The Muscular System

Muscle Facts 45% body weight Over 600 muscles Muscles are bundles of muscle fibers held together by connective tissue Takes 17 muscles to smile, 43 to frown, every 2000 frowns creates a wrinkle

3 Types of Muscle Skeletal Smooth Cardiac Application: Make a trifold and in each column draw and describe the 3 types of muscle. Include where located and how controlled (voluntary vs. involuntary)

Skeletal Muscle Attach to bones of skeleton Striped or striated Also called voluntary Bundles of muscle cells Each cell is multinucleate Fleshy body parts, provide movement Most attach to bones: facial to skin

4 Functions of Skeletal Muscles Attach to bones to provide voluntary movement and involuntary movement Produce heat and energy for the body Help maintain posture Protect internal organs

Smooth (Visceral) Muscle Small, short, spindle shaped 1 nucleus located in center of cell Do not have any striations – appear smooth Unattached to bones, act slowly, do not tire easily, can remain contracted for a long time INVOLUNTARY Walls of internal organs (except heart)

Cardiac Muscle Found only in heart Branched, striated, interconnected chains 1 nucleus Involuntary No independent cell contraction Requires constant oxygen supply > 30 seconds w/o oxygen – cells die

3 types of muscle cell video https://www.khanacademy.org/science/healthcare-and-medicine/heart-muscle-contraction/v/three-types-of-muscle

4 Characteristics of Muscle Excitability: ability to respond to a stimulus such as a nerve impulse Contractibility: muscle fibers stimulated by nerves contract or become short and thick causing movement Extensibility: ability to be stretched Elasticity: allows muscle to return to its original shape after it has contracted or stretched

Muscle attachments: Muscles are attached at both ends Can be attached to bones, ligaments, cartilage, tendons, skin, to other muscles Fascia: touch, sheetlike membrane that covers and protects

Origin vs. Insertion When muscle attaches to bone, end that does not move is called the origin End that moves when muscle contracts is insertion Belly – central body of muscle

Muscle Action/Movement Using DHO, define the following: Adduction Abduction Flexion Extension Rotation Circumduction

Adduction: moving a body part toward the midline Abduction: moving a body part away from the midline Flexion: decreasing the angle between 2 bones, bending a body part Extension: increasing the angle between 2 bones, straightening a body part Rotation: turning a body part around its own axis (head) Circumduction: moving in a circle at a joint (swinging arm)

What is muscle tone: State of partial contraction State of readiness to act Muscles are partially contracted at all times Loss of muscle tone occurs in paralysis Lack of use causes atrophy (shrink) Contracture – severe tightening of flexor muscle

Contractures

Application: Using Body Structures and Functions, explain how the muscles are a source of heat and energy. Be sure to include how ATP is involved in this process.

Muscle need energy to function Adenosine Triphosphate - ATP – major source of energy Cells bring in oxygen, glucose, etc Muscle stimulated ATP released producing heat for our body and energy for muscle contracting

During process of ATP release creating energy/heat: lactic acid (byproduct of cellular metabolism) builds up Increased lactic acid levels in muscles cause muscle fatigue WHY? Vigorous exercise – blood can’t transport enough oxygen to complete oxidation of glucose in muscles – muscles contract anaerobically So why does resting help a cramp?

Fibromyalgia Chronic, widespread muscular pain S&S: muscle stiffness, numbness, tingling in arms or legs, fatigue, sleep disturbances, memory and mood issues, headaches and depression Causes:unknown Tx: pain relief, PT, massage, exercise, stress reduction, pain meds, muscle relaxers

Muscular Dystrophy A group of inherited diseases that lead to chronic,progressive muscle atrophy. Usually begins in childhood S&S: muscle atrophy including heart and respiratory system muscles leading to total disability and early death. Causes: inherited- genetic defect Tx: PT

Living with Muscular Dystrophy

Myasthenia Gravis Chronic condition where nerve impulses are not properly transmitted to the muscles leading to progressive muscle weakness and paralysis. S&S: eye weakness, drooping eyelids, altered speech, difficulty swallowing or chewing Causes: unknown but may be autoimmune Tx: no cure but cholinesterase inhibitors seems to increase communication bw muscles and nerves, corticosteroids limit antibody production, immunosuppressants, plasmapharesis

Muscle Spasms also known as cramps. Sudden, painful, involuntary muscle contractions S&S: cramps Causes: overexertion, dehydration, low electrolyte levels, poor circulation TX: gentle pressure and massage, stretching of muscle to relieve spasm

Muscle Strain Overstretching of or an injury to a muscle or tendon S&S: myalgia, swelling, limited movement Causes: prolonged or sudden exertion Tx: rest, muscle relaxers, pain meds, ibuprofen, elevation, compression, hot/cold applications

Tennis Elbow Inflammation of the tendon that connects the arm to the elbow S&S: pain at elbow Causes: repetitive use of arm Tx: pain relief, ice packs

Shin Splints Injury to muscle tendon in front of shin S&S: pain in shin Causes: running/jogging Tx: proper fitting shoes with arch support

Rotator Cuff Disease Inflammation of group of tendons that surround shoulder joint S&S: repetitive swinging action of joint Causes: pain at shoulder Tx: rest, PT, surgery

Rotator Cuff Surgery 3 Signs of Rotator Cuff injury by PT