Definitions

Anatomy - is the branch of science concerned with describing the bodily structure of humans, animals, and other living organisms. (What we are made of.)

Physiology - is the branch of biology that is concerned with how the various body parts function and work together. (How the body works.)

Muscular System

- there are more than 600 muscles in the human body

-- this makes up half of our body weight.

- without muscles, bones could not move

There are 3 different kinds of muscles:

1. Skeletal muscle

         - attached to bones and make movement possible

         - skeletal muscles are attached to bones by tendons

         - tendons are tough, elastic bands of tissue

- skeletal muscle is called voluntary muscles because you control when it moves

2. Smooth muscle

- found in the walls of blood vessels, the stomach and other body organs

- smooth muscle is called involuntary because you do not control it

- The central nervous system adjusts its contraction as required.

- These muscles do not tire easily and can stay contracted for a long period of time.

- This is important because the stomach, intestines eye blinking and blood vessels are smooth muscles

3. Cardiac muscle

         - found in the walls of the heart

- cardiac muscle pumps blood through the heart and the rest of the body

Muscle Action

- when a muscle contracts, the cells in the muscle shorten

- as the muscle shortens, it pulls on the bone to which it is attached

- movement of the bone causes the body part to move

- muscles can only pull bones - they cannot push

- one muscle might bend your arm but a different muscle is needed to straighten it

- for this reason, muscles always work in pairs

- the muscle that bends a joint is called a flexor (ex. hamstrings)

Muscle contraction

1.      An electrical impulse comes from the brain or spinal cord.

(Voluntary or involuntary)

2.      The signal travels along the nerve to the muscle site (the neuromuscular junction) and attempts to jump the gap.

3.      A chemical reaction takes place deep within the muscle fibre (many times over), affecting the entire muscle group.

4.      At the molecular level, the reaction causes the filaments to slide with respect to each other.

5.      The muscle fibre contracts

Types of muscle contraction

1.      Concentric contraction - the muscle shortens while working.

2.      Eccentric contraction - the muscles lengthens while working.

3.      Isometric contraction - the muscle force is equal to the resistance and the muscle doesn’t change

Musculo-skeletal system

-Bodily movement is carried out by the interaction of the muscular and skeletal systems.

-For this reason, they’re often grouped as the musculo-skeletal system.

-Muscles are connected to bones by tendons.

-Bones are connected to each other by ligaments.

-Where bones meet one another is typically called a joint.

-Muscles which cause movement of a joint are connected to two different bones and contract to pull them together.

(An example would be the contraction of the biceps and a relaxation of the triceps. This produces a bent elbow. Contraction of the triceps and relaxation of the biceps produces the effect of straightening the arm.)

Muscle Problems

- a charley horse is caused by a bruise and tears in a muscle, which cause bleeding in the muscle

- a muscle spasm is caused when a muscle contracts quickly and involuntarily

- a muscle cramp is a strong and persistent spasm that does not relax

- sore muscles are caused by small tears in muscles caused by over-use

- sore muscles can be avoided by warming up before exercise

Anatomical position - standing erect, facing the observer, arms are at the sides with palms facing forward.

Superior - toward the head

Inferior - away from the head

Anterior - the front of the body or body part

Posterior - the back of the body or body part

Medial - toward the midline that divides left and right

Lateral - to the side away from the midline

Proximal - closer to the torso

Distal - farther away from the torso