This section is from the book "The Human Body: An Elementary Text-Book Of Anatomy, Physiology, And Hygiene", by H. Newell Martin. Also available from Amazon: The Human Body.
Each muscle is an organ composed of several tissues. Its essential constituent is a number of fibres consisting of striped muscular tissue. These are supported and protected by connective tissue; intertwined with blood and lymph vessels, which convey nourishment and carry off waste matters; and penetrated by nerves which govern their activity.
A loose sheath of connective tissue, the perimysium, envelopes the whole muscle in a sort of case; from it partitions run in and subdivide the belly of the muscle into bundles or fasciculi which run from tendon to tendon, or the whole length of the muscle when it has no tendons. The coarseness or fineness of meat depends on the size of these fasciculi, which may be readily seen in a piece of boiled beef. In good carving, meat is cut across the fasciculi, or " across the grain," as it is then more easily broken up by the teeth ; the polygonal areas seen on the surface of a slice of beef are cross sections of the fasciculi. The larger fasciculi are subdivided by fine partitions of connective tissue into smaller (Fig. 32), each consisting of a few muscular fibres enveloped in a close network of minute blood-vessels. Where a muscle tapers the muscle fibres in the fasciculi are less numerous and when a tendon is formed they disappear altogether, leaving only the connective tissue.
Is a muscle an organ or a tissue? What is the chief tissue in it called? What things exist in it besides striped muscular tissue? What is the use of each?
What is the perimysium? How is a muscle divided into fasciculi? How far do the fasciculi extend? When is meat coarse in texture? Why is beef carved across the grain? Of what are the fasciculi composed?