a&p the muscular system physiology, naming, & physics chapter 6
TRANSCRIPT
![Page 1: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/1.jpg)
A&P The Muscular System Physiology, Naming, & Physics
Chapter 6
![Page 2: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/2.jpg)
The Muscular System
Interactions of Skeletal Muscles in the Body
• Skeletal Muscles usually work in groups, i.e. perform “group actions”
• Muscles are usually arranged in antagonistic pairs – flexor-extensor– abductor-adductor, etc.
![Page 3: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/3.jpg)
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
Brachialisflexes forearm
![Page 4: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/4.jpg)
How Skeletal Muscles Produce Movement
• Origin: the attachment of the muscle to the bone that remains stationary
• Insertion: the attachment of the muscle to the bone that moves
• Belly/Body: the fleshy part of the muscle between the tendons of origin and/or insertion
origin
insertion
body
![Page 5: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/5.jpg)
Interactions of Skeletal Muscles in the Body
• Prime Mover (agonist): the principle muscle that causes a movement – ex: biceps brachii,
flexion of forearm
• Antagonist: the principle muscle that causes the opposite movement– ex: triceps brachii,
extension of forearm
![Page 6: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/6.jpg)
Antagonists of the Forearm
![Page 7: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/7.jpg)
Antagonists of the Thigh
![Page 8: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/8.jpg)
Antagonists of the Foot
![Page 9: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/9.jpg)
Interactions of Skeletal Muscles in the Body
• Synergists: muscles that assist the prime mover – ex: extensor carpi (wrist) muscles are synergists for
the flexor digitorum muscles when you clench your fist
• Fixators: synergists that stabilize the origin of a prime over – ex: several back muscles that stabilize scapula when
the deltoid flexes the arm
![Page 10: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/10.jpg)
Functional Roles of Skeletal Muscles
• Group Actions: most movements need several muscles working together
While the prime movers (agonist and synergists) are contracting to provide the desired movement
• other muscles (antagonists) are relaxing & being stretched out passively
• agonist and antagonist change roles depending on the action• e.g., abduction versus adduction
• Synergists and Fixators become Agonists and Antagonists in different movements
![Page 11: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/11.jpg)
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
![Page 12: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/12.jpg)
Muscles Named by Location
• Epicranius (around cranium)
• Tibialis anterior (front of tibia)
tibialis anterior
![Page 13: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/13.jpg)
Naming Skeletal Muscles• Shape:
– deltoid (triangle)
– trapezius (trapezoid)
– serratus (saw-toothed)
– rhomboideus (rhomboid)
– orbicularis and sphincters (circular) Rhomboideus
major
![Page 14: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/14.jpg)
Muscles Named by Size
• maximus (largest)• minimis (smallest)• longus (longest)• brevis (short)• major (large)• minor (small)
Psoas major
Psoas minor
![Page 15: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/15.jpg)
Muscles Named by Direction of Fibers
• Rectus (straight)-parallel to long axis
• Transverse
• Oblique
Rectusabdominis
External oblique
![Page 16: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/16.jpg)
• biceps (2)
• triceps (3)
• quadriceps (4)
Muscles Named for Number of Origins
Biceps brachii
![Page 17: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/17.jpg)
Muscles Named for Origin and Insertion
Sternocleidomastoid originates from sternum and clavicle and inserts on mastoid process of temporal bone
origins
insertion
![Page 18: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/18.jpg)
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
Adductormagnus
![Page 19: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/19.jpg)
Arrangement of Fascicles
• Parallel (strap-like), ex: sartorius
• Fusiform (spindle shaped), ex: biceps femoris
![Page 20: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/20.jpg)
Arrangement of Fascicles
• Pennate ("feather shaped"), ex: extensor digitorum longus
• Bipennate, ex: rectus femoris
• Multipennate, ex: deltoid
![Page 21: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/21.jpg)
Arrangement of Fascicles
• Convergent, ex: pectoralis major
• Circular (sphincters), ex: orbicularis oris
![Page 22: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/22.jpg)
Arrangement of Fascicles• 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 = greater power – convergent, pennate,
bipennate, multipennate
![Page 23: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/23.jpg)
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 opposing movement
• Effort: the force exerted to achieve action
![Page 24: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/24.jpg)
Levers• A lever is acted upon at 2 different points by:
1) resistance or load• the force that opposes movement• the load or object (bone or tissue) to be moved
2) 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)
![Page 25: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/25.jpg)
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.
![Page 26: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/26.jpg)
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
![Page 27: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/27.jpg)
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
![Page 28: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/28.jpg)
Lever Systems and Leverage• First-class lever: (EFR) Effort-Fulcrum-Resistance
![Page 29: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/29.jpg)
Leverage Systems and Leverage• Second class lever: (FRE) Fulcrum-Resistance-Effort
![Page 30: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/30.jpg)
Leverage Systems and Leverage• Third-class lever: (FER) Fulcrum-Effort-Resistance
![Page 31: A&P The Muscular System Physiology, Naming, & Physics Chapter 6](https://reader036.vdocuments.us/reader036/viewer/2022062421/56649e3c5503460f94b2e6d3/html5/thumbnails/31.jpg)
Skeletal Muscles
Know the muscles, their origins and insertions.