The musculoskeletal system (also known as the locomotor system) is an organ system that gives animals the ability to physically move using the muscles and skeletal system. This article is about the biological unit. ... For other uses, see Animal (disambiguation). ... A top-down view of skeletal muscle Muscle (from Latin musculus little mouse [1]) is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... Skeleton is also a winter sport: see skeleton (sport). ...

The human musculoskeletal system consists of the human skeleton, made by bones attached to other bones with joints, and skeletal muscle attached to the skeleton by tendons. The human musculoskeletal system is the musculoskeletal system that gives us the ability to move. ...

Hydrostatic musculoskeletal system

Among others, cnidarians and annelids, have a hydrostatic skeleton similar to a water-filled balloon, these animals can move by contracting the muscles surrounding the fluid-filled pouch, creating pressure within the pouch that causes movement. Animals such as earthworms use their hydrostatic skeletons to change their body shape as they move forward, from long and skinny to short and stumpy. Arthropoda have their muscles attached to an exoskeleton.this is the bone ligament in the place Classes Anthozoa - Corals and sea anemones Cubozoa - Sea wasps or box jellyfish Hydrozoa - Hydroids, hydra-like animals Scyphozoa - Jellyfish Cnidaria is a phylum containing some 10,000 species of relatively simple animals found exclusively in aquatic environments (most species are marine). ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... A hydrostatic skeleton is one in which the bodys shape and/or function is maintained by an incompressible fluid such as blood or hemolymph. ... Families   Acanthodrilidae   Ailoscolecidae   Alluroididae   Almidae   Criodrilidae   Eudrilidae   Exxidae   Glossoscolecidae   Lumbricidae   Lutodrilidae   Megascolecidae   Microchaetidae   Ocnerodrilidae   Octochaetidae   Sparganophilidae Earthworm is the common name for the largest members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - Trilobites (extinct) Subphylum Chelicerata Arachnida - Spiders, Scorpions, etc. ... An exoskeleton is an external anatomical feature that supports and protects an animals body, in contrast to the internal endoskeleton of, for example, a human. ...

Muscle contraction initiation

Main article: Muscle contraction

In mammals, when a muscle contracts, a series of reactions occur. Muscle contraction is stimulated by the motor neuron sending a message to the muscles from the somatic nervous system. Depolarization of the motor neuron results in neurotransmitters being released from the nerve terminal. The space between the nerve teminal and the muscle cell is called the neuromuscular junction. These neurotransmitters diffuse across the synapse and bind to specific receptor sites on the sarcolemma (cell membrane of the muscle fiber). When enough receptors are stimulated, an action potential is generated and the permeability of the sarcolemma is altered. This process is known as initiation. A top-down view of skeletal muscle A muscle contraction (also known as a muscle twitch or simply twitch) occurs when a muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. ... In vertebrates, the term motor neuron (or motoneuron) classically applies to neurons located in the central nervous system (CNS) which project their axons outside the CNS and directly or indirectly control muscles. ... The somatic nervous system is that part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and also reception of external stimuli. ... Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a presynaptic and a postsynaptic neuron. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... A neuromuscular junction is the junction of the axon terminal of a motoneuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscles surface. ... Muscle system The sarcolemma is the cell membrane of a muscle cell. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ... For other uses, see Initiation (disambiguation). ...

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