High-Stakes Field Blocks:
• Cornual Nerve Block (Cattle): 5-10mL lidocaine halfway along temporal ridge between lateral canthus and horn base; blocks V2 branch
• Goat Modification: Must block TWO sites—posterior (Cornual/V2) AND dorsomedial (Infratrochlear/V1)
• Peterson Eye Block: Targets Foramen Orbitorotundum; 15-20mL at 'V' notch (supraorbital process + zygomatic arch + coronoid process junction); blocks III, IV, VI, V1, V2
• Auriculopalpebral Block: Subcutaneous over zygomatic arch; motor block only (akinesia), NOT sensory—cornea still feels pain!
• Safety: Always aspirate before injection—Internal Maxillary Artery adjacent to Foramen Orbitorotundum

Clinical Anesthesia Techniques

Mastery of cranial nerve anatomy enables precise regional anesthesia essential for veterinary practice—particularly dehorning and ocular surgery.

1. The Cornual Nerve Block (Dehorning)

Objective: Anesthesia of the horn bud/horn for painless dehorning or disbudding.

Anatomy (Ox): The Cornual nerve is a branch of the Zygomaticotemporal nerve (from V2). It emerges from the orbit, running along the lateral border of the frontal bone's temporal ridge, covered by skin and thin frontalis muscle.

Technique:

1. Palpate the temporal ridge between the lateral canthus of the eye and the horn base.
2. Insert needle halfway along this line, just ventral to the crest.
3. Deposit 5-10mL Lidocaine subcutaneously and deeply along the periosteum.
4. Wait 10 minutes. Test with needle prick before proceeding.

2. The "Goat Trap" Modification

Critical Difference: The goat horn is supplied by TWO nerves:

• Cornual nerve (from V2, like ox)
• Cornual branch of the Infratrochlear nerve (from V1)

Dual Technique Required:

1. Site 1: Posterior to the lateral canthus (standard cornual block).
2. Site 2: Dorsomedial to the eye, near the medial canthus, to catch the Infratrochlear branch.

Failure to perform both blocks results in violent head shaking, vocalization, and failed restraint.

3. The Peterson Eye Block (Enucleation)

Objective: Complete anesthesia and akinesia of the globe and orbit for enucleation (removal of the eye), usually due to Squamous Cell Carcinoma ("Cancer Eye").

Anatomy: This high-skill block targets the Foramen Orbitorotundum, blocking CN III, IV, VI (motor) and V1, V2 (sensory).

Landmarks (The "V" Notch):

• Supraorbital Process of frontal bone (cranially)
• Zygomatic Arch (ventrally)
• Coronoid Process of the Mandible (caudally)

Technique:

1. Insert a curved 18G needle (10-12cm) at the notch formed by these structures.
2. Advance horizontally and slightly caudally/medially.
3. "Walk" the needle off the cranial border of the Coronoid Process of the mandible.
4. Advance until it hits the bony plate of the sphenoid near the Foramen Orbitorotundum.
5. ASPIRATE! The Internal Maxillary Artery is adjacent—intravascular injection causes seizures.
6. Inject 15-20mL slowly.

Result: Eye immobilized (akinesia) and numb (anesthesia). Note: Auriculopalpebral nerve (CN VII) is NOT blocked here; eyelids may still flutter unless separately blocked.

4. The Auriculopalpebral Block

Objective: Stop eyelids from closing (akinesia) during eye examination or minor procedures.

Nerve: Auriculopalpebral branch of CN VII (facial).

Technique: Palpate the nerve crossing the dorsal aspect of the Zygomatic Arch. Inject 5mL subcutaneously.

Critical Limitation: This is a MOTOR block only. Sensation remains INTACT (cornea can still feel pain via V1). Use ONLY for examination, not surgery. For painful procedures, combine with topical anesthesia or retrobulbar block.