histology
Last reviewed 01/2018
In common with the main branches of the aorta, the arch has the histological structure of an elastic artery. Hence, it contains from inside to outermost:
- tunica intima:
- endothelial cells
- connective tissue, mainly collagen and elastin
- occasional smooth muscle cell
- tunica media:
- prominent fenestrated layers of elastin surrounding wall in a continuous sheet
- abundant smooth muscle cells
- adventitia:
- connective tissue
- blood supply to the outer layers of the vessels, the vasa vasorum
- fine nerve fibres
- fibroblasts
- occasional smooth muscle cells
In addition, the adventitia of the arch of the aorta contains baroreceptors. Their afferent fibres are carried by the vagus nerve to the nucleus of tractus solitarius. They are part of the homeostatic mechanism for regulating blood pressure.