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)

Anatomy of the Muscular System Muscles of the Head and Neck Anatomy of the Muscular System Figure 7-12(a)

Anatomy of the Muscular System 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)

Anatomy of the Muscular System Muscles of the Shoulder Anatomy of the Muscular System Figure 7-17(a)

Anatomy of the Muscular System Muscles of the Shoulder Anatomy of the Muscular System Figure 7-17(b)

Anatomy of the Muscular System Muscles that Move the Arm Anatomy of the Muscular System Figure 7-18(a)

Anatomy of the Muscular System Muscles that Move the Arm Anatomy of the Muscular System Figure 7-18(b)

Anatomy of the Muscular System Muscles That Move the Forearm and Wrist Anatomy of the Muscular System Figure 7-19

Anatomy of the Muscular System Muscles That Move the Thigh Anatomy of the Muscular System Figure 7-20(a)

Anatomy of the Muscular System Muscles That Move the Thigh Anatomy of the Muscular System Figure 7-20(b)

Anatomy of the Muscular System Muscles That Move the Leg Anatomy of the Muscular System Figure 7-21

Anatomy of the Muscular System 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)