Changes

The bicarotid trunk arises from the brachiocephalic trunk and runs cranially before branching into the '''common carotid arteries'''. The common carotid arteries ascend either side of the trachea together with the recurrent laryngeal nerve and vagosympathetic trunk. They supply small branches to the trachea, oesophagus and adjacent muscles. Major branches are the '''cranial and caudal thyroid arteries'''. The cranial thyroid artery gives rise to the '''cranial laryngeal artery''' and '''ascending pharyngeal artery'''. The common carotid artery ends by dividing into '''internal and external carotid arteries''' and the '''occipital artery'''.

The bicarotid trunk arises from the brachiocephalic trunk and runs cranially before branching into the '''common carotid arteries'''. The common carotid arteries ascend either side of the trachea together with the recurrent laryngeal nerve and vagosympathetic trunk. They supply small branches to the trachea, oesophagus and adjacent muscles. Major branches are the '''cranial and caudal thyroid arteries'''. The cranial thyroid artery gives rise to the '''cranial laryngeal artery''' and '''ascending pharyngeal artery'''. The common carotid artery ends by dividing into '''internal and external carotid arteries''' and the '''occipital artery'''.

*Occipital artery: Supplies muscles of the nuchal region, caudal meninges, middle and internal ear. It anastamoses with the vertebral artery to form part of the blood supply to the brain.  

*Occipital artery: Supplies muscles of the nuchal region, caudal meninges, middle and internal ear. It anastamoses with the vertebral artery to form part of the blood supply to the brain.  

*Internal carotid artery: Passes through the guttural pouch on its course to enter the cranial cavity. This artery forms the principle blood supply to the brain.

*Internal carotid artery: Passes through the [[Equine Upper Respiratory Tract - Horse Anatomy#Guttural Pouches|guttural pouch]] on its course to enter the cranial cavity. This artery forms the principle blood supply to the brain.

*External carotid artery: Largest of the terminal branches from the common carotid artery. It continues as the maxillary artery to supply muscles, bones and organs of the head. It does not provide blood supply to the brain.

*External carotid artery: Largest of the terminal branches from the common carotid artery. It continues as the maxillary artery to supply muscles, bones and organs of the head. It does not provide blood supply to the brain.