dr. Muh. Ardi Munir, M.Kes, Sp.OT, FICS, M.HDept. of Anatomy / Orthopaedic &Traumatologi UnTad

General Principles of Musculoskeletal System

Functions of the Musculoskeletal System

- Support and frame work- Protect the body and its organs- Provide motion / locomotors function- Hemopoetik system- storage & exchange of Calcium & phosphate ions

Major Substructures

- skeleton- joints- ligaments- muscles- tendons- neurological elements responsible for locomotor control.

Properties

- macroscopic- microscopic- physiologic- biochemistry- biomechanics

SkeletonConsists: bones & cartilagesBones: - provide a framework of levers - protect organ - contain marrow --> produce blood cells - storage & exchange of Ca & phosphate ions

Cartilage: - hyaline: articular, costal, respiratory, nasal - elastic: external ear, epiglottis - fibrocartilages: intervertebral disc, meniscus

Bones- Types: long, short, flat, irregular- Parts: compact - spongious - medullary cavity

diaphysis, epiphysis, metaphysis periosteum

- blood & nerve supply - microscopic structure- development:

osteogenesis & ossification increase in size & maturity, & aging

Skeleton

Intramembranous Ossification

Endochondral Ossification

Cartilages

Types: - hyaline in embryo, epiphysial disc, ribs, articular, respiratory tract - fibrocartilage in certain cartilagineous joint, articular disc - elastic cartilage in auricle & auditory tube

Joints (arthroses)

Classification: synarthroses: - articulationes fibrosae & cartilagineae diarthroses : - articulationes synoviales

OR Solid joints : - fibrous & cartilagineous joints Cavitated joints: - synovial joints

Morphology of a Synovial Joint

Synovial joints

Types: according to axis of movement: - uni-, bi-, triaxial

According to the shapes of articular surfaces: - plane, hinge (ginglymus), condylar, spheroidal,

ellipsoidal, pivot (trochoid), saddle

Synovial JointsMovements:

- active - passive

Blood supply: plexus subsynovial nerve supply : - vasomotor fibers - pain fibers - fibers to detect speed and direction of

movement - fibers to detect joint position

MUSCULAR SYSTEM

• Muscle cells/myocytes function --> movement

• Classification - Skeletal muscle - Cardiac muscle - Smooth muscle

Skeletal Muscle

• Muscle fibers - extrafusal - intrafusal (muscle spindle)

• endomysium• fasciculi• perimysium• epimysium

Attachment of skeletal muscle

• Tendons

• Aponeuroses

• Fascia

• Origin

• Insertion

Naming of Muscles

o The names given to individual muscles usually descriptive, based on their:

- shape - size - number of heads or bellies - position - depth - attachment - action

• These terms are often used in combination

Blood Supply

• From adjacent vessels: one or several anastomosing vessels

• Artery enters on the deep surface• Form neurovascular bundle with veins and

nerves• Veins have valves• Lymphatic vessels commence at epimysium

& perimysium

Motor Units

• A functional unit formed by a motor neuron and all the muscle fibers that it innervates

• Accounts for simultaneous contraction of a number of fibers within a muscle

• Size: small in muscles for precision tasks large in postural muscles

Gradation of muscle contraction

Strategy:

•Increase the impulse frequency of motorneuron

•Increase the number of motor unit recruited

Fiber type of adult skeletal muscle

• Classification of muscle fibers – morphology: red, white – histochemistry: myosin ATPase, myosin

phenotype – physiology: fast & slow contracting, fatigue

resistant. – biochemistry: oxidative, glycolytic, etc.

Muscle Histochemistry

Functional implications of shape and fiber architecture

Direction of action:• The resultant force generated by a muscle is

directed along the line of tendon

• Muscle with twist geometry: the fibers shorten and brought to the same plane

Force and Range of Contraction

Force: - Summation of actin-myosin cross-bridges - depend on the cross sectional area

Range: - Summation of subtraction of min-max

overlapping between actin and myosin - depend on the length of the fibers

Study of muscle action

• Anatomical method• Localized electrical stimulation• Manual palpation• EMG• EMG + other tools• Clinical method

Actions of muscles

• Isometric vs isotonic contraction

• concentric vs eccentric

Classification of muscle role

• Prime mover

• antagonist

• fixator

• synergist

Biomechanics

• First Class Lever

• Second Class Lever

• Third Class Lever

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