Cranial Nerve V + CN VII Flashcards
What are the nuclei of CN V?
3 Sensory (Chief, mesencephalic, spinal) 1 Motor (trigeminal)
What is the attachment of CN V to the brain stem?
Laterally merging with middle cerebellar peduncle
What are the major branches of the trigeminal nerve?
Ophthalmic (sensory)
Maxillary (sensory)
Mandibular (sensory and motor)
What is the ganglia if the trigeminal nerve?
Trigeminal in posterior portion of cavernous sinus
Summarize the structure-functions of the trigeminal nerve
Sensory to the face and motor to the muscles of 1st pharyngeal arch
• Three sensory nuclei located throughout the brainstem
- most serve as sensory nuclei for other cranial nerves as well
- One motor nucleus located in the pons
- Attaches to the lateral pons
- Sensory ganglion (trigeminal/Gasserian/semilunar) located in Meckel’s cave (a space created in the cavernous dural venous sinus)
- Has three divisions
- Ophthalmic
- Maxillary
- Mandibular
Where is the sensory nucleus# of the trigeminal nerve?
Sensory ganglion (trigeminal/semilunar/gasserian) located in the middle cranial fossa lateral to the cavernous sinus
Where are the roots of the trigeminal nerve?
Attaches to the lateral portion of the pons
Situated close to the middle cerebellar peduncle
Describe the trigeminal ganglion
- Pure sensory ganglion
- Found in the middle cranial fossa
- Along the lateral wall of the cavernous venous sinus
• Divides into 3 major divisions, each serves a ”3rd” of the face
- Ophthalmic (CNV1)
- Maxillary (CNV2)
- Mandibular (CNV3), is joined by the motor root to form a single nerve
Describe the significance of the ophthalmic branch of the trigeminal nerve CN1
Sensory nerve of the orbit and surrounding area
Passes through superior orbital fissure Lateral wall of the cavernous sinus
▪Sensory supply to skin from the orbital fissure to the vertex
▪Central portion of the bridge of the nose
▪Cornea & Eyeball
▪Conjunctiva
▪Lacrimal gland
▪Ethmoid, frontal and sphenoid sinuses
▪Internal portion of nasal alae
▪Anterior-superior most portion of nasal septum
What does the ophthalmic nerve provide sensory nerve?
Sensory: Eye, Forehead, Part of Nasal Cavity, Paranasal Sinuses, Meninges (Dura mater)
Nasociliary:
Nasociliary
- Gives anterior & posterior ethmoidal branches
- Mediates corneal reflex
- Receives sensory from eyeball
What does maxillary CN V2 do?
Sensory nerve of the pterygopalatine fossa, nose and surrounding area
Passes through foramen rotundum Lateral wall of the cavernous sinus
- Communicates with the pterygopalatine ganglion
- Continues into the infraorbital foramen and exits on the face
- Sensory supply to skin below the orbit and lateral aspect of the nose
- Maxillary sinus
- Upper jaw teeth
- Area over the lateral temple
Describe the sensory locations of the maxillary CN V2
Sensory: Cheek, Upper Lip, Lower Eyelid, Upper teeth, Part of Nasal Cavity, Paranasal Sinuses, Tympanic membrane, Meninges (Dura Mater)
What is the significance of the mandibular nerve?
Sensory nerve of the oral cavity, parotid gland and surrounding area
Passes through foramen ovale into the infratemporal fossa
Does NOT pass through the cavernous sinus
- Sensory to the lower jaw teeth, area anterior to the ear and parotid gland
- Sensory to the mucosa and skin of the cheek and chin
- Motor to the muscles of mastication (temporalis, medial and lateral pterygoid and masseter), as well as anterior belly of digastric, tensor veli pallatini, tensor tympani and mylohyoid
What does the mandibular supply sensory to?
Sensory: Lower lip, Lower teeth, Chin, Anterior 2/3 of Tongue, Meninges (Dura
Mater), Temporomandibular joint
What does the mandibular nerve supply motor to?
Motor: Muscles of 1st pharyngeal arch • MAST MATT
• masseter
• temporalis
• 2 pterygoid muscles (medial & lateral) • mylohyoid
• anterior belly of the digastric
• tensor veli palatini
• tensor tympani
Describe innervation of the meninges by the trigeminal nerve
V1: falx cerebri, anterior cranial fossa and tentorium cerebelli
• V2: medial aspect of middle cranial fossa
• V3: lateral aspect of the middle cranial fossa
• Posterior cranial fossa is innervated by the cervical nerves
How do we test the trigeminal nerve?
• 1) Inspection • 2) Palpation • Muscles of mastication • 3) Touch areas of V1, V2, V3 • 4) Corneal reflex • Touch the cornea and response will be to close eye • 2 Components • V1 of CN V: Sensory to cornea of the eye • CN VII: Closes the eye • 5) Jaw-jerk reflex • Tests 2 components of V3 with reflex hammer • Sensory branch • Motor branch
What’s the significance if herpes zoster-shingles?
The herpes zoster virus remains dormant in the cell bodies of the trigeminal nerve ganglion
Reactivated viruses follow the dermatomes innervated by the nerve
Consequences may include blindness
Usually unilateral
What are the nuclei of the facial (VII) nerve?
1 Special Sensory (nucleus solitaris) 1 Motor (facial) 1 parasympathetic (superior salivatory nucleus)
Where does the facial nerve attach to the brainstem?
Ventrolateral to the Pontomedullary junction
What are the major branches
Greater petrosal (parasympathetic) Chorda tympani (special sense and parasympathetic) Motor trunk (main portion will branch further)
Where is the ganglia of the facial nerve?
Geniculate in petrous temporal bone
Summarize facial nerve function
• Motor to muscles from second pharyngeal arch
• Special sensory to tongue – taste
• Parasympathetic to pterygopalatine and
submandibular ganglia
Where are the nuclei of the facial nerve?
Nuclei:
• motor, located at the pontomedullary junction
• sensory, nucleus solitarius in the medulla oblongata
• parasympathetic, superior salivatory nucleus in the pons
What is the route of the facial nerve?
• Attaches to the brainstem at the lateral aspect of the pontomedullary junction
• Sensory ganglion is located in the temporal bone and is named the geniculate
ganglion
• Exits the cranial cavity through the internal acoustic meatus
- Travels through the temporal bone
- via facial canal
• Main motor branch exits skull through the stylomastoid foramen & passes through the parotid gland
What is the 2nd pharyngeal arch nerve?
Facial nerve
What are the nuclei of the facial nerve?
one (1) sensory, one (1) parasympathetic &
one (1) motor nucleus
Also receives general sensory fibers from the spinal
trigeminal nucleus
Where are the motor and sensory root of the facial nerve located?
Motors root and sensory root- attaches to pontomedullary junction
Situated close to the vestibulocochlear nerve
What is the route of Great petrosal?
Greater petrosal
- Parasympathetic fibers branch off at the location of the geniculate ganglion
- Meets up with the deep petrosal nerve before entering the pterygoid canal
What is the route of the Chorda tympani?
Chorda tympani
-special sensory fibers (to solitary nucleus) join the facial nerve after passing through the middle ear between the incus and stapes
- The cell bodies are located in the geniculate ganglion
- Receive its parasympathetic (efferent) fibers at the junction point
What is the route of the facial nerve?
Passes through the internal acoustic meatus
Through the bone surrounding the inner ear
Forms geniculate ganglion
Gives the greater petrosal nerve
Passes through the facial canal, gives the nerve to stapedius
Continues and receives chorda tympani
Exits stylomastoid foramen
What are the special fibers of the facial nerve?
Parasympathetic fibers arise from the superior salivatory nucleus
• attaches to brainstem in separate root– nervus intermedius
- joins the facial nerve and exits cranial cavity via internal acoustic meatus • fibers pass through the geniculate ganglion (no synapse)
- travels in the:
- greater petrosal nerve that joins the sympathetic fibers from internal carotid plexus (deep petrosal nerve) to form the nerve of the pterygoid canal – goes to the pterygopalatine ganglion
- chorda tympani nerve that “jumps onto” the lingual nerve in the infratemporal fossa and synapse in the submandibular ganglion
- Special sensory fibers travel with the nervus intermedius to the brainstem and carries caries taste sensation from the anterior 2/3rd tongue to the solitary nucleus
Describe the extracranial course of Facial nerve
- Exits the stylomastoid foramen
- MOTOR only at this point
- Gives the posterior auricular and branches to the posterior belly of digastric and stylohyoid
- Passes anteriorly into the parotid gland
- Divides into two trunks which pass through the parotid at different depths
- Because a portion of the nerve travels through the glandular tissue any infection or tumor growth will affect the nerve as well
How is the facial nerve tested?
- Crease up the forehead:
- frontalis muscle
- occipitalis muscle
- Keep eyes closed against resistance:
- orbicularis oculi
- Reveal the teeth:
* orbicularis oris - Puff out the cheeks or whistle:
* buccinator
What is the significance of facial lesions?
PNS(Lower motor lesions)
- All functions
- all functions
- parasympathetic to the nasal cavity, paranasal sinuses and lacrimal gland
- motor function and taste to the ant. 2/3 of tongue, parasympathetic to the submandibular and sublingual glands
- taste to ant. 2/3 of tongue and parasympathetic to sublingual and submandibular glands
- motor function to muscles of facial expression
What is facial nerve “bells” palsy?
Any injury that presents risk to the facial nerve may result in paralysis of associated muscles. Infection, trauma, surgery, tumors.
Contrast upper and lower motor lesions of the facial lesions?
UMN Lesion (within the cortex)
• Upper 1⁄2 side of the face is spared (“Upper spares upper”)
• Lower 1⁄2 side of the face is affected
LMN Lesion (within the brainstem/spinal cord)
• Upper and lower 1⁄2 side of the face is affected
• Complete palsy on one side of the face
