Muscular System

Goals

Content: Students will refresh over the muscular system as well as learn how

muscles get their names (nomenclature). The students will be able to categorize the various muscles of the human body based

on their nomenclature.

Language: Students will learn and utilize correct anatomical vocabulary to describe and label the different muscle types of the

human body.

Muscle Functions

• Movement

• Protection

• Posture and Support

• Heat

Muscle

• Over 600 muscles

• 40 – 50 % of total body weight

• 215 pairs of muscles

– Aggregate muscle action

Muscle Nomenclature

• Appearance

• Location

• Function

• Shape

– Deltoid

– rhomboid

Muscle Nomenclature

• Size

– Gluteus Maximus

– Teres Minor

Muscle Nomenclature

• Number of Divisions

– Biceps Brachii

Muscle Nomenclature

• Direction of fibers

– External Oblique

Muscle Nomenclature

• Location

– Rectus femoris

– Palmaris longus

Muscle Nomenclature

• Points of Attachement

– Coracobrachialis

– Flexor Digitorum Longus

Muscle Nomenclature

Action

– Erector spinae

Muscle Nomenclature

Action and Shape

Pronator quadratus

Action and Size

Adductor magnus

Shape and Location

Serratus anterior

Muscle Nomenclature

Location and Attachment

Brachioradioalis

Location and Number of Divisions

Biceps femoris

Muscle Nomenclature

Groups of muscles

Shape

hamstrings

Number of Divisions

quadriceps

triceps

Muscle Nomenclature

Groups of muscles

Location

peroneals

abdominal

shoulder girdle

Action

hip flexors

rotator cuff

Muscle Nomenclature

Myofilaments

• Actin – thin proteins

• Myosin – thick proteins

Myofilaments

Sarcomere

Contractile unit of a muscle fiber

What fiber joins muscles to bones?

Tendons

Muscle-tendon Functions

• Flexibility

• Strength

• Muscular power

• Muscular endurance

Joints ROM

Maximum force on a unit

Rate of muscular force applied

to move a load

Ability of a muscle to exert a

force repeatedly or constantly

Muscle fatigue, soreness, pain – build-up of lactic acid in the muscles

Structural Damage in Muscle Fibers

• The vertical lines are the “z -lines” that define the boundaries of the muscle sarcomere

• Microscopic damage can lead to disruption of the z-lines and contribute to soreness

• The amount of weight lifted relative to the person's body weight

• Measured as a ratio:

Relative Strength = weight lifted (lb.) body weight (lb.)

Relative Strength

Fibers and Shape

• Determine a muscle’s ability to exert force

– Cross section diameter

• Greater = greater

• Determine range through which it can exert force onto the bone it is attached

– Ability to shorten

• Longer muscles shorten through a greater range = more effective moving joints through large ranges of motion

Classification by Fiber Arrangement

• Parallel

run longitudinally or somewhat parallel with the muscle’s long axis

• Pennate

(feather-like) tendons run down the muscle’s long axis, and fibers run obliquely to the tendon

Parallel Structures

• Fibers are longer

• Run parallel to the length of the muscle

• Pull bones through a greater ROM

Parallel Structures• Flat

– Thin and broad

• Rectus abdominus

• External oblique

• Fusiform

– Spindle shaped with a central belly that tapers to tendons on the ends

• Brachialis

• Brachioradialis

• Strap

– More uniform

• Sartorius

Parallel Structures• Radiate (triangular or fan-shaped)

– Combo of flat and fusiform

• Pectoralis major

• Trapezius

• Sphincter (circular)

– Endless strap around openings

• Orbicularis oris

• Orbicularis oculi

Pennate Structures

• Shorter fibers run oblique to tendons

• Greater cross section = greater force

• Most muscles in the body

• To provide more force than fusiform, but less ROM

Example: sit-ups

Pennate Structures

• Types

– Unipennate . . . Biceps femoris

– Bipennate . . . Rectus femoris

– Multipennate . . . Deltoid

Class Activity

• Scavenge the room.

• Find something that would be considered fusiform.

• Find something that would be considered pennate

• Classify the following items as:

fusiform

unipennate

bipennate

multipennate

Class Activity

Skeletal Muscle Tissue Properties

• Irritability or Excitability

• Conductivity

• Contractility

• Distensibility or Extensibility

• Elasticity

responds to nervous stimuli

wave of excitement

pulling ends together

stretched

recoil from a stretch

Reciprocal Inhibition or Innervation

• Agonists

muscles that cause or help cause motion

• Antagonists

perform opposite to the movement being

done

Example: hip flexors & hip extensors

• Synergistic Muscles – same function, work together

PresentationsYou may utilize the following website or any others you find

useful (do not use Wikipedia) to chose a muscle.

http://www.ptcentral.com/muscles/index.html

For the muscle use the internet or other resources to find

the following:

1. State the anatomical and if pertinent the “everyday”

name of the muscle.

2. Identify the muscle’s prime movement if possible

(ex. It is the agonist of flexing the upper arm)

3. State the muscle(s) that is(are) the antagonist(s) for the

muscle’s prime movement.

4. State if there are any synergists acting in conjunction

with the muscle for this action.

Presentations

5. State the muscle fiber arrangement type ( Ex. fusiform,

unipennate, bipennate, or multipennate)

6. State how the muscle received its name or classification.

7. Give an example of a movement that has this muscle

utilizing an isometric contraction.

8. Give an example a movement that has this muscle

utilizing both isotonic contractions (eccentric and

concentric).

9. Make a hypothesis regarding the fiber type this muscle

would most likely have. Also give logical reasoning as to

why you believe this to be so.

10.State a possible “lab” that you could perform to test your

hypothesis in #9.

11. Construct or draw (paint) a figure showing the muscle fiber arrangement as well as it correct anatomical position.

12. Provide a table that distinguishes the 5 muscle properties for the muscle by a picture-graph. You may forego the table and create a slide for each property and picture-graph if desired.

( Ex. )

13. Find or create a video showing the muscle at work (contracting/extending)

contractibility