The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . nd deep cardiac plexuses. Embryology. In the article on the arteries {.) the formation and coal-escence of the two primitive ventral aortae to form the heart arenoticed, so that we may here start with a straight median tubelying ventral to the pharynx and being prolonged cephalad intothe ventral aortae and caudad into the vitelline veins. Thissoon shows four dilatations, which, from the tail towards thehead end, are called the sinus venosus, the auricle, the ventricleand the truncus arteriosus
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . nd deep cardiac plexuses. Embryology. In the article on the arteries {.) the formation and coal-escence of the two primitive ventral aortae to form the heart arenoticed, so that we may here start with a straight median tubelying ventral to the pharynx and being prolonged cephalad intothe ventral aortae and caudad into the vitelline veins. Thissoon shows four dilatations, which, from the tail towards thehead end, are called the sinus venosus, the auricle, the ventricleand the truncus arteriosus. As the tubular heart grows morerapidly than the pericardium which contains it, it becomes bentinto the form of an S laid on its side (CO), the ventral convexitybeing the ventricle and the dorsal the auricle. The passagefrom the auricle to the ventricle is known as the auricular canal,and in the dorsal and ventral parts of this appear two thickenings This is often called bulbus arteriosus, but it will be seen thatthe term is used rather differently in comparative .anatpmy. ANATOMY] HEART 131. —Formation of Septa. Diagram of the formation of some of the septa of the heart (viewed from the right side). Sinus venosus. Au. Auricle. Endocardial cushions formingseptum intermedium. V. Septum venlriculorum. T. Ar. Septum aorticum intruncus ar-teriosus. Ventral aorta. known as endocardial cushions, which approach one another andleave a transverse slit between them (fig. 3, ). Eventuallythese two cushions fuse in the middle line, obliterating thecentral part of the slit, while the lateral parts remain as the twoauriculo-ventricular orifices; this fusion is known as the septumintermedium. From the bottom (ventral convexity) of theventricle an antero-posterior median septum grows up, which is the septum inferius orseptum venlriculorum(fig. 3, V). Posteriorly(caudally) this septumfuses with the septumintermedium, but ante-riorly it is free at thelower part of th
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
