1. Muscular system
Chapter 8

2. What do muscles do?
All movements require muscles, which are organs that use chemical energy to contract.
Walking, breathing, eating, sneezing, all require muscles
Provide muscle tone
Propel body fluids and food
Generate heart beats
Distribute heat
Maintain posture

3. Types of muscle Skeletal (majority of this chapter)
Attaches to bone and consciously controlled
Smooth-hollow internal organs, irises, blood vessels
Cardiac-heart

4. Rules of muscular activity
1. Muscles get shorter as they contract
2. Muscles cross at least one joint
3. Muscles have an origin and insertion
Origin: immovable end of muscle
Insertion: movable end
4. When a muscle contracts, its insertion is pulled toward the origin.

5. Interactions of muscles
Skeletal muscles function in groups.
Prime Mover: the muscle doing the majority of the work during a movement
Synergists: helper muscles
Antagonists: opposing muscles

6. Muscular movements
Insertion
(moveable end)
Origin
(immovable end)

7. Muscular movements
Flexion: angle between joint is decreased

8. Muscular movements Extension: angle of joint is increased
Hyperextension: extension beyond normal anatomical position
Abduction: moving a part away from midline
Adduction: moving a part toward midline
Rotation: moving a part around an axis
You will look up the rest of the muscle movements for homework tonight (P in book)

9. Major skeletal muscles
Named according to:
1. Size (pectoralis major)
2. Shape (orbicularis oris)
3. Location (tibialis anterior)
4. Movement (extensor digitorum)
5. Number of attachments (biceps brachii)
About 650 muscles in the human body

10. Major skeletal muscles

11. Muscles of facial Expression
Epicranius-raises eyebrow
Orbicularis Oculi-closes eye
Orbicularis Oris-closes and protrudes lips
Buccinator-puckers cheeck
Zygomaticus-raises corner of mouth (Smile)
Platysma-draws angle of mouth downward

12. Muscles of mastication
(Chewing)
Masseter: elevates mandible
Temporalis: elevates mandible

13. Muscles that move head
Sternocleidomastoid: pulls head to one side, toward chest, or raises sternum
Splenius capitis: rotates head, bends head to one side, or brings head to upright position
Semispinalis capitis: extends head, bends head to one side, rotates head

14. Muscles that move head

15. Muscles that move arm

16. Back, Chest Muscles
Trapezius: rotates scapula, raises arm, raises scapula, pulls scapula medially, pulls shoulder down
Deltoid: abducts arm, extends/flexes humerus
Latissimus Dorsi: extends/adducts arm, rotates arm inwardly, pulls shoulder down
Rhomboid Major: raises and adducts scapulae
Levator Scapulae: elevates scapulae
Pectoralis Minor: pulls scapula anteriorly and down
Pectoralis Major: pulls arm anteriorly and across chest, rotates humerus, adducts arm

17. Abdominals External Oblique Rectus Abdominus Transversus Abdominus
Internal Oblique

18. Muscles that Move Forearm

19. Move forearm
Biceps Brachii: flexes forearm at elbow and rotates hand laterally
Brachioradialis: flexes forearm at elbow
Triceps Brachii: extends forearm at elbow

20. Move Hand Flexor Carpi Radialis: flexes and abducts wrist
Palmaris longus: flexes wrist
Flexor Carpi Ulnaris: flexes and adducts wrist
Extensor Carpi Ulnaris: extends and adducts wrist
Extensor Digitorum: extends fingers
Extensor Carpi radialis brevis: extends wrist and abducts hand

21. THigh

22. Thigh Muscles Gluteus maximus: extends thigh
Gluteus medius: abducts and rotates thigh medially
Sartorius: flexes leg/thigh, abducts thigh, rotates thigh laterally, rotates leg medially
Semitendinosus: flexes leg, extends thigh
Semimembranosus: flexes leg, extends thigh
Quadriceps femoris (4 parts): extends leg at knee

23. Muscles that move foot

24. Muscles that move foot
Tibialis anterior: dorsiflexion and inversion of foot
Extensor digitorum longus: dorsiflexion and eversion of foot; extension of foot
Gastrocnemius: plantar flexion of foot and flexion of leg at knee
Flexor digitorum longus: plantar flexion and inversion of foot, flexion of four lateral toes
Tibialis posterior: plantar flexion and inversion of foot