Chapter 8MUSCULAR SYSTEM

All movements require muscles, which are organs that use chemical energy to contract. Walking, breathing, eating, sneezing, all require

muscles

Provide muscle tonePropel body fluids and foodGenerate heart beatsDistribute heatMaintain posture

WHAT DO MUSCLES DO?

Skeletal (majority of this chapter) Attaches to bone and consciously controlled

Smooth-hollow internal organs, irises, blood vessels

Cardiac-heart

TYPES OF MUSCLE

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.

RULES OF MUSCULAR ACTIVITY

Skeletal muscles function in groups.

Prime Mover: the muscle doing the majority of the work during a movement

Synergists: helper muscles

Antagonists: opposing muscles

INTERACTIONS OF MUSCLES

MUSCULAR MOVEMENTS

Origin(immovable end)

Insertion(moveable end)

Flexion: angle between joint is decreased

MUSCULAR MOVEMENTS

Extension: angle of joint is increasedHyperextension: extension beyond normal anatomical

position

Abduction: moving a part away from midlineAdduction: 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. 167-170 in book)

MUSCULAR MOVEMENTS

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

MAJOR SKELETAL MUSCLES

MAJOR SKELETAL MUSCLES

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

MUSCLES OF FACIAL EXPRESSION

(Chewing)

Masseter: elevates mandible

Temporalis: elevates mandible

MUSCLES OF MASTICATION

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

MUSCLES THAT MOVE HEAD

MUSCLES THAT MOVE HEAD

MUSCLES THAT MOVE ARM

Trapezius: rotates scapula, raises arm, raises scapula, pulls scapula medially, pulls shoulder down

Deltoid: abducts arm, extends/flexes humerusLatissimus Dorsi: extends/adducts arm, rotates arm

inwardly, pulls shoulder downRhomboid Major: raises and adducts scapulaeLevator Scapulae: elevates scapulaePectoralis Minor: pulls scapula anteriorly and downPectoralis Major: pulls arm anteriorly and across

chest, rotates humerus, adducts arm

BACK, CHEST MUSCLES

External Oblique

Rectus Abdominus

Transversus Abdominus

Internal Oblique

ABDOMINALS

MUSCLES THAT MOVE FOREARM

Biceps Brachii: flexes forearm at elbow and rotates hand laterally

Brachioradialis: flexes forearm at elbowTriceps Brachii: extends forearm at elbow

MOVE FOREARM

Flexor Carpi Radialis: flexes and abducts wristPalmaris longus: flexes wristFlexor Carpi Ulnaris: flexes and adducts wristExtensor Carpi Ulnaris: extends and adducts wristExtensor Digitorum: extends fingersExtensor Carpi radialis brevis: extends wrist and

abducts hand

MOVE HAND

THIGH

Gluteus maximus: extends thighGluteus medius: abducts and rotates thigh mediallySartorius: flexes leg/thigh, abducts thigh, rotates

thigh laterally, rotates leg mediallySemitendinosus: flexes leg, extends thighSemimembranosus: flexes leg, extends thighQuadriceps femoris (4 parts): extends leg at knee

THIGH MUSCLES

MUSCLES THAT MOVE FOOT

Tibialis anterior: dorsiflexion and inversion of footExtensor digitorum longus: dorsiflexion and eversion

of foot; extension of footGastrocnemius: plantar flexion of foot and flexion of

leg at kneeFlexor digitorum longus: plantar flexion and inversion

of foot, flexion of four lateral toesTibialis posterior: plantar flexion and inversion of foot

MUSCLES THAT MOVE FOOT