The thoracic aorta is the most superior division of the aorta and is divided into three sections:
The thoracic aorta begins at the aortic valve, located obliquely just to the left of the midline at the level of the third intercostal space. It terminates as it exits the thorax to enter the abdomen through the median arcuate ligament between the diaphragmatic crurae anterior to the T12 vertebral body.
It supplies blood to the chest, upper limbs, head and neck.
Typical measurements for adults (there can be considerable variation dependent on age):