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Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
The human appendix averages 9 cm (3.5 in) in length, ranging from 5 to 35 cm (2.0 to 13.8 in). The diameter of the appendix is 6 mm (0.24 in), and more than 6 mm (0.24 in) is considered a thickened or inflamed appendix. The longest appendix ever removed was 26 cm (10 in) long. [3]
The young Robert Ernst Eduard Wiedersheim, probably in early 1874 by Alfredo Noack in Genoa. [1]Robert Ernst Eduard Wiedersheim (21 April 1848 – 12 July 1923) was a German anatomist who is famous for publishing a list of 86 "vestigial organs" in his book The Structure of Man: An Index to His Past History.
Vestigial structures are anatomical structures of organisms in a species which are considered to have lost much or all of their original function through evolution. [8] These body parts can be classed as additional to the required functioning of the body. In human anatomy, the vermiform appendix is sometimes classed as a vestigial remnant.
A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the vitelline duct.It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population, [1] with males more frequently experiencing symptoms.
Thus the zoologist Newman stated in the Scopes Trial: "There are, according to Wiedersheim, no less than 180 vestigial structures in the human body, sufficient to make of a man a veritable walking museum of antiquities." Some of the vestigial organs or organs containing evolutionary vestigial structures, as listed on the article about him: Adenoids
Main article: List of systems of the human body. Nervous system in a human body. There are 11 distinct organ systems in human beings, [2] which form the basis of human anatomy and physiology. The 11 organ systems: the respiratory system, digestive and excretory system, circulatory system, urinary system, integumentary system, skeletal system ...