PNS3 Flashcards
What 2 Functional Components (nerve fiber types) does the Trigeminal Nerve, CN V, contain?
- GSA
2. SVE
CN V Afferents mediate general sensation in what 7 areas?
- Skin of the face and anterior scalp
- Oral, nasal & paranasal mucosa (including lingual and body mucosa)
- Most Dura
- Cornea and Conjunctiva
- Teeth & Gingiva
- Nasopharyngeal mucosa
- PROPRIOCEPTION from 1st arch muscles & TMJ
CN V emerges from the lateral aspect of the Midpons as a large Sensory Root (GSA) and a smaller Motor Root (SVE). What cranial fossa is this in?
The POSTERIOR CRANIAL FOSSA.
The SVE fibers of the trigeminal nerve are limited to which branch? Which of the 3 branches contain GSA fibers?
The MANDIBULAR DIVISION of CN V = V3 is the ONLY division to contain SVE fibers. ALL divisions of CN V contain GSA fibers.
The SVE fibers from CN V are BRANCHIAL Motor Nerves or BRANCHIAL EFFERENTS. What muscle group do they innervate?
The Branchial Efferent fibers of V3 innervate the 8 muscles derived from the 1st pharyngeal arch.
What is the Sensory Ganglion that ALL GSA & SVE fibers return to before being sorted and projected to brainstem nuclei?
The TRIGEMINAL GANGLION
After exiting the Trigeminal Ganglion GSA fibers from all 3 divisions project to 3 main Sensory (brainstem) Nuclei. 1. Mesencephalic Nucleus 2. Pontine Trigeminal Nucleus 3. Spinal Trigeminal Tract & Nucleus What is the purpose of each?
- Mesencephalic Nucleus: Proprioception
- Pontine Trigeminal (Principal Sensory) Nucleus: Touch sensation from the face
- Spinal Trigeminal Tract & Nucleus: Pain & temperature.
- Note: Spinal Trigeminal also receives GSA inputs from CN VII, IX, X.
What are the 3 Sensory Nuclei that CN V sends GSA fibers to?
- Mesencephalic Nucleus
- Pontine Trigeminal (principal sensory) Nucleus
- Spinal Trigeminal Tract & Nucleus
SVE fibers of CN V arise from what Nucleus before traveling to the Trigeminal Ganglion? What part of the pons is this nucleus located in? Note: it is the same location as CN V itself.
SVE fibers arise from the MOTOR or MASTICATOR NUCLEUS in the TEGMENTUM of the PONS.
Note: Both names describe actions of the SVE fibers. Motor b/c SVE fibers are motor neurons that cause muscle contraction. Masticator b/c SVE fibers innervate the masticatory muscles associated with V3
Of the 3 sensory nuclei associated with CN V, mesencephalic, pontine trigeminal, and spinal trigeminal nuclei, which contains PRIMARY Sensory Neurons (directly receive inputs from the CN V subdivision) and which 2 contain Secondary Neurons (that receive inputs from primary neurons in the TRIGEMINAL GANGLION)?
- PRIMARY Neurons = MESENCEPHALON (proprioception)
- SECONDARY Neurons = Pontine & Spinal Trigeminal Nuclei.
The trigeminal ganglion sits in the Trigeminal Impression on the floor of the Middle Cranial Fossa in what Dural ‘cave?’
MECKEL’S CAVE
How do each of the 3 CN V divisions exit the skull? To where?
V1 - Opthalmic division - exits via the Superior Orbital Fissure to the ORBIT
V2 - Maxillary Division - Exits via the Foramen Rotundum to the PTERYGOPALATINE FOSSA
V3 - Mandibular Division - Exits via the Foramen Ovale to the INFRATEMPORAL FOSSA
Like CN III, CN IV, & CN VI what two CN V divisions pass through the Cavernous Sinus en route to leaving the middle cranial fossa? What is a danger to this?
- V1 (Opthalmic) & V2 (Maxillary) divisions pass through the cavernous sinus.
- This makes them vulnerable to compression.
Not all fibers of V1, V2, & V3 leave the skull. All 3 divisions contribute MENINGEAL BRANCHES. What do these branches do?
The CN V Meningial Branches innervate DURA of the Anterior and Middle Cranial Fossa as well as the FALX CEREBRI and TENTORIUM CEREBELLI.
The Mandibular Nerve (V3) DERMATOME cover the majority of the skin overlying the mandible and the temporal bones. However, the skin overlying the angle of the mandible is innervated cutaneus branches from another source. What? What is a possible side affect, involving referred pain, of this innervation?
- The skin overlying the mandible is innervated by Cutaneus branches of the CERVICAL PLEXUS.
- Certain people may experienced Referred Pain in here. This is an indication of a Heart Attack (MI).
What are the 5 major Cutaneous branches of the Opthalmic division of the Trigeminal Nerve (V1)?
- Supraorbital N.
- Supratrochlear N.
- Palpebral Branch of Lacrimal N.
- Infratrochlear N.
- External Nasal Branch of Anterior Ethmoid
What are the 3 major Cutaneous branches of the Maxillary division of the Trigeminal Nerve (V2)?
- Infraorbital N.
- Zygomaticofacial N.
- Zygomaticotemporal N.
What are the 3 major Cutaneous branches of the Mandibular division of the Trigeminal Nerve (V3)?
- Mental N.
- Buccal N.
- Auriculotemporal N.
What 4 Ganglia of the head are all suspended from branches of CN V & all send postganglionic fibers via terminal branches of the nerve to reach their targets?
The 4 PARASYMPATHETIC GANGLIA of the head all ‘piggyback’ with the Trigeminal Nerve to reach their destinations.
V1 has three main branches in the orbit. What is a useful pneumonic to help remember them? What are they?
NFL
- Nasociliary N.
- Frontal N.
- Lacrimal N.
The Nasociliary nerve has two branches; one that goes to the nose and one that stays in they orbit. What is the orbital branch called and what does it do?
The orbital branch is called the LONG CILIARY NERVES and have CILIARY GANGLION.
-These nerve branches convey sensation from the CORNEA (Very Sensitive). It is the Afferent Limb of the Corneal Reflex (V1-V2)
What are the 2 branches of the FRONTAL Nerve? Describe each briefly.
- SUPRAORBITAL N. Innervates forehead & scalp skin & the Frontal Sinus (couple minor branches)
- SUPRATROCHLEAR N. Innervates Conjuctiva (membrane that covers the white of eye & lines inner surface of lids), Upper Lid, skin of Forehead & Lateral Nose.
What is the purpose of the INFRATROCHLEAR N.? Note: A branch of the Nasociliary N. The Nasociliary N. enters the orbit through the annular tendon.
Infratrochlear N. innervates the lacrimal sac and related structures. Also lateral nose.
What are the 2 branches of the Nasociliary N. that innervate the nasal cavity?
ANTERIOR & POSTERIOR ETHMOIDAL NERVES
The V2, Maxillary Nerve, exits the skull through the Foramen Rotundum into what Fossa where it branches Extensively?
PTERYGOPALLATINE FOSSA.