Cranial Nerve V (Trigeminal)

Pharmacology / Cardio & Renal / Heart Failure Drugs

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The trigeminal nerve (Cranial nerve V) plays a significant role in various clinical conditions. Both herpes simplex virus-1 (HSV-1) and varicella-zoster virus (VZV) can remain dormant in the trigeminal ganglia, with VZV also able to remain dormant in the dorsal root. Herpes zoster ophthalmicus presents as a painful vesicular rash in the V1 dermatome, potentially leading to blindness due to acute keratitis. Cavernous sinus syndrome features a range of symptoms including ophthalmoplegia, Horner's syndrome, and loss of sensation in various facial regions.

An orbital floor fracture may result in injury to the infraorbital nerve, a branch of V2, causing loss of sensation and reduced vertical gaze. Injuries to the inferior alveolar nerve, a branch of V3, are often associated with dental procedures and can lead to loss of sensation in the lower facial regions. Motor lesions involving V3 cause the jaw to deviate towards the affected (weak) side. Temporomandibular disorder increases the sensitivity of V3, resulting in symptoms such as jaw pain, tinnitus, and muffled hearing. Finally, trigeminal neuralgia is characterized by recurring episodes of acute-onset shock-like pain, primarily affecting the V2 and V3 branches of the trigeminal nerve.

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1. V shield - Cranial nerve V
2. Terrifying tri-gem serpent - Trigeminal nerve
3. Hermes statue inside serpent’s body - Herpes simplex virus-1 (HSV-1) can remain dormant in the trigeminal ganglia
4. Zeus statue inside serpent’s body - Varicella-zoster virus (VZV) can remain dormant in the trigeminal ganglia
5. Zeus statue + tree roots - VZV can remain dormant in the dorsal root
6. Red blisters - Herpes zoster ophthalmicus = painful vesicular rash in V1 dermatome (e.g. forehead, bridge of nose, periorbital regions)
7. Blind one-eyed serpent - Herpes zoster ophthalmicus = acute keratitis from corneal involvement that may cause blindness in some cases
8. Rock falling over cavern - Cavernous sinus syndrome = ophthalmoplegia (CN III, IV, VI), Horner’s syndrome (postganglionic sympathetic pupillary fibers), loss of corneal sensation (V1), and loss of midface sensation (V2)
9. Fractured orb below eye of second head - Orbital floor fracture can cause injury to the infraorbital nerve, a branch of V2
10. Falling feathers near second head - Orbital floor fracture = loss of sensation in the cheek, upper lip, upper teeth/gums from damage to the infraorbital nerve; reduced vertical gaze from entrapment of inferior rectus
11. Pulling bottom tooth of third head - Dental procedures are a notable cause of injury to the inferior alveolar nerve, a branch of V3
12. Falling feathers near third head - Inferior alveolar nerve block/injury = loss of sensation in the lower lip, lower teeth/gums, and chin
13. Broken chariot near third head - Motor lesion involving V3 = jaw deviates toward affected (weak) side
14. Jaw pushed towards broken chariot - Motor lesion involving V3 = Jaw deviates towards affected (weak) side
15. Stabbing jaw + tin can helmet covering ears - Temporomandibular disorder → increased sensitivity of V3, leading to jaw pain, tinnitus, and muffled hearing
16. Lightning strike - Trigeminal neuralgia = recurring episodes of acute-onset shock-like pain in the distribution of the trigeminal nerve, primarily V2 and V3