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Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb 10 The Muscular System Part A.

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Presentation on theme: "Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb 10 The Muscular System Part A."— Presentation transcript:

1 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb 10 The Muscular System Part A

2 Interactions of Skeletal Muscles  Skeletal muscles work together or in opposition  Muscles only pull (never push)  As muscles shorten, the insertion generally moves toward the origin  Whatever a muscle (or group of muscles) does, another muscle (or group) “undoes”

3 Muscle Classification: Functional Groups  Prime movers – provide the major force for producing a specific movement  Antagonists – oppose or reverse a particular movement  Synergists  Add force to a movement  Reduce undesirable or unnecessary movement  Fixators – synergists that immobilize a bone or muscle’s origin

4 Naming Skeletal Muscles  Location of muscle  Shape of muscle – deltoid = triangle  Relative size – maximus, minimus, longus  Direction of fibers relative to body or bone axis  rectus – parallel  Transversus - perpendicular  Oblique – angle  Number of origins – biceps = two origins  Location of attachment –points of origin or insertion  Action – flexor, extensor, abductor, adducer etc…

5 Arrangement of Fascicles Figure 10.1

6 Bone-Muscle Relationships: Lever Systems  Lever – a rigid bar that moves on a fulcrum, or fixed point  Effort – force applied to a lever  Load – resistance moved by the effort

7 Bone-Muscle Relationships: Lever Systems Figure 10.2a  Mechanical advantage  Effort is less than load

8 Bone-Muscle Relationships: Lever Systems Figure 10.2b  Mechanical disadvantage  Effort is greater than load

9 Lever Systems: First Class Figure 10.3a  Examples of both mechanical advantage and disadvantage

10 Lever Systems: Second Class Figure 10.3b  Always a mechanical advantage

11 Lever Systems: Third Class Figure 10.3c  Always a mechanical disadvantage

12 Major Skeletal Muscles: Posterior (dorsal) View  27 superficial muscles divided into 7 body regions Figure 10.5b

13 Major Skeletal Muscles: Anterior (ventral) View  40 superficial muscles divided into 10 body regions Figure 10.4b

14 Shoulder Muscles Figure 10.13a Prime movers

15 Shoulder Muscles Figure 10.13b

16 Shoulder Muscles Figure 10.14d Rotator cuff muscles

17 Muscles of the Neck: Head Movements Figure 10.9a Major head flexor Lateral head movements

18 Muscles of the Neck: Head Movements Figure 10.9b Head extension

19 Muscles of Respiration  External intercostals – superficial layer that lifts the rib cage Figure 10.10a  Internal intercostals – deep layer that aids in forced expiration

20 Muscles of Respiration: The Diaphragm Figure 10.10b  Diaphragm – most important muscle in inspiration

21 Muscles of the Abdominal Wall Figure 10.11a

22 Muscles of the Abdominal Wall Figure 10.11b

23 Muscles Crossing Hip and Knee Joints  Most anterior compartment muscles of the hip and thigh flex the femur at the hip and extend the leg at the knee  Posterior compartment muscles of the hip and thigh extend the thigh and flex the leg  The medial compartment muscles all adduct the thigh  These three groups are enclosed by the fascia lata

24 Movements of the Thigh at the Hip: Flexion and Extension  The ball-and-socket hip joint permits flexion, extension, abduction, adduction, circumduction, and rotation  Most important thigh flexors  iliopsoas (prime mover),  tensor fasciae latae,  rectus femoris  The medially located adductor muscles and sartorius assist in thigh flexion

25  Thigh extension  hamstring muscles  biceps femoris, semitendinosus, & semimembranosus  Forceful extension is aided by the gluteus maximus Movements of the Thigh at the Hip: Flexion and Extension

26 Figure 10.19a Movements of the Thigh at the Hip: Flexion and Extension

27  Abduction and rotation  gluteus medius & gluteus minimus,  antagonized by the lateral rotators  Thigh adduction by five adductor muscles  adductor magnus, adductor longus, & adductor brevis; the pectineus, & the gracilis Movements of the Thigh at the Hip: Other Movements

28 Figure 10.20a Movements of the Thigh at the Hip: Other Movements

29 Movements of the Knee Joint  The sole extensor of the knee is the quadriceps femoris  The hamstring muscles flex the knee, and are antagonists to the quadriceps femoris Figure 10.19a


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