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Functions of the trigeminal nerve
- Somatic Sensory
- Somatic (Branchial) Motor
- Principle sensory nerve for the head
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Which pharyngeal arch is associated with the trigeminal nerve?
1st pharyngeal arch
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What is the sensory root of the trigeminal nerve mainly composed of?
Psuedounipolar neurons that make up the trigeminal ganglion (semilunar ganglion)
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Where can you find the trigeminal/ semilunar ganglion?
In a dural recess lateral to the cavernous sinus
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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)
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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
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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
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Where does the opthalmic nerve pass?
Superior orbital fissure
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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
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How do you test the opthalmic branch of the trigeminal nerve?
Corneal (blink) reflex by touching the cornea
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What ganglion is associated with the opthalmic branch of the trigeminal nerve?
Ciliary ganglion
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What is the ciliary ganglion?
A small group of postsynaptic parasympathetic nerve cell bodies
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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
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How does the ciliary ganglion receive sensory fibers from V1?
via the sensory or nasociliary root of the ciliary ganglion
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How does the ciliary ganglion receive presynaptic parasympathetic fibers from CN III?
via the parasympathetic or oculomotor root of the ciliary ganglion
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How does the ciliary ganglion receive postsynaptic sympathetic fibers from the internal carotid plexus?
via the sympathetic root of the ciliary ganglion
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Where do the short ciliary nerves come from?
They arise from the ciliary ganglion
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What kind of fibers do the short ciliary nerves carry?
- Postsynaptic parasympathetic fibers
- Afferent fibers from nasociliary nerve
- Postsynaptic sympathetic fibers
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What do the short ciliary nerves do?
Carry parasympathetic and sympathetic fibers to the ciliary body and the iris
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Where do the long ciliary nerves come from?
They branch off from the nasociliary nerve
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What kind of fibers do the long ciliary nerves carry?
- Postsynaptic sympathetic fibers
- Afferent fibers from iris and cornea
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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
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What do the long ciliary nerves do?
Convey postsynaptic sympathetic fibers to the dilator pupillae and afferent fibers from the iris and cornea
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What are the main branches of the Opthalmic nerve (V1)?
- Tentorial nerve
- Lacrimal nerve
- Frontal nerve
- Nasociliary nerve
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What are the branches of the frontal nerve?
- Supraorbital nerve
- Supratrochlear nerve
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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
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From an embryoloist's perspective, the maxillary branch (V2) of the trigeminal nerve innervates...
Derivatives of the maxillary prominence of the 1st pharyngeal arch
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CN V2 leaves the cranium through
Foramen rotundum in the greater wing of the sphenoid and enters the pterygopalatine fossa
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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
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Which ganglion is associated with CN V2
Pterygopalatine ganglion
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What type of fibers does the pterygopalatine ganglion have?
Parasympathetic fibers
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What kind of fibers pass through the pterygopalatine ganglion?
- Sympathetic fibers
- General sensory fibers
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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
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Where do the sympathetic fibers found in the pterygopalatine ganglion come from?
From the deep petrosal nerve (which arises from the internal carotid plexus)
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What are the branches of the zygomatic nerve?
- Zygomaticofacial nerve
- Zygomaticotemporal nerve
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What does the zygomaticotemporal do thats special?
Gives rise to a communicating branch which conveys postsynaptic parasympathetic fibers to the lacrimal gland
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How does the Maxillary nerve exit the skull?
Through the infraorbital foramen as the infraorbital nerve
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