Each skeletal muscle is an individual organ of the human body. Each is
made up of several types of tissues--mainly, striated muscle fibers and FCT (fibrous
connective tissue). Each is attached to and moves bones. Bones are parts of the skeleton
serving as levers.
a. General Construction of a Skeletal Muscle. The large portion of
a muscle is known as its belly or fleshy belly. This muscle is attached to bones by
tendons or aponeuroses. Tendons and aponeuroses are similar to each other. However,
tendons are cord-like and aponeuroses are broad and flat. The fleshy portion may be
directly connected to the bone. If so, it is called a "fleshy attachment."
b. Muscular NAVL (Nerves, Arteries, Veins, Lymphatics).
(1) From the main NAVL (nerve, artery, vein, lymphatic), there are
branches going to each muscle. These muscular branches are bound together by an FCT sheath
to form a neurovascular bundle.
(2) The motor point is that specific location on the surface of the muscle
where the neurovascular bundle enters.
(3) A motor unit is the single motor neuron and the number of striated
muscle fibers activated by it (innervation). The importance of the motor unit is that its
fibers work in unison. Either all fibers within a unit contract or none contract. When a
certain amount of force is needed, one unit after another is recruited until just enough
units are available to produce the desired action.
