Muscles

Interesting Muscle Facts Thirty facial muscles create looks like surprise, happiness, sadness, and frowning Eye muscles are the busiest muscles in the body. Scientists estimate they may move more than 100,000 times a day Largest muscle in the body is the gluteus maximus muscle in the buttocks. It takes 10 muscles to smile, 12 muscles to frown. Smallest muscle in our body is in the inner ear and is called stapes

What makes our bodies move? MUSCLES!!! Marionettes are puppets on strings. By pulling different strings, you make these puppets dance, bow or wave their arms. Your skeleton is similar to the puppet’s body. It does not move unless something pulls on its bones. The strings that pull on your bones are your MUSCLES.

What is Muscle? Muscle is a tissue composed of bundles of elongated cells capable of contraction and relaxation to produce movement in an organ or body part.

Parts of the muscle Tendon: white cord made up of extremely strong tissues Connects muscle to the bone Body: thick part of the muscle Aponeurosis: membrane of connective tissue separating the muscle from the adjacent muscles

Tendon vs. Ligament A tendon is a fibrous connective tissue which attaches muscle to bone. Tendons may also attach muscles to structures such as the eyeball. A tendon serves to move the bone or structure. A ligament is a fibrous connective tissue which attaches bone to bone, and usually serves to hold structures together and keep them stable. Tendinitis is inflammation, irritation, and swelling of a tendon, which is the fibrous structure that joins muscle to bone. In many cases, tendonosis (tendon degeneration) is also present. Causes, incidence, and risk factors    Return to top Tendinitis can occur as a result of injury, overuse, or with aging as the tendon loses elasticity. It can also be seen in systemic diseases such as rheumatoid arthritis or diabetes. Tendinitis can occur in any tendon, but some commonly affected sites are the shoulder, the wrist, the heel (Achilles tendonitis), and the elbow.

Functions of Muscles Movement of limbs and organs Posture maintenance Even while you are still your muscles are continuously at work in order to maintain your posture Joint stabilization Without muscles, some of our joints would not stay in place Heat Release Muscle contraction requires chemical energy 75% of this chemical energy is transformed into thermal energy (ie. heat). The thermal energy that is released helps maintain body temperature at 37°C

Voluntary vs. Involuntary Muscle Muscle can be voluntary or involuntary Voluntary - consciously controlled by the brain Ex: raising your arm to scratch your head Involuntary - not consciously controlled by the brain. Ex: the contraction of the diaphragm during inhalation

There are 3 Types of Muscle All the functions of muscle are carried out by 3 different muscle tissues: Skeletal (Striated) Smooth Cardiac

Skeletal Muscle (voluntary -striated)

Skeletal Muscle The only muscles that perform voluntary movements. Striated appearance Attached to the bones of the skeleton Can generate a lot of force but tire easily: low endurance

Smooth Muscle (Involuntary - no striations)

Smooth Muscle Involuntary No striations Make up the walls of the internal organs such as the bladder, stomach, and uterus. Do not generate as much force as skeletal muscle but do not tire easily: medium endurance

Cardiac Muscle (involuntary, no striations)

Cardiac Muscle Involuntary No striations Found only in the heart Has great strength and endurance

Antagonistic Muscles All muscles work in pairs. Whether they are striated muscle, smooth muscle or cardiac muscle makes no difference, all muscles must work in pairs.

Antagonistic Muscle Pair When biceps contracts, the triceps elongates and relaxes. When the triceps contracts the biceps elongates and relaxes. biceps triceps

Review Questions What is a muscle? Describe the 3 parts of a muscle. What is the difference between a tendon and a ligament? What are the 4 functions of muscles? What are the 3 different types of muscles and where can they be found in the body? Give an example of an antagonistic muscle pair. What happens to the shape of a muscle when it contracts? And when it relaxes?