ANATOMY OF THE MUSCULAR SYSTEM

Anatomy of the Muscular System

•

Origin

•

Insertion

Muscle attachment that remains fixed 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)