Anatomi Sistem Muskulo – Skeletal Manusia

Anatomi sistem muskulo – skeletal manusia

Ns. Herlina,M.Kep.,Sp.Kep.An

PENDAHULUAN

• Sistem muskulo skeletal terdiri dari tulang sendi, oto dan struktur pendukung lainya : tendon, ligamen, fasia, dan bursae

• Pertumbuhan dan perkembangan struktur ini terjadi selama masa anak-anak dan remaja

• Pada usia 25 tahun pengerasan tulang telah lengkap

TULANG• 206 tulang membentuk kerangka orang dewasa (20%

dari massa tubuh) 80 tulang kerangka aksial 126 tulang kerangka apendikularis

• Kesehatan dan fungsi tulang sangat bergantung pada sistem tubuh yang lain

• Struktur tulangmemberi perlindungan terhadap organ vital (otak, jamtung, dan paru)

• Kerangka tulang merupakan kerangka yang sangat kuat untuk memyangga struktur tubuh dan otot yang melekat ke tulang memungkinkan tubuh bergerak

4

Bone Classification

• Bone Classification:

• tulang panjang• tulang pendek• Sesamoid Bones• Flat Bones• Irregular Bones• Wormian Bones (sutural)

(a) (e)

(b)

(c)

(d)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Pembagian skeletal• Axial skeletonTd: kerangka tulang kepala dan leher, tengkorak,

kolumna vertebrae, tulang iga, tulang hioid sternum• Apendikular skeletonTd: 1. kerangka tulang lengan dan kaki 2. ekstrimitas atas : skapula, klavikula, humerus, ulna,

radial ; tangan (karpal, metakarpal, falang) 3. ekstrimitas bawah : tulang pelvik, femur, patela,

tibia, fibula; kaki : tarsal, metatarsal, falang

Classification of Bones on the Classification of Bones on the Basis of ShapeBasis of Shape

Slide 5.4cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 5.1

Tulang panjang

• Bentuknya silindris• Berukuran panjang seperti batang (doiafisis) • Tersusun atas tulang kompakta• Kedua ujungnya berbentuk bulat/episis tersusun

atas tulang kanselus• Tulang diafisis memiliki lapisan luar berupa tulang

kompakta yang mengelilingi sebuah rongga tengah yang disebut kanalmedula

• Kanal medula mengandung sumsum kuning.

• Sumsung kuning terdiri dari lemak dan pembuluh darah tetapi suplay atau eritrositnya tidak terlalu banyak

• Tulang epifise terdiri dari tulang spongiosa yangmengandung sumsung merah yang isinya sama dengansumsum kuning dandibungkus oleh selapis tipis tulang kompakta.

• Bagian luar tulang panjang dilapisi jaringan fibrosa kuat yg disebut periosteum.

• Lapisan ini kaya pembuluh darah yang menembus tulang

Tiga kelompok yang menyuplai tulang panjang

• Sejumlah arteri kecil menembus tulang kompakta untuk menyuplai kanal dan system harvesrs

• Banyak arteri yang lebih besar menembus tulang kompakta untuk menyuplai tulang spongiosa dan sumsum merah

• Satu atau dua arteri besar menyuplai kanal medula. Arteri ini disebutarteri nutrien yang kemudian masuk ke foramen nutrien

• Periosteum memberikan nutrisi tulang dibawahnya melalui pembuluh darah

• Jika periosteum robek maka tulang dibawahnya akan mati

• Periosteum berperan dalam pertambahan ketebalan tulang melalui kerja osteoblast

• Periosteum tidak ditemukan pada permukaan sendi. Fungsiperiosteum digantikan oleh tulang rawan hialin (tulang rawan sendi)

11

Parts of a Long Bone• Epiphysis

• Distal• Proximal

• Diaphysis• Metaphysis• Compact bone• Spongy bone• Articular cartilage• Periosteum• Endosteum• Medullary cavity• Trabeculae• Bone marrow

• Red marrow and yellow marrow

Femur

Periosteum

Yellow marrow

Medullary cavity

Space containingred marrow

Spongy bone

Compact bone

Articular cartilage

Epiphyseal plates

Proximalepiphysis

Distalepiphysis

Diaphysis

Endosteum


Tulang Pendek

• Bentuknya hampir sama dengan tulang panjang tetapi bagian distal lebih kecil daripada bagian tulang panjang,

• Bagian distal lebih kecil daripada bagian proksimal

• Berukuran pendek dan kecil

Tulang Pipih

• Contoh: sternum, kepala, skapula, panggul• Bentuknya gepeng• Berisis sel-sel pembentuk darah• Melindungi organ vital dan lunak di bawahnya• Terdiri dari 2lapisan tulang kompakta dan bagian

tengan terdapat lapisan spongiosa• Dilapisi periosteum yang dilewati oleh dua

kelompokpembuluh darah untukmenyuplay tulang kompaktadan tulang spongiosa

Tulang tak beraturan

• Contoh: tulang vertebrae, tulang telinga tengah• Mempunyai bentuk unik sesuai fungsinya• Terdiri dari tulang spongiosa yang dibungkus oleh

selapis tipis tulang kompakta• Diselubungi oleh periosteum seperti tulang pipih

keculai pada peermukaan sendinya• Periosteum tsb memberi dua kelompok pembuluh

darah untuk menyupali tulang kompakta danspongiosa

Tulang sesamoid

• Contoh: patela• Merupakan tulang kecil yang terletak di

sekitar tulang yang berdekatan dengan persendian

• Berkembang bersama tendon dan fasia

STRUKTUR TULANG

• Tulang tersusun oleh jaringan kompakta (kortikal) dan kanselus (trabekularatau spongiosa)

• Tulang kompaktasecaramakroskopis terlihatpadat tetapi secara mikroskopis terdiri dari sistem Havers

• Sistem havers tardiri dari kanal havers

• Sebuah kanal havers terdiri dari pembuluh darah, saraf, dan pembuluh limfe, lamela (lempengan tulang yang mengelilingi kanal sentral), kaluna (ruang di antara lamela yang mengandung sel-seltulang atau osteosit dan saluran limfe), dan kanalikuli (saluran kecil yang menghubungkan lakuna dan kanal sentral)

• Saluran ini mengandung pembuluh limfe yang membawa nutrien dan oksigen ke osteosit

• Tulang kanselus juga keras seperti tulang kompakta, tetapi secara mikroskopis terlihat berlubang-lubang (spons)

• Secara miskroskopistulang kanselus terlihat lebih besar dan mengandung sedikit lamela

Microscopic Anatomy of BoneMicroscopic Anatomy of Bone

Slide 5.10b

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

Figure 5.3


Slide 5.11a


Lacunae Cavities containing

bone cells (osteocytes)

Arranged in concentric rings

Lamellae Rings around the

central canal Sites of lacunae Figure 5.3


Slide 5.11b


Canaliculi Tiny canals Radiate from the

central canal to lacunae

Form a transport system

Figure 5.3

22

Spongy Bone• Spongy bone is aka cancellous bone

(a)

(c)

Spongy bone Compact bone

(b)

Spongybone

Compactbone

Remnant ofepiphyseal plate

Spongybone

Compactbone


a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.

Sel-sel penyusun tulang • Osteoblas : berfungsi menghasilkan jaringan osteosid

danmenyekresi fosfatase alkali yg berperan penting dalam pengendapan kalsium dan fosfat dalam matriks tulang

• Osteosit : adl sel-sel tulang dewasa yang bertindak sebagai lintasan untuk pertukaran kimiawi melalui tulang yang padat

• Osteoklast: sel-sel berinti banyak yang memungkinkan mineral dan matriks tulang dapat diabsorbsi . Sel ini menghasilkan enzim proteolitik yang memecah matriks dan beberapa asam yang melarutkan mineral tulang, sehinggakalsium dan fosfat terlepas ke dalam darah

PERTUMBUHAN &METABOLISME TULANG

Pertumbuhan dan metabolisme tulang dipengaruhi oleh beberapa mineral dan hormon sbb:

1. Kalsium dan fosfor. Jika Ca meningkat, jumlah fosfor berubah. Keseimbangan Ca &fosfor dipertahankan oleh hormon kalsitonin & paratoroid (PTH)

2. Kalsitonin. Diproduksi oleh kelenjar tiroid. Menurunkan konsentrasi Ca Serum.

3. Vitamin D: diperlukan agar kalsium dan fosfor dapatdiabsorbsi dari usus dandigunakan oleh tubuuh. Defisiensi vit D mengakibatkan defisit mineralisasi, deformitas, patah tulang

4. Hormon paratiroid (PTH). bilaCamenurunmaka PTHmeningkat dan menstimulasi tulang untukmeningkatkan aktivitas osteoblastik dan menyumbangka kalsium darah

5. Hormon pertumbuhan/GH: bertanggung jawab meningkatkan panjang tulang dan jumlah matriks tulamg

6. glukokortikoid: mengatur metabolisme protein untuk mengurangi ataupun mengintensifkan matriks organik ditulang danmembantu pengaturan klasiumdi intestinumdan absorbsi fosfor

7. hormon seksuala.Estrogen: menstimulasi aktivitas osteoblasttik

dan cenderung menghambat hormon paratiroid. Estrogen menurun saat menopause sehingga tjd penurunan kadar kalsium pada tulang dalamwaktu lama menyebabkan osteoporosis

b.Androgen seperti testosteron: meningkatkan anabolisme dan massa tulang

28

Factors Affecting Bone Development, Growth and Repair

• Deficiency of Vitamin A – retards bone development• Deficiency of Vitamin C – results in fragile bones • Deficiency of Vitamin D – rickets, osteomalacia• Insufficient Growth Hormone – dwarfism• Excessive Growth Hormone – gigantism, acromegaly • Insufficient Thyroid Hormone – delays bone growth• Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates• Physical Stress – stimulates bone growth

FUNGSI SKELETAL

1. Memberi struktur dan bentuk tubuh2. Mendukung jaringan sekitarnya (otot dan tendon)3. Melindungi organ tubuh (jantung, otak, paru, dan

jaringan lunak)4. Membantu pergerakan melalui pergerakan otot

danpembentukan sendi5. Membentuk sel-sel darahmerah dalamsumsum tulang

merah6. Sebagai tempaat penyimpanan garam mineral,seperti

garam kalsium dan fosfor

Klasifikasi sendi

• Sendi sinartrosis (sendi tidak bergerak sama sekali) : sutura tulang tengkorak

• Sendi amfiartrosis (sendi bergerak bebas): pelvik, simfisis, tibia

• Sendi diartrosis/sinovial (sendi bergerak bebas). Contoh: siku, lutu, pergelangan tangan

Gerakan sendi sinovial

1. Abduksi: gerakan tungkai menjauhi tubuh2. Adduksi: gerakan tungkai mendekati tubuh3. Ekstensi: meluruskan tungkai pada persendian4. Fleksi: membengkokkan tungkai pada sendi5. Dorso-fleksi: membengkokkan pergelangan

agarkaki keatas6. Plantar-fleksi: meluruskan pergelangan ke

arah bawah

7. pronasi: memutar lengan atas shg telapak tangan berada di bawah

8. Supinasi: memutarlengan atas sehingga telapak tangan berada diatas

9. Inversi: memutar ke dalam10.sirkumduksi: bergerak ke dalam lingkaran11.Internal rotasi: bergerak kedalam pada satu sumbu

pusat12. Eksternal rotasi: bergerak ke luar padasumbu pusat

Klasifikasi sendi berdasarkan strukturnya

1. Fibrosa : tidak memiliki tulang rawan, dan tulang satunya dihubungkan oleh jaringan penyambung fibrossa. Contoh: sutura tulang tengkorak, perlekatan tulang tibia dan fibula bagian distal

2. Kartilago : sendi yang ujung-ujung tulangkanya terbungkus oleh tulang rawan hialin, disokong oleh ligamen dan hanya dapat sedikit bergerak

Fibrous JointsFibrous Joints

Slide 5.46Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Bones united by fibrous tissue – synarthrosis or largely immovable.

Figure 5.27d, e

• Kartilago dibagi menjadi 2:a.Sinkondrosis: sendi-sendi yang seluruh

persendiannya diliputi oleh tulang rawan hialin. Contoh: sendi-sendi kosto-kondral

b.Simfisis: sendi yang tulang-tulangnya memiliki suatu hubungan fibrokartilago dan selapis tipis tulang rawan hialinyang menyelimutii permukaan sendi. Contoh: simfisis pubis dan sendi tulang punggung

Cartilaginous Joints – mostly Cartilaginous Joints – mostly amphiarthrosisamphiarthrosis


Bones connected by cartilage

Examples Pubic

symphysis

Intervertebral joints

Figure 5.27b, c

3. Sendi sinovial : sendi yang dapat digerakkan serta memiliki rongga sendi dan permukaan sendi dilapisi tulang rawan hialin

The Synovial JointThe Synovial Joint


Figure 5.28

Struktur Anatomi sendi sinovial

Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape

Slide 5.52a


Figure 5.29a–c

Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape

Slide 5.52b


Figure 5.29d–f

OTOT

• Otot skeletal secara volunter dikendalikan oleh sistem saraf pusat dan perifer

• Penghubung antara saraf motorik perifer dan sel-sel otot dikenal sebagai motor end-plate

• Otot dibagi dalam 3kelompok dengan funsi utama untuk kontraksi dan menghasilkan gerakan sebagian atau seluruh tubuh

• Kelompokotot: 1. otot lurik, 2. otot viseral, 3. otot jantung

Types of muscle tissue:Skeletal muscle tissue

• Associated with & attached to the skeleton• Under our conscious (voluntary) control• Microscopically the tissue appears striated • Cells are long, cylindrical & multinucleate

Cardiac muscle tissue• Makes up myocardium of heart• Unconsciously (involuntarily) controlled• Microscopically appears striated• Cells are short, branching & have a single nucleus• Cells connect to each other at intercalated discs

Smooth (visceral) muscle tissue• Makes up walls of organs & blood vessels• Tissue is non-striated & involuntary• Cells are short, spindle-shaped & have a single nucleus• Tissue is extremely extensible, while still retaining ability to contract

Anatomy of skeletal muscles

Skeletal muscle

fiber (cell)

Muscle Fascicle

Surrounded by perimysium

Surrounded by endomysium

endomysium

perimysium

Skeletal muscle

Surrounded by epimysium

epimysiumtendon

Fungsi otot skelet

• Mengontrol pergerakan, mempertahankanposturtubuh, dan menghasilkan panas

KONTRAKSI OTOT

Struktur laindalam sistemmuskuloskeletal

1. Ligamen : sekumpulan jaringan fibrosa yang tebal yang merupakan akhir suatu otot dan berfungsi mengikat tulang

2. Tendon: perpanjangandari pembungkus fibrosa yang membungkus setiap ototdanberkaitan dengan periosteum jaringan penyambung yang mengelilingi tendon, khususnya pada pergelangan kaki dan tumit

3. Fasia : suatu permukaan jaringan penyambung longgar yang di dapatkan langsung di bawah kulit sebagai fasia superfisial jaringan penyambung fibrosa yang membungkus otot, saraf, dan pembuluh darah

4. Bursae: suatu kantong kecildari jaringan penyambung, yang digunakan di atas bagian yang bergerak, contoh: busae olekranon yang terletak di antara prosesus dan kulit

TUGAS BACA

Microanatomy of a Muscle Fiber (cell)

Microanatomy of a Muscle Fiber (Cell)

sarcolemmatransverse (T) tubules sarcoplasmic

reticulumterminal cisternae

myofibril

thin myofilament

thick myofilament

triad

mitochondria

nuclei

myoglobin

Muscle fiber

myofibril

Thin filaments Thick filaments

Thin myofilamentMyosin molecule ofthick myofilament

sarcomereZ-line

Thin Myofilament

(myosin binding site)

Z-line (Z-disc)

Thick myofilament

(has ATP & actin binding

site)

M-line

Play IP sliding filament theory p.5-14 for overview of thin & thick filaments

Sarcomere

Z line Z lineA band

H zone

I band Zone of overlap M line

Zone of overlap

Thin myofilaments Thick

myofilaments

Sliding Filament Theory• Myosin heads attach to actin molecules (at binding (active) site)

• Myosin “pulls” on actin, causing thin myofilaments to slide across thick myofilaments, towards the center of the sarcomere

• Sarcomere shortens, I bands get smaller, H zone gets smaller, & zone of overlap increases

• As sarcomeres shorten, myofibril shortens. As myofibrils shorten, so does muscle fiber

• Once a muscle fiber begins to contract, it will contract maximally

• This is known as the “all or none” principle

Physiology of skeletal muscle contraction• Skeletal muscles require stimulation from the nervous system in order to contract

• Motor neurons are the cells that cause muscle fibers to contract

cell body

dendrites

axonSynaptic terminals

(synaptic end bulbs)telodendriaaxon hillock

motor neuron

End bulbs contain vesicles filled with Acetylcholine (Ach)

telodendria

Synaptic terminal

(end bulb)

Neuromuscular junction

Synaptic vessicles

containing ACh

Motor end plateof sarcolemma

Synaptic cleftNeuromuscular

junction

Overview of Events at the neuromuscular junction• An action potential (AP), an electrical impulse, travels down the axon of the motor neuron to the end bulbs (synaptic terminals)

• The AP causes the synaptic vesicles to fuse with the end bulb membrane, resulting in the release of Acetylcholine (ACh) into the synaptic cleft

• ACh diffuses across the synaptic cleft & binds to ACh receptors on the motor end plate

• The binding of ACh to its receptors causes a new AP to be generated along the muscle cell membrane

• Immediately after it binds to its receptors, Ach will be broken down by Acetylcholinesterase (AChE) – an enzyme present in the synaptic cleft

Figure 7-4(b-c)2 of 5Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Synapticcleft

Arrival of an action potential at the synaptic terminal

Sarcolemma ofmotor end plate

Arriving action potential

Vesicles

AChAChE moleculesAChreceptorsite

Action potential

Synaptic terminal

Axon

Sarcolemma

Musclefiber

• An action potential (AP), an electrical impulse, travels down the axon of the motor neuron to the end bulbs (synaptic terminals)


Synapticcleft

Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft.

Release of acetylcholine




Vesicles


Action potential

Synaptic terminal

Axon

Sarcolemma

Musclefiber

•The AP causes the synaptic vesicles to fuse with the end bulb membrane, resulting in the release of Acetylcholine (ACh) into the synaptic cleft


Synapticcleft

Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft.

The binding of ACh to the receptors increases the membrane permeability to sodium ions. Sodium ions then rush into the cell.

ACh binding at the motor and plateRelease of acetylcholine




Vesicles


Action potential

Synaptic terminal

Axon

Sarcolemma

Musclefiber

Na+

Na+

Na+

•ACh diffuses across the synaptic cleft & binds to ACh receptors on the motor end plate

•The binding of ACh to its receptors causes a new AP to be generated along the muscle cell membrane

•Immediately after it binds to its receptors, ACh will be broken down by Acetylcholinesterase (AChE) – an enzyme present in the synaptic cleft

Table 7-1

Physiology of Skeletal Muscle Contraction•Once an action potential (AP) is generated at the motor end plate it will spread like an electrical current along the sarcolemma of the muscle fiber

• The AP will also spread into the T-tubules, exciting the terminal cisternae of the sarcoplasmic reticula

•This will cause Calcium (Ca+2 ) gates in the SR to open, allowing Ca+2 to diffuse into the sarcoplasm

•Calcium will bind to troponin (on the thin myofilament), causing it to change its shape. This then pulls tropomyosin away from the active sites (myosin binding sites) of actin molecules.

•The exposure of the active sites allow myosin to bind to actin, and cause the sliding of the filaments

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin CummingsFigure 7-53 of 7

Resting sarcomere

Myosin head

Active-site exposure

Troponin

ActinTropomyosin

ADP

P+

ADPP +

ADPP+

Active site

Sarcoplasm

Ca2+

Ca2+

ADP

P +

• Calcium (Ca+2 ) gates in the SR open, allowing Ca+2 to diffuse into the sarcoplasm• Calcium will bind to troponin (on the thin myofilament), causing it to change its shape. • This then pulls tropomyosin away from the active sites of actin molecules.

Physiology of skeletal muscle contraction – events at the myofilaments


Resting sarcomere

Myosin head

Active-site exposure Cross-bridge formation

Troponin

ActinTropomyosin

ADP

P+

ADPP +

ADPP+

Active site

Sarcoplasm

Ca2+

Ca2+

ADP

P +

ADP+ P

Ca2+

ADP+P

Ca2+

• Myosin heads are “energized” by the presence of ADP + PO43- at the ATP binding

site (energy is released as phosphate bond of ATP breaks)

• Once the active sites are exposed, the energized myosin heads hook into actin molecules forming cross-bridges



Resting sarcomere

Myosin head

Active-site exposure Cross-bridge formation

Pivoting of myosin head

Troponin

ActinTropomyosin

ADP

P+

ADPP +

ADPP+

Active site

Sarcoplasm

Ca2+

Ca2+

ADP

P +

ADP+ P

Ca2+

ADP+P

Ca2+

Ca2+

ADP + P

Ca2+

ADP + P

• Using the stored energy, the attached myosin heads pivot toward the center of the sarcomere

• The ADP & phosphate group are released from the myosin head


Resting sarcomere

Myosin head


Cross bridge detachment

Cross-bridge formation


Troponin

ActinTropomyosin

ADP

P+

ADPP +

ADPP+

Active site

Sarcoplasm

Ca2+

Ca2+

ADP

P +

ADP+ P

Ca2+

ADP+P

Ca2+

Ca2+

ADP + P

Ca2+

ADP + P

Ca2+

ATP

ATP

Ca2+

• A new molecule of ATP binds to the myosin head, causing the cross bridge to detach from the actin strand• The myosin head will get re-energized as the ATP ADP+P

• As long as the active sites are still exposed, the myosin head can bind again to the next active site


Resting sarcomere

Myosin head

Myosin reactivation


Cross bridge detachment

Cross-bridge formation


Troponin

ActinTropomyosin

ADP

P+

ADPP +

ADPP+

Active site

Sarcoplasm

Ca2+

Ca2+

ADP

P +

ADP+ P

Ca2+

ADP+P

Ca2+

Ca2+

ADP + P

Ca2+

ADP + P

Ca2+

ATP

ATP

Ca2+

Ca2+

Ca2+

ADPP +

+ P

ADP

http://www.youtube.com/watch?v=CepeYFvqmk4 -animation

http://www.youtube.com/watch?v=kvMFdNw35L0 –

animation with Taylor Swift song


http://www.youtube.com/watch?v=CepeYFvqmk4

http://www.youtube.com/watch?v=kvMFdNw35L0

Physiology of Skeletal Muscle Contraction• If there are no longer APs generated on the motor neuron, no more ACh will be released

• AChE will remove ACh from the motor end plate, and AP transmission on the muscle fiber will end

• Ca+2 gates in the SR will close & Ca+2 will be actively transported back into the SR

• With Ca+2 removed from the sarcoplasm (& from troponin), tropomyosin will re-cover the active sites of actin

• No more cross-bridge interactions can form

• Thin myofilaments slide back to their resting state

Table 7-1

Skeletal muscle fibers shorten as thick filaments interact with thin filaments (“cross bridge”) and sliding occurs (“power stroke”). The trigger for contraction is the calcium ions released by the SR when the muscle fiber is stimulated by its motor neuron. Contraction is an active process; relaxation and the return to resting length is entirely passive.

These physiological processes describe what happen at the cellular level – how skeletal muscle fibers contract

But what about at the organ level? How do skeletal muscles (like your biceps brachii) contract to create useful movement?

• Skeletal muscles are made up of thousands of muscle fibers

• A single motor neuron may directly control a few fibers within a muscle, or hundreds to thousands of muscle fibers

• All of the muscle fibers controlled by a single motor neuron constitute a motor unit

The size of the motor unit determines how fine the control of movement can be –

small motor units precise control (e.g. eye muscles large motor units gross control (e.g. leg muscles)

Play IP Contraction of motor units p. 3-7

Recruitment is the ability to activate more motor units as more force (tension) needs to be generated

There are always some motor units active, even when at rest. This creates a resting tension known as muscle tone, which helps stabilize bones & joints, & prevents atrophy

Play IP Contraction of motor units p. 3-7

Hypertrophy – “stressing” a muscle (i.e. exercise) causes more myofilaments/myofibrils to be produced within muscle fibers; allows for more “cross bridges” resulting in more force (strength) as well as larger size

Anatomy of the Muscular System

•OriginMuscle attachment that remains

fixed•Insertion

Muscle attachment that moves•Action

What joint movement a muscle produces

i.e. flexion, extension, abduction, etc.

• For muscles to create a movement, they can only pull, not push

• Muscles in the body rarely work alone, & are usually arranged in functional groups surrounding a joint

• A muscle that contracts to create the desired action is known as an agonist or prime mover

• A muscle that helps the agonist is a synergist

• A muscle that opposes the action of the agonist, therefore undoing the desired action is an antagonist

Skeletal muscle movements at joints

Flexion/extension

Abduction/adduction

Rotation – left/right; internal(medial)/external(lateral)

pronation/supination

Elevation/depression

Protraction/retraction

Dorsiflexion/plantarflexion

Inversion/eversion

Naming of skeletal muscles

• An Overview of the Major Skeletal Muscles

Figure 7-11(a)

• An Overview of the Major Skeletal Muscles

Figure 7-11(b)

TERIMAKASIHSEMOGA MENJADI ILMU YANG

BERMANFAAT

Anatomi Sistem Muskulo – Skeletal Manusia

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