Muscular System

Introduction Over 600 muscles make up the muscular system MUSCLES ARE = Bundles of muscle fibers that are held together by connective tissue

Characteristics of Muscles Excitability/Irritability = ability to respond to a stimulus such as a nerve impulse Contractibility = When muscle fibers are stimulated by nerves they contract = become short and thick This causes movement

Characteristics of Muscles Extensibility = Ability to be stretched Elasticity = Allows the muscle to return to its original shape after it has contracted or stretched

Kinds of Muscles CARDIAC Form the walls of the heart Contract to circulate blood Involuntary = function without conscious thought or control

Kinds of Muscles VISERAL/SMOOTH Found in the internal organs of the body (digestive system, respiratory system, blood vessels, and eyes) Contract to cause movement in these systems Involuntary

Kinds of Muscles SKELETAL Attached to bones Voluntary = person has control over their action Will focus on SKELETAL muscles in the following sections

Function of Skeletal Muscles Attach to bones to provide voluntary movement Produce heat and energy Help maintain posture Protect internal organs

DID YOU KNOW? You need 17 muscles to smile, but you need 43 muscles to frown Every 2000 frowns create one wrinkle

Major Muscles of the Body Masseter Located = cheek to lower jaw Biting and chewing Sternocleidomastoid Located = Side of the neck Turns and flexes the head

Major Muscles of the Body Trapezius Located = Upper back and neck Extends head, moves shoulders Deltoid Located = Shoulder Abducts arm, is an injection site

Major Muscles of the Body Biceps brachii Located = Upper arm Flexes lower arm Triceps brachii Extends lower arm Pectoralis major Located = Upper chest Adducts and flexes upper arm

Major Muscles of the Body Intercostals Located between ribs Moves ribs for breathing Rectus abdominus Located = anterior ribs to pubis (pelvis) Compresses abdomen Latissimus dorsi Located = posterior spine around to chest Extends and adducts upper arms

Major Muscles of the Body Gluteus maximus Located = buttocks Extends thigh, is an injection site Sartorius Located = front of thigh, runs diagonal Abducts thigh, flexes leg Tibialis anterior Located = front of lower leg (tibia side) Flexes and inverts the foot

Quadriceps Muscles Group of four muscles located in the anterior thigh. Rectus Femoris Vastus Medialis Vastus Lateralis Vastus Intermedialis.

Major Muscles of the Body Soleus Located = posterior lower leg Gastrocnemius Flexes the foot

Methods of Attachment Tendon Strong, tough connective tissue cord Examples: Achilles tendon, which attaches the gastrocnemius muscle on the calf of the leg to the heel bone

Images of tendons

Methods of Attachment Fascia Tough, sheet like membrane Covers and protects the tissue Example: lumbodorsal fascia, which surrounds the deep muscles of the trunk and back

Images of Fascia

Methods of Attachment ORIGIN and INSERTION When muscle attach to bones, one end becomes the origin and one end becomes the insertion ORIGIN = end that does not move INSERTION = end that moves when muscle contracts

Movements of Muscles ADDUCTION Moving a body part toward the midline ADD to the body

Movements of Muscles ABDUCTION Moving a body part away from the midline Opposite of ADD

Movements of Muscles FLEXION Decrease the angle between two bones or the bending of a body part

Movements of Muscles EXTENSION Increasing the angle between two bones or straightening a body part

Movements of Muscles ROTATION CIRCUMDUCTION Turning a body part around its own axis Example Turning head side to side Turning (rotating) wrist CIRCUMDUCTION Moving in a circle at a joint Example = swinging the arm in a circle

Muscle Tone MUSCLE TONE = Muscles are partially contracted at all times even though they may not be in use This is also called a “state of readiness to act”

Loss of Muscle Tone This is called ATROPHY or WASTING AWAY This can occur in severe illnesses such as paralysis Occurs when muscles are not used for a long period of time This is called ATROPHY or WASTING AWAY

Contractures Lack of use can also result in a CONTRACTURE This is a severe tightening of a flexor muscle Results in bending of a joint FOOT DROP is a common contracture Also fingers, wrists, and knees, as well as other joints, can be affected

Contractures

Muscle spasms usually occur in the legs or feet sudden painful, involuntary muscle contractions usually occur in the legs or feet causes are overexertion, low electrolyte levels, or poor circulation gentle pressure and stretching of muscle are used to relieve the spasm

Strain Frequent sites include the back, arms, legs is an overstretching of or injury to a muscle and/or tendon Frequent sites include the back, arms, legs prolonged or sudden muscle exertion is usually the cause. symptoms are muscle pain, swelling and limited movement Tx- rest, muscle relaxants, or pain medications, elevating the extremity and alternating hot & cold applications

Diseases of the Muscles Fibromyalgia Chronic, widespread pain experienced in specific muscle sites (tender points) Etiology (cause) is unknown but stress, weather, and poor physical fitness seems to affect this condition 80% - 90% diagnosed are women

Diseases of the Muscles Fibromyalgia - Symptoms Muscle stiffness Numbness or tingling in the arms or legs Fatigue Sleep disturbances, Headaches Depression

Diseases of the Muscles Fibromyalgia Treatment is directed toward pain relief Physical therapy Massage therapy Exercise Stress reduction techniques Medication to relax muscles Medication for pain Medication for sleep and depression

Diseases of the Muscles Muscular Dystrophy Group of inherited diseases Leads to chronic progressive muscle atrophy Muscles shrink in size and lose strength Usually appears in early childhood Most types result in total disability and early death

Muscular Dystrophy Treatment = physical therapy to slow progression of the disease, prevent contractures No known cure or drug treatment

Tetanus Infectious disease caused by contamination of wounds from the bacteria Clostridium tetani Spores produced by the bacteria live in the soil and animal feces The usual locations for the bacteria to enter the body are puncture wounds, such as those caused by rusty nails, splinters or insect bites, burns or IV drug sites. Tetanus is acquired through contact with the environment; it is not transmitted from person to person

Tetanus Tetanus results in severe, uncontrollable muscle spasms. Lockjaw – severe spasms cause the jaw to “lock” Muscles used to breathe can spasm possibly leading to death

Treatment / Prevention: Tetanus Treatment / Prevention: Vaccinations: series of 5 shots starting at 2 months old – DTaP. Tetanus booster every 10 years Wound care Antibiotics

REVIEW What is the difference between voluntary and involuntary muscles? What is the action of cardiac, visceral/smooth, and skeletal muscles? How does a tendon differ from a fascia? What is the origin and insertion of a muscle?

REVIEW What happens to muscle tone in a severe illness such as paralysis? What is a contracture? What is fibromyalgia? What is muscular dystrophy?