Heart depending on what is counted as a chamber. The atrium and ventricle are sometimes considered "true chambers", while the others are considered "accessory chambers". Primitive fish have a four-chambered heart, but the chambers are arranged sequentially so that this primitive heart is quite unlike the four-chambered hearts of mammals and birds. The first chamber is the sinus venosus, which collects deoxygenated blood from the body through the hepatic and cardinal veins. From here, blood flows into the atrium and then to the powerful muscular ventricle where the main pumping action will take place. The fourth and final chamber is the
Craig (given name) Craig (given name) Craig is a Scottish, Irish & Welsh masculine given name, all variations derive from the same Celtic branch. The name has two origins. In some cases it can originate from a nickname, derived from the Scottish Gaelic word "creag", meaning "rock," similar to Peter. In other cases, the given name originates from the Scottish surname "Craig", which is also derived from the same Scottish Gaelic word. Cognate forms of "creag" include the Irish "creig", Manx "creg", and Welsh "craig". The English word "crag" also shares an origin with these Celtic words. The given name "Craig" is popular