The Skeletal Muscular and Levers System Muscular Physics

The Skeletal, Muscular and Levers System Muscular Physics

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

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 3

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 4

Hydrostatic Skeletons Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Longitudinal muscles Anterior Circular muscles Longitudinal muscles contracted Circular muscles contracted Longitudinal muscles contract, and segments catch up Circular muscles contract, and anterior end moves forward 5

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 6

Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Bell Jellyfish propelled upward Contractile fibers Bell pulsates Water expelled from bell Water enters bell a. Water expelled from siphon b. Squid propelled backward 7

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 8

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 9

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 10

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 11

Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Immovable Joint Bone Suture Fibrous connective tissue a. Freely Movable Joint Slightly Movable Joints Fibrous capsule Synovial fluid Fibrous joints Cartilaginous Joints Synovial membrane Articular cartilage c. Body of vertebra Intervertebral disk Articular cartilage 12 b.

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 13

Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Ball-and-Socket a. Gliding Joint Hinge Joint b. c. Combination Joint d. 14

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.

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

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

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

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

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

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

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

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

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

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

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

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)

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.

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

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

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

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

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

Skeletal Muscles

Web sites • Interactive muscular system: http: //www. getbodysmart. com/ap/muscularsystem/menu/men u. html 5 -8 th grade muscle activity: http: //www. whitakercenter. org/Education/Curriculum%20 Guides/Grades%206 -8/6 -8%20 Simple%20 Machines/Building%20 Levers%20 Post. pdf http: //teachhealthk-12. uthscsa. edu/curriculum/levers. asp