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As with anatomical structures, sequence homology between protein or DNA sequences is defined in terms of shared ancestry. Two segments of DNA can have shared ancestry because of either a speciation event or a duplication event . Homology among proteins or DNA is typically inferred from their sequence similarity.
The shoulderblades are the scapular area and the breastbone is the sternal region. The abdominal area is the region between the chest and the pelvis. The breast is called the mamma or mammary, the armpit as the axilla and axillary, and the navel as the umbilicus and umbilical. The pelvis is the lower torso, between the abdomen and the thighs.
All vertebrate forelimbs are homologous, meaning that they all evolved from the same structures. For example, the flipper of a turtle or of a dolphin , the arm of a human, the foreleg of a horse, and the wings of both bats and birds are ultimately homologous, despite the large differences between them.
A phenome is the set of all traits expressed by a cell, tissue, organ, organism, or species. The term was first used by Davis in 1949, "We here propose the name phenome for the sum total of extragenic, non-autoreproductive portions of the cell, whether cytoplasmic or nuclear.
Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny [ 1 ] (the evolution of species). The science began in the classical era , continuing in the early modern period with work by Pierre Belon who noted the similarities of the skeletons ...
[2] [3] In 1893, Robert Wiedersheim published The Structure of Man, a book on human anatomy and its relevance to evolutionary history. This book contains a list of 86 human organs he considered vestigial, which he called "wholly or in part functionless, some appearing in the Embryo alone, others present during Life constantly or inconstantly.
Two ideas about the homology of arms, hands, and digits exist. That digits are unique to tetrapods; and [6] [7] That homologous antecedents to digits were present in the fins of early sarcopterygian fish. [8] Until recently, few transitional forms were known to elaborate on this transition.
The three anatomical planes of the body: the sagittal, transverse (or horizontal), frontal planes. Anatomy is often described in planes, referring to two-dimensional sections of the body. A section is a two-dimensional surface of a three-dimensional structure that has been cut. A plane is an imaginary two-dimensional surface that passes through ...