Equine Regional Anaesthesia

when doing nerve blocks on head of horse, what nerve focused on

trigeminal

-opthalmic

-mandibular

-maxillary

what n supplies this area

retrobulbar

what n supplies this area

zygomatic

what n supplies this area

lacrimal

what n supplies this area

infratrochlear

what n supplies this area

supraorbital

sensory nerve branches of ophthalmic branch of trigeminal for eye anaesthetic

-supraorbital

-lacrimal

-zygomatic

-infratrochlear

-retrobulbar

what ist eh supraorbital n also called

frontal n

where does the supraorbital n pass through and where does it block

-top of eye

-supraorbital foramen

where is the lacrimal nerve

adjacent to lateral canthus of eye

what does the zygomatic nerve innervate (and so blocks)

lower eyelid

skin over zygomatic arch

what is the infratrochlear nerve closely associated with, how can you find it

medial canthus

Theres a small palpable notch on the inside of a horses orbit  where you can feel it

what does a retrobulbar nerve block anaesthetise

• inner part of eye

• Anaesthetises all the ciliary body nerves

how is supraorbital nerve block carried out

-palp orbital ring

-and pinch over narrowest portion index finger will fall onto the supraorbital foramen

-anaesthetic to upper eyelid

how is retrobulbar nerve block carried out? why do one over another?

• Getting needle to back of the horses eye

  • Curve a spinal needle to the same curvature of the globe so it goes round to the back of the eye

  • But if are pushing through an area that might be neoplasia or infection you can push it to the back of the eye

• Go through the supraorbital fossa

  • Go down in that space on the top of the horses skull putting a straight spinal needle down there so it comes out at the back of the eye

maxillary nerve entrance and exit

maxillary foramen to exit infraorbital foramen

what would we block if we want to anaesthetise the maxillary cheek teeth (PM and M)

maxillary branch at the maxillary foramen

-beneath eye

if we wanted to block skin of muzzle, what would we do

block maxillary branch at the infraorbital foramen

how to identify infraorbital foramen and supraorbital foramen

• if you put your middle finger in what's called the incisive notch

  • the notch that's formed between the incisive bone and the sharp part of the nasal bone.

• And if you put your thumb at the rostral end of the facial crest, then your index finger is going to fall into that infra orbital foreman.

• there's a strap like muscle that runs over the top of that.

  • might just need to push that to the side.

  • if you push that dorsally, then your index finger is going to fall into sort of a little halo or rim → That is the super orbital foreman.

mandibular nerve entrance and exit

mandibular foramen to mental foramen

what nerve would you block to block teeth of mandible

-mandibular branch at mandibular foramen (triangulate to get far in)

how would you block the mandibular branch at the mandibular foramen

• need to triangulate the position of the maxillary foramen,

• then put a long spinal needle

• either from the ventral surface or sort of an angle behind the vertical ramus of the mandible

• drawing a cross on the side of the horse's face,

  • the horizontal line is going to be at the level of the occlusal surface of the cheek teeth.

  • the other line is going to be running straight down vertically down from the lateral canthal of the eye.

  • And where those two lines bisect is going to be roughly the side of the mandibular foramen.

what would you block to anaesthetise soft tissue around ventral part of horses face block

mandibular branch at the mental foramen

what is being done here

• finding the infraorbital foramen

• index finger at infraorbital foramen

what is being done here

• maxillary branch blocked at the maxillary foramen

• needle has gone in at infraorbital foramen but goes all the way back to the maxillary foramen

what is being done here

retrobulbar via getting needle behind eye

what is being done here

retrobulbar nerve block → via the supraorbital foramen

what foramen can be seen here

supraorbital foramen