Chapter 5 The Muscular System

Name three things that differentiate Type I and Type II muscle fibers.

Type I, slow twitch fibers , have a relatively slower contraction time and a high resistance o fatigue. They contain a high number of mitochondria, large amounts of myoglobin, and have an ample capillary supply, giving them a rich, red color. Type IIB, fast twitch fibers, produce powerful , high velocity contractions for short periods. They contain few mitochondria, low myoglobin content, and few capillaries, which give them a lighter, whitish color.

What is the difference between voluntary and involuntary muscles?

Voluntary muscles can be controlled by the will; involuntary muscles are not controlled by the will and receive nerve stimulation from the automatic nervous system.

Name three types of muscular tissue and give examples of where they are found.

Voluntary or striated muscles is found in the muscles that attach to the skeleton; involuntary nonstriated muscle is found in the hollow muscular organs such as the stomach, intestines, bladder, and blood vessels; heart cardiac muscle is found only in the heart.

Why is it important for the massage practitioner to understand how muscles function?

When massage practitioners understand how muscles function, they are better able to apply massage techniques that can relax tense muscles and rejuvenate tired muscles

When the elbow is flexed, is the triceps the prime mover or the antagonists?

When the elbow is flexed, the triceps become the antagonist.

What is acetylcholine? Where is it found, and what does it do?

Acetylcholine is a chemical neurotransmitter found at the myoneural junction. When a nerve impulse travels to the end of a motor neuron, acethycholine is released and travels across the gap to excite the muscle cell to contact.

Which joints have limited motion?

Amphiarthrotic joints have limited motion.

Explain the difference between isometric and isotonic muscle contractions.

An isometric muscle contraction is a static contraction wherein the distance between the ends of he muscle does not change, and so there is no movement. With an isotonic muscle contraction, the distance between the ends of the muscle changes, and there is movement.

Which tissues are found in muscles?

Beside the muscle fibers, muscle contains a variety of connective tissue, blood and other fluids, blood and lymph vessels, and nerves.

What is fascia?

Fascia is connective tissue that organizes muscles onto functional groups, surrounds each individual muscle, extends inward throughout the muscle creating muscle bundles, and eventually surrounds each muscle fiber. The fascia projects beyond the ends of the muscles to other structures. The superficial fascia is situated just below the skin and covers the entire muscular.

Do diarthrotic joints remain motionless or are they capable of free movement?

Diarthrotic joints are freely movable.

What is meant by extensibility of muscle?

Extensibility is the ability of muscle fibers to lengthen and stretch.

What is meant by the term motor unit?

A motor unit is all of the muscle fibers that are controlled by a single motor neuron.

Explain the difference between eccentric and concentric contractions. What do they have in common?

Eccentric and concentric muscle contraction are both isotonic contractions. In a concentric contraction , the ends of the contracting muscle are coming closer. In an eccentric contraction, the ends of the contracting muscle are moving farther apart.

What is muscle atrophy?

Muscle Atrophy is a degenerative process caused by muscle disuse. The muscle fibers reduce in size , blood supply is reduced, and the muscle weakens.

To what does the term agonist or prime mover refer?

Prime mover and agonist both refer to the primary muscle that is responsible for a specific movement.

To which structures are skeletal muscles attached?

Muscles are attached to bones, cartilage, ligaments, tendons, skin, and sometimes to each other.

What is the structure and function of muscles?

Muscles are contractile fibrous issue that produces various movements of the body.

Which molecular structure provides the energy for muscle contraction?

Muscles receive energy from the breaking down of adenosine triphosphate ATP into adenosine diphosphate ADP.

What is the relationship between oxygen debt and muscle fatigue?

Oxygen debt results from the muscles expending energy faster than the body can supply the oxygen needed to produce the energy. When oxygen debt becomes extreme, the muscles stop functioning in a condition known as muscle fatigue.

What are skeletal muscles?

Skeletal muscles are striated muscles attached to the bones of the skeleton.

Are synarthrotic joints movable or immovable?

Synarthrotic joints, as in the skull, are functionally immovable.

Which structure attaches the muscle to the bone?

Tendon or sinew attaches muscles to the bone.

Which characteristics enable muscles to produce movements?

The characteristics that enable muscles to produce movement are irritability, contractility, and elasticity.

What is the function of fibrous connective tissue in muscle?

The function of fibrous tissue connective tissue is to organize and support muscle tissue blood vessels, and nerves. Connective tissue anchors the muscles fibers and connects them to the structures that they act on.

What is the functional unit of skeletal muscle?

The functional unit of skeletal muscle is the muscle cell or muscle fiber.

What is the insertion of a muscle? Give an example.

The insertions of a muscle refers to the attachments that perform the action , such as muscles attached to skin, other muscles, or the more distal and movable attachment.

What is the origin of a muscle? Give an example.

The origin of a muscle refers to the more fixed bones, that act as anchors for movements.

What structures cause the striated appearance of skeletal muscles?

The striated appearance of voluntary muscle is due to the arrangement of the actin and myosin in the myofibrils.

What does the term myofascial refer to?

The term myofascial was coined to refer to the combination of muscle tissue and its related connective tissue or fascia.

What are the three components of motion?

The three components of motion are flexion, extension, adduction or abduction, and rotation.

Name and locate the three connective tissue layers of muscle.

The three layers of connective muscle are the epimysium, which covers the muscle, the perimysium, which separates the muscle bundles, and the endomysium, which surrounds each muscle cell.

Approximately how many muscles are there in the human body?

There are approximately 600 muscles in the human body.

Describe three degrees of muscle strain.

There are three degrees or grades of muscle strain. Grade I is an overstretching of a few of the muscle fibers with a minimal tearing of fibers. Grade II involves a partial tear of between 10 and 50 percent of the muscle fibers. Grade III is the most severe injury, with between 50 to 100 percent muscle tearing.