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The conversion to full-time bipedalism in our distant ancestors is the main argument for the adaptations our muscle structure and function have made. By having to center the force of gravity on two feet, the human thigh bone developed an inward slope down to the knee which may have allowed their gluteal abductors to adapt to the stress and ...
The plantaris muscle is composed of a thin muscle belly and a long thin tendon. The muscle belly is approximately 5–10 centimetres (2–4 inches) long, and is absent in 7–10% of the human population. It has some weak functionality in moving the knee and ankle but is generally considered redundant and is often used as a source of tendon for ...
Ape skeletons. A display at the Museum of Zoology, University of Cambridge.From left to right: Bornean orangutan, two western gorillas, chimpanzee, human. The evolution of human bipedalism, which began in primates approximately four million years ago, [1] or as early as seven million years ago with Sahelanthropus, [2] [3] or approximately twelve million years ago with Danuvius guggenmosi, has ...
Another view is that muscles cells evolved more than once, and any morphological or structural similarities are due to convergent evolution, and the development of shared genes that predate the evolution of muscle – even the mesoderm (the mesoderm is the germ layer that gives rise to muscle cells in vertebrates).
The coracoid process acts as an attachment and origin for a large number of muscles (attached muscles not labeled here). The coracoid process is a thick curved process attached by a broad base to the upper part of the neck of the scapula; [2] it runs at first upward and medially; then, becoming smaller, it changes its direction, and projects forward and laterally.
In 2015, the third version of TimeTree was released, with 2,274 studies and 50,632 species, represented in a spiral tree of life, [29] free to download. In 2015, the first draft of the Open Tree of Life was published, in which information from nearly 500 previously published trees was combined into a single online database, free to browse and ...
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] Assessment of the vestigiality must generally rely on comparison with homologous features in related species.
The A band stays the same width. At full contraction, the thin and thick filaments overlap. Contraction in more detail. Contraction is achieved by the muscle's structural unit, the muscle fiber, and by its functional unit, the motor unit. [4] Muscle fibers are excitable cells stimulated by motor neurons. The motor unit consists of a motor ...