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Muscular system Chapter 8.

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Presentation on theme: "Muscular system Chapter 8."— Presentation transcript:

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

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