the muscular system pp

7/30/2019 The Muscular System PP

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Copyright John Wiley & Sons, Inc. All rights reserved.

Chapter 11

The MuscularSystem

Lecture slides prepared by Curtis DeFriez, Weber State University


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Naming Muscles

Locationtibialis anterior

Tibialis anterior


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Sizegluteus maximus

Number of Attachmentso biceps; triceps

Naming Muscles


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Location/Direction of Fiberstransversus abdominus

Naming Muscles


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Attachments(origin & insertion)o stylohyoid;

sternocleidomastoid

Naming Muscles

Styloid

process

Hyoid

bone


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Muscle actionlevator scapulae

adductor magnus

tensor tympani

Naming Muscles

Levator scapulae


7/45Copyright John Wiley & Sons, Inc. All rights reserved.

Combination of aboveFibularis longus

Naming Muscles



Muscles produce movement by exerting force on

tendons which in turn pull on bones and other

supporting structures like the skin.

In order to produce movement around a joint, one bone must be stationary while

another bone moves.

The attachment of a muscle's tendon to the stationary, usually proximal bone, iscalled the origin.

Origins and Insertions



Insertion

of thelong headof thebiceps




Triceps:Origin:Scapula near shoulder jointUpper lateral and posterior sitesof humerusPosterior surface of humerusInsertion: Back of olecranon process of ulnaAction: Straighten (extend) the arm

Biceps:Origin: ScapulaInsertion: RadiusAction: pronate and flex thearm




Muscles, tendons, bones, and joints can form threedifferent types of levers in the body.

When producing movement, bones act as levers,

and joints function as the fixed point

of movement called the fulcrum.

In a lever, the point of movement

(fulcrum) is acted on by two

different forces: Effort and load.

Musculoskeletal Levers




There are few first-class leversin the body




Second class levers always provide a distinct mechanical

advantage in producing force.

Like a pry bar




Third-class levers are the most common and favor speed

and range of motion over maximum force.



Coordination Among Muscles

Movements are often the result of several skeletal muscles acting as agroup.

Most skeletal muscles are arranged in opposing (antagonistic) pairs at

joints.

Within opposing pairs, theprime mover oragonist(the leader) is themuscle primarily responsible for causing the desired movement.


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The antagoniststretches and yields to the effects of the prime mover.In flexing the forearm at

the elbow, the brachialis

is the prime mover or

agonists, and the triceps

brachii is the antagonist.


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Synergists are muscles used to prevent unwanted movements atintermediate joints, or otherwise aid the movement of the prime mover.

The biceps acts synergistically with the brachialis.

Fixator muscles are a type of synergist muscle that are used to steady theproximal joints of a prime mover.

Shoulder stabilizers for the forearm flexors


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Major Skeletal MusclesLearn the origin, insertion and action of the major skeletal muscles of

the body as directed by your instructor.

Some of the more common muscles of the head and neck include:

Orbicularis oris

Extraocular muscles

Sternocleidomastoid

Rectus abdominus

External oblique


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Major Skeletal Muscles

The muscles of facial expression move skin rather than bonesaround a joint.

Orbicularis oris

Action: Closes andprotrudes lips for kissing

Origin: Surrounding the

opening of the mouth

Insertion: The skin at the

corner of the mouth Orbicularisoris


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MasseterOrigin: Maxilla and

zygomatic arch

Insertion: Mandible

Action: Closes the mouth

Muscles that move the mandible (lower jaw)

Also called muscles of mastication

Masseter


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Major Skeletal MusclesThe Extraocular muscles

3 pair give each eye very

precise movement

Origin: Back of the orbit

Insertion: Different parts

of the eyeball

Action: Precise and rapid

movement of the eyes


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Muscles that move the head

Sternocleidomastoid (commonly abbreviated as SCM)Origin: Clavicle and sternum

Insertion: Mastoid

process of temporal bone

Action: Flex and

rotate the head

Sternocleidomastoid


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Major Skeletal MusclesSome of the more common muscles that originate on the

trunk include:

Pectoralis major and

minor

Anterior abdominal

muscle group

Latissimus dorsi

Biceps brachii

Diaphragm

Trapezius

Deltoid


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Muscles that move the pectoral girdle (shoulder)

Pectoralis minor

Origin: Ribs 35

Insertion: Coracoid process of the

scapula

Action: Internally rotates the

shoulder

Pectoralis major

Origin: Clavicle and sternum

Insertion: Proximal

humerus

Action: Adducts and medially

rotates the

arm at the shoulder joint


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Major Skeletal MusclesMuscles that move the pectoral girdle (shoulder)

Deltoid Muscle

Origin: Lateral clavicle and upper scapula

Insertion: Deltoid tuberosity

on the shaft of the humerus

Action: Abducts, flexes, andmedially rotates the upper arm

at the shoulder joint

Deltoid


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Muscles that move the pectoral girdle (shoulder)

Trapezius

Origin: Occipital bone and

cervical spine

Insertion: Clavicle, scapula and

lower thoracic vertebrae

Action: Supports the arm and

moves the scapula up, down,

in, and out

Trapezius


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Muscles that move the pectoral girdle

(shoulder)

Latissimus dorsi

Origin: Thoracic and lumbar

vertebrae and the iliac bone

Insertion: Mid-humerus

Action: Drives arm inferiorly

and posteriorly (the

swimmers muscle)

Latissimusdorsi


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Anterior abdominal wall

Rectus abdominisOrigin: Pubic bone

Insertion: Ribs and sternum

External oblique

Origin: Ribs 512

Insertion: Iliac crest and

linea alba

Actions: Flexes vertebral column

and compresses abdomen


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The main muscle of inspiration is the

diaphragm.

Origin: Inferior 6 ribs

(anteriorly) and lumbar

vertebrae (posteriorly)Insertion: Central

tendon

DiaphragmCentraltendon


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Some of the more common muscles of the extremities

include:

Quadriceps group: Rectus femoris, along

with the vastus lateralis, vastus

intermedius, and vastus medialis

Tibialis anterior

Gastrocnemius

Soleus

Triceps brachii

BrachioradialisThenar muscles

Hypothenar muscles

Gluteus maximus

Biceps femoris


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Major Skeletal MusclesMuscles that move the Radius and Ulna

Biceps brachii

Origin: Scapula

Insertion: Radius

Action: Flexes and

supinates forearm at

elbow joint and flexes

arm at shoulder joint

Brachialis

Origin: Distal anterior surface

of humerus

Insertion: Ulna

Action: Flexor of forearm at

elbow


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Major Skeletal MusclesMuscles that move the Radius and Ulna

Triceps brachiiOrigin: Scapula and posterior surface of

humerus

Insertion: Olecranon

process of ulnaAction: Extends

forearm at elbow

joint and arm

at shoulder joint


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Muscles that move the Radius and Ulna

Brachioradialis

Origin: Humerus

Insertion: Distal radiusAction: Supinates the forearm

at the radioulnar joint


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Muscles that move the wrist, hand,

thumb,

and finger

Thenar: lateral aspect of palm

Hypothenar: medial aspect of palm

Action: Oppose thumb

against other 4 fingers Thenar

Hypothenar


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Muscles that move the femur

Gluteus maximus

Origin: Iliac crest, sacrum, and

coccyx

Insertion: Femur

Action: Extends and laterally

rotates thigh at hip joint

Gluteusmaximus


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Muscles that move the femur, tibia, and

fibula

Quadricep group (Rectus femoris, vastus

lateralis, vastus intermedius, and vastus

medialis)

Origin: Iliac spine and proximal femur

Insertion: Patella and proximal tibia

Action: Flexes thigh at high joint and

extends leg at knee joint



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Muscles that move the femur, tibia,

and fibulaHamstring group: (Biceps femoris,

Semitendinosus, and

Semimembranosus)

Origin: Ischial tuberosityInsertion: Proximal tibia and

fibula


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Muscles that move the femur, tibia, and

fibula

Tibialis anterior

Origin: Tibia

Insertion: First cuneiform

and first metatarsal

Action: Dorsiflexes and

inverts the foot

M j Sk l l M l


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Muscles that plantar flex the foot at the ankle

joint (standing on tip toes)

Gastrocnemius and soleus muscles

function as one often called the

gastrocsoleus muscle

Origin: Femur, capsule of

knee, and head of fibula

Insertion: Calcaneus by way

of calcaneal (Achilles) tendon


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Exercise-induced muscle damageAfter intense exercise, electron micrographs reveal considerable

muscle damage including torn sarcolemmas and disrupted Z-

discs.

Blood levels of proteins normally confined only to muscle

(including myoglobin and the enzyme, creatine kinase) increase

as they are released from damaged muscle.

Imbalances of Homeostasis


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SpasmA sudden involuntary contraction of a single muscle within a large

group of muscles usually painlessCramp

Involuntary and often painful muscle contractionsCaused by inadequate blood flow to muscles (such as in

dehydration), overuse and injury, and abnormal blood electrolyte

levels



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Disease States and Disorders

Fibrosis (myofibrosis) Replacement of muscle fibers by excessive amounts of

connective tissues (fibrous scar tissue)

Myosclerosis Hardening of the muscle caused by calcification

Both myosclerosis and muscle fibrosis occur as a result of trauma

and various metabolic disorders.


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AgingIn part due to decreased levels of physical activity, with aging,

humans undergo a slow, progressive loss of skeletal muscle mass

that is replaced largely by fibrous connective tissue and adipose

tissue.

Muscle strength at 85 is about half that at age 25.

Compared to the other two fiber types, the relative number of

slow oxidative fibers appears to increase.


the muscular system pp

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