KNES 455G Chapter 4 Essentials-audio part 1

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Chapter 4 Biomechanics:

Chapter 4 Biomechanics KNES 455G

Musculoskeletal System:

Musculoskeletal System Axial Skeleton Consists of the skull, vertebral column, ribs and sterum Appendicular Skeleton Shoulder Girdle, bones of the arm, wrists and hands Pelvic girdle, bones of the leg, ankle and feet

Joints:

Joints Joints form the junction between bones Fibrous  allow virtually no movement Cartilaginous allow some movement Synovial Joints allow considerable movement Training mainly centers around the synovial joints Articulating bones ends are covered in hyaline cartilage Joint is encapsulated and the capsule is filled with synovial fluid

Joints cont…:

Joints cont… Uniaxial joints: essentially rotate about one axis (elbow) Biaxial joints: allow rotation about two perpendicular axis (wrist and ankle) Multiaxial joints: allow for rotation about all three perpendicular axis (hip and shoulder)

Skeletal Musculature:

Skeletal Musculature Muscle origin: proximal attachment Muscle insertion: distal attachment Muscle Attachment Fleshy attachment (usually proximal att) muscle fiber infuse directly into the bone Fibrous attachment involves a tendon blend into the connective tissue covering of the bone and muscle sheath.

Muscle Anatomy:

Muscle Anatomy Agonist: The muscle most directly involved in bringing about a movement. Synergist: A muscle that assists indirectly in a movement, such as providing a stabilizing function. Antagonist: A muscle that can slow down or stop a movement, assists in joint stabilization and braking action near the end of the range of a motion.

Muscles:

Muscles

Levers of the MC System:

Levers of the MC System Lever: a rigid or semi-rigid body that, when subjected to force (that does not pass through the pivot point) exerts a force on any object impeding its ability to rotate Fulcrum: the pivot point of a lever Moment Arm: The perpendicular distance from the line of action of the force to the fulcrum Torque: The degree to which a force tends to rotate an object about a specific fulcrum.

Levers of the MC System:

Levers of the MC System Muscle force: force generated by biochemical activity, or the stretching of noncontractile tissue, that tends to draw the opposite ends of a muscle together. Resistive force: Force generated by a source external to the body (i.e. gravity) Mechanical advantage: the ratio of the movement arm through which an applied force acts to that through which a resistive force acts. It is the ratio of the product of the applied force and length of the lever to the product of the resistance force and its moment arm.

First Class Lever:

First Class Lever A lever for which the muscle force and the resistive forces act on opposite sides of the fulcrum. (figure on previous slide)

Second Class Lever:

Second Class Lever A lever for which the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting through a longer moment arm. (allows muscle force to be less than resistive force)

Levers:

Levers

Third Class Lever:

Third Class Lever A lever for which the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting through a moment arm shorter than the resistive force. Muscle force higher than resistive force.

Muscle Forces:

Muscle Forces Most muscles in the human body operate at a mechanical advantage less than 1.0 That is the internal muscle force are greater than the forces applied by the body on external objects.

authorStream Live Help