Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4/e) – Chapter 22

Chapter 22 - The muscular system. This chapter focuses on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles.

The Muscular

System

Learning Outcomes

22.1 List the functions of muscle

22.2 List the three types of muscle tissue and

describe the locations and characteristics of each.

22.3 Describe how visceral (smooth) muscle

produces peristalsis.

22.4 Explain how muscle tissue generates energy

Learning Outcomes (cont.)

22.5 Describe the structure of a skeletal muscle.

22.6 Define the terms origin and insertion.

22.7 List and define the various types of body

movements produced by skeletal muscles.

22.8 List and identify the major skeletal muscles

of the body, giving the action of each

Learning Outcomes (cont.)

22.9 Explain the differences between strain and

sprain injuries.

22.10 Describe the changes that occur to the

muscular system as a person ages.

22.11 Describe the causes, signs and symptoms,

and treatments of various diseases and disorders of the muscular system.

You will focus on the differences among three muscle tissue 

types, the structure of skeletal muscles, muscle actions, and 

the names of skeletal muscles. 

– Heat production

Skeletal Muscle

• Skeletal muscles

– Attached to bones by tendons

– Cross joints so when they contract, bones they attach

to move

• Smooth muscle

– Found on organ walls

– Contractions produce movement of organ contents

• Cardiac muscle

– Produces atrial and ventricular contractions

– This pumps blood from the heart into the blood

vessels

Control of Body Openings and Passages

• Sphincters

– Valve-like structures formed by muscles

– Control movement of substances in and

out of passages – Example:

• A urethral sphincter prevents or allows urination

– Moving your body can

make you warmer if you are cold

Apply Your Knowledge

True or False:

_ Skeletal muscles are attached to bones by ligaments.

_ Contractions of smooth muscle produce movement of

Types of Muscle Tissue

Types of Muscle Tissue (cont.)

Produces body movements and facial expressions

Voluntary

Smooth

Muscle

Walls of hollow organs, blood vessels, and iris

Moves contents through organs;

Skeletal Muscle

• Muscle fibers respond to the

neurotransmitter acetylcholine

– Causes skeletal muscle to contract

• Following contraction, muscles release the

enzyme acetylcholinesterase

– Breaks down acetylcholine

– Allows muscle to relax

Smooth Muscle

• Multiunit smooth muscle

– In the iris of the eye and walls of blood

vessels – Responds to neurotransmitters and hormones

• Visceral smooth muscle

– In walls of hollow organs

– Responds to neurotransmitters AND

– Stimulate each other to contract so that

muscle fibers contract and relax together in a rhythmic motion – peristalsis

Smooth Muscle (cont.)

• Peristalsis – rhythmic contraction

that pushes substances through

tubes of the body

• Neurotransmitters for smooth muscle

contraction

– Acetylcholine

– Norepinephrine

– Will cause or inhibit contractions,

depending on smooth muscle type

Cardiac Muscle

• Intercalated discs

– Connect groups of cardiac

muscle – Allow the fibers in the groups to

contract and relax together

• Allows heart to work as a pump

• Self-exciting – does not need

nerve stimulation to contract

– Nerves speed up or slow down

contraction

Cardiac Muscle (cont.)

• Neurotransmitters

– Acetylcholine – slows

heart rate – Norepinephrine –

speeds up rate

Apply Your Knowledge

Match the following:

_ Stimulate each other to

Production of Energy for Muscle

• ATP (adenosine

triphosphate)

– A type of chemical

energy– Needed for

sustained or repeated muscle contractions

• Muscle cells must have three ways to store or make ATP

– Creatine phosphate

• Rapid production of energy

– Aerobic respiration

• Uses body’s store of glucose

– Lactic acid production

• Small amounts of ATP

Oxygen Debt

• Develops when skeletal muscles are used

strenuously for several minutes and cells are

low in oxygen

Lactic   acid  which builds up

acetylcholine onto muscle fibers

Apply Your Knowledge

Match the following:

Structure of Skeletal Muscles

Connective Tissue Coverings

• Fascia

– Covers entire skeletal

muscles – Separates them from

each other

• Tendon

– A tough, cord-like

structure made of fibrous connective tissue

– Connects muscles to

bones

• Aponeurosis

– A tough, sheet-like structure made of fibrous connective tissue

– Attaches muscles to other muscles

Connective Tissue Coverings (cont.)

• Epimysium

– A thin covering that is just below the fascia of

a muscle and surrounds the entire muscle

• Perimysium

– Connective tissue that divides a muscle into

sections called fascicles

• Endomysium

– Covering of connective tissue that surrounds

individual muscle cells

Apply Your Knowledge

Match the following:

Thin covering under the fascia that

surrounds the muscle

Separates muscles from each

other

Connects muscles to bones

Divides a muscle into sections

called fascicles

Surrounds individual muscle cells

Attaches muscles to other

Attachments and Actions of Skeletal Muscles

Attachments and Actions (cont.)

• Movement usually produced by a group of

muscles

– Prime mover (agonist) – muscle responsible

for most of the movement

– Synergists – muscles that help the prime

mover by stabilizing joints

– Antagonist – muscle that produces

movement opposite to prime mover

• Relaxes when prime mover contracts

extending a body part

past the normal

Adduction – moving a

body part toward the anatomical position

Figure of Body  Movements

Body Movements (cont.)

Back

Body Movements (cont.)

Circumduction – moving a

body part in a circle

Pronation – turning the

palm of the hand down

Supination – turning

the palm of the

hand up

Body Movements (cont.)

Inversion – turning the sole

of the foot medially

Eversion – turning the sole

of the foot laterally

Retraction – moving a body part posteriorly

Protraction – moving a

body part anteriorly

Body Movements (cont.)

Elevation – lifting a

body part; for example, elevating the shoulders as in a shrugging expression

Depression – lowering a

body part; for example, lowering the shoulders

Apply Your Knowledge

ANSWER: Move the patient’s leg away from its position

in the anatomical position

The doctor has asked you to abduct the patient’s leg

so he can see the patient’s wound In order to position

the patient correctly, what will you have to do?

Correct!

Major Skeletal Muscles

• The muscle name

attachments of the muscle

• As you study muscles, you will find

it easier to remember them if you think

about what the name describes.

Muscles of the Head

• Sternocleidomastoid

– Pulls the head to one

side – Pulls the head to the

• Orbicularis oris

– Allows the lips to pucker

Muscles of the Head (cont.)

Arm Muscles

• Pectoralis major

– Pulls the arm across

the chest – Rotates and adducts

the arms

• Latissimus dorsi

– Extends and adducts

the arm and rotates the arm inwardly

Arm Muscles (cont.)

• Deltoid

– Abducts and extends

the arm at the shoulder

Arm Muscles (cont.)

– Flexes the arm at the

elbow – Rotates the hand laterally

Arm Muscles (cont.)

Wrist, Hand, and Finger Muscles

• Flexor carpi radialis

and flexor carpi ulnaris

– Flex and abduct the wrist

• Palmaris longus

– Flexes the wrist

• Flexor digitorum

profundus

– Flexes the distal joints of

the fingers, but not the thumb

Wrist, Hand, and Finger Muscles (cont.)

• Extensor carpi radialis longus and brevis

– Extend the wrist and abduct the hand

• Extensor carpi ulnaris

– Extends the wrist

• Extensor digitorum

– Extends the fingers, but not the thumb

Respiratory Muscles

• Diaphragm

– Separates the thoracic

cavity from the abdominal cavity

– Its contraction causes

inspiration

• External and internal

intercostals

– Expand and lower the

ribs during breathing

Abdominal Muscles

• External and internal obliques

– Compress the abdominal wall

• Transverse abdominis

– Also compresses the abdominal wall

• Rectus abdominis

– Flexes the vertebral column

– Compresses the abdominal wall

Click for View of Abdominal Muscles

Abdominal Muscles (cont.)

Pectoral Girdle

• Trapezius

– Raises the arms

– Pulls the shoulders downward

• Pectoralis minor

– Pulls the scapula downward

– Raises the ribs

Click for View of Pectoral Girdle Muscles

Leg Muscles

• Iliopsoas major

– Flexes the thigh

• Gluteus maximus

– Extends the thigh

• Gluteus medius and

minimus

– Abduct the thighs

– Rotate them medially

Leg Muscles (cont.)

• Adductor longus and

magnus

– Adduct the thighs – Rotate them laterally

• Biceps femoris, semitendinosus, and

Leg Muscles (cont.)

• Rectus femoris, vastus

lateralis, vastus medialis,

and vastus intermedius

– Extend the leg at the knee

• Sartorius

– Flexes the leg at the knee

and thigh – Abducts the thigh, rotating the

thigh laterally but rotating the lower leg medially

Ankle, Foot, and Toe Muscles

• Tibialis anterior

– Inverts the foot and points

the foot up (dorsiflexion)

• Extensor digitorum longus

– Extends the toes and points

the foot up

• Gastrocnemius

– Flexes the foot and flexes the

leg at the knee

Ankle, Foot, and Toe Muscles (cont.)

Apply Your Knowledge

ANSWER: You would look at the back of his leg, and

the muscles involved would be the biceps femoris,

semitendinosus, and semimembranosus These three

muscles are known as the hamstring group

Your patient complains of hurting his hamstring when

running today You would look at what part of the leg,

and what muscles would be involved?

Bravo!

Muscle Strains and Sprains

• Strains – injuries due to over-stretched

muscles or tendons

• Sprains – more serious injuries that result

in tears to tendons, ligaments, and/or

Muscle Strains and Sprains (cont.)

• Prevention

– Warm up muscles

muscle temperature and makes muscle more pliable

– Stretching

be done after the warm-up or after exercising

– Cooling down or slowing down

blood in the legs and helps remove lactic acid from muscles

Aging and the Musculoskeletal System

• Contractions become slower and not as

strong

– Dexterity and gripping ability decrease

– Mobility may decrease

• Assistive devices helpful

• Routine exercise

– Swimming

– Physical therapy

Botulism Affects the gastrointestinal tract and

various muscle groups

Fibromyalgia Fairly common condition that causes

chronic pain primarily in joints, muscles, and tendons

System (cont.)

Rhabdomyolysis A condition in which the kidneys become

damaged after serious muscle injuries

Tetanus

(lockjaw) Painful inflammation of a tendon and the tendon-muscle attachment to a bone

Torticollis

(wryneck) Acquired or congenital; spasm or shortening of the sternocleidomastoid

muscle; head bends to affected side and chin rotates to opposite side

Trichinosis An infection caused by parasites

(worms)

Apply Your Knowledge

ANSWER: Muscular dystrophy is an inherited disorder

characterized by muscle weakness and a loss of

muscle tissue

The doctor has told your patient that his son has

muscular dystrophy disorder What is muscular

dystrophy?

In Summary

22.1 The functions of muscles include movement, stability,

control of body openings and passages, and the production of heat

22.2 The three types of muscle tissue are striated

voluntary skeletal muscle, smooth involuntary visceral muscle, and specialized striated and involuntary

cardiac muscle

22.3 Peristalsis is the rhythmic contraction produced by

smooth muscle to push substances through various tubes in the body

In Summary (cont.)

22.4 Muscles create energy in three ways Creatine

phosphate is a rapid method for muscles to create energy, aerobic respiration uses stored glucose to produce ATP in the Krebs cycle, and lactic acid production occurs when a cell is low in oxygen and coverts pyruvic acid to lactic acid

22.5 Skeletal muscle is composed of connective tissues,

skeletal muscle tissue, blood vessels, and nerves

The coverings of skeletal muscles include fascia, tendon, aponeurosis, epimysium, perimysium, and endomysium

In Summary (cont.)

22.6 The origin of a muscle is the attachment site of the

muscle to the less movable bone during muscle contraction The insertion of a muscle is the

attachment site for the muscle to the more movable bone during muscle contraction

22.7 The body movements produced by skeletal muscles

include flexion, extension, hyperextension, dorsiflexion, plantar flexion, abduction, adduction, rotation, circumduction, pronation, supination,

inversion, eversion, retraction, protraction, elevation, and depression

In Summary (cont.)

22.8 The major muscles of the head are

sternocleidomastoid, splenius capitis, frontalis, orbicularis oris and oculi, zygomaticus, platysma, masseter, and temporalis The upper extremity muscles include pectoralis major, latissimus dorsi, deltoid, subscapularis, biceps brachii, brachialis, brachioradialis, triceps brachii, supinator and pronator teres, flexor carpi radialis and ulnaris, plamaris

longus, flexor digitorum profundus, extensor carpi radialis longus and brevis, and extensor digitorum

The major respiratory muscles are the diaphragm and the external and internal intercostals

In Summary (cont.)

22.8 (cont.) The abdominal muscles include external and

internal obliques, transverse abdominis, and rectus abdominis The pectoral girdle muscles include

trapezius and pectoralis minor The muscles of the lower extremity include iliopsoas major; gluteus

maximus, medius, and minimus; adductor longus and magnus; biceps femoris; semitendinosus and

semimembranosus; rectus femoris; vastus lateralis, medius, and intermedius; sartorius; tibialis anterior;

extensor digitorum longus; gastrocnemius; soleus;

and flexor digitorum longus

In Summary (cont.)

22.9 Strain injuries involve injuries to muscles and/or

tendons Sprains are more serious injuries that result

in tears to tendons, ligaments, and/or the cartilage of joints

22.10 The common diseases of aging include arthritis,

fractures, osteoporosis, and muscular decline Aging causes a decline in strength and speed of muscle contractions Dexterity and gripping abilities lessen and mobility often decreases related to skeletal and muscular decline

In Summary (cont.)

22.11 The diseases of the muscular system, as well as their

symptoms and treatments, vary widely and are discussed in the Pathophysiology section of this chapter Some of the common diseases discussed include botulism, fibromyalgia, muscular dystrophy, myasthenia gravis, tendonitis, tetanus, and torticollis