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Muscles near the ankle helped provide the push during walking and running. There are many advantages and disadvantages to this altered posture and gait. The ability to grab something with four appendages was lost but what was gained was the ability to hold a club or throw a spear and use the other free hand for another task. [ 9 ]
The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. [1] According to the sliding filament theory, the myosin ( thick filaments ) of muscle fibers slide past the actin ( thin filaments ) during muscle contraction, while the two groups of filaments ...
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 ...
Push and pull factors in migration according to Everett S. Lee (1917-2007) are categories that demographers use to analyze human migration from former areas to new host locations. Lee's model divides factors causing migrations into two groups of factors: push and pull.
Examples include kneading bread dough, wringing out a towel, avoiding laser-beams or miming the shape of an imaginary object. In some cases, and historically, this is referred to as Shaping, though many practitioners feel that all three Modes of Shape Change are "shaping" in some way, and that the term is thus ambiguous and overloaded.
The parallel muscle architecture is found in muscles where the fibers are parallel to the force-generating axis. [1] These muscles are often used for fast or extensive movements and can be measured by the anatomical cross-sectional area (ACSA). [3] Parallel muscles can be further defined into three main categories: strap, fusiform, or fan-shaped.
Agonist muscles are also called prime movers since they produce most of the force, and control of an action. [6] Agonists cause a movement to occur through their own activation. [7] For example, the triceps brachii contracts, producing a shortening (concentric) contraction, during the up phase of a push-up (elbow extension).
For example, if the quadriceps femoris and hamstring contract simultaneously at a high intensity, the stronger muscle (traditionally the quadriceps) overpowers the weaker muscle group (hamstrings). This can result in a common muscular injury known as a pulled hamstring , more accurately called a muscle strain .