Muscle Anatomy: Fascicles, Sarcomeres, and Attachments - Anatomy and Physiology
- What is a fascicle in skeletal muscle?
- A bundle of muscle fibers enclosed by perimysium.
- How does an aponeurosis differ from a tendon?
- A tendon is a cordlike attachment; an aponeurosis is a broad, flat sheet. Both are dense regular connective tissue.
- Which connective tissue layer surrounds each individual muscle fiber?
- The endomysium, a fine areolar connective tissue.
- Which band of a sarcomere contains only thin filaments and is bisected by the Z disc?
- The I band (light band).
- Which connective tissue layer surrounds each fascicle?
- The perimysium.
- How does a muscle's origin differ from its insertion?
- The origin attaches to the less movable bone; the insertion attaches to the bone that moves when the muscle contracts.
- Which connective tissue layer surrounds an entire skeletal muscle?
- The epimysium, a dense irregular connective tissue sheath.
- What structures mark the boundaries of a sarcomere?
- Two adjacent Z discs. A sarcomere runs from one Z disc to the next.
- Which band of a sarcomere spans the full length of the thick filaments?
- The A band (dark band).
- How does a pennate fascicle arrangement affect muscle function compared with a parallel arrangement?
- Pennate muscles pack in more fibers at an angle to the tendon, producing more force but shortening less.
- What is the H zone of a sarcomere?
- The central part of the A band where only thick filaments are present, with the M line in its middle.
- What fascicle arrangement does the deltoid muscle have?
- Multipennate. Many feather-like bundles insert onto several tendons that converge on one attachment.