The Muscular System Chapter 7 The anatomical system of a species that allows it to move. The muscular system in vertebrates is controlled through the nervous system, although some muscles are (such as the cardiac muscle) can be completely autonomous.

Overview of Muscular System Types of Muscle Tissue Under voluntary control Skeletal muscles Under involuntary control Cardiac muscle Smooth muscle visceral organs

Overview of Muscular System Skeletal muscles attach to bones directly or indirectly Perform five functions Produce movement of skeleton Maintain posture and body position Support soft tissues Guard entrances and exits Maintain body temperature

Anatomy of Skeletal Muscles Gross Anatomy Connective tissue organization Epimysium Fibrous covering of whole muscle Perimysium Fibrous covering of fascicle Endomysium Fibrous covering of a single cell (a muscle fiber) Tendons (or aponeurosis)- at each end of the muscle, the collagen fibers of all three layers come together to form either a bundle or a broad sheet.

Anatomy of Skeletal Muscles The Organization of a Skeletal Muscle Figure 7-1

Anatomy of a Muscle Fiber

Anatomy of a Muscle Fiber Microanatomy of a Muscle Fiber Sarcolemma Plasma membrane Sarcoplasm cytoplasm Sarcoplasmic reticulum (SR) Like smooth ER Transverse tubules (T tubules) Myofibrils (contraction organelle) Sarcomeres Inside a single fiber

Anatomy of Skeletal Muscles Sarcomere—Repeating structural unit of the myofibril Components of a sarcomere Myofilaments Thin filaments (mostly actin) Thick filaments (mostly myosin) Z lines at each end Anchor for thin filaments Filament – a chain of cells

Anatomy of a Muscle Fiber Figure 7-2(a)

Anatomy of a Muscle Fiber The Organization of a Single Muscle Fiber Figure 7-2(b)

Anatomy of Skeletal Muscles The Organization of a Single Muscle Fiber Figure 7-2(cde)

Anatomy of Skeletal Muscles Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber Figure 7-3 (1 of 2)

Anatomy of Skeletal Muscles Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber Figure 7-3 (2 of 2)