Medical assisting Administrative and clinical procedures (5e) Chapter 25 The muscular system

The human body has more than 600 individual muscles. Although each muscle is a distinct structure, muscles act in groups to perform particular movements. 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 (cont.)

25.1 Describe the functions of muscle

25.2 Compare the three types of muscle tissue

including their locations and characteristics.

25.3 Explain how muscle tissue generates energy

25.4 Describe the structure of a skeletal muscle

Learning Outcomes (cont.)

25.5 Recognize the terms origin and insertion

25.6 Identify the major skeletal muscles of the

body, giving the action of each

25.7 Summarize the changes that occur to the

muscular system as a person ages

25.8 Describe the causes, signs and symptoms,

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

• Muscles contract and relax to cause movement

• 600 individual muscles in the body

You will focus on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions,

and the names of skeletal muscles

Functions of Muscle

• The ability to contract enables muscles to

– Allow movement

– Provide stability

– Control body openings and passages

– Warm the body

Functions of Muscle (cont.)

• Skeletal muscles

– Contractions result in movement

• Smooth muscle – contractions move organ

contents

• Cardiac muscle – contractions pump blood from

the heart

Functions of Muscle (cont.)

– Helps maintain a normal temperature

Control of Body Openings and Passages

• Sphincters

– Valve-like structures

– Control movement in and out of

passages

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

• Muscle cells or myocytes – muscle fibers

– Sarcoplasm

– Sarcoplasmic reticulum

– Myofibrils

• Long structures in sarcoplasm

• Striations – arrangement of filaments

Muscle structure

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

• Skeletal muscle fibers

– Contract in response to the neurotransmitter

acetylcholine

– After contraction, muscles release the enzyme

acetylcholinesterase

• Breaks down acetylcholine

• Allows muscle to relax

Smooth Muscle

• Multiunit smooth muscles – respond to

neurotransmitters and hormones

• Visceral smooth muscles

– Responds to neurotransmitters ~ acetylcholine and

norepinephrine – Stimulate each other to contract ~ peristalsis

Cardiac Muscle

• Intercalated discs

– Connect groups of cardiac muscle

– Allow the heart to work as a pump

• Self-exciting

• Responds to neurotransmitters

– Acetylcholine

– Norepinephrine

Apply Your Knowledge

Match the following:

_ Self-exciting

_ Contract in response to acetylcholine

_ Stimulate each other to contract

C

B Smooth muscle

C Cardiac muscle

Production of Energy for Muscle

• ATP

• Muscle cells make ATP by

– Creatine phosphate ~ rapid production of energy

– Aerobic respiration ~ uses body’s store of glucose

– Lactic acid production from pyruvic acid

Muscle fatigue

Oxygen Debt

Strenuous use of skeletal muscles depletes

cells of oxygen

To liver for conversion to

glucose, requiring more energy

and oxygen to make ATP

Oxygen debt

Match the following:

_ Rapid production of energy

_ Needed for sustained or

repeated muscle contractions _ Uses body’s store of glucose

_ Muscle fatigue

_ With strenuous exercise,

converts to lactic acid

Apply Your Knowledge

Structure of Skeletal Muscles

• Skeletal muscles – the major organs of the

Structure of Skeletal Muscles (cont.)

• Connective tissue coverings

– Fascia

– Tendon

– Aponeruosis

– Epimysium – Perimysium – Endomysium

Muscle structure

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

• Attachment types

– Origin ~ for a less

movable bone– Insertion ~ for a

more movable bone

Attachments and Actions of Skeletal

mover

Attachments and Actions of Skeletal

Attachments and Actions of Skeletal

Attachments and Actions of Skeletal

Apply Your Knowledge

ANSWER:

True or false?

opposite to a prime mover

Synergists stabilize joints

Origin is an attachment site for the less moveable

bone during muscle contraction

Insertion is an attachment site for the more moveable

bone during muscle contraction

Major Skeletal Muscles

• Name often describes muscle by

Muscles of the Head

– Frontalis– Orbicularis oris– Orbiuclaris oculi– Zygomaticus – Platysma

Skeletal muscles

Arm Muscles (cont.)

Muscles of the Wrist, Hand, and Fingers

• Flexor carpi radilas

• Felxor carpi ulnaris

Respiratory Muscles

• Diaphragm

– Separates thoracic and abdominal cavities

– Contracts for inspiration

• External and internal intercostals – expand and

lower the ribs

For diagram

Skeletal Muscles (cont.)

• Muscles of the Pectoral Girdle

– Trapezius – Pectoralis minor

For diagram

Leg Muscles

• Iliopsoas major

• Gluteus maximus

• Gluteus medius and minimus

• Adductor longus and magnus

Skeletal muscles

Leg Muscles (cont.)

• Biceps femoris, semitendinosus, and

Ankle, Foot, and Toe Muscles

Apply Your Knowledge

Matching:

raises the eyebrows

chewing

expand and lower ribs

compress the abdominal wall

extends the thigh

extends the leg at the knee

Aging and the Musculoskeletal System

• Speed and strength of muscle contractions

Diseases and Disorders of the Muscular

System

various muscle groups

chronic pain primarily in joints, muscles, and tendons

Diseases and Disorders of the Muscular

System (cont.)

toxins released from muscle cells after serious muscle injuries

tendon-muscle attachment to a boneTetanus

(lockjaw) Muscle spasms in the jaw, keck and facial muscles; high mortality rate

Diseases and Disorders of the Muscular

System (cont.)

Torticollis

(wryneck) A cervical deformity in which the head bends toward the affected side while the

chin rotates to the opposite side

ingested by eating undercooked meat

Apply Your Knowledge

ANSWER: Speed and strength of muscle contractions

decrease with aging.

The aging process results in:

• Decreased dexterity and gripping ability

• Decreased mobility

1 What changes occur to the muscular system as

a result of aging?

Apply Your Knowledge

True or False:

Botulism is a condition resulting in chronic pain in

joints,

muscles and tendons

Kidney damage due to toxins released by serious

muscle injuries is the condition called rhabdomyolysis

Tetanus is caused by a toxin and causes muscle

spasms in the jaw, neck, and facial muscles

Lockjaw is caused by spasm or shortening of the

In Summary

25.1 The functions of muscles include movement,

stability, control of body openings and passages, and the production of heat Valve- like

muscular structures called sphincters control

passage of substances into and out of organs

like the stomach and bladder.

.

25.2 The three types of muscle tissue are striated,

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

striated and involuntary cardiac muscle

In Summary (cont.)

25.3 There are three ways muscles create energy

Creatine phosphate, aerobic respiration, and lactic acid production.

25.4 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.)

25.5 The origin of a muscle is the attachment site of

the muscle to the less moveable bone during muscle contraction The insertion of a muscle is the attachment site for the muscle to the more moveable bone during muscle contraction

25.6 The major muscles of the head and the upper

extremity, major respiratory muscles, abdominal muscles, pectoral girdle muscles and those of the lower extremity are covered in this learning outcome.

In Summary (cont.)

22.7 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.

22.8 There are many common diseases and

disorders of the muscular system with varied signs, symptoms, and treatments

least once a day.

~Roger von Oech

End of Chapter 25