Changes

The brachiocephalic trunk arises from the aortic arch and privides blood supply to the thoracic limbs, neck, head and ventral thorax. It branches cranially to give rise to the subclavian arteries and the bicarotid trunk.

The brachiocephalic trunk arises from the aortic arch and privides blood supply to the thoracic limbs, neck, head and ventral thorax. It branches cranially to give rise to the subclavian arteries and the bicarotid trunk.

=====Bicarotid Trunk=====

=====Bicarotid Trunk=====

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 [[Equine Upper Respiratory Tract - Horse Anatomy#Trachea|trachea]] together with the recurrent laryngeal nerve and vagosympathetic trunk. They supply small branches to the [[Equine Upper Respiratory Tract - Horse Anatomy#Trachea|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 [[Equine Upper Respiratory Tract - Horse Anatomy#Trachea|trachea]] together with the recurrent laryngeal nerve and vagosympathetic trunk. They supply small branches to the [[Equine Upper Respiratory Tract - Horse Anatomy#Trachea|trachea]], [[Alimentary System - Horse Anatomy#Oesophagus|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 [[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.

*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.

After forming the above branches, the subclavian artery continues around the first rib to enter the thoracic limb as the '''axillary artery'''.

After forming the above branches, the subclavian artery continues around the first rib to enter the thoracic limb as the '''axillary artery'''.