1. Introduction to the Muscular System

2. Organization of Skeletal Muscle Fibers
fascicles
fibers
fibers of a single fascicle always parallel
fascicles of a muscle can be arranged in various ways
Tendon – mostly made of collagen fibers

3. Muscles are classified by how the fascicles are organized
Parallel (e.g., biceps brachii muscle)
most common arrangement
Convergent (e.g.,pectoralis muscle)
fascicles fan or triangle shaped, converge to attach

4. Muscles are classified by how the fascicles are organized
Pennate (unipennate, bipennate and multipennate)
fasicles form angle toward tendon
Circular (e.g.,orbicularis oris)
sphincter, contracts to reduce diameter of opening

5. Classification of Muscle
Skeletal-
found in limbs
Cardiac-
found in heart
Smooth-
Found in viscera
Striated, multi- nucleated
Striated, 1 nucleus
Not striated, 1 nucleus
voluntary
involuntary

6. Origins and Insertions
The ends of skeletal muscles are always attached to other structures
fixed end is called ORIGIN
usually attached to bone or cartilage
movable end is called INSERTION
usually attached to the bone it moves

7. How are muscles named? location in the body Origin and Insertion
e.g., temporalis muscle
Origin and Insertion
first part = origin, 2nd part = insertion
Fascicle Organization
e.g., Rectus means “straight”
e.g., transverse means “across”
e.g., oblique means “oblique angle”

8. How are muscles named? Relative Position
e.g., superficialis, internus, lateralis, etc…
Structural Characteristics (shape and size)
e.g., deltoid, rhomboid, major, longus, etc…
Action
e.g., abductor, extensor, rotator, etc…

9. Characteristics of Muscle
Skeletal and smooth muscle are elongated
Muscle cell = muscle fiber
Contraction of a muscle is due to movement of microfilaments (protein fibers)
All muscles share some terminology
Prefixes myo and mys refer to muscle
Prefix sarco refers to flesh

10. Muscular Actions Agonists (prime mover) Antagonist Synergists Fixators
responsible for a particular movement
Antagonist
against movement of agonist
Synergists
aid agonists, stabilize an action
Fixators
specialized synergists
immobilize the origin of agonist so all tension is exerted at the insertion point