Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Skeletal Muscle Actions 1

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. The immovable end of a muscle is the origin, while the movable end is the insertion; contraction pulls the insertion toward the origin. Some muscles have more than one insertion or origin. 2 Origin and Insertion

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. B.Interaction of Skeletal Muscles 1.Of a group of muscles, the one doing the majority of the work is the agonist (prime mover). 2.Helper muscles are called synergists 3.Opposing muscles are called antagonists. 4.Muscles that stabilize a joint so the prime mover can act at more distal joints is are fixators 5.The relationships between muscles depends on the action – roles can and do change. 4

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Major Skeletal Muscles 5

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. A.Muscles are named according to any of these: size, shape, location, action, number of attachments, direction of its fibers, or combinations of the above. 1.Pectoralis major – 2.Deltoid – 3.Extensor digitorum – 4.Biceps brachii – 5.Sternocleidomastoid – 6.External oblique – 6 size and location shape action number of attachments and location attachments location and direction of fibers

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. B.Muscles of Facial Expression 1.Muscles of facial expression attach to underlying bones and overlying connective tissue of skin, and are responsible for the variety of facial expressions possible in the human face. 2.There are 43 facial muscles 12

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Table Epicranius (frontalis & Occipitalis): elevated eyebrows 2.Orbicularis oculi: closes eyes 3.Orbicularis oris: compresses and purses lips “kiss muscle” 4.Buccinator: compresses cheeks 5.Zygomaticus: elevates corner of mouth 6.Platysma: Depresses lower lip and angle of mouth, and tenses skin of neck 7.Nasalis: depresses tip of nose and elevates nostrils 8.Mentalis: protrudes lower lip (“pout”) Muscles of Facial Expression

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Muscles of Mastication Chewing movements include up and down as well as side-to-side grinding motions of muscles attached to the skull and lower jaw. Chewing muscles include the masseter and temporalis. Masseter: elevates & protracts mandible Temporalis: Elevates and retracts mandible 16

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Muscles that Move the Head 1.Paired muscles in the neck and back flex, extend, and turn the head. 2.Major muscles include the sternocleidomastoid, splenius capitis, and semispinalis capitis. 19

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Table Sternocleidomastoid : each laterally flexes head to the same side, rotates head to the opposite side. Aid in forceful inhalation 2.Scalenes: Flex head and neck, elevates first two ribs during forceful inhalation 3.Splenius capitis: rotates head, laterally flexes head, brings head upright 4.Semispinalis capitis : extends head and neck, laterally flexes head, rotates head Muscles that Move the Head

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 22 Sternocleidomastoid Scalenes

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 23 Splenius capitis Semispinalis capitis

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Muscles of the abdominal Wall 1.Rectus abdominis: (makes your 6-pack) compresses abdomen, flexes vertebral column 2.External oblique: compresses abdomen, flexes, and rotates vertebral column 3.Internal oblique: compresses abdomen, flexes and rotates vertebral column 4.Transverse abdominis: compresses abdomen, flexes and rotates vertebral column 26

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Inguinal Hernia 28

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Neck/Back extensors Erector Spinae muscles (all extend neck and vertebral column and maintain posture) 1.Iliocostalis 2.Longissimus: also rotates head 3.Spinalis 1.Quadratus lumborum: extends and laterally flexes vertebral column 31

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. E.Muscles that Move the Pectoral Girdle 1.The chest and shoulder muscles move the scapula. 2.Major muscles include the trapezius, rhomboideus major, levator scapulae, serratus anterior, and pectoralis minor. 34

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Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Table

Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. F.Muscles that Move the Arm 1.Muscles connect the arm to the pectoral girdle, ribs, and vertebral column, making the arm freely movable. 2.Flexors include the coracobrachialis and pectoralis major. 3.Extensors include the teres major and latissimus dorsi. 4.Abductors include the supraspinatus and the deltoid. 5.Rotators are the subscapularis, infraspinatus, and teres minor. 38

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