Lever Systems: Bone-Lever Systems: Bone-Muscle RelationshipsMuscle Relationships

Bone-Muscle Bone-Muscle Relationships: Lever Relationships: Lever

SystemsSystemsLever- rigid bar; free to turn about Lever- rigid bar; free to turn about

fixed point ex. bonefixed point ex. bonea. Fulcrum- fixed point; ^ a. Fulcrum- fixed point; ^

ex. jointex. jointb. Load- resistance moved; L b. Load- resistance moved; L

ex. part of bodyex. part of bodyc. Force- pull from contraction; F c. Force- pull from contraction; F

ex. muscleex. muscle

Bone-Muscle Bone-Muscle Relationships: Lever Relationships: Lever

SystemsSystems

Figure 10.2a

Mechanical advantage

Bone-Muscle Bone-Muscle Relationships: Lever Relationships: Lever

SystemsSystems

Figure 10.2b

Mechanical disadvantage

Lever RelationshipsLever Relationships

• Effort farther than load from fulcrum Effort farther than load from fulcrum equals mechanical advantageequals mechanical advantage

• Effort nearer than load to fulcrum Effort nearer than load to fulcrum equals mechanical disadvantageequals mechanical disadvantage

Lever Systems: ClassesLever Systems: Classes

a. 1st Class- Fulcrum between Load & Force; seesaw; a. 1st Class- Fulcrum between Load & Force; seesaw;

stability stability

Ex. Head tiltEx. Head tilt

b. 2nd Class- Load between Fulcrum & Force; b. 2nd Class- Load between Fulcrum & Force; wheelbarrow; lift wheelbarrow; lift

Ex. Raising body with toesEx. Raising body with toes

c. 3rd Class- Force between Fulcrum & Load; shovel; c. 3rd Class- Force between Fulcrum & Load; shovel; rapid mov’trapid mov’t

Ex. Flex forearmEx. Flex forearm

Lever Systems: ClassesLever Systems: Classes

Figure 10.3a

Lever Systems: ClassesLever Systems: Classes

Figure 10.3b

Lever Systems: ClassesLever Systems: Classes

Figure 10.3c

In this example the force is located between the weight and the fulcrum

In this case the fulcrum is located between the force and weight

In this example the weight is situated between the force and the fulcrum

Machines of the Body

Prime movers and synergist muscles

Agonist and antagonist muscles

Apart from assisting in locomotion does the muscular system play any other role?

Posture; this includes the erector spinae muscles and the muscles of the trunk.

Salient points

• Muscle groups are classified upon the the arrangement of the muscles fibres, this provides a wide range of muscle types.

• The origin of the muscle is that attachment at which the bone is stationary

• The insertion of the muscle is at that attachment where the bone is moving

• Muscle can have several different roles; they can be agonists, antagonists and synergists

• Not all muscles are involved in locomotion, they also enable other important bodily functions, for example, respiration, provide movement for the eye, assist in swallowing and speech

Major Skeletal Muscles: Major Skeletal Muscles: Anterior ViewAnterior View

• The 40 superficial The 40 superficial muscles here are muscles here are divided into 12 divided into 12 regional areas of regional areas of the bodythe body

Figure 10.4b

Major Skeletal Muscles: Major Skeletal Muscles: Posterior ViewPosterior View

• The 27 superficial The 27 superficial muscles here are muscles here are divided into seven divided into seven regional areas of regional areas of the bodythe body

Figure 10.5b

Origin

Insertion