1. The Skeletal, Muscular and Levers System
Muscular Physics

2. Movement The physical constraints to movement
gravity and frictional drag
occur in every environment, differing only in degree
Involves skeletal and muscular systems
Muscle have microtubules and microfilaments
Needs energy

3. Types of Skeletal Systems
Changes in movement occur because muscles pull against a support structure, called the skeletal system
-Zoologists recognize three types:
-Hydrostatic skeletons
-Exoskeletons
-Endoskeletons

4. Hydrostatic Skeletons
Are found primarily in soft-bodied invertebrates, both terrestrial and aquatic
Locomotion in earthworms
-Involves a fluid-filled central cavity and surrounding circular & longitudinal muscles
-A wave of circular followed by longitudinal muscle contractions move fluid down body
-Produces forward movement

5. Longitudinal muscles contracted
Hydrostatic Skeletons
Anterior
Circular muscles
Longitudinal muscles
contracted
Longitudinal muscles contracted
contract, and anterior
end moves forward
contract, and segments
catch up
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6. Hydrostatic Skeletons
Locomotion in aquatic invertebrates
-Occurs by fluid ejections or jetting
-Jellyfish produce regular pulsations in bell
-Squeezing some of water contained beneath it
-Squids fill mantle cavity with sea water
-Muscular contractions expel water forcefully through the siphon, and the animal shoots backward

7. Jellyfish propelled upward Contractile fibers Bell pulsates expelled
Water
enters
bell
Contractile fibers
expelled
from bell
Bell
pulsates
Jellyfish
propelled
upward
Water expelled
from siphon
Squid
backward b. a.
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8. Exoskeletons The exoskeleton surrounds the body as a rigid hard case
-Composed of chitin in arthropods
An exoskeleton provides protection for internal organs and a site for muscle attachment
-However, it must be periodically shed, in order for the animal to grow
-It also limits body size

9. Endoskeletons
Endoskeletons are rigid internal skeletons that form the body’s framework and offer surfaces for muscle attachment
-Echinoderms have calcite skeletons, that are made of calcium carbonate
-Bone, on the other hand, is made of calcium phosphate

10. Endoskeletons Vertebrate endoskeletons have bone and/or cartilage
-Bone is much stronger than cartilage, and much less flexible
Unlike chitin, bone and cartilage are living tissues
-They can change and remodel in response to injury or physical stress

11. Joints Joints are the locations where one bone meets another
-1. Immovable joints = Join bones
-2. Slightly movable joints = Involve fibrous connective tissue or cartilage
-3. Freely movable joints = Also called synovial joints
-Contain a lubricating fluid

12. Slightly Movable Joints
Body of
vertebra
Fibrous
joints
Fibrous Joints
Intervertebral
disk
Articular
cartilage
connective
tissue
Bone
Suture
Immovable Joint a.
Slightly Movable Joints
Cartilaginous Joints b.
Synovial membrane
Synovial fluid
Fibrous capsule
Articular cartilage
Freely Movable Joint c.
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13. Joints Movable joints can be divided into four types
-Ball-and-socket joints = Permit movement in all directions
-Hinge joints = Allow movement in only one plane
-Gliding joints = Permit sliding of one surface over another
-Pivot joints = Allow rotation

14. Ball-and-Socket Combination Joint Hinge Joint Gliding Joint a. d. b.
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15. The Muscular System Interactions of Skeletal Muscles in the Body
Muscles usually work in groups, i.e. perform “group actions”
Muscles are usually arranged in antagonistic pairs
flexor-extensor
abductor-adductor, etc.

16. How Skeletal Muscles Produce Movement
Muscles exert force on tendons that pull on bones
Muscles usually span a joint
Muscle contraction changes the angle or position of one bone relative to another
Brachialis
flexes forearm

17. How Skeletal Muscles Produce Movement
origin
Origin: the attachment of the muscle to the bone that remains stationary
Insertion: the attachment of the muscle to the bone that moves
Belly: the fleshy part of the muscle between the tendons of origin and/or insertion
belly
insertion

18. Naming Skeletal Muscles
Location of the muscle
Shape of the muscle
Relative Size of the muscle
Direction/Orientation of the muscle fibers/cells
Number of Origins
Location of the Attachments
Action of the muscle

19. Muscles Named by Location
Epicranius (around cranium)
Tibialis anterior (front of tibia)
tibialis anterior

20. Naming Skeletal Muscles
Trapezius
Shape:
deltoid (triangle)
trapezius (trapezoid, 2 parallel sides)
serratus (saw-toothed)
rhomboideus (rhomboid, 4 parallel sides)
orbicularis and sphincters (circular)
Deltoid
Rhomboideus
major
Serratus anterior

21. Muscles Named by Size Psoas minor maximus (largest) minimis (smallest)
longus (longest)
brevis (short)
major (large)
minor (small)
Psoas major

22. Muscles Named by Direction of Fibers
Rectus (straight)-parallel to long axis
Transverse
Oblique
Rectus
abdominis
External oblique

23. Muscles Named for Number of Origins
Biceps (2)
Triceps (3)
Quadriceps (4)
Biceps brachii

24. Muscles Named for Origin and Insertion
Sternocleidomastoid originates from sternum and clavicle and inserts on mastoid process of temporal bone
insertion
origins

25. Muscles Named for Action
Flexor carpi radialis (extensor carpi radialis) –flexes wrist
Abductor pollicis brevis (adductor pollicis) –flexes thumb
Abductor magnus – abducts thigh
Extensor digitorum – extends fingers
Adductor
magnus

26. Movements
Range of motion: depends on length of muscle fibers (fascicles); long fibers = large range of motion
parallel and fusiform muscles
Power: depends on total number of muscle fibers; many fibers = great power
convergent, pennate, bipennate, multipennate

27. Lever Systems and Leverage
Lever: i.e. bones, a rigid rod that moves on some fixed point
Fulcrum: i.e. joint, a fixed point
Resistance:
the force that opposes movement
the load or object (bone or tissue) to be moved
Effort:
the force exerted to achieve a movement
the effort is provided by muscle(s)
Motion is produced when the effort exceeds the resistance (isotonic contraction)

28. Lever Systems and Leverage
Leverage: the mechanical advantage gained by a lever
Power: muscle tension (effort) farther from joint (fulcrum) produces stronger contraction (opposes greater resistance)
Range of motion (ROM): muscle tension (effort) closer to joint (fulcrum) produces greater range of motion.

29. Mechanical Advantage Load is near fulcrum, effort is far away
Only a small effort is required to move an object
Allows a heavy object to be moved with a small effort
Example: car jack

30. Mechanical Disadvantage
Load is far from the fulcrum, effort is near the fulcrum
a large effort is required to move the object
allows object to be moved rapidly, a “speed lever”
throwing a baseball

31. Lever Systems and Leverage
First-class lever: (EFR) Effort-Fulcrum-Resistance

32. Leverage Systems and Leverage
Second class lever: (FRE) Fulcrum-Resistance-Effort

33. Leverage Systems and Leverage
Third-class lever: (FER) Fulcrum-Effort-Resistance

34. Skeletal Muscles

35. Web sites Interactive muscular system: 5-8th grade muscle activity:
5-8th grade muscle activity: