📝 STANDARD DESCRIPTION:
Path: Left ventricle → Aortic semilunar valve → Ascending Aorta → Aortic Arch → Descending Thoracic Aorta → through aortic hiatus → Abdominal Aorta.
From the Aortic Arch — branches in OX:
1. Brachiocephalic Trunk (only one branch in ox — short).
It gives off:
- Left Subclavian artery (to left forelimb)
- Bicarotid Trunk → splits into Right & Left Common Carotid arteries (to head)
- Continues as Right Subclavian artery (to right forelimb).
Descending Thoracic Aorta — branches:
- Bronchoesophageal artery (to bronchi & oesophagus).
- Dorsal Intercostal arteries (one pair per intercostal space, from about 4th to 13th).
📚 DETAILED DESCRIPTION:
THE BIG ARTERY OF THE BODY — AORTA
The aorta is the largest artery. It carries oxygen-rich blood from the left ventricle to the entire body.
PARTS:
• Ascending Aorta: Short part rising from the left ventricle; gives off the LEFT and RIGHT coronary arteries (which supply the heart muscle itself).
• Aortic Arch: Curves backward over the base of heart at the level of the 4th-5th rib; here it gives off the brachiocephalic trunk.
• Descending Thoracic Aorta: Runs caudally on the LEFT side of the vertebral column (slightly off midline) until it pierces the diaphragm through the aortic hiatus.
BRANCHES OF THE ARCH IN OX (very important):
The ox has a unique pattern — only ONE big artery comes off the arch: the Brachiocephalic Trunk. It then branches like this:
1. Gives off the Left Subclavian artery (to the left forelimb and chest wall).
2. Then gives off the Bicarotid Trunk — a short common stem that quickly splits into the right and left Common Carotid Arteries (one to each side of the head).
3. Continues forward as the Right Subclavian artery (to right forelimb and right side of neck).
Compare with horse/dog: there the brachiocephalic trunk gives off the carotids and right subclavian, while the LEFT subclavian comes directly off the arch (two branches off the arch).
BRANCHES OF DESCENDING THORACIC AORTA:
• Bronchoesophageal artery: Single small artery — supplies bronchi and thoracic oesophagus.
• Dorsal Intercostal arteries: Pair for each intercostal space, from approximately the 4th to the 13th. Runs in the costal groove with the intercostal vein and nerve (V-A-N order). The first 2-3 spaces are supplied by the costocervical trunk (from subclavian) instead.
END OF THORACIC AORTA: Passes through the aortic hiatus along with azygos vein and thoracic duct, then becomes the abdominal aorta.
// COMPARATIVE ANALYSIS
| HORSE |
TWO branches from the arch: Brachiocephalic trunk + Left Subclavian directly. (Brachiocephalic gives bicarotid + right subclavian.) |
| DOG |
Same as horse — Brachiocephalic + Left Subclavian off arch. Carotids come off the brachiocephalic separately (no bicarotid trunk). |
| PIG |
Pattern like ox — single brachiocephalic. |
| FOWL |
Aortic arch curves to the RIGHT (not left as in mammals). |
CLINICAL RELEVANCE
Aortic Rupture (Horse): Rare but fatal — typically near the ligamentum arteriosum at the arch. Sudden death.
Persistent Right Aortic Arch (PRAA, dog): Birth defect where right (not left) arch persists; forms a vascular ring around the oesophagus → calf/puppy regurgitates solid food.
