BHS: Anatomy and Physiology: Muscular System Anatomy

Tendons

Connect muscle to bone. Made of very tough collagen fibers in the form of dense regular connective tissue.

Sarcolemma

Cell membrane of a muscle cell.

Myofibrils

Long fibers that make up muscle cells. Made of thick filaments (myosin) and thin filaments (actin) that contract the muscle.

Epimysium

A sheath of elastic tissue that surrounds an entire muscle and protects muscles from friction against bones and other muscles.

Perimysium

Holds the fascicles together, provides structural support for the muscle.

Endomysium

Connective tissue surrounding each individual muscle fiber. Contains nerves and blood vessels.

Fascicle

A bundle of muscle fibers.

How is a muscle organized?

Tendons connect muscles to bone. The epimysium surrounds the entire muscle. The perimysium surrounds the fascicle. Inside the fascicle, the individual muscle fibers are held together by the endomysium.

Which types of muscle move voluntarily?

Skeletal muscle (not cardiac or smooth)

Actin

Thin filaments of muscles.

Myosin

Thick filaments of muscles.

Sarcomere

The contractile unit of a myofibril.

Z disc

Separates the sarcomeres from one another; where actin filaments intersect.

A band

The entire length of myosin.

I band

Thin filaments only.

H zone

Thick filaments only.

Do the lengths of actin and myosin change during a muscle contraction?

No. They just move so that they are overlapping more.