High-Yield Points:
• Common Carotid Artery (in carotid sheath) — chief artery of head; branches at level of larynx into:
– External Carotid — main artery of face, jaws, tongue, dura.
– Internal Carotid — to brain (via carotid rete in ox).
– Occipital — to brain & deep neck.

Important Branches of External Carotid:
• Lingual artery — to tongue.
• Facial artery — over mandibular notch (HORSE PULSE SITE).
• Maxillary artery — through alar canal; supplies face, palate, teeth, eye.
• Superficial Temporal artery — to temporalis & horn (KEY in dehorning hemorrhage).
• Cornual (Horn) artery — branch of superficial temporal; supplies horn — must be ligated during dehorning to prevent fatal hemorrhage.
• Infraorbital, Supraorbital, Auricular, Lingual arteries.

ARTERIAL SUPPLY OF THE HEAD & NECK

I. COMMON CAROTID ARTERY (CCA):
• Origin: Off the brachiocephalic trunk (right) or directly from the aortic arch (left in some species).
• Course: Ascends in the carotid sheath, deep in the jugular furrow, alongside the trachea & oesophagus.
• Termination: At the level of the larynx → branches into external carotid + occipital + internal carotid (when present).

II. INTERNAL CAROTID ARTERY:
• In Ox: Functional in young, becomes obliterated in adults — replaced by the maxillary route via the carotid rete mirabile at the base of the brain.
• In Horse: Persists; passes through guttural pouch and enters cranium via foramen lacerum.
• In Dog: Patent through life; standard route to brain.

III. EXTERNAL CAROTID ARTERY (the workhorse for the head):
• Lingual a. — main artery to the tongue (entered when ligating Stenson's duct).
• Facial a. — Wraps around ventral border of mandible at mandibular notch. Standard pulse site in HORSE.
• Caudal Auricular a. — to ear.
• Superficial Temporal a. — major branch crossing zygomatic arch; gives rise to:
– Cornual (Horn) artery — supplies horn base. MUST be ligated during dehorning to prevent severe hemorrhage from the cut horn base.
– Auriculopalpebral a. — to eye and ear region.
• Maxillary a. — terminal branch; runs through alar canal, gives off:
– Inferior alveolar a. (mandibular teeth via mandibular foramen).
– Infraorbital a. (upper teeth via infraorbital canal).
– Sphenopalatine, Greater palatine, Buccal arteries to palate, sinuses, cheek.
– External ophthalmic a. + branches to eye, lacrimal gland.

IV. CAROTID RETE MIRABILE (in Ox & Sheep):
• Network of small arteries at the base of the brain.
• Function: brain cooling — counter-current heat exchange between cool venous blood (from nasal cavity sinuses) and arterial blood; protects brain from overheating in hot pastures.
• Same anatomical principle present in giraffe (massive rete handles pressure changes when raising/lowering neck).

V. AGE-RELATED ARTERY CHANGES IN OX:
The internal carotid regresses and the brain comes to depend almost entirely on the maxillary artery + carotid rete. This is why the Peterson's eye block works so reliably — local anaesthetic placed near the rete diffuses to multiple cranial nerves.