Skeletal Muscle Actions Skeletal muscles generate a great

Antagonistic Pairs • Muscles work in antagonistic pairs. • This means that they oppose

Antagonistic Pairs • Muscles cannot push on a joint; they can only pull a

The Origin • The origin of any muscle is the bone to which a

The Insertion • The insertion of a muscle is the bone to which a

Origin and Insertion Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction

Interaction of Skeletal Muscles • Prime mover (agonist) – primarily responsible for movement •

Lifespan Changes • Myoglobin, ATP, and creatine phosphate decline • By age 80, half

Muscles of Facial Expression and Mastication Copyright © The Mc. Graw-Hill Companies, Inc. Permission

Muscles That Move the Head and Vertebral Column Copyright © The Mc. Graw-Hill Companies,

Muscles That Move the Pectoral Girdle Copyright © The Mc. Graw-Hill Companies, Inc. Permission

Major Skeletal Muscles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction

Muscles That Move the Arm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles That Move the Forearm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Cross Section of the Forearm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles That Move the Hand Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles of the Abdominal Wall Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles of Pelvic Outlet Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for

Muscles That Move the Thigh Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles That Move the Leg Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

Muscles That Move the Foot Copyright © The Mc. Graw-Hill Companies, Inc. Permission required

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Skeletal Muscle Actions • Skeletal muscles generate a great variety of body movements. • The action of each muscle mostly depends upon the kind of joint it is associated with and the way the muscle is attached on either side of that joint. 1

Antagonistic Pairs • Muscles work in antagonistic pairs. • This means that they oppose each other in their action upon bones of the skeleton. • Since all muscles move across at least one joint, antagonistic pairs move joints in opposite directions.

Antagonistic Pairs • Muscles cannot push on a joint; they can only pull a joint in one direction. • For example, the biceps can flex the elbow joint, but is unable to extend it. The extensor of the elbow is the triceps. Therefore, they oppose each other as antagonistic pairs.

The Origin • The origin of any muscle is the bone to which a muscle is attached that remains stationary or does NOT move. • For example, the muscle which moves your jawbone as you chew ( the masseter) has its origin on the cheekbone (the zygomatic).

The Insertion • The insertion of a muscle is the bone to which a muscle is attached that moves. • While the origin of the masseter is the zygomatic, the insertion is on the jawbone itself, the mandible. • During contraction, the muscle insertion moves toward the origin.

Origin and Insertion Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Coracoid process • Origin – immovable end • Insertion – movable end Origins of biceps brachii Tendon of long head Tendon of short head When a muscle contracts, its insertion is pulled toward its origin Biceps brachii Radius Insertion of biceps brachii 6

Interaction of Skeletal Muscles • Prime mover (agonist) – primarily responsible for movement • Synergists – assist prime mover • Antagonist – resist prime mover’s action and cause movement in the opposite direction of the prime mover 7

Lifespan Changes • Myoglobin, ATP, and creatine phosphate decline • By age 80, half of muscle mass has atrophied • Adipose cells and connective tissues replace muscle tissue • Exercise helps to maintain muscle mass and function 8

Muscles of Facial Expression and Mastication Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Epicranial aponeurosis Frontalis Epicranius Occipitalis Temporalis Orbicularis oculi Zygomaticus major Zygomaticus minor Masseter Buccinator Sternocleidomastoid Orbicularis oris Platysma (a) Temporalis Lateral pterygoid Medial pterygoid Buccinator 9 (b) (c)

Muscles That Move the Head and Vertebral Column Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Splenius capitis (cut) Longissimus capitis Semispinalis capitis (cut) Semispinalis capitis Splenius capitis Spinalis cervicis Longissimus cervicis Iliocostalis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis lumborum Quadratus lumborum 13

Muscles That Move the Pectoral Girdle Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Levator scapulae Supraspinatus Infraspinatus Teres minor Teres major Rhomboid minor Rhomboid major Trapezius Deltoid Latissimus dorsi (a) Rhomboid minor Trapezius Rhomboid major Deltoid Latissimus dorsi (b) (c) (d) 15

Major Skeletal Muscles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Trapezius Serratus anterior External oblique Frontalis Orbicularis oculi Zygomaticus Masseter Orbicularis oris Sternocleidomastoid Deltoid Pectoralis major Biceps brachii Brachialis Brachioradialis Rectus abdominis Tensor fasciae latae Sartorius Rectus femoris Adductor longus Gracilis Vastus medialis Vastus lateralis Fibularis longus Tibialis anterior Gastrocnemius Soleus Extensor digitorum longus 18

Major Skeletal Muscles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Temporalis Occipitalis Sternocleidomastoid Trapezius Deltoid Teres minor Infraspinatus Teres major Brachialis Triceps brachii Rhomboid Latissimus dorsi External oblique Gluteus medius Gluteus maximus Adductor magnus Biceps femoris Semitendinosus Semimembranosus Gracilis Vastus lateralis Sartorius Gastrocnemius Calcaneal tendon Fibularis longus Soleus 19

Muscles That Move the Arm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Sternocleidomastoid Pectoralis minor Internal intercostal External intercostal Trapezius Deltoid Pectoralis major Serratus anterior Rectus abdominis Linea alba (band of connective tissue) Internal oblique External oblique Transversus abdominis Aponeurosis of external oblique 20

Muscles That Move the Arm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Levator scapulae Supraspinatus Spine of scapula Deltoid Infraspinatus Teres minor Teres major Long head of triceps brachii Lateral head of triceps brachii (a) Levator scapulae Supraspinatus Infraspinatus Teres minor Teres major Triceps brachii (b) (c) (d) 21

Muscles That Move the Forearm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Trapezius Clavicle Subscapularis Deltoid Coracobrachialis Medial border of scapula Short head of biceps brachii Long head of biceps brachii Brachialis (a) Subscapularis Coracobrachialis Biceps brachii (short and long heads) (b) (c) Brachialis (d) 22

Muscles That Move the Forearm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Biceps brachii Brachialis Supinator Pronator teres Brachioradialis Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Extensor carpi radialis longus Flexor carpi ulnaris Flexor digitorum superficialis Pronator quadratus Flexor retinaculum (a) (b) Pronator teres Flexor digitorum superficialis Flexor carpi radialis Pronator quadratus 23 (c) (d) (e)

Cross Section of the Forearm Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Abductor pollicis longus m. Extensor digitorum m. Flexor pollicis longus m. Extensor carpi ulnaris m. Radius Extensor pollicis longus m. Extensor carpi radialis brevis m. Ulna Extensor carpi radialis longus m. Plane of section Flexor digitorum profundus m. Pronator teres m. Ulnar n. Brachioradialis m. Ulnar a. Radial n. Flexor carpi ulnaris m. Radial a. Median n. Flexor carpi radialis m. Flexor digitorum superficialis m. Anterior Palmaris longus m. 24

Muscles That Move the Hand Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Triceps brachii Brachioradialis Extensor carpi radialis longus Flexor carpi ulnaris Extensor carpi radialis brevis Extensor carpi ulnaris Extensor digitorum Extensor carpi radialis longusand brevis Extensor retinaculum Extensor carpi ulnaris Extensor digitorum (a) (b) (c) 25

Muscles of the Abdominal Wall Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Rectus abdominis External oblique Internal oblique Transversus abdominis Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Peritoneum Linea alba (a) Internal oblique External oblique Skin (e) Transversus abdominis Rectus abdominis External oblique Internal oblique (b) (c) Transversus abdominis (d) 26

Muscles of Pelvic Outlet Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Scrotum Penis Ischiocavernosus Bulbospongiosus Anus (a) Coccygeus Levator ani Urogenital diaphragm (c) Superficial transversus perinei Levator ani Gluteus maximus External anal sphincter (b) Clitoris Urethral orifice Vaginal orifice Anus Coccyx Rectum Vagina Urethra Symphysis pubis 27

Muscles That Move the Thigh Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Psoas major Psoas minor Iliacus Tensor fasciae latae Sartorius Rectus femoris Vastus lateralis Quadriceps femoris tendon (patellar tendon) Patellar ligament Pectineus Adductor longus Adductor magnus Sartorius Vastus intermedius Gracilis Vastus medialis (a) (b) Adductor brevis Gracilis Adductor longus Adductor magnus (e) (d) (c) Psoas major Psoas minor Iliacus (f) (g) 28

Muscles That Move the Thigh Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Gluteus medius Tensor fasciae latae Gluteus maximus Sartorius Rectus femoris Vastus lateralis Biceps femoris Iliotibial tract (band) (a) Gluteus medius Gluteus maximus (b) (c) Gluteus minimus Piriformis (d) 29

Muscles That Move the Leg Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Gluteus medius Gluteus maximus Adductor magnus Vastus lateralis covered by fascia Gracilis Biceps femoris Semitendinosus Semimembranosus Sartorius Gastrocnemius Semitendinosus (a) Semimembranosus Biceps femoris (short head) (b) Biceps femoris (long head) (c) 30

Muscles That Move the Leg Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Lateral Medial Semitendinosus m. Semimembranosus m. Long head of biceps femoris m. Gracilis m. Adductor magnus m. Short head of biceps femoris m. Plane of section Sciatic n. Adductor longus m. Great saphenousv. Femoralv. and a. Sartorius m. Vastus medialis m. Shaft of femur Vastus lateralis m. Vastus intermedius m. Adipose tissue Rectus femoris m. Skin Anterior 31

Muscles That Move the Leg Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Plantaris Iliotibial tract (band) Semitendinosus Soleus Biceps femoris Semimembranosus Gracilis Sartorius Gastrocnemius: Medial head Lateral head Fibularis longus (b) (c) Soleus Calcaneal tendon Fibularis brevis Flexor digitorum longus Tibialis posterior Flexor retinaculum Calcaneus (a) Flexor digitorum longus Fibular retinacula 32 (d) (e)

Muscles That Move the Foot Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Patellar ligament Tibialis anterior Gastrocnemius Fibularis longus Extensor digitorum longus Soleus Fibularis brevis Tibia Extensor retinacula (a) Tibialis anterior Fibularis tertius (b) Extensor digitorum longus Extensor hallucis longus (c) (d) 33

Muscles That Move the Foot Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Biceps femoris Vastus lateralis Gastrocnemius Head of fibula Fibularis longus Soleus Tibialis anterior Extensor digitorum longus Calcaneal tendon Fibularis brevis Fibularis tertius Extensor retinacula Fibular retinacula (a) Fibularis longus Fibularis brevis 34 (b) (c)