Muscular SystemTypes of Body Movements

600+ skeletal muscles attached to bone or connective tissue at no less than 2 pointsOrigin – attached to immovable boneInsertion – attached to movable bone

MUSCLE MOVES TOWARD ORIGIN DURING CONTRACTION

Most Common Types of Body Movements

Flexion (decrease angle) Extension (increase angle) Abduction (moving limb away) Adduction (moving limb toward) Rotation (move bone along

longitudinal axis) Circumduction (combination)

Common Types of Movement (cont.)

Pronation (moving palm up to down; forces radius to cross ulna)

Supination (moving palm down to up into anatomical position; radius and ulna parallel)

Inversion (turning sole of foot medially) Eversion (turning sole of foot laterally) Dorsiflexion ( ankle movement/ instep up) Plantar flexion (straighten ankle/instep

down)

Types of Muscles Movement is result of team of muscles. Whatever team

can do, another team can reverse. Prime Mover (agonist) = the muscle (of team) that has

major responsibility for causing a particular movement Ex: biceps brachii for elbow flexion

Antagonist = muscles that oppose or reverse movement (located opposite side of joint from agonist) Ex: triceps brachii antagonizes biceps brachii, but is also

prime mover for forearm extension Synergist = muscles that help prime mover

Add force and reduce undesirable movements Fixators = specialized synergists (stabilize)

Immobilize bone or muscle’s origin (i.e,scapula)

Naming Skeletal Muscle Muscles are named on the basis of several

criteria (Look for the hints!) Direction of muscle fiber (and fascicles)- in

relation to lines like midline and axis of limb) rectus [straight] – run parallel oblique –run at a slant transversus – at right angles

Rectus femoris – straight muscle of thigh Transversus abdominus

Naming Skeletal Muscle (cont.)

Relative size of muscle maximus [largest] – gluteus maximus minimus [smallest]- gluteus minimus longus [long]- fibularis longus brevis [short] – extensor pollicis brevis

Number of origins Biceps [2], triceps [3], quadriceps [4]

biceps brachii, triceps brachii, quadriceps femoris

Naming Skeletal Muscle (cont.) Location of muscle’s origin and

insertion Ex: intercostal muscle

“costal” = rib runs between the ribs

Ex: temporalis muscle overlies temporal bone

Ex: sternocleidomastoid muscle “sternum” and “clavicle” [origin] mastoid process of temporal [insertion]

Naming Skeletal Muscle (cont.) Shape of the muscle

Deltoid = triangular Trapezius = trapezoid

Action of the muscle Flexor – flexor digitorum superficialis

Flexes wrist and middle phalanges Extensor – extensor carpi radialis longus

Action, joint (wrist), lies close to radius of the forearm, size rel. to other wrist extensors

Adductor – adductor longus Adducts, medially rotates thigh

Muscle Mechanics –Fascicle Arrangement

Review muscle force and speed Patterns of fascicle arrangement

Circular – concentric rings (sphincters) Orbicularis oculi (eye); orbicularis oris (mouth)

Convergent – fascicles converge to single tendon of insertion(triangular or fan-shaped) Pectoralis major

Parallel (& fusiform)– straplike or spindle shaped Sartorius (thigh to knee) – longest muscle in body Biceps brachii – flexes elbow, supinates forearm

Muscle Mechanics –Fascicle Arrangement (cont.)

Pennate – attach obliquely to central tendon Unipennate (one side of tendon) – extensor

digitorum longus (leg) Bipennate (from opposite sides of tendon) –

rectus femoris (thigh) [like a feather] Multipennate – [like many feathers together]

Deltoid muscle (shoulder)

Muscle Mechanics –Fascicle Arrangement (cont.)

Arrangement determines range of movement and power

Parallel = shorten most but not powerful

Power depends on total muscle cells in muscle (more cells=more power)

Bipennate and multipennate = most fibers but shorten little & very powerful

Bone-Muscle Relationships – lever systems

Lever systems- partnerships between muscular and skeletal systems

Lever – rigid bar that moves on a fixed point (fulcrum) when force applied

Applied force (effort) moves a resistance (load) Joints = fulcrums Bones = levers Muscle contraction = effort (applied at insertion) Load = bone + tissues + what is moved with

lever

Bone-Muscle Relationships – lever systems (cont.)

Lever operates at mechanical advantage when load is close to fulcrum and effort is applied far from fulcrum Used to move large load over small distance

(power lever) Slower, more stable, strength is priority

Lever operates at mechanical disadvantage when load is far from fulcrum and effort is applied near fulcrum Force greater than the load moved (speed lever) Force lost, but speed and range of movement

gained

Bone-Muscle Relationships – lever systems (cont.)

Lever classes First-class lever

Effort applied at one end of lever; load at other end; fulcrum between (scissors) Lift head off chest some act at mechanical advantage; others disadvantage

Second-class lever Effort applied at one end; fulcrum at the other end; load

between (wheelbarrow) (uncommon) Standing on toes

Third-class lever Effort applied between the load and fulcrum (tweezers)

(act at great speed & mechanical disadvantage) Most skeletal muscle