1. Arrangement of Fascicles in Muscles
Skeletal muscles – consist of fascicles
Fascicles – arranged in different patterns
Fascicle arrangement – tells about action of a muscle
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

2. Arrangement of Fascicles in Muscles
Types of fascicle arrangement
Parallel – fascicles run parallel to the long axis of the muscle
Strap-like – sternocleidomastoid
Fusiform – biceps brachii
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

3. Arrangement of Fascicles in Muscles
Types of fascicle arrangement
Convergent
Origin of the muscle is broad
Fascicles converge toward the tendon of insertion
Example – pectoralis major
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

4. Arrangement of Fascicles in Muscles
Types of fascicle arrangement
Pennate
Unipennate – fascicles insert into one side of the tendon
Bipennate – fascicles insert into the tendon from both sides
Multipennate – fascicles insert into one large tendon from all sides
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

5. Arrangement of Fascicles in Muscles
Circular
Fascicles are arranged in concentric rings
Surround external body openings
Sphincter – general name for a circular muscle
Examples
Orbicularis oris and orbicularis oculi
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

6. Arrangement of Fascicles in Muscles
Figure 11.3
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

7. Lie anterior and posterior to the body axis Muscles of the
Axial Muscles
Lie anterior and posterior to the body axis
Muscles of the
Thorax, abdomen, and pelvis
Many muscles of the
Neck and some of the head
Function to move the trunk and maintain posture
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

8. Limb muscles arise from lateral parts of nearby myotomes Extensors
Muscle mass dorsal to limb bones
Flexors
Muscle mass ventral to limb bones
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

9. Limb Muscles
Figure 11.4e
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

10. Interactions of Skeletal Muscles in the Body
A muscle cannot reverse the movement it produces
Another muscle must undo the action
Muscles with opposite actions lie on opposite sides of a joint
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

11. Muscles Classified into Several Functional Groups
Prime mover (agonist)
Has major responsibility for a certain movement
Antagonist
Opposes or reverses a movement
Synergist – helps the prime mover
By adding extra force
By reducing undesirable movements
Fixator
A type of synergist that holds a bone firmly in place
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

12. Muscle Compartments of the Limbs
Dense fibrous connective tissue divides limb muscles into compartments
Muscles in opposing compartments are
Agonist and antagonist pairs
Each compartment is innervated by a single nerve
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

13. Naming the Skeletal Muscles
Location
Example – the brachialis is located on the arm
Shape
Example – the deltoid is triangular
Relative size
Maximus, minimus, and longus indicate size
Example – gluteus maximus and gluteus minimus
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

14. Naming the Skeletal Muscles
Direction of fascicles and muscle fibers
Name tells direction in which fibers run
Example – rectus abdominis and transversus abdominis
Location of attachments – name reveals point of origin and insertion
Example – brachioradialis
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

15. Naming the Skeletal Muscles
Number of origins
Two, three, or four origins
Indicated by the words biceps, triceps, and quadriceps
Action
The action is part of the muscle’s name
Indicates type of muscle movement
Flexor, extensor, adductor, or abductor
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings