Chapter 10 *Lecture PowerPoint The Muscular System *See separate FlexArt PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction • Facts about muscles – Muscles constitute nearly half of the body’s weight and occupy a place of central interest in several fields of health care and fitness • Physical and occupational therapy, athletes, dancers, trainers, acrobats, nurses, and more – Muscular system is closely related to other systems covered previously – Chapters 11 and 12 will examine the mechanisms of muscle contraction at the cellular and molecular levels 10-2 Introduction • In this chapter we will cover: – Structural and functional organization of muscles – Muscles of the head and neck – Muscles of the trunk – Muscles acting on the shoulder and upper limb – Muscles acting on the hip and lower limb Figure 10.5 10-3 The Structural and Functional Organization of Muscles • Expected Learning Outcomes – Describe the varied functions of muscles. – Describe the connective tissue components of a muscle and their relationship to the bundling of muscle fibers. – Describe the various shapes of skeletal muscles and relate this to their functions. – Explain what is meant by the origin, insertion, belly, action, and innervation of a muscle. 10-4 The Structural and Functional Organization of Muscles Cont. – Describe the ways that muscles work in groups to aid, oppose, or moderate each other’s actions. – Distinguish between intrinsic and extrinsic muscles. – Describe in general terms the nerve supply to the muscles and where these nerves originate. – Explain how the Latin names of muscles can aid in visualizing and remembering them. 10-5 The Structural and Functional Organization of Muscles • About 600 human skeletal muscles • Constitute about half of our body weight • Three kinds of muscle tissue – Skeletal, cardiac, smooth • Specialized for one major purpose – Converting the chemical energy in ATP into the mechanical energy of motion • Myology—the study of the muscular system 10-6 The Functions of Muscles • Movement – Move from place to place, movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth – Role in communication: speech, writing, nonverbal communications • Stability – Maintain posture by preventing unwanted movements – Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over – Stabilize joints 10-7 The Functions of Muscles • Control of openings and passageways – Sphincters: internal muscular rings that control the movement of food, bile, blood, and other materials within the body • Heat production by skeletal muscles – As much as 85% of our body heat • Glycemic control – Regulation of blood glucose concentrations within its normal range 10-8 Connective Tissues of a Muscle Copyright © The McGraw-Hill Companies, Inc. 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Tendon Fascia Skeletal muscle Muscle fascicle Nerve Blood vessels Epimysium Perimysium Figure 10.1a Endomysium Muscle fiber Muscle fascicle Perimysium Muscle fiber (a) 10-9 Connective Tissues and Fascicles • Endomysium – Thin sleeve of loose connective tissue surrounding each muscle fiber – Allows room for capillaries and nerve fibers to reach each muscle fiber – Provides extracellular chemical environment for the muscle fiber and its associated nerve ending • Perimysium – Slightly thicker layer of connective tissue – Fascicles: bundles of muscle fibers wrapped in perimysium – Carry larger nerves and blood vessels, and stretch receptors 10-10 Connective Tissues and Fascicles • Epimysium – Fibrous sheath surrounding the entire muscle – Outer surface grades into the fascia – Inner surface sends projections between fascicles to form perimysium • Fascia – Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue 10-11 Connective Tissues of a Muscle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Perimysium Endomysium Muscle fiber, c.s. Fascicle, c.s. Muscle fiber, l.s. Fascicle, l.s. (c) Victor Eroschenko Figure 10.1c 10-12 Fascicles and Muscle Shapes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Unipennate Triangular Bipennate Parallel Multipennate Fusiform Tendon Circular Belly Pectoralis major Tendon Palmar interosseous Rectus femoris Rectus abdominis Deltoid Biceps brachii Orbicularis oculi Figure 10.2 • Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles 10-13 Muscle Compartments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior Lateral Medial Tibia Fibula Posterior Interosseous membrane Artery, veins, and nerve Intermuscular septa Fasciae Key Subcutaneous Anterior compartment fat Lateral compartment Posterior compartment, deep layer Figure 10.3 Posterior compartment, superficial layer • A group of functionally related muscles enclosed and separated from others by connective tissue fascia • Contains nerves, blood vessels that supply the muscle group – Thoracic, abdominal walls, pelvic floor, limbs • Intermuscular septa separate one compartment from another 10-14 Muscle Attachments • Indirect attachment to bone – Tendons bridge the gap between muscle ends and bony attachment • Collagen fibers of the endo-, peri-, and epimysium continue into the tendon • From there into the periosteum and the matrix of bone • Very strong structural continuity from muscle to bone • Biceps brachii, Achilles tendon • Aponeurosis—tendon is a broad, flat sheet (palmar aponeurosis) • Retinaculum—connective tissue band that tendons from separate muscles pass under 10-15 Muscle Attachments • Direct (fleshy) attachment to bone – Little separation between muscle and bone – Muscle seems to immerge directly from bone • Margins of brachialis, lateral head of triceps brachii 10-16 Muscle Origins and Insertions • Origin Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. – Bony attachment at stationary end of muscle Origins Origins Humerus Scapula • Belly Bellies – Thicker, middle region of Extensors: Flexors: Triceps brachii Biceps brachii muscle between origin Long head Brachialis and insertion Lateral head • Insertion Insertion Radius – Bony attachment to Insertion Ulna mobile end of muscle Figure 10.4 10-17 Muscle Origin and Insertions • Also can be determined by proximal or distal or superior and inferior attachments, especially on limbs (nontraditional) • Some muscles insert not on bone but on the fascia or tendon of another muscle or on collagen fibers of the dermis – Distal tendon of the biceps brachii inserts on the fascia of the forearm – Facial muscles insert in the skin 10-18 Functional Groups of Muscles • Action—the effects produced by a muscle – To produce or prevent movement • Four categories depending on action – Prime mover (agonist) • Muscle that produces most of force during a joint action – Synergist: muscle that aids the prime mover • Stabilizes the nearby joint • Modifies the direction of movement 10-19 Functional Groups of Muscles Cont. – Antagonist: opposes the prime mover • Relaxes to give prime mover control over an action • Preventing excessive movement and injury • Antagonistic pairs—muscles that act on opposite sides of a joint – Fixator: muscle that prevents movement of bone 10-20 Functional Groups of Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Prime mover—brachialis Origins Origins Humerus Scapula • Synergist—biceps brachii Bellies Extensors: Flexors: • Antagonist—triceps brachii Triceps brachii Biceps brachii Long head Brachialis Lateral head • Fixator—muscle that holds scapula firmly in place Insertion Radius – Rhomboids Insertion Ulna Figure 10.4 10-21 Intrinsic and Extrinsic Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Intrinsic muscles— entirely contained Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Common Tendon sheath First dorsal flexor within a region, such interosseous tendon Tendon of flexor Adductor as the hand digitorum profundus pollicis Tendon of flexor digitorum superficialis Tendon of flexor – Both its origin and Lumbricals pollicis longus Flexor Opponens digiti minimi Flexor pollicis digitorum insertion there brevis Flexor digiti superficialis Abductor pollicis brevis Abductor digiti Flexor minimi Opponens pollicis Flexor retinaculum pollicis longus Tendons of: • Extrinsic muscles— Tendons of: Abductor pollicis Flexor carpi ulnaris longus Flexor carpi Flexor digitorum radialis superficialis act on a designated Flexor pollicis Palmaris longus longus Flexor region, but has its digitorum (a) Palmar aspect, superficial superficialis origin elsewhere tendons Figure 10.31a Flexor – Fingers: extrinsic digitorum profundus muscles in the tendons forearm (b) Intermediate flexor Figure 10.28b 10-22 Muscle Innervation • Innervation of a muscle—refers to the identity of the nerve that stimulates it – Enables the diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function • Spinal nerves arise from the spinal cord – Emerge through intervertebral foramina – Immediately branch into a posterior and anterior ramus – Innervate muscles