Equine Nerve blocks Flashcards
What are the branches of the trigeminal nerve?
Ophthalmic
Maxillary
Mandibular
Which is CNV
Trigeminal
Which nerve branch do you block for peri-orbital region surgery?
Ophthalmic branch of trigeminal (sensory)
Occulomotor (motor)
Examples or periorbital surgery
Eyelid surgery
Enucleation (also need to anaesthesia optic nerve)
Removal of third eyelid
What are the 5 blocks required to fully desensitise periorbital and retrobulbar region?
Supraorbital/frontal nerve block
Lacrimal block
Zygomatic nerve block
Infratrochlear block
Retrobulbar block
Describe the supraorbital/frontal nerve block
Anaesthetises frontal branch of the ophthalmic branch
○ Frontal branch passes through the supraorbital foramen
Easy to palpate by following orbital rim
○ Pinch over narrowest point of rim
○ Index finger will fall onto supraorbital foramen
Will desensitise supper eyelid
Describe the lacrimal block
Anaesthetises lateral canthus
Place needle in lacrimal notch
○ Palpate dorsolateral rim of the orbit
○ Adjacent to lateral canthus of horses eye
Or use a line block on the lateral third of the dorsal orbital rim
Describe the zygomatic nerve block
Desensitisation of lower eye lid
Branch of the maxillary branch
○ Travels through the orbit
○ Zygomatic nerve provides sensory innervation to skin over zygomatic bone
Use line block along ventrolateral orbital rim
Describe the Infratrochlear nerve block
Desensitises medial canthus and third eyelid
Closely associated with medial canthus
Runs through the trochlear notch on medial aspect of dorsal orbital rim
○ Small notch that is palpable on inside of horses orbit
Inject into dorsal rim of orbit, almost at medial canthus
Describe the Retrobulbar nerve block
Desensitises inside of eye and blocks motor function
Blocks:
Ciliary nerves
Optic nerve
Oculomotor
Abducens
Inject into retrobulbar space at the back of eye (behind the globe)
1. Use curved needle with same curvature of globe and insert through and around eye
2. Inject through supraorbital fossa at top of horses eye directly down
Where does the maxillary branch run?
Enters into maxillary forman
Exits via infraorbital foramen
What does the maxillary branch do?
Provides sensory innervation to cheeks, lower eyelids and upper lip
Which nerves do you block for dental surgery?
Maxillary and mandibular branches or trigeminal
Describe the Maxillary nerve block
To anaesthetise maxillary cheek teeth
○ Anesthetise nerve before entering maxillary foramen
○ Just beneath horses eye (below zygomatic arch)
To anaesthetise skin around muzzle/nares
○ Inject into infraorbital foramen
How do you find the Infraorbital foramen?
Place middle finger into naso-incisive notch
Place thumb at rostral end of facial crest
Index finger will fall into infraorbital foramen
Strap-like muscle lies over foramen so will need to be pushed dorsally