How is muscle attached to bone

Portions of the epimysium project inward to divide the muscle into compartments. Each compartment contains a bundle of muscle fibers. Each bundle of muscle fiber is called a fasciculus and is surrounded by a layer of connective tissue called the perimysium. Within the fasciculus, each individual muscle cell, called a muscle fiber, is surrounded by connective tissue called the endomysium. Skeletal muscle cells fibers , like other body cells, are soft and fragile.

The connective tissue covering furnish support and protection for the delicate cells and allow them to withstand the forces of contraction. In essence, these connective tissue attachments allow the tension created by the contractile component of the muscle to be transmitted to the associated bones so that joint movement can occur. Structure of skeletal muscle and related connective tissue.

Attachments of muscles onto bones A directly, or indirectly through a B tendon or C aponeurosis. In most cases this text uses the terms proximal attachment and distal attachment to refer to the specific sites of these connective tissue attachments of muscles onto bone s in order to reflect the concept that when a muscle contracts, either end can move, depending on the goal and conditions of the movement.

For example, when flexing the elbow as you lift a weight biceps curl; see table 2. In many movements of the limbs, open versus closed kinematic chain terminology explained in chapter 1 is used to reflect which attachment is moving.

For movements for which kinematic chain terminology does not work well, the text provides clarification by identifying which bone or body segment is moving.

The terminology of customary and reverse muscle actions can also be used to describe whether the distal customary or proximal reverse segment is moving.

For example, the thigh moving on the trunk customary action of hip flexors is shown in figure 2. Customary and reverse muscle actions of the hip flexors. A Raising the thigh on the trunk, B raising the trunk on the thigh. Dancer: Merett Miller as a dancer with Sacramento Ballet. When learning the actions of muscles, it is easier to first picture movements that involve the distal segment moving.

Hence, examples of movements given in chapters 3 through 7 in "Description and Functions of Individual Muscles" sections emphasize such distal segment movements. However, examples of the proximal segment moving are often included in these chapters in the "Muscular Analysis of Movements" sections. An important tool for predicting the action of a given muscle is to picture its line of pull. You can roughly approximate the line of pull of a muscle by drawing an imaginary double-headed arrow with its base at each attachment and pointing toward the center of the muscle.

In instances in which a muscle has a broad attachment, you would draw the arrow to approximately bisect the broad attachment as seen in figure 2. Then, picture what movement of the interposed joint would occur if one attachment moved toward the other or if the two attachments moved toward each other.

For example, if you imagined the distal attachment of the gluteus medius shown in figure 2. Readers are encouraged to approach learning muscle actions in this manner rather than by rote memorization to make the learning process easier, to provide a logic self-check procedure, and to promote retention. Learning the muscular system often involves memorizing details about each muscle, like where a muscle attaches to bones and how a muscle helps move a joint.

In textbooks and lectures these details about muscles are described using specialized vocabulary that is hard to understand. Here is an example: The triceps brachii has three bellies with varying origins scapula and humerus and one insertion ulna.

It is a prime mover of elbow extension. The anconeus acts as a synergist in elbow extension. What does all that textbook jargon mean?

The triceps brachii has four places where it attaches to the scapula, humerus, and ulna. A skeletal muscle attaches to bone or sometimes other muscles or tissues at two or more places. If the place is a bone that remains immobile for an action, the attachment is called an origin. If the place is on the bone that moves during the action, the attachment is called an insertion. The triceps brachii happens to have four points of attachment: one insertion on the ulna and three origins two on the humerus and one on the scapula.

The muscles surrounding synovial joints are responsible for moving the body in space. These muscle actions are often paired, like flexion and extension or abduction and adduction.

Skeletal muscles vary considerably in size, from tiny muscles inside the middle ear to very large muscles in the upper leg. Each skeletal muscle consists of hundreds or even thousands of skeletal muscle fibers. The fibers are bundled together and wrapped in connective tissue, as shown Figure below. The connective tissue supports and protects the delicate muscle cells and allows them to withstand the forces of contraction. It also provides pathways for nerves and blood vessels to reach the muscles.

Skeletal muscles work hard to move body parts. They need a rich blood supply to provide them with nutrients and oxygen and to carry away their wastes. Skeletal Muscle Structure. Skeletal muscles are attached to the skeleton by tough connective tissues called tendons see Figure above. Many skeletal muscles are attached to the ends of bones that meet at a joint.