Sketch skeletal muscle fibers as seen under the microscope in the space provided. Be sure to label the structures listed in step 4 in your drawing. After observing the structure of individual muscle fibers, it is time to investigate the relationship between individual muscle fibers and whole muscles. A whole skeletal muscle, such as the biceps brachii muscle, consists of many individual muscle fibers bundled together with connective tissue (figure 11.3).
Each individual muscle fiber is covered by a layer of connective tissue called the endomysium (endo-, within + mys, muscle). Several muscle fibers are bundled together into fascicles by a surrounding layer of connective tissue called the perimysium (peri-, around + mys, muscle). Finally, the entire skeletal muscle is surrounded by a layer of connective tissue called the epimysium (epi-, upon + mys, muscle). The epimysium is an extension of the deep fascia, which will be discussed shortly.
The Correct Answer and Explanation is :
Sketching the Structure of a Skeletal Muscle Fiber:
- Start with individual muscle fibers: Skeletal muscle fibers are long, cylindrical, and striated. Draw long, parallel lines to represent these fibers. Each muscle fiber contains many smaller myofibrils, which give the muscle its striated (striped) appearance. These striations are created by repeating units called sarcomeres.
- Label the muscle fiber: Label the muscle fiber as “Muscle Fiber (Cell).” Inside this fiber, you can draw myofibrils (lines within the fiber that are perpendicular to the fiber’s length).
- Connective Tissue Layers:
- Endomysium: This layer surrounds each muscle fiber. Draw a thin outline around a single fiber to represent this connective tissue. Label it as “Endomysium.”
- Perimysium: Muscle fibers are grouped into fascicles. Draw several fibers grouped together and encircle them with a thicker layer to represent the perimysium. Label it “Perimysium.”
- Epimysium: This is the outermost layer of connective tissue surrounding the entire muscle. Draw a larger surrounding layer around all the fascicles and label it “Epimysium.”
- Blood Vessels and Nerves: You can add small vessels (capillaries) and nerve fibers within the connective tissue layers. These supply oxygen and nutrients to muscle fibers, and are present in the perimysium.
Explanation:
Skeletal muscles, such as the biceps brachii, are made up of bundles of muscle fibers. Each muscle fiber is wrapped in a connective tissue layer called the endomysium, which provides a pathway for nerves and blood vessels. The muscle fibers are grouped together into fascicles, each surrounded by a layer of connective tissue called the perimysium. The entire muscle, including all the fascicles, is surrounded by the epimysium, a thicker outer layer of connective tissue.
These connective tissues not only help to organize the muscle but also serve as conduits for blood vessels and nerves that are essential for muscle function. The epimysium blends into the tendon, which attaches the muscle to the bone. Together, these structures allow for the coordinated contraction and force generation required for movement.
Let me generate the image for you!
Here is the diagram showing the structure of skeletal muscle fibers, with labels for the different connective tissue layers: the endomysium, perimysium, and epimysium, as well as the muscle fibers themselves. You can use this as a visual reference for your study. Let me know if you need any further details!
