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Functions of the trigeminal nerve
- Somatic Sensory
- Somatic (Branchial) Motor
- Principle sensory nerve for the head
Which pharyngeal arch is associated with the trigeminal nerve?
1st pharyngeal arch
What is the sensory root of the trigeminal nerve mainly composed of?
Psuedounipolar neurons that make up the trigeminal ganglion (semilunar ganglion)
Where can you find the trigeminal/ semilunar ganglion?
In a dural recess lateral to the cavernous sinus
What are the divisions formed by the peripheral processes of the ganglionic neurons?
- 1. Opthalmic nerve (V1)
- 2. Maxillary nerve (V2)
- 3. Mandibular nerve (V3)
Where does the motor root of the trigeminal nerve go?
- Passes inferior to the trigeminal ganglion (semilunar ganglion)
- Distributed exclusively by the Mandibular nerve (V3)
- Joins with sensory fibers of V3 as it goes through foramen ovale
What makes the opthalmic nerve (V1) different from the other two branches?
- It is not a branchial nerve and does not supply pharyngeal arch derivatives
- It serves structures derived from paraxial mesoderm of frontonasal process of embryo
Where does the opthalmic nerve pass?
Superior orbital fissure
What does the opthalmic nerve supply?
- Sensory only to:
- Cornea, upper conjunctiva, mucosa of anterosuperior nasal cavity, frontal and ethmoidal sinuses, superior eyelid, forehead, scalp, skin of dorsum of external nose, anterior and supratentorial dura mater
How do you test the opthalmic branch of the trigeminal nerve?
Corneal (blink) reflex by touching the cornea
What ganglion is associated with the opthalmic branch of the trigeminal nerve?
What is the ciliary ganglion?
A small group of postsynaptic parasympathetic nerve cell bodies
From what sources does the ciliary ganglion receive fibers?
- Three sources:
- 1. Sensory fibers from CN V1
- 2. Presynaptic parasympathetic fibers from CN III
- 3. Postsynaptic sympathetic fibers from the internal carotid plexus
How does the ciliary ganglion receive sensory fibers from V1?
via the sensory or nasociliary root of the ciliary ganglion
How does the ciliary ganglion receive presynaptic parasympathetic fibers from CN III?
via the parasympathetic or oculomotor root of the ciliary ganglion
How does the ciliary ganglion receive postsynaptic sympathetic fibers from the internal carotid plexus?
via the sympathetic root of the ciliary ganglion
Where do the short ciliary nerves come from?
They arise from the ciliary ganglion
What kind of fibers do the short ciliary nerves carry?
- Postsynaptic parasympathetic fibers
- Afferent fibers from nasociliary nerve
- Postsynaptic sympathetic fibers
What do the short ciliary nerves do?
Carry parasympathetic and sympathetic fibers to the ciliary body and the iris
Where do the long ciliary nerves come from?
They branch off from the nasociliary nerve
What kind of fibers do the long ciliary nerves carry?
- Postsynaptic sympathetic fibers
- Afferent fibers from iris and cornea
Why do the long ciliary nerves have less types of fibers than the short ciliary nerves?
Because the long ciliary nerves bypass the ciliary ganglion
What do the long ciliary nerves do?
Convey postsynaptic sympathetic fibers to the dilator pupillae and afferent fibers from the iris and cornea
What are the main branches of the Opthalmic nerve (V1)?
- Tentorial nerve
- Lacrimal nerve
- Frontal nerve
- Nasociliary nerve
What are the branches of the frontal nerve?
- Supraorbital nerve
- Supratrochlear nerve
What are the branches of the nasociliary nerve?
- Sensory root of the ciliary ganglion
- Short ciliary nerve
- Long ciliary nerve
- Infratrochlear nerve
- Anterior and posterior ethmoidal nerves
From an embryoloist's perspective, the maxillary branch (V2) of the trigeminal nerve innervates...
Derivatives of the maxillary prominence of the 1st pharyngeal arch
CN V2 leaves the cranium through
Foramen rotundum in the greater wing of the sphenoid and enters the pterygopalatine fossa
What does the maxillary nerve (CN V2) do in the pterygopalatine fossa?
- Gives off two ganglionic branches to the pterygopalatine ganglion (sensory roots of the pterygopalatine ganglion that suspend it)
- Gives off the zygomatic nerve
Which ganglion is associated with CN V2
What type of fibers does the pterygopalatine ganglion have?
What kind of fibers pass through the pterygopalatine ganglion?
- Sympathetic fibers
- General sensory fibers
Where do the parasympathetic fibers found in the pterygopalatine ganglion come from?
- Facial nerve (CN VII) by way of its first branch, the greater petrosal nerve
- GPN joins the deep petrosal nerve
- Passes foramen lacerum and forms the nerve of the pterygopalatine canal
- Parasympathetic fibers from GPN synapse in pterygopalatine ganglion
Where do the sympathetic fibers found in the pterygopalatine ganglion come from?
From the deep petrosal nerve (which arises from the internal carotid plexus)
What are the branches of the zygomatic nerve?
- Zygomaticofacial nerve
- Zygomaticotemporal nerve
What does the zygomaticotemporal do thats special?
Gives rise to a communicating branch which conveys postsynaptic parasympathetic fibers to the lacrimal gland
How does the Maxillary nerve exit the skull?
Through the infraorbital foramen as the infraorbital nerve