Muscles in the Body 20121

8/11/2019 Muscles in the Body 20121

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MUSCLES

IN THE BODY

5. 10.2012

Kaan YcelM.D., Ph.D.

http://yeditepepharmanatomy.wordpress.com


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Dr.Kaan Ycel yeditepepharmanatomy.wordpress.comArticulations in the body

http://www.youtube.com/yeditepeanatomy

The muscular system consists of all the muscles of the body. The disciplined related to the study of muscles is

myology. All skeletal muscles are composed of one specific type of muscle tissue. These muscles move the

skeleton, therefore, move the body parts.

There are three muscle types:

Skeletal striated muscle is voluntary somatic muscle that makes up the gross skeletal muscles. Striated

muscles are innervated by the somatic nervous system. Cardiac striated muscle is involuntary visceral muscle that forms most of the walls of the heart and adacent

parts of the great vessels

Smooth muscle !unstriated muscle" is involuntary visceral muscle. #on$striated and cardiac muscles are

innervated by the autonomic nervous system.

%any terms provide information about a structure&s shape, si'e, location, or function or about the

resemblance of one structure to another. %uscles may be described or classified according to their shape, for

which a muscle may also be named.

A prime mover !agonist" is the main muscle responsible for producing a specific movement of the body. A

fi(ator steadies the pro(imal parts of a limb. A synergist complements the action of a prime mover. An antagonist

is a muscle that opposes the action of another muscle.

The facial muscles !muscles of facial e(pression" move the skin and change facial e(pressions to convey

mood. %ost muscles attach to bone or fascia and produce their effects by pulling the skin.

The platysma !). flat plate" is a broad, thin sheet of muscle in the subcutaneous tissue of the neck. *t helps

depress the mandible and draw the corners of the mouth inferiorly.

Cutaneous !sensory" innervation of the face and anterosuperior part of the scalp is provided primarily by the

trigeminal nerve !C# +", whereas motor innervation to the facial muscles is provided by the facial nerve !C#

+**".

The sternocleidomastoid !SC%" muscle is a broad, strap$like muscle that has two heads: The rounded

tendon of the sternal head attaches to the manubrium, and the thick fleshy clavicular head attaches to the superior

surface of the clavicle. Trape'ius is a large, flat triangular muscle that covers the posterolateral aspect of the neck

and thora(.our anterior pectoral muscles move the pectoral girdle: pectoralis maor, pectoralis minor, subclavius, and

serratus anterior.

The name latissimus dorsi !-. widest of back" was well chosen because the muscle covers a wide area of the

back. This large, fan$shaped muscle passes from the trunk to the humerus and acts directly on the glenohumeral

oint and indirectly on the pectoral girdle !scapulothoracic oint".

The si( scapulohumeral muscles including the deltoid muscle are relatively short muscles that pass from the

scapula to the humerus and act on the glenohumeral oint.

f the four maor arm muscles, three fle(ors !biceps brachii, brachialis, and coracobrachialis" are in the

anterior !fle(or" compartment, supplied by the musculocutaneous nerve, and one e(tensor !triceps brachii" is in

the posterior compartment, supplied by the radial nerve.

There are /0 muscles crossing the elbow oint, some of which act on the elbow oint e(clusively, whereasothers act at the wrist and fingers.

The fle(or muscles of the forearm are in the anterior !fle(or$pronator" compartment of the forearm and are

separated from the e(tensor muscles of the forearm by the radius and ulna and, in the distal two thirds of the

forearm, by the interosseous membrane that connects them. The e(tensor muscles of the forearm are in the

posterior !e(tensor$supinator" compartment of the forearm, and all are innervated by branches of the radial nerve.

The intrinsic muscles of the hand are located in five compartments.

The gluteus ma(imus is the most superficial gluteal muscle. *t is the largest, heaviest, and most coarsely

fibered muscle of the body. The main actions of the gluteus ma(imus are e(tension and lateral rotation of the

thigh.

The posterior thigh muscles include the hamstring muscles. There are four muscles in the anterior

compartment of the leg. The large anterior compartment of the thigh contains the anterior thigh muscles, thefle(ors of the hip and e(tensors of the knee. The posterior compartment of the leg !plantarfle(or compartment" is

the largest of the three leg compartments. The superficial group of calf muscles !muscles forming prominence of

1calf2 of posterior leg" includes the gastrocnemius, soleus, and plantaris. The gastrocnemius and soleus share a

common tendon, the calcaneal tendon, which attaches to the calcaneus. The calcaneal tendon !-. tendo calcaneus,

Achilles tendon" is the most powerful !thickest and strongest" tendon in the body.3


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Dr.Kaan Ycel yeditepepharmanatomy.wordpress.comMuscles in the body

The muscular system consists of all the muscles of the body. The disciplined related

to the study of muscles is myology. Musculus muscle! is deri"ed from the word mus#mouse$ musculus# little mouse. All s%eletal muscles are composed of one speci&c type of

muscle tissue. These muscles mo"e the s%eleton' therefore' mo"e the body parts.

. . TYPES OF MUSCLES

There are three muscle types:

( )%eletal striated muscle is "oluntary somatic muscle that ma%es up the gross s%eletal

muscles that compose the muscular system' mo"ing or stabili*ing bones and other

structures e.g.' the eyeballs!. )triated muscles are inner"ated by the somatic ner"ous

system.

( +ardiac striated muscle is in"oluntary "isceral muscle that forms most of the walls of

the heart and ad,acent parts of the great "essels' such as the aorta' and pumps blood.

( )mooth muscle unstriated muscle! is in"oluntary "isceral muscle that forms part of the

walls of most "essels and hollow organs "iscera!' mo"ing substances through them by

coordinated se-uential contractions pulsations or peristaltic contractions!. on#striated

and cardiac muscles are inner"ated by the autonomic ner"ous system.All s%eletal muscles' commonly referred to simply as muscles'0 ha"e 1eshy' reddish'

contractile portions one or more heads or bellies! composed of s%eletal striated muscle.

)ome muscles are 1eshy throughout' but most also ha"e white non#contractile portions

tendons!' composed mainly of organi*ed collagen bundles' that pro"ide a means of

attachment. 2hen referring to the length of a muscle' both the belly and the tendons are

included. 3n other words' a muscle4s length is the distance between its attachments.

Most s%eletal muscles are attached directly or indirectly to bones' cartilages' ligaments' orfascias or to some combination of these structures. )ome muscles are attached to organs

the eyeball' for e5ample!' s%in such as facial muscles!' and mucous membranes intrinsic

tongue muscles!. Muscles are organs of locomotion mo"ement!' but they also pro"ide

static support' gi"e form to the body' and pro"ide heat.

The architecture and shape of muscles "ary. The tendons of some muscles form 1at

sheets' or aponeuroses' that anchor the muscle to the s%eleton usually a ridge or a series

of spinous processes! and/or to deep fascia such as the latissimus dorsi muscle of the

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. GENERAL CONSIDERATIONS ON


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bac%!' or to the aponeurosis of another muscle such as the obli-ue muscles of the

anterolateral abdominal wall!.

1.2. MUSCLE TERMINOLOGY

Many terms pro"ide information about a structure4s shape' si*e' location' or function or

about the resemblance of one structure to another.

Muscles may be described or classi&ed according to their shape' for which a muscle may

also be named:

( 6lat muscles ha"e parallel &bers often with an aponeurosis7for e5ample' the e5ternal

obli-ue broad 1at muscle!. The sartorius is a narrow 1at muscle with parallel &bers.

( 8ennate muscles are feather#li%e 9. pennatus' feather! in the arrangement of their

fascicles' and may be unipennate' bipennate' or multi#pennate7for e5ample' the e5tensor

digitorum longus unipennate!' the rectus femoris bipennate!' and deltoid multi#pennate!.

( 6usiform muscles are spindle shaped with a round' thic% belly or bellies! and tapered

ends7for e5ample' biceps brachii.

( +on"ergent muscles arise from a broad area and con"erge to form a single tendon7for

e5ample' the pectoralis ma,or.

( uadrate muscles ha"e four e-ual sides 9. -uadratus' s-uare!7for e5ample' the rectus

abdominis' between its tendinous intersections.( +ircular or sphincteral muscles surround a body opening or ori&ce' constricting it when

contracted7for e5ample' orbicularis oculi closes the eyelids!.

( Multi#headed or multi#bellied muscles ha"e more than one head of attachment or more

than one contractile belly' respecti"ely. ;iceps muscles ha"e two heads of attachment

e.g.' the biceps brachii!' triceps muscles ha"e three heads e.g.' triceps brachii!' and the

digastric and gastrocnemius muscles ha"e two bellies.

6igure


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.3. CONTRACTION OF MUSCLES

)%eletal muscles function by contracting$ they pull and ne"er push. 2hen a muscle

contracts and shortens' one of its attachments usually remains &5ed while the other more

mobile! attachment is pulled toward it' often resulting in mo"ement. Attachments of

muscles are commonly described as the origin and insertion$ the origin is usually the

pro5imal end of the muscle' which remains &5ed during muscular contraction' and theinsertion is usually the distal end of the muscle' which is mo"able. =owe"er' this is not

always the case. )ome muscles can act in both directions under di>erent circumstances.

2hereas the structural unit of a muscle is a s%eletal striated muscle &ber' the

functional unit of a muscle is a motor unit' consisting of a motor neuron and the muscle

&bers it controls. 2hen a motor neuron in the spinal cord is stimulated' it initiates an

impulse that causes all the muscle &bers supplied by that motor unit to contract

simultaneously.

.4. FUNCTIONS OF MUSCLES

Muscles ser"e speci&c functions in mo"ing and positioning the body.

A prime mo"er agonist! is the main muscle responsible for producing a speci&c mo"ement

of the body. 3t contracts concentrically to produce the desired mo"ement' doing most of

the wor% e5pending most of the energy! re-uired. A &5ator steadies the pro5imal parts of

a limb through isometric contraction while mo"ements are occurring in distal parts. A

synergist complements the action of a prime mo"er. An antagonist is a muscle that



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opposes the action of another muscle. The same muscle may act as a prime mo"er'

antagonist' synergist' or &5ator under di>erent conditions.

.5. NERVES AND ARTERIES TO MUSCLES

?ariation in the ner"e supply of muscles is rare$ it is a nearly constant relationship. 3n the

limb' muscles of similar actions are generally contained within a common fascial

compartment and share inner"ation by the same ner"es. The blood supply of muscles is

not as constant as the ner"e supply and is usually multiple. Arteries generally supply the

structures they contact.

The facial muscles muscles of facial e5pression! mo"e the s%in and change facial

e5pressions to con"ey mood. Most muscles attach to bone or fascia and produce their

e>ects by pulling the s%in.

The occipitofrontalis is a 1at digastric muscle which ele"ates the eyebrows and produce

trans"erse wrin%les across the forehead. This gi"es the face a surprised loo%.

)e"eral muscles alter the shape of the mouth and lips during spea%ing as well as during

such acti"ities as singing' whistling' and mimicry. The shape of the mouth and lips iscontrolled by a comple5 three#dimensional group of muscular slips' which include the

following:

( @le"ators' retractors' and e"ertors of the upper lip.

( Depressors' retractors' and e"ertors of the lower lip.

( The orbicularis oris' the sphincter around the mouth.

( The buccinator in the chee%.

6igure . 6acial muscleshttp://www."idport.co/refli#/science/$!an%od&/M!sc!lar'&ste/$ead(aceM!scles.htm

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2. MUSCLES OF THE FACE & SCALP
http://www.kidport.com/reflib/science/HumanBody/MuscularSystem/HeadFaceMuscles.htmhttp://www.kidport.com/reflib/science/HumanBody/MuscularSystem/HeadFaceMuscles.htmhttp://www.kidport.com/reflib/science/HumanBody/MuscularSystem/HeadFaceMuscles.htmhttp://www.kidport.com/reflib/science/HumanBody/MuscularSystem/HeadFaceMuscles.htm


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The platysmaB. 1at plate! is a broad' thin sheet of muscle in the subcutaneous tissue of

the nec%. 3t helps depress the mandible and draw the corners of the mouth inferiorly.

+utaneous sensory! inner"ation of the face and anterosuperior part of the scalp is

pro"ided primarily by the trigeminal ner"e + ?!' whereas motor inner"ation to the facial

muscles is pro"ided by the facial ner"e + ?33!.

6igure C. 8latysma

http://antrani".or)/!scles-of-the-head/

The sternocleidomastoid (SCM) muscleis a broad' strap#li%e muscle with two

heads. ne head attaches on the sternum' and the other on the cla"icle. ;ilateral

contractions of the )+Ms will cause e5tension of the ele"ating the chin. Acting unilaterally'

the )+M laterally 1e5es the nec% bends the nec% sideways! and rotates the head so the

ear approaches the shoulder of the ipsilateral same! side.

6igure E. )ternocleidomastoid muscle

http://dassa)e.co/wp-content/!ploads/2011/02/'*M+s#l.pn)


3. MUSCLES OF THE NECK
http://antranik.org/muscles-of-the-head/http://dmmassage.com/wp-content/uploads/2011/02/SCM_smbl.pnghttp://antranik.org/muscles-of-the-head/http://dmmassage.com/wp-content/uploads/2011/02/SCM_smbl.png


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Trapezius is a large' 1at triangular muscle that co"ers the posterior aspect of the

nec% and the superior half of the trun%. The trape*ius pro"ides a direct attachment of the

pectoral girdle to the trun%. 3t was gi"en its name because the muscles of the two sides

form a trape*ium B. irregular four#sided &gure!. The trape*ius assists in suspending the

upper limb.

6our anterior a5ioappendicular muscles pectoral muscles! mo"e the pectoral girdle.

Pectoralis majoris the biggest of these four. The pectoralis majoris a large' fan#

shaped muscle that co"ers the superior part of the thora5. 3t produces powerful adduction

and medial rotation of the arm.

The super&cial and intermediate groups of e5trinsic bac% muscles attach the superior

appendicular s%eleton of the upper limb! to the a5ial s%eleton in the trun%!.

The posterior shoulder muscles are di"ided into three groups:

( )uper&cial e5trinsic shoulder muscles: trape*ius and latissimus dorsi.

( Deep e5trinsic shoulder muscles: two muscles

( 3ntrinsic shoulder muscles: deltoid' teres ma,or' and the four rotator cu> muscles.

The namelatissimus dorsi9. widest of bac%! was well chosen because the muscle

co"ers a wide area of the bac%. passes from the trun% to the humerus and acts directly on

the shoulder ,oint and indirectly on the pectoral girdle. The latissimus dorsi e5tends'

retracts' and rotates the humerus medially e.g.' when folding the arms behind the bac% or

scratching the s%in o"er the opposite scapula!.

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4. MUSCLES OF PECTORAL AND SCAPULAR


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The deltoid is a thic%' powerful' coarse#te5tured muscle co"ering the shoulder and

forming its rounded contour. As its name indicates' the deltoid is shaped li%e the in"erted

Bree% letter delta F!. The deltoid abducts the arm.

6igure G. Muscles of the chest and abdomenhttp://api.nin).co/files/wY2w)d%w10DK&&d3p456!7w8K*Y%;6D


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The iceps rac!iiis the 1e5or of the arm. The brachialis is the main 1e5or of the

forearm. The triceps brachii is the main e5tensor of the forearm.

6igure J. Muscles of the arm

http://.#p.#lo)spot.co/->Y@9-'6w/?&68E"t;/777777777nB/5M&cdMs6/s1C00/#icepF!scle.;p)

There are


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6igure


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and in"ert the foot and 1e5 the toes. The super&cial group of calf muscles muscles

forming prominence of calf0 of posterior leg! includes the gastrocnemius' soleus' and

plantaris. The gastrocnemius and soleus share a common tendon' the calcaneal tendon'

which attaches to the calcaneus. The calcaneal tendon 9. tendo calcaneus' Achillestendon! is the most powerful thic%est and strongest! tendon in the body. These muscles

raise heel during wal%ing$ 1e5 the leg at the %nee ,oint. 6our muscles ma%e up the deep

group in the posterior compartment of the leg.

f the indi"idual muscles of the foot' ect body posture. The deeper the muscle is located

i.e. the closer to the spine!' the more powerful e>ect it will ha"e' and therefore' the

greater capacity it will ha"e for creating and maintaining a healthy spine. 6rom deep to

super&cial the abdominal muscles are:

trans"erse abdominal

internal obli-ues

e5ternal obli-ues

rectus abdominis

The trans"erse abdominus muscle is the deepest of the H abdominal muscles. The

rectus abdominus muscle is the most super&cial of the abdominal muscles co"ered by the

aponeurosis of the trans"ersus abdominis. The rectus abdominis has tendineous

intersections.

6igure


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Muscles in the Body 20121

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