14.2: Gross Anatomy of Skeletal Muscles
The connective tissues play a significant role in arranging the muscle fibers into a hierarchical structure that forms a complete muscle. Consider a muscle like the bicep brachii, commonly called the bicep. This muscle comprises thousands of muscle fibers enclosed by a protective layer of connective tissue called the endomysium. The endomysium is primarily composed of reticular fibers, a type of thin collagen fiber. It allows the exchange of nutrients and waste products at the fiber level, keeping the muscle fibers healthy and functional.
The endomysium is continuous with other layers of connective tissue called the perimysium and epimysium. The perimysium organizes the fibers into groups called fascicles, which are responsible for the synchronized contraction of the bicep muscle during actions such as lifting objects. The organization of fibers into fascicles also helps to distribute the network of nerves and blood vessels more evenly throughout the muscle.
Numerous fascicles are collectively held together by an epimysium, the outermost connective tissue covering the entire muscle. The epimysium also extends from the muscle to form the tendons, which connect the bicep muscle to the bones of the forearm and shoulder. This continuity allows the force generated by muscle contractions to be effectively transferred to the bones, resulting in movement.
These connective tissues, which form the epimysium, perimysium, and endomysium, play a vital role in the structure and function of skeletal muscles. They facilitate muscle contraction and bone movement while supporting and protecting muscle fibers, ensuring their nourishment and overall health.
