Equine Nerve blocks

Question 1

What are the branches of the trigeminal nerve?

Answer 1

Ophthalmic
Maxillary
Mandibular

Question 2

Which is CNV

Answer 2

Trigeminal

Question 3

Which nerve branch do you block for peri-orbital region surgery?

Answer 3

Ophthalmic branch of trigeminal (sensory)
Occulomotor (motor)

Question 4

Examples or periorbital surgery

Answer 4

Eyelid surgery
Enucleation (also need to anaesthesia optic nerve)
Removal of third eyelid

Question 5

What are the 5 blocks required to fully desensitise periorbital and retrobulbar region?

Answer 5

Supraorbital/frontal nerve block
Lacrimal block
Zygomatic nerve block
Infratrochlear block
Retrobulbar block

Question 6

Describe the supraorbital/frontal nerve block

Answer 6

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

Question 7

Describe the lacrimal block

Answer 7

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

Question 8

Describe the zygomatic nerve block

Answer 8

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

Question 9

Describe the Infratrochlear nerve block

Answer 9

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

Question 10

Describe the Retrobulbar nerve block

Answer 10

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

Question 11

Where does the maxillary branch run?

Answer 11

Enters into maxillary forman
Exits via infraorbital foramen

Question 12

What does the maxillary branch do?

Answer 12

Provides sensory innervation to cheeks, lower eyelids and upper lip

Question 13

Which nerves do you block for dental surgery?

Answer 13

Maxillary and mandibular branches or trigeminal

Question 14

Describe the Maxillary nerve block

Answer 14

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

Question 15

How do you find the Infraorbital foramen?

Answer 15

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

Question 16

What does the mandibular nerve do?

Answer 16

Motor and sensory innervation of mandible

Question 17

Where does the mandibular nerve run?

Answer 17

Enters mandibular foramen
Exits via mental foramen

Question 18

Describe the Mandibular nerve block

Answer 18

Used to anaesthetise mandible
Two injections to anaesthetise at mandibular foramen - triangulate
* Located on inside of jaw
* Insert long spinal needle from ventral surface and angle behind vertical ramus of mandible
* Where needles meet is mandibular foramen
One injection for mental foramen
○ In diastema between incisors and cheek teeth
For soft tissues