ANATOMY OF THE MUSCULAR
SYSTEM
Anatomy of the Muscular System
•Origin
Muscle attachment that remains
fixed
•Insertion
Muscle attachment that moves
•Action
What joint movement a muscle
produces
i.e. flexion, extension, abduction,
etc.
Organization of Muscle Fibers
 Four patterns of fascicle organization:
 (1) Parallel muscle
 (2) Convergent muscle
 (3) Pennate muscle
 (4) Circular muscle
Parallel Muscle
 Muscle fibers arranged parallel to the
long axis of the muscle
 EX: most of the skeletal muscles, like
biceps
 When parallel muscle contracts, it gets
shorter in length and larger in diameter
Convergent Muscle
 The muscle fibers are spread over a
broad area, but all the fascicles
converge at one common
attachment site
 Muscle fibers spread out like a fan
or broad triangle
 EX: pectoralis muscles
Pennate Muscle
 Fascicles form a common angle with the
tendon, and contain more muscle fibers
than parallel muscles, so more tension is
produced during contraction
 EX: unipennate – all fibers on the same
side of the tendon: extensor digitorum
 Bipennate – fibers on both sides of the
tendon: rectus femoris
Circular Muscle
 Fibers are concentrically arranged
around an opening or a recess
 When the muscle contracts, the
diameter of the opening closes
 EX: orbicularis oculis
• For muscles to create a movement,
they can only pull, not push
• Muscles in the body rarely work alone,
& are usually arranged in groups
surrounding a joint
• A muscle that contracts to create the
desired action is known as an agonist or
prime mover (EX: biceps contracts)
• A muscle that helps the agonist is a
synergist
• A muscle that opposes the action of the
agonist, therefore undoing the desired
action is an antagonist (EX: triceps
extends the elbow)
How Muscles are Named…
 1. Orientation of muscle fibers
 2. Location
 3. Relative Position
 4. Structure, Shape, and Size
 5. Origin and Insertion
 6. Action
How Muscles are Named…
 1. Orientation of fibers
 Rectus = straight
 Transversus = fibers run across the long axis of the body
 Oblique = fibers run at an oblique angle to the long axis
How Muscles are Named…
 2. Location
 Muscles are named for their location or body region
 EX: temporalis, frontalis, femoris
How Muscles are Named…
 3. Relative Position
 Muscles visible at the surface of the body are called externus
or superficialis
 Deeper muscles are called internus or profundis
How Muscles are Named…
 4. Structure, Shape, and Size
 Some muscles named for the number of tendons of origin
(EX: biceps or triceps brachii)
 Shape: deltoid, rhomboid
 Long muscles called longus (long) or longissimus (longest)
 Short muscles called brevis
How Muscles are Named…
 5. Origin and Insertion
 First name will indicate origin, second name the insertion
 EX: genioglossus muscle
 Origin = chin (genio)
 Insertion = tongue (glossus
How Muscles are Named…
 6. Action
 Some muscles are named for the action they produce when
contracted.
 EX: extensor, flexor, retractor, abductor, adductor, levator,
pronator, etc
How Muscles are Named: Action
 Flexion = decreasing the angle between 2 bones (dorsiflexion




= decrease angle between foot and the shin; plantar flexion =
pointing toes
Extension = increasing the angle between 2 bones
Abduction = moving a body part away from the midline
Adduction = moving a body part toward the midline
Circumduction = movement in a circular motion
How Muscles are Named: Action
 Rotation = turning movement of a bone around its long axis
 Supination = thumbs up
 Pronation = thumbs down
 Inversion = turning sole of foot in
 Eversion = turning sole of foot out
 Elevation = lifting a body part
 Depression = returning body part to its pre-elevated position
An Overview of the
Major Skeletal
Muscles
Figure 7-11(a)
An Overview of the
Major Skeletal Muscles
Figure 7-11(b)
 Muscles of the Head and Neck
Anatomy of the Muscular System
Figure 7-12(a)
 Muscles of the Head and Neck
Anatomy of the Muscular System
Figure 7-12(c)
Anatomy of the Muscular System
Muscles of the
Spine
Figure 7-14
Anatomy of the Muscular System
Oblique and Rectus Muscles
and the Diaphragm
Figure 7-15(a)
 Muscles of the Shoulder
Anatomy of the Muscular System
Figure 7-17(a)
 Muscles of the Shoulder
Anatomy of the Muscular System
Figure 7-17(b)
 Muscles that Move the Arm
Anatomy of the Muscular System
Figure 7-18(a)
 Muscles that Move the Arm
Anatomy of the Muscular System
Figure 7-18(b)
 Muscles That Move the Forearm and Wrist
Anatomy of the Muscular System
Figure 7-19
 Muscles That Move the Thigh
Anatomy of the Muscular System
Figure 7-20(a)
Muscles That Move the Thigh
Anatomy of the
Muscular System
Figure 7-20(b)
 Muscles That Move the Leg
Anatomy of the Muscular System
Figure 7-21
 Muscles That Move the Foot and Toes
Anatomy of the Muscular System
Figure 7-22(a)
Anatomy of the Muscular System
Muscles That Move the
Foot and Toes
Figure 7-22(b)
Anatomy of the Muscular System
Muscles That Move the Foot
and Toes
Figure 7-22(c)
Anatomy of the Muscular System
Muscles That Move the
Foot and Toes
Figure 7-22(d)