Internal carotid artery mainly of historical significance. The segments of the internal carotid artery are as follows: The internal carotid artery is a terminal branch of the common carotid artery; it arises around the level of the fourth cervical vertebra when the common carotid bifurcates into this artery and its more superficial counterpart, the external carotid artery. The cervical segment, or C1, or cervical part of the internal carotid, extends from the carotid bifurcation until it enters the carotid canal in the skull anterior to the jugular foramen. At its origin, the internal carotid artery is somewhat dilated. This part of the artery
Carotid body may involve mitochondrial oxygen sensors and the haem-containing cytochromes that undergo reversible one-electron reduction during oxidative-phosphorylation. Haem reversibly binds O with an affinity similar to that of the carotid body, suggesting that haem containing proteins may have a role in O, potentially this could be one of the complexes involved in oxidative-phosphorylation. This leads to increases in reactive oxygen species and rises in intracellular Ca. However, whether hypoxia leads to an increase or decrease in reactive oxygen species is unknown. The role of reactive oxygen species in hypoxia sensing is also under question. The oxygen dependent enzyme haem-oxidase has also