Muscular System

Functions of MusclesProduce movement

Maintain postureStabilize jointsGenerate heat

Vocabulary ATP Acetylcholine Antagonist Abduction Adduction Atrophy Extension Flexion fixators

hypertrophy Insertion Isometric contraction Isotonic contraction Muscle tone Muscle fatigue Motor unit Neuromuscular junction Origin Oxygen debt Prime mover synergist

Three classes of muscles

Cardiac Smooth Skeletal

Body location

Cell shape

contraction

Functional Characteristics Irritability

Ability to receive and respond to stimuli

Contractility Can shorten

Extensibility Can stretch

Elasticity Regain shape

Levers For movement to occur, bones and muscles

interact as a simple machine called a lever.

Four basic components of levers Rigid bar, a fulcrum on which the bar turns, the

resistance, and the force needed to move the bar. Bicep curl: forearm bones are the rigid bar, elbow

joint is the fulcrum, the weight in the hand is the resistance, and the biceps brachii muscle in the front of the arm generates the energy to move the weight.

Gross Anatomy of skeletal muscle Tendons attach muscle to

bone Connective tissue wrappings

Fascia covers the muscle Epimysium covers each

bundle of muscle fibers (fascicles)

Perimysium covers each individual fascicle

Skeletal Muscle activity Must be stimulated by a nerve first Neurotransmitters (acetylcholine) are

hormones stimulated by the nerve impulse to initiate a muscular contraction.

Calcium – these ions are needed for the physiology of a muscle contraction; located in the sarcoplasmic reticulum

All-or-none response- muscle cell fiber (myofibril) contract completely

ATP Only source of energy for muscle activity Limited amounts from cellular respiration Produced by muscle in two ways

Creatine phosphate- ATP reserve for later when oxygen supplies are low during anaerobic activity.

Aerobic respiration At rest and low-intensity workouts

5 Golden Rules of Skeletal Muscle ActivityAll muscles cross at least one jointThe bulk of the muscle lies proximal to

the joint it crossesAll muscles have at least two

attachments: origin and insertionDuring contraction insertion moves

toward originMuscles can only pull; never push

Exercise and muscles Muscle tone

(Hypertrophy)

State of continuous muscle contraction

Atrophy

Wasting away of muscle not being used

What is strength? Amount of force that can be applied by a muscle

during maximum contraction.

Three types of strengthening exercises Isometric: contracts the muscle without changing

its length. Example: quad set

Isotonic: shortens and lengthens muscle through a complete range of motion.

Example: leg press or a squat

Isokinetic: Resistance is given at a fixed speed of movement with accommodating resistance.

Use of a device with a mechanical pressure system to produce a constant speed of motion; use for diagonostics or rehab.

Major Skeletal Muscles Over 600 skeletal

muscles in the body. A muscles name often

describes the muscle itself. Muscles’ size (gluteus

maximus) Shape (trapezius) Location (tibialis anterior) Action (pronator teres) Number of attachments

(triceps)

Several muscles work in groups for common action: Rotator cuff muscles:

Supraspinatus, infraspinatus, subscapularis, teres minor

Quadriceps: rectus femoris, vastus medialis, v. lateralis, v. intermedius

Hamstrings: biceps femoris, semitendinosis, semimbranosis

Identify the actions of the following muscles Biceps brachii Brachioradialis Buccinator Deltoid Diaphragm External obliques Hamstring (muscle group) Gastrocnemius Gluteus maximus Gluteus medius Intercostals masseter

Latissimus dorsi Pectoralis major Quadriceps muscle

group Rectus abdominis Sartorius Soleus Sternocleidomastoid Tibialis anterior Trapezius Triceps brachii

Orthopedic topics Osteomyelitis Chondromalacia Lateral ankle sprain Meniscus tear Rotator cuff tear SLAP lesion Bankart tear Epicondylitis ACL tear MCL tear

Osteoarthritis Bucket handle meniscal

tear Ligament sprains Muscle strain Spondylolysis Osgood Schlatter’s

disease Jumper’s knee Iliotibial band friction

syndrome

Bursitis March fracture Colles’ fracture Avulsion fractures Turf toe Plantar fasciitis Herniated disk osteoporosis

Duchenne’s muscular dystrophy

Muscular sclerosis