Chapter 10 The Muscular System

Muscles and Body Movements Muscles are attached to at least two points Origin – attachment to an immoveable bone Insertion – attachment to a movable bone

Effects of Exercise on Muscle Results of increased muscle use Increase in muscle size Increase in muscle strength Increase in muscle efficiency Muscle becomes more fatigue resistant

Types of Ordinary Body Movements Flexion Extension Rotation Abduction Circumduction

Body Movements

Special Movements Dorsifelxion Plantar flexion Inversion Eversion Supination Pronation Opposition

Types of Muscles Prime mover – muscle with the major responsibility for a certain movement Antagonist – muscle that opposes or reverses a prime mover Synergist – muscle that aids a prime mover in a movement and helps prevent rotation Fixator – stabilizes the origin of a prime mover

Naming of Skeletal Muscles Direction of muscle fibers Example: rectus (straight) Relative size of the muscle Example: maximus (largest)

Naming of Skeletal Muscles Location of the muscle Example: many muscles are named for bones (e.g., temporalis) Number of origins Example: triceps (three heads)

Naming of Skeletal Muscles Location of the muscles origin and insertion Example: sterno (on the sternum) Shape of the muscle Example: trapezoid (triangular) Action of the muscle Example: flexor and extensor (flexes or extends a bone)

Head and Neck Muscles Orbicularis oculi (25) Zygomaticus (25) Orbicularis oris (25) Mentalis (25) Masseter (25) Temporalis (25) Sternocleidomastoid (26)

Green= sternocleidomastoid Important for muscle in rotation, flexion, and extension of the head.

Deep Trunk and Arm Muscles Plate A: sternocleidomastoid (26), trapezius (31), deltoid (33), latissimus dorsi (33) Plate B; Erector spinae (27) a) iliocstalis (27), b) longissimus (27), c) spinalis (27) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Trunk Muscles Plate a: deltoid(33), pectoralis major (33), biceps (34), brachialis (34), brachioradialis (34) Plate b: rectus abdominis (28), transversus abd. (28), internal oblique (28), external obl. (28) Slide 6.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Iliopsoas: Psoas major Iliacus Play a role in hip joint flexion and balancing the torso during sitting.

Deep Trunk and Arm Muscles Plate A: sternocleidomastoid (26), trapezius (31), deltoid (33), latissimus dorsi (33) Plate B; Erector spinae (27) a) iliocstalis (27), b) longissimus (27), c) spinalis (27) Slide 6.40 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscles of the Pelvis, Hip, and Thigh Iliopsoas (41) a) iliacus b) psoas major Sartorius (41) Quadriceps femoris (41) a) rectus femoris b) vastus lateralis c) vastus medialis d) vastus intermedius located under rect. Fem. Adductor Group (40) a) adductor magnus b) adductor longus c) adductor brevis

Muscles of the Lower Leg Plate B: Gastrocnemius (43) Soleus (43) Slide 6.42

Superficial Muscles: Anterior Orbicularis oris vastus medialis Pectoralis major tibialis anterior External oblique tensor fascia lata Sternocleidomastoid rectus abdominus Biceps brachii Deltoid transversus abdominus Vastus lateralis Frontalis Rectus femoris Sartorius Gracilis Adductor group Peroneus longus Temporalis Orbicularis oculi Zygomaticus Masseter Slide 6.43

Superficial Muscles: Posterior Gluteus maximus Gluteus medius Gluteus minimus (under maximus) Adductor muscles Gastrocnemius Soleus Latissimus dorsi Deltoid Semitendinosus semimembranosus Trapezius Biceps femoris Triceps brachii External oblique Slide 6.44