The Muscular System. Approximately 40% of your body weight Approximately 650 muscles Muscles only pull (they can’t push) You have over 30 facial muscles

The Muscular System

• Approximately 40% of your body weight • Approximately 650 muscles• Muscles only pull (they can’t push)• You have over 30 facial muscles• Eye muscles move more than 100,000 times a day

MUSCLES

Muscle Functions:

Muscle plays six important roles in the body:

1. Produce skeletal movement2. Maintains posture and body position3. Support soft tissues (abdominal wall & pelvic cavity)4. Guard entrances and exits (digestive and urinary

tracts)5. Maintain body temperature (energy is converted to

heat)6. Store nutrient reserves (proteins are broken down &

amino acids are used)

There are 3 types of muscle tissue

1. Skeletal2. Cardiac3. Smooth

Skeletal Muscles

• - organs that are composed mainly of skeletal muscle tissue, but they also contain connective tissues, nerves, and blood vessels.

• Each cell is a single muscle fiber.• Muscle fibers form bundles called fascicles.• Directly or indirectly attached to the bones of

the skeleton

Organization of Skeletal Muscle Tissue:

Three layers of connective tissue are part of each muscle:

1. Epimysium – dense layer of collagen fibers that surround the entire muscle

2. Perimysium – divides the muscle into a series of compartments each containing a bundle of muscle fibers (fascicle); contains collagen & elastic fibers, blood vessels and nerves that maintain blood flow

3. Endomysium – flexible, elastic connective tissue layer; surrounds the individual skeletal muscle cells and interconnects adjacent muscle fibers

Fascicle Arrangement• The muscle fibers in a single fascicle are parallel, but the

organization of fascicles in skeletal muscles can vary• The arrangement is correlated with muscle power and

range of motion (structure determines function)• Skeletal muscles are classified as:1. Parallel muscles (most common) – fascicles are parallel

to the long axis of the muscle2. Convergent muscles – converge at a common

attachment site; fibers spread out and pull in different directions

3. Pennate muscles – form a common angle with the tendon

4. Circular muscles – cocentrically arranged around an opening

Organization of Skeletal Muscle Tissue:

• End of the muscle, the collagen fibers of the epimysium, perimysium, and endomysium come together to form a tendon or aponeurosis

• Tendons and aponeuroses attach muscles to bone

• Origin – where the fixed end of the muscle attaches to the bone (cartilage or connective tissue)

• Insertion – where the movable end of the muscle attaches to another structure

Origin/Insertion Example:• Gastrocnemius – calf muscle

that extends from the distal portion of the femur to the calcaneus

• When it contracts it pulls the calcaneus toward the knee

• Origin – femur• Insertion - calcaneus

Slide 6.36a

Naming of Skeletal Muscles:

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· Direction of muscle fibersExample: rectus (straight)

· Relative size of the muscleExample: maximus (largest)

Slide 6.36b



· Location of the muscle

Example: many muscles are named for bones (e.g., temporalis)

· Number of origins

Example: triceps (three heads)

Slide 6.37



· Location of the muscles origin and insertion

Example: sterno (on the sternum)

· Shape of the muscle Example: deltoid (triangular)

· Action of the muscle Example: flexor and extensor

Axial and Appendicular Muscles:

• Axial muscles arise on the axial skeleton (60% of skeletal muscles)

• Position the head and spinal column and move the rib cage

• Appendicular muscles stabilize and move the appendicular skeleton (40% of skeletal muscles)

Slide 6.38

Head and Neck Muscles


Figure 6.14

Slide 6.39

Trunk Muscles


Figure 6.15

Slide 6.40

Deep Trunk and Arm Muscles


Figure 6.16

Slide 6.41

Muscles of the Pelvis, Hip, and Thigh


Figure 6.18c

Slide 6.42

Muscles of the Lower Leg


Figure 6.19

Slide 6.43

Superficial Muscles: Anterior


Figure 6.20

Slide 6.44

Superficial Muscles: Posterior


Figure 6.21

Muscle Actions:• Agonist (prime mover) – a muscle whose contraction

is mostly responsible for producing a particular movement

Example – biceps brachii• Antagonist – a muscle whose action opposes that of

a particular agonistExample – triceps brachii• Agonists and antagonists are functional opposites• Synergists – help a larger agonist work efficiently

Muscle Tone and Contractions

• Muscle Tone – resting tension in a skeletal muscle

• Isotonic muscle contraction – tension rises and the skeletal muscle’s length changes (lifting)

• Isometric muscle contraction – the muscle as a whole does not change length, and the tension produced never exceeds the load (holding)

Slide 6.32

Types of Ordinary Body Movements:


· Flexion – bending at the joint

· Extension - straightening at the joint

· Hyperextension – over extension of joint

· Rotation – rotating on axis

· Abduction – moving away from the midline

· Adduction – moving toward the body

· Circumduction – circular movement

Slide 6.33

Body Movements


Figure 6.13

· Dorsiflexion – movement of foot in upward motion

· Plantar flexion – movement of foot in downward motion

Special Movements:

Slide 6.34

Special Movements


· Inversion = tilt of foot away from midline

· Eversion = tilt of

foot towards midline

Special Movements

· Opposition

· Supination

· Pronation

Muscle Analysis• Choose a sport or activity where movement is involved

(football, yoga, softball, swimming, skate boarding, etc.)• Write a short story about the sport/activity (choose a

competition, game, or practice)• Include 10 muscles and 5 movements in the story that

the participant(s) demonstrates • Circle the muscle names & underline the movements in

your story• You must include one picture with your story• Use the “arts and supplies” to complete your final draft• The story is a classwork grade of 20 points (1 point for

each required term and 5 points for your picture/creativity)

Muscular System Injuries

• TSWBAT identify injuries of the muscular system.

• TSWBAT compare a strain and sprain. • TSWBAT list the elements of RICE for

first aid of muscular system injuries.

What is a strain?Strains are injuries that involve the stretching or tearing of a musculo-tendinous (muscle and tendon) structure

What is a sprain?A sprain is an injury involving the stretching or tearing of a ligament (tissue that connects bone to bone)

Strain vs. Sprain

Ankle Sprains

Examples of Strains

Sprains and Strains are categorized according to severity.

Grade I (mild) sprain or strain involves some stretching or minor tearing of a ligament or muscle.

Grade II (moderate) sprain or strain is a ligament or muscle that is partially torn but still intact.

Grade III (severe) sprain or strain means that the ligament or muscle is completely torn, resulting in joint instability.

First Aid

•R – rest•I - immobilize (ice)•C - compression•E - elevation

Duchenne Muscular Dystrophy (DMD)Definition - One of nine types of muscular dystrophy, a group of genetic,

degenerative diseases primarily affecting voluntary muscles.

Cause - An absence of dystrophin, a protein that helps keep muscle cells intact.

Information obtained from: http://www.mda.org/disease/dmd.html

http://abcnews.go.com/Nightline/Video/playerIndex?id=2883365

http://abcnews.go.com/Nightline/Video/playerIndex?id=2883365

DMD continued.....Onset - Early childhood - about 2 to 6 years.Symptoms - Generalized weakness first affecting the muscles

of the hips, pelvic area, thighs and shoulders. Calves are often enlarged.

Progression - DMD eventually affects all voluntary muscles, and the heart and breathing muscles.

Inheritance - X-linked recessive. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms

ACL Surgery:• Most surgery for ACL injuries involves replacing the

ACL with tissue called a graft• Usually an autograft (tendon taken from another part

of the body) is used • The most common grafts used are the tendon of the

kneecap or one of the hamstring tendons• Another choice is allograft tissue, which is taken from a

deceased donor

Paralysis:• Loss of muscle function in part of your body• Occurs when something goes wrong with the way

messages pass between your brain and muscles• Can be complete or partial; occur on one or both

sides of your body; one area or widespread• Paraplegia: lower half of your body• Quadriplegia: arms and legs• Due to strokes, injuries (spinal cord), or a broken neck

Documents

The Muscular System. Approximately 40% of your body weight Approximately 650 muscles Muscles only pull (they can’t push) You have over 30 facial muscles