Pages 196-203

Muscles and Body MovementsMovement is attained as a result of a muscle

moving an attached boneMuscles are attached to at least two points

1. Origin: attaches to an immovable/less movable bone

2. Insertion: attaches to a movable bone

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Musclecontracting

Origin

Brachialis

Tendon

Insertion

Types of Body MovementsFlexion

Decreases the angle of the jointBrings two bones closer togetherTypical of bending hinge joints (e.g., knee and

elbow) or ball-and-socket joints (e.g., the hip)Extension

Opposite of flexionIncreases angle between two bonesTypical of straightening the elbow or kneeExtension beyond 180° is hyperextension

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Flexion

Flexion

Extension

Extension

Hyperextension

(a) Flexion, extension, and hyperextension of the shoulder and knee

(b) Flexion, extension,and hyperextension

Extension

Flexion

Hyperextension

Types of Body MovementsRotation

Movement of a bone around its longitudinal axis

Common in ball-and-socket jointsExample: moving the atlas around the dens of

axis (i.e., shaking your head “no”)

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(c) Rotation

Rotation

Lateralrotation

Medialrotation

Types of Body MovementsAbduction

Movement of a limb away from the midlineAdduction

Opposite of abductionMovement of a limb toward the midline

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Abduction

Adduction Circumduction

(d) Abduction, adduction,and circumduction

Types of Body MovementsCircumduction

Combination of flexion, extension, abduction, and adduction

Common in ball-and-socket jointsProximal end of bone is stationary, and distal

end moves in a circle

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Abduction

Adduction Circumduction

(d) Abduction, adduction,and circumduction

Special MovementsDorsiflexion

Lifting the foot so that the superior surface approaches the shin (toward the dorsum)

Plantar flexionDepressing the foot (pointing the toes)“Planting” the foot toward the sole

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(e) Dorsiflexion and plantar flexion

Dorsiflexion

Plantar flexion

Special MovementsInversion

Turning sole of foot mediallyEversion

Turning sole of foot laterally

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(f) Inversion and eversion

Inversion Eversion

Special MovementsSupination

Forearm rotates laterally so palm faces anteriorly

Radius and ulna are parallelPronation

Forearm rotates medially so palm faces posteriorly

Radius and ulna cross each other like an X

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S

(g) Supination (S) and pronation (P)

Supination(radius and ulnaare parallel)

Pronation(radius rotatesover ulna)

S PP

Special MovementsOpposition

Moving the thumb to touch the tips of other fingers on the same hand

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(h) Opposition

Opposition

Types of MusclesPrime mover— muscle with the major

responsibility for a certain movementSynergist— muscle that aids a prime mover in a

movement and helps prevent rotationFixator— stabilizes the origin of a prime mover

Antagonist— muscle that opposes or reverses a prime mover

It is the actions of all muscles involved that provide smooth, coordinated and precise movement.

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Naming Skeletal MusclesSkeletal muscles can be named according to:direction of muscle fibers: rectus (straight)relative size of the muscle: maximus (largest)location of the muscle: temporalis (temporal

bone)number of origins triceps (three heads)location of origin and insertion: sterno (on the

sternum)shape of the muscle: deltoid (triangular)action: flexor/extensor (flex/extend a bone)

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Figure 6.15 Relationship of fascicle arrangement to muscle structure.

(a)

(b)

(c)

(e)

(f)

(g)

(a) Circular(orbicularis oris)

(b) Converent(pectoralis major)

(c) Fusiform(biceps brachii)

(d) Parallel(sartorius)

(e) Multipennate(deltoid)

(g) Unipennate(extensor digitorumlongus)

(f) Bipennate(rectusfemoris)

(d)