Smooth muscle Contraction

1. Smooth muscle Contraction • Spindle Shaped • Central nuclei • Lack Striations, transverse tubules, and lack well developed sacroplasmic reticulum • Actin and myosin thin and randomly distributed • Multi-unit-Separate units • Muscle of iris and blood vessels • Visceral-Sheets of spindle cells • Respond as a single unit • Rhythmicity- spontaneous • peristalsis

2. Internal organs- • outer longitudinal • Inner circular Contraction Impulses travel across the membrane- Calcium diffuses into the cell from the extracellular fluid. Calcium binds to a protein calmodulin-activating contraction. Nt- Ach and Norepi, stimulates/ inhibits contractions altering degrees of contraction. Smooth- slow and longer contraction

3. Terms • Origin • Insertion • Prime mover-Agonist • Assist a prime mover-Synergists • Antagonist- movement in the opposite direction or resist a prime mover,

4. Skeletal Muscle Actions • origin – immovable end • insertion – movable end • prime mover (agonist) – primarily responsible for movement • synergists – assist prime mover • antagonist – resist prime mover’s action and cause movement in the opposite direction

5. Muscular Tissue Three Types of Muscle Tissues • Cardiac Muscle • wall of heart • not under conscious control • striated • Skeletal Muscle • usually attached to bones • under conscious control • striated • Smooth Muscle • walls of most viscera, blood vessels, skin • not under conscious control • not striated

7. Smooth Muscle Fibers • Compared to skeletal muscle fibers • shorter • single nucleus • elongated with tapering ends • myofilaments randomly organized • no striations • lack transverse tubules • sarcoplasmic reticula not well developed

8. Cardiac Muscle • only in the heart • muscle fibers joined together by intercalated discs • fibers branch • network of fibers contracts as a unit • self-exciting and rhythmic • longer refractory period than skeletal muscle

9. Orbicularis oculi-blinking/closes eyelids Orbicularis oris-closes lips/protrudes lips-kissing Buccinator-compresses cheeks as in blowing air Zygomaticus-raises corner of mouth/smiling Platysma-pouting/draws mouth downward & elevates skin Frontalis-elevates eyebrows & creases skin Muscles of Facial Expression-CNVII

11. Masseter-elevates mandible Temporalis-elevates mandible Pterygoid Medial-elevates and moves it from side to side Lateral-depresses and protracts Muscles of Mastication-CNV3

13. Muscles of Head and Vertebra • Paired muscles- flex, extend, and rotate the head and hold the torso erect. • Sternocleidomastoid-flex and rotates • Extend and rotate • Splenius capitis • Semispinalis capitis • Erector spinae

14. Muscle of the Pectoral Girdle • Trapezius- raises scapula and shoulders, elevates clavicle, extends neck and head • Serratus Anterior -pulls scapula forward and downward, used when pushing something. • Damage to the long thoracic nerve-results in winged scapula • Rhomboids-retracts, elevates, and rotates • Levator Scapula-elevates scapula • Pectoralis minor- pulls scapula in forward and downward, raise ribs in forceful inhalation

18. Muscles That Move the Arm • Flexors • Coracobrachialis • Pectoralis major- also adducts arm • Extensors • Teres Major • Latissimus dorsi- also adducts arm (swimmer muscle) • Abductors • Deltoid – most prominent muscle of the shoulder-axillary nerve-fracture to the neck of humerus-unable to abduct the arm • Supraspinatus • Rotators cuff muscles • Subscapularis • Infraspinatus • Teres minor • Supraspinatus

19. Movement of Forearm Biceps brachii-flexes and laterally rotates elbow Brachialis- strongest flexor of elbow Brachioradialis-aids in flexing Triceps- opposes-extends elbow

20. Muscle of the Abdominal area • Compress the abdominal cavity and increases pressure, used during forceful exhalation or defecation • Rectus abdominis-six pack • External oblique-fibers runs downward to pelvic girdle • Internal oblique-fibers run upward to lower ribs • Transversus abnominis- deepest layer-runs horizontally across • Linea alba- connective tissue band that runs from xiphoid to symphysis pubis

23. Transversus abdnominis

24. Muscles of the Thigh • Anterior group- primary flexors of thigh • Psoas • iliacus • Posterior group- extends the thigh • Gluteus muscles- maximus-the largest muscle in the body • Tensor fasciae latae-extends from ilium to the iliotibial tract- abducts, rotates, and flexes • Adductors • Pectineus-flexes • Adductor brevis, longus, magnus-flex and rotate • Gracilis- straplike band from the pubic bone to tibia

26. Pectineus

27. Gluteus Muscle

28. Extends leg at knee Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Quadriceps Femoris groupExtensor

29. Biceps femoris Semimembranosus Semitendinosus Sartorius-strap like that passes obliquely across the front of thigh- abducts and rotates laterally Flexors of kneeHamstring Muscles

30. Semitendinosus Semimembranosus