit & emerge through bony foramina to supply the skin
The infraorbital nerve emerges from the infraorbital foramen to supply??
the lower eyelid, cheek, nose & upper lip
What PS supply is carried by the CN V3?
PS via submandibular and otic ganglia to submandibular and sublingual glands and parotid gland
Sensory supply from CN V divisions?
V1: Scalp, eye, upper face, sinuses
V2: Middle face, palate, sinuses, nasopharnyx, nose, upper mouth
V3: Lower face, temple, anterior 2/3 tongue, mouth floor (lower teeth and gums)
The lingual nerve carries the _______ _______nerve which is a branch of CN VII
The lingual nerve carries the chorda tympani nerve which is a branch of CN VII
Where is the pain of trigeminal neuralgia felt?
Trigeminal neuralgia: terrible pain usually in CN V3 & occasionally in CN V2 distribution
What motor root is found in CN V3?
Motor root for the muscles of mastication
Note: All derivatives of the 1st pharyngeal arch
Apart from the muscle of mastication, what other muscles are supplied by CN V3?
- Tensor tympani muscle in the middle ear
- Tensor palati (the latter via the branch to medial pterygoid)
- Mylohyoid
- Anterior belly of digastric (via its inferior alveolar branch)
In the jaw jerk reflex, which nuclei in the brainstem is the synapse in?
The mesencephalic nucleus of CN V
Why? Bc it’s wanting to interpret proprioception hence NOT in chief sensory
What is the course of the CN VII?
The motor root of CN VII (to the muscles of facial expression) emerges (with the nervus intermedius) in the angle between the lower pons & the cerebellum (known as cerebellopontine angle)
CN VII with the nervus intermedius enters the petrous temporal bone at the internal acoustic meatus with CN VIII & the labyrinthine artery
CN VII with the nervus intermedius takes a tortuous course through the middle ear while giving off taste & parasympathetic branches
CN VII sends a branch to stapedius (the muscle that dampens the movement of stapes) before emerging from the stylomastoid foramen to supply (mainly) the muscles of facial expression
CN VII emerges from the stylomastoid foramen & sends branches to supply the occipitalis & auricular muscles before dividing to form a plexus within the parotid gland (superficial to the external carotid artery & retromandibular vein) that sends branches to the muscles of facial expression (plus the digastric & stylohyoid)
What is hyperacusis?
When hearing is amplified
Why is the passage of the CN VII through the internal acoustic meatus risky?
CN VII is at risk of compression at this site & such proximal injury will affect the muscles of facial expression & stapedius causing hyperacusis
What is the role of stapedius?
Muscle that dampens the movement of stapes
Where are the cell bodies for taste fibres found?
In the geniculate ganglion
At birth the _____ _______has not formed & CN VII is at risk of compression/injury during forceps delivery leading to paralysis of the facial muscles
At birth the mastoid process has not formed & CN VII is at risk of compression/injury during forceps delivery leading to paralysis of the facial muscles
What are the branches of the facial nerve CN VII?
Hint: ‘Two Zebras Befriended My Cat’
Temporal branch: To frontalis and orbicularis oculi
Zygomatic: To orbicularis oculi and upper lip muscles
Buccal: To buccinator and lip lip muscles
Marginal mandibular: To lower lip muscles
Cervical: To platysma
(branching occurring within the parotid gland)
What is the cortical control of facial nerve nuclei?
Upper motor neurone:
Upper 1/2 face = bilateral
Lower 1/2= Contralateral
lower motor neurone:
Whole face= Contralateral
Difference in the presentation of lesions of the UMN and LMNs of facial nerve?
UPM lesions e.g. stoke:
- Upper face sparing
- Contralateral weakness/paralysis of lower face
LMN lesions e.g. Bell’s palsy:
Weakness or paralysis of whole ipsilateral half
Clinical sign of CN VII injury distal to stylomastoid foramen?
Ipsilateral facial muscle paralysis
If injury to CN VII is within the petrous temporal bone or proximal to it (e.g. Bell’s palsy & acoustic neuroma), what is the presentation?
If injury is within the petrous temporal bone or proximal to it (e.g. Bell’s palsy & acoustic neuroma) then there is: Ipsilateral facial muscle paralysis
Hyperacusis
Taste disturbances (there may also be an effect on the adjacent CN VIII)
The ________ ______ branch of CN VII dips inferior to the mandible overlying the submandibular gland & consequently it is at risk during surgery on this gland
The lower lip muscles may be paralysed causing saliva to dribble from the mouth
The marginal mandibular branch of CN VII dips inferior to the mandible overlying the submandibular gland & consequently it is at risk during surgery on this gland
The lower lip muscles may be paralysed causing saliva to dribble from the mouth
In the corneal reflex, what nerve and nuclei is involved?
Afferent CN V1 (nasociliary nerve)
To the Chief sensory nucleus (discriminative touch) then synapse to —-> Facial motor nucleus
Efferent: CN VII
Direct & consensual responses = Bilateral blink response
