#Class 4 - The Muscular System

Jan 15, 2025

Objectives

• Mention the three types and the four key functions of muscle tissues

• Describe the structure and functions of the skeletal muscle tissue

• Describe the organization of skeletal muscle and its connective tissue

coverings

• Describe the muscle attachment sites: origin and insertion

• Define the lever and fulcrum and compare the three types of levers

• Identify the types of fascicle arrangements of muscles

• Describe the coordination among muscles for functioning

• Name the skeletal muscles by their features

• TD Chapter 10, 11

3 Types of Muscle Tissue

Skeletal Muscle

Cardiac muscle tissue

Smooth Muscle

Functions of Muscles

  • Producing Body Movements

  • Stabilizing body positions

  • Storing & moving substances within the body

  • Generating heat, thermogenesis

Anatomy of the Skeletal Muscles

Each muscle cell is covered by connective tissue called endomysium

  • The muscle cells are arranged in small bundle (fasicles) covered by connective tissue around the bundles called the perimysium

  • The entire muscle is then encased in a thick layer of connective tissue known as the epimysium.

  • Perimysium covering the fascicle

3 Layers (Outside to Inside)

  1. Epimysium - Around entire muscle

  2. Perimysium - Around fascicles (bundles)

  3. Endomysium - Around individual muscle fibers

Mnemonic

"EPI-PERI-ENDO = Entire-Part-Individual

  • EPImysium = Entire muscle

  • PERImysium = Part of muscle (fascicles/bundles)

  • ENDOmysium = Individual fibers

Tendons: Tendons are extensions of the three coverings attaching the muscle to the periosteum of the bone

youtube: anatoli

3 Types of levers: EFL, FLE, FEL

Mnemonic “123 FRE”

Fulcrom

Resistance

Effort

1st class - Fulcrom in middle = mechanical advantage / mechanical disadvantage

2nd class - Resistance in middle, fulcrom on one end, effort on other = mechanical advantage

3 class - Effort in middle, fulcrom on me end, resistance on the other = mechanical disadvantage

Effects of Fascicle Arrangement

The muscle fascicles, muscle fibers are all arranged parallel to each other

The 5 pattern with respect to tendons:

  1. Parallel

  2. Fusiform (spindle-shaped) - hamstrings, bicep

  3. Circular - esophogal sphincter, eyes

  4. Triangular - pectoralis major

  5. Pennate (feather shaped) - extensor digitorum

Parallel - stretch

Pennate - deltoid

Arrangement of muscles for movement

  1. Agonist - prime mover

  2. Antagonist - stretches / yields to effects of prime mover

  3. Synergist - aids prime mover

  •  Fixator - stabilizes