Muscular System

The muscular system makes up nearly half the weight of the human body. The muscles provide the forces that enable the body to move. Muscles stretch across joints to link one bone with another and work in groups to respond to nerve impulses.

There are three types of muscle

• Skeletal Muscle
• Smooth Muscle
• Cardiac Muscle

Skeletal Muscle

• There are nearly 650 skeletal muscles in the human body
• Skeletal muscles are attached to the skeleton
• They work in pairs: one muscle moves the bone in one direction and the other moves it back again
• Skeletal muscles are voluntary muscles - in other words we think about what movements we want to make (at least, usually!) and send messages via our nervous system to tell the appropriate muscle(s) to contract.
• Muscle contractions can be short, single contractions or longer ones.

Smooth Muscle

• Smooth muscle is found in our internal organs: in our digestive system, our blood vessels, our bladder, our respiratory organs and, in a female, the uterus.
• Smooth muscle can stretch and maintain tension over extended periods
• Smooth muscles are involuntary muscles - in other words we do not have to think about contracting them because they are controlled automatically by the nervous system.

Cardiac Muscle

• Cardiac muscle is found only in the heart.
• It can stretch, just like smooth muscle, and contract like skeletal muscle.
• It is a twitch muscle - it only does short single contractions
• Like smooth muscle, cardiac muscle is involuntary.

Muscle Contraction / Movement: Nerve impulses bring about muscle contraction and contraction causes fiber shortening so light and dark fibers become closer together. As contraction of muscle ends, fibers relax and muscle length is once again attained due to increased length of muscle fiber.

Major Skeletal Muscles

The muscular body is divided into ten different areas where muscles can be found: facial, neck, shoulder, arm, forearm, thorax, abdomen, hip, pelvis/thigh, leg.

• Facial: In the facial are one finds all the muscles which move the face. Orbicularis oculi-sound are the two muscles that move the eye are. Frontalis-sound andTemporalis-sound are the two muscles which move the forehead and sides of your head. Zygomaticus-sound and Masseter-sound are the two muscle that work in conjunction to move tyoou jaw and upper lip area. Orbicularis oris-sound is the muscle which moves your lips.
• Neck: The neck area is almost entirely moved by the sternohyoid-sound and Sternocleidomastoid-sound. These muscles allowthe neck to move your head left and right. They work with the platysma muscle to control how far you can move your head left and right. What allows your head to move up and down is the trapezius-sound. The trapezius is so large that it extend down to the shoulder and thorax area. The trapezius is a good example of how some muscles are named by their shape. the trapezius looks just like a trapezoid.
• Shoulder: A group of muscles all work together to move the whole shoulder area. This group takes into account the trapezius-sound, deltoid-sound, infraspinatus-sound, teres major-sound, and the rhomboid major-sound. The rhomboid major is called so because its shaped like the geometric shape of a rhombus. Along with the help of the ball and socket joint-hyperlink in your shoulder, these group of muscles allow your arm to throw a softball, pick things over your head, and give your arms a good strech early in the morning.

• Arm: Most known amongst teenage weight lifters is the arm area. The famous bicep brachii-sound is the muscle that allows you to bring your forearm close to your body and form a huge ball of muscle which catches a lot of attention amongst weight lifters. The tricep brachii-sound and brachialis-sound are the two other muscles located in the arm region. These muscles allow a person to do push-ups!
• Forearm: A majority of the muscle in the forearm help control a part of the arm. Amongst these is the Berachiodialis major-sound, palmaris longus-sound, and Flexor carpi radialis-sound. The name of the flexor carpi radialis is a good example of how muscles are named by their function and location. This muscle is named carpi because of the bones that it helps move, the carples. Also, the name of radialis is made by the bone that its attached to, the radius.
• Thorax: The thorax is the set of muscles which carrying your head, arms, stomach, and any other upper body areas. These muscles are the trapezius-sound and latissimus dorsi-sound. Usually, the majority of the muscles of the thorax can be damaged easily is one dose not stretch before exercise, or lifts a heave load.
• Abdomen: The abdominal area consists of the muscles that allows you to bend down and move your waist from side to side. The internal oblique-sound and external oblique-sound are the muscles that move your body from left to right. The Transversus abdominus-sound and Rectus abdominus-sound, along with the trapezius-sound an latissimus dorsi-sound allow you to bend down and grab objects.
• Hip: Only two muscles make up the hip area. These are the gluteus medius-sound and gluteus maximus-sound. Probably the laziest muscles in the whole system the gluteus set of muscles are used only to sit down on.
• Pelvis/Thigh: An overlaping of muscles is what makes this area so firm. The pelvis area is usualy refered to as the upper part of the leg. Muscles like the pectineus-sound and illiopsoas-sound , which help support the upper leg area are known as pelvic muscles. Thigh muscles are very rich in capillaries and support the whole body. The upper thigh muscles are abductor longus-sound, Gracilis-sound, Sartorius-sound, and Tensor fasciae latea. The lower thigh muscles are rectus femoris-sound, vastus lateralis-soundand medialis-sound. Located in the back of your leg are the hamstrings-sound. These muscles help you run, jump, and walk!
• Leg: Helping the thigh region support the body is the Leg region. These muscles like the Gastrocnemius-sound, soleus-sound, porenius longus-sound, and Tibialis anterior-sound absorb the impact when one walks and runs.

Smallest Muscle: The smallest muscle of the skeleton is the stapedius, which measures 1/20th of an inch. It is the activator of the stirrup that sends vibrations from the eardrum to the inner ear.

Largest Muscle: The largest muscle is the latissimus dorsi. This is the flat muscle of the back that operates during arm movement.

Fastest Muscle: The eye muscle is the fastest reacting muscle of the whole body. It contracts in less than 1/100th of a second.

Longest Muscle: The longest muscle in your body is the sartorius.

There are over 650 muscles in your body. A smile uses 17 muscles, a frown uses 43.

So, Keep Smiling :)