Muscle Anatomy

Macroscopic Anatomy - Tendons connect the muscles to bone and are made up of numerous fascicles all clustered together surrounded by epimysium

-Fascicle: a bundle of muscle fibers all put together surrounded by perimysium

-Muscle fiber (muscle cell): a cluster of myofibril surrounded by endomysium

-Myofibrils: long proteins chains that make up muscle cells

- Myofilaments: filaments within the myofibrils

Muscle Coverings Deep Fascia –surrounds the muscles; allows for communication and connection between muscles Epimysium - under the fascia; decreases the friction between muscles Perimysium –groups muscle fibers into bundles Endomysium –encloses a single muscle fiber

What is a muscle fiber (cell) made out of? Microscopic Anatomy: Cell membrane - sarcolemma. Multiple nuclei and mitochondrion are found within the cell Cytoplasm, called sarcoplasm, is almost completely filled with long protein chains called myofibrils.

What does each myofibril look like?

Myofibril Structure Each myofibril has an alternating light (I) and dark (A) band. Each light I band has a darker midline called a Z line. Each dark A band has a lighter central area called the H zone. Middle area of the H zone is called the M-line. One Z line to another Z line is called a Sarcomere.

Let’s take a closer look at a Sarcomere Composed of long proteins called myofilaments. 2 Types: Thick (myosin) filament – filled with myosin protein heads (act like hands). Thin (actin) filament – made of a protein called actin which allows myosin heads to grab onto it.

Let’s take a closer look at Myosin

Let’s take a closer look at Actin

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