2 What do muscles do?All movements require muscles, which are organs that use chemical energy to contract.Walking, breathing, eating, sneezing, all require musclesProvide muscle tonePropel body fluids and foodGenerate heart beatsDistribute heatMaintain posture
3 Types of muscle Skeletal (majority of this chapter) Attaches to bone and consciously controlledSmooth-hollow internal organs, irises, blood vesselsCardiac-heart
4 Rules of muscular activity 1. Muscles get shorter as they contract2. Muscles cross at least one joint3. Muscles have an origin and insertionOrigin: immovable end of muscleInsertion: movable end4. 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 movementSynergists: helper musclesAntagonists: opposing muscles
7 Muscular movementsFlexion: angle between joint is decreased
8 Muscular movements Extension: angle of joint is increased Hyperextension: extension beyond normal anatomical positionAbduction: moving a part away from midlineAdduction: moving a part toward midlineRotation: moving a part around an axisYou 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
11 Muscles of facial Expression Epicranius-raises eyebrowOrbicularis Oculi-closes eyeOrbicularis Oris-closes and protrudes lipsBuccinator-puckers cheeckZygomaticus-raises corner of mouth (Smile)Platysma-draws angle of mouth downward
12 Muscles of mastication (Chewing)Masseter: elevates mandibleTemporalis: elevates mandible
13 Muscles that move headSternocleidomastoid: pulls head to one side, toward chest, or raises sternumSplenius capitis: rotates head, bends head to one side, or brings head to upright positionSemispinalis capitis: extends head, bends head to one side, rotates head
24 Muscles that move footTibialis 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
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