Presentation file about biomechanics.ppt

Mr. Jason S. Martinez
Mr. Jason S. Martinez – NIS Almaty
Biomechanics
ANIMAL MOVEMENT

Learning Objective
 Explain the biomechanics of animal movement

Vocabulary
 Myofibril
 Myosin
 Actin
 Fascicle
 Sarcomere
 Synarthrosis
 Amphiarthrosis
 Biomechanics
 Locomotion
 Kinesiology
 Anatomy
 Flexion
 Extension
 Adduction
 Abduction

Biomechanics

Kinesiology
 Kinesiology is the study of human
movement.
 Biomechanics is one of the many
academic sub disciplines of
kinesiology.

What is Biomechanics?
 Biomechanics - the study of the movement of living things
using the science of mechanics
 Biomechanics in kinesiology involves the precise
description of human movement and the study of the
causes of human movement.

Branches of Biomechanics
 The major branches of mechanics used in most
biomechanical studies.
 Fluid mechanics - mechanics of fluids
 Rigid body mechanics – solid bodies
 Static – objects at rest
 Dynamics – moving objects
 Kinematics
 Kinetics

Anatomy and Biomechanics
 Anatomy - the study of the structure of the human body.
 The study of biomechanics requires an understanding of the structure of
musculoskeletal systems and their mechanical properties
 Anatomy provides essential labels for musculoskeletal structures and joint motions
relevant to human movement.

Muscles & Bone
Movement

Ligaments
 Attaches bone to bone

Tendons
 Attach muscles to bones

Cartilage
Cartilage
 Is a type of connective tissue that bends
easily
 Most of the skeleton of an embryo is
cartilage
 In adults, it only remains in the joints, the
ears, the nose and at the end of the ribs
 Cushions the joints

Bones
 Organs composed of moist, living tissues
 Pink=fibrous connective, forms new bone after
fractures
 Blue=cartilage, forms cushion-like surface for
joints
 Inside are osteocytes that secrete bone matrix
 Yellow bone marrow is stored fat from blood to
bone
 Red bone marrow produces RBC’s

The Appendicular Skeleton
Pectoral girdle:
 Arm bones
 Wrist and hand bones
 Scapula (shoulder blades)
 Clavicles (collar bones)
Pelvic girdle:
 Pelvis
 Leg bones
 Ankle and foot bones

Made up of
 Cranium (skull)
 Vertebral column (backbone)
 Sternum (breast bone)
 Rib cage
The Axial Skeleton

Joints
 The place where bones meet is called a joint
 Synarthrosis - immovable (i.e.. the skull)
 Amphiarthrosis - moveable

Joints
Moveable joints:
1. Hinge = elbow and knee
2. Ball-and-Socket = shoulder and
hip
3. Pivot = base of the skull
4. Gliding joint = wrists

Muscle Structure Review

Dissecting Muscles
 Muscles consist of bundles of muscle fibers
(cells), oriented parallel to each other
 Cells are bundles of myofibrils, which are
composed of the contractile proteins actin
(thin) and myosin (thick)
 Proteins form a striped banding pattern that
characterizes skeletal muscles
 Contractile unit of skeletal muscle is the
sarcomere

Contracting Filament Model
 Sarcomere contracts when thin
filaments slide over thick
 Sarcomere shortens, but length of
filaments don’t change
 Heads of myosin (thick) filaments
bind ATP so they can bind to actin
(thin) filaments
 Head produces power stroke
which moves the actin toward the
center of the sarcomere when ADP
is released

Muscle Fiber Types
Each muscle has a mix of the above types
Slow fibers better designed for endurance Activities
Fast fiber - Weight lifting

Motion in Vertebrates
 Motion and locomotion are produced by muscles
pulling on bones.
 Joints in the skeleton allow for parts of the body
to flex and extend, allowing for motion.
Ligaments attach bones to bones at the joints.
 Muscles attach to bones by tendons. Origin is on
a bone that remains stationary. Insertion is on a
bone that moves.

Creating Movement
 Muscle action shortens or contracts
muscles
 The agonist moves the muscle while
the antagonist reverses the movement
 Antagonistic pairs of muscles are found
in all animals

Joint Motions
 Anatomy also has specific terminology de-
scribing the major rotations of bones at joints.
“Flexion” refers to a decrease in joint angle in
the sagittal plane, while “extension” is motion
increasing joint angle.
 (a) Flexion and extension movements occur in
a sagittal plane about a mediolateral axis
 (b) adduction/abduction of the hip joint
occurs in a frontal plane about an
anteroposterior axis

Movement
 Flexion - decreases angle of a joint.
 Extension - increases angle of a joint.
 Abduction - movement away from midline.
 Adduction - movement toward midline.
 Rotation - turning around an axis.

Lever Systems
 Muscles and bones work together around joints
as systems of levers.
 Lever systems of muscles and skeletons can be
designed either for power or speed.
 The ratio of load arm (resistance) to power arm
(effort) determines the power.
 A low load arm to power arm ratio provides high
power but low speed
 A high load arm to power arm ratio provides high
speed but lower power.
Power
L:P = 2
Speed
L:P = 5

Bipedalism

Bipedalism
 Upright walking in humans requires a fluid alternation
between stance phase and swing phase activity for each leg.
 Key features are the push-off, using the great toe at the
beginning of the swing phase, and the heel-strike, at the
beginning of the stance phase.

Arm swinging
Erect (bipedal)

Feet
Bipedal walking
resulted in a number of postcranial
changes in the legs and feet . .
.

Legs
 Leg bones are much stouter in most primates and
have more pronounced dorsal ridges

Understanding Physical Anthropology and Archaeology, 8th ed., p. 224
Comparison of muscles that act to extend the hip.

Hinge joint
 A hinge joint allows flexing and extending
along one plane.
 Pairs of muscles work opposite one another
to create motion.

Ball and socket joint
 A ball and socket
arrangement allows
rotational movement.
 Multiple pairs of muscles
allow movement in a range
of directions.

Advantages for Locomotion
 It is easier to get food
 It its easier to find shelter
 An organism can move away from
dangerous conditions or predators
 It is easier to find mates and
reproduce

Why Bipedalism?

Acheulian biface (“hand axe”)
Understanding Physical Anthropology and Archaeology, 9th ed., p. 239

Locomotion in
Vertebrates

Types of Locomotion
• Swimming
▫ Gravity not a problem, but friction is
 Water supports weight, but is dense and presents resistance
▫ Legs as oars, jet-propelled, and undulating side to side or up and down
▫ Streamlined body shapes aids increased speed
• Locomotion on land
▫ Need to be able to support self and overcome gravity
 Air presents little resistance, but also little support
▫ Energy expenditure to propel forward and keep from falling down
 Muscles and skeleton more important that streamline shape

Types of Locomotion (cont.)
• Hopping
▫ Tendons in legs store energy when landing, like a spring for the next jump
 Cost free energy boost
▫ Rest with tail and hind feet on ground
 Costs little energy to maintain
• Walking and running
▫ Overcome friction between foot and ground
▫ Walking: 4 legged – 3 on ground all times; 2 legged – part of 1 at all times
▫ Running: 4 legged – 2 -3 feet move at once if not all
▫ Momentum stabilizes body position

Types of Locomotion (cont.)
 Crawling
 Friction adds considerable resistance because of increased contact
 Undulate body side to side, inch forward, or peristalsis
 Flying
 Wings developed to completely overcome gravity
 Shape must alter air current to create lift
 Air pressure underneath is greater
 All based on mircotubule or microfilament systems. Animals in motion

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