Biological Sciences
Skeletal Muscle
Skeletal muscle is a type of muscle tissue that is attached to bones and is responsible for voluntary movements of the body. It is striated in appearance due to the arrangement of its protein filaments. Skeletal muscle is under conscious control and is involved in activities such as walking, running, and lifting objects.
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12 Key excerpts on "Skeletal Muscle"
eBook - PDF- Connie Allen, Valerie Harper(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
S keletal muscles are organs composed of Skeletal Muscle tissue and connective tissue. These organs also contain nerves and blood vessels. The Skeletal Muscle fibers within Skeletal Muscles contract (shorten) and cause movement of our skeleton or skin. The signal for contraction is carried by neurons that innervate each Skeletal Muscle fiber. We consciously control con- traction of Skeletal Muscles, so the contraction is called voluntary. A. Connective Tissue Coverings Skeletal Muscle fibers are elongated muscle cells that are striated and multinucleated. The striations are light and dark stripes along the muscle cell. A Skeletal Muscle fiber is actually many embryonic cells that have fused together to form one large muscle cell with multiple nuclei. Individual Skeletal Muscle fibers are surrounded by a layer of mostly reticular connective tissue called endomysium O B J E C T I V E S M A T E R I A L S • compound microscope and lens paper • prepared microscope slides of Skeletal Muscle tissue and neuromuscular junction • model of 3-D Skeletal Muscle fiber(s) Skeletal Muscle Structure 12 1 Describe the structure of skeletal tissue and Skeletal Muscle fibers 2 Identify the connective tissue structures in Skeletal Muscle 3 Describe the structure of the sarcomere 4 Describe the structure of the neuromuscular junction 175 (endo- = within; mys = muscle). Skeletal Muscle fibers are grouped into bundles of 10–100 muscle fibers called fascicles. Each fascicle is surrounded by a layer of dense irregular connective tissue called perimysium (peri- = around). A muscle is formed from a number of fascicles that are surrounded by a dense irregular connective tissue layer called epimysium (epi- = on; upon). Tendons, con- nective tissues that attach the muscle to bone, are formed from endomysium, perimysium, and epimysium that ex- tend beyond each Skeletal Muscle fiber. The connective tissues surrounding Skeletal Muscle fibers separate and electrically insulate these cells.
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
1. Producing body movements. Body movements such as walk- ing, running, writing, or nodding the head rely on the integrated functioning of Skeletal Muscles, bones, and joints. 2. Stabilizing body positions. Skeletal Muscle contractions stabi- lize joints and help maintain body positions, such as standing or sitting. Postural muscles contract continuously when a person is awake; for example, sustained contractions of your neck muscles hold your head upright. 8.2 Skeletal Muscle Tissue 175 Bone covered by periosteum Tendon Perimysium Epimysium Fascicle Muscle fiber (cell) Muscle fiber Myofibril Perimysium Perimysium Endomysium Sarcoplasm Striations Sarcolemma Filament Nucleus Myofibril Somatic motor neuron Blood capillary Endomysium Epimysium Skeletal Muscle Fascicle Transverse sections Components of a Skeletal Muscle Transverse plane Tendon Bone Skeletal Muscle FIGURE 8.1 Organization of Skeletal Muscle and its connective tissue coverings. A Skeletal Muscle consists of individual muscle fibers (cells) bundled into fascicles and surrounded by three connective tissue layers. Q Starting with the connective tissue that surrounds an individual muscle fiber (cell) and working toward the outside of a Skeletal Muscle, list the connective tissue layers in order. Functions of Muscular Tissue 1. Produce body movements. 2. Stabilize body positions. 3. Store and move substances within the body. 4. Produce heat. Partly unraveled Skeletal Muscle fiber with densely packed myofibrils Muscle fiber Myofibrils SEM 720x Eye of Science/Science Source 176 CHAPTER 8 The Muscular System turn, consists of two types of protein filaments called thin fila- ments and thick filaments (Figure 8.2b), which do not extend the entire length of a muscle fiber. Filaments overlap in specific pat- terns and form compartments called sarcomeres (SAR-kō-mērs; -meres = parts), the basic functional units of striated muscle fibers (Figure 8.2b, c).
eBook - PDF- D. J. Lowrie, Jr., D.J. Lowrie(Authors)
- 2020(Publication Date)
- Thieme(Publisher)
As described below, it is striated, meaning that, when Skeletal Muscle cells are oriented longitudinally and examined under high magnification, alter- nating dark and light bands are visible. With a few exceptions, named muscles (biceps brachii, pectoralis major) are com- posed of Skeletal Muscle. • Cardiac muscle is found in the heart. Cardiac muscle is also striated but is involuntary. • Smooth muscle is involuntary and is found in visceral organs, such as the gastrointestinal, respiratory, urinary, and repro- ductive systems. It is also found in the body wall, specifically as smooth muscle of blood vessels as well as arrector pili mus- cles of the hair follicles. Smooth muscle is so named because it is not striated. This chapter will focus on Skeletal Muscle structure and function, which serves as a model system for muscle in general. The next chapter will describe cardiac and smooth muscle, with a focus on how these muscle types differ from Skeletal Muscle. 13.2 Organization of Skeletal Muscles Skeletal Muscles such as the biceps brachii are composed of Skeletal Muscle cells, bundled together by connective tissue (Fig. 13.1). Skeletal Muscle cells are commonly called muscle fibers (myofibers) because they are very long compared to their diameter, which is also large. Muscle fibers within most muscles are aligned parallel to the long axis of the muscle, so that they all shorten in the same direction. Within a muscle, groups of muscle cells are bundled together into fascicles (Fig. 13.1). The connective tissue component of a muscle is organized into three types: • Epimysium surrounding the entire muscle • Perimysium around fascicles • Endomysium between individual muscle cells Muscle fiber (muscle cell) Epimysium Myofibril Muscle fascicle Endomysium Perimysium Fig. 13.1 Diagram of a Skeletal Muscle (e.g., biceps brachii).
eBook - PDF- Connie Allen, Valerie Harper(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
E X E R C I S E 1 2 S K E L E TA L M U S C L E S T R U C T U R E 175 S keletal muscles are organs composed of Skeletal Muscle tissue and connective tissue. These organs also contain nerves and blood vessels. The Skeletal Muscle fibers within Skeletal Muscles contract (shorten) and cause movement of our skeleton or skin. The signal for contraction is carried by neurons that innervate each Skeletal Muscle fiber. We consciously control contrac- tion of Skeletal Muscles, so the contraction is called voluntary. A. Skeletal Muscle Tissue and Connective Tissue Coverings Skeletal Muscle fibers (cells) are striated and multinucle- ated. The striations are light and dark stripes along the muscle cell. A Skeletal Muscle fiber is actually many embryonic cells that have fused together to form one large cell with multiple nuclei. O B J E C T I V E S M A T E R I A L S • compound microscope and lens paper • prepared microscope slides of Skeletal Muscle tissue and neuromuscular junction • model of 3-D Skeletal Muscle fiber(s) Skeletal Muscle Structure 12 E X E R C I S E 1 Describe the structure of skeletal tissue and Skeletal Muscle fibers 2 Identify the connective tissue structures in Skeletal Muscle 3 Describe the structure of the sarcomere 4 Describe the structure of the neuromuscular junction 175 Individual Skeletal Muscle fibers are surrounded by a layer of areolar connective tissue called endomysium (endo- = within; mys = muscle). Skeletal Muscle fibers are grouped into bundles called fascicles that are surrounded by a layer of dense regular connective tissue called perimysium (peri- = around). A muscle is formed from a number of fascicles that are surrounded by a dense regular connective tissue layer called epimysium (epi- = on; upon). Tendons, connective tissues that attach the muscle to bone, are formed from endomysium, perimy- sium, and epimysium that extend beyond each Skeletal Muscle fiber.
eBook - PDF- Y. H. Hui(Author)
- 2012(Publication Date)
- CRC Press(Publisher)
2.2.3 Skeletal Muscle Skeletal.muscle.is.the.most.abundant.type.of.muscle.in.the.animal.body . .Contractile,.structural,.and. regulatory. proteins. in. this. muscle. type. are. highly. organized. into. a. distinct. striated. pattern . . Skeletal. muscle.is.so.named.as.it.is.attached.to.the.skeletal.framework.of.the.animal,.in.various.configurations,. producing.different.types.of.levers.and.ultimately.movement . .Skeletal.muscle.fibers.(cells).can.range.in. length.from.10. μ m.to.more.than.a.few.centimeters . .To.provide.genetic.material.along.the.whole.length. of.skeletal.muscle.fibers,.these.specialized.cells.are.multinucleated . .Nuclei.in.mature.skeletal.muscle. fibers.are.located.along.the.periphery.of.the.fiber . .Skeletal.muscle.contraction.is.directly.stimulated.by. somatic.efferent.nerves.and.therefore.this.muscle.type.is.often.referred.to.as.voluntary.muscle.(Goll.and. others.1984;.Gerrard.and.Grant.2006a) . 2.3 Muscle Growth and Development Although.skeletal,.smooth,.and.cardiac.muscles.take.on.widely.different.characteristics.and.functions.in. their.mature.form,.early.events.leading.to.their.development.are.similar . .The.development.and.subse-quent.growth.of.muscle.is.the.product.of.complex.cellular.changes.that.accompany.myogenesis.and.the. growth.of.this.dynamic.tissue.pre-.and.postnatally . .To.more.efficiently.produce.muscle.that.results.in. high-quality.meat.products,.it.helps.to.have.an.understanding.of.these.events.and.the.processes.by.which. they.can.be.manipulated . 2.3.1 Myogenesis The.embryonic.cells.that.ultimately.become.muscle,.with.few.exceptions,.are.derived.from.the.mesoder-mal.layer.of.the.developing.embryo,.a.layer.that.also.gives.rise.to.fat.and.bone.tissue . .As.mesodermal. cells.become.more.prominent,.they.begin.to.organize.into.cuboidal.clusters.known.as.somites .
eBook - PDF- Connie Allen, Valerie Harper(Authors)
- 2013(Publication Date)
- Wiley(Publisher)
E X E R C I S E 1 2 S K E L E TA L M U S C L E S T R U C T U R E 173 S keletal muscles are organs composed of Skeletal Muscle tissue and connective tissue. These organs also contain nerves and blood vessels. The Skeletal Muscle fibers within Skeletal Muscles contract (shorten) and cause movement of our skeleton or skin. The signal for contraction is carried by neurons that innervate each Skeletal Muscle fiber. We consciously control contrac- tion of Skeletal Muscles, so the contraction is called voluntary. A. Skeletal Muscle Tissue and Connective Tissue Coverings Skeletal Muscle fibers (cells) are striated and multinucle- ated. The striations are light and dark stripes along the muscle cell. A Skeletal Muscle fiber is actually many em- bryonic cells that have fused together to form one large cell with multiple nuclei. O B J E C T I V E S M A T E R I A L S • compound microscope, lens paper, prepared microscope slides of Skeletal Muscle tissue and neuromuscular junction • model of 3-D Skeletal Muscle fiber(s) Skeletal Muscle Structure 12 E X E R C I S E 1 Describe the structure of skeletal tissue and Skeletal Muscle fibers 2 Identify the connective tissue structures in Skeletal Muscle 3 Describe the structure of the sarcomere 4 Describe the structure of the neuromuscular junction 173 Individual Skeletal Muscle fibers are surrounded by a layer of areolar connective tissue called endomysium (endo- within; mys muscle). Skeletal Muscle fibers are grouped into bundles called fascicles that are sur- rounded by a layer of dense regular connective tissue called perimysium (peri- around). A muscle is formed from a number of fascicles that are surrounded by a dense regular connective tissue layer called epimysium (epi- on; upon). Tendons, connective tissues that attach the muscle to bone, are formed from endomysium, perimy- sium, and epimysium that extend beyond each Skeletal Muscle fiber.
eBook - PDF- Gerard J. Tortora, Mark Nielsen(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
2. Contractility (kon′-trak-TIL-i-tē) is the ability of muscular tissue to contract forcefully when stimulated by a nerve 10.1 Overview of Muscular Tissue OBJECTIVE • Compare the three types of muscular tissue with regard to function and special properties. Types of Muscular Tissue As you learned in Chapter 3, there are three types of muscular tissue: skeletal, cardiac, and smooth (see Table 3.9). Myology (mī-OL-ō-jē; myo- = muscle; -logy = study of ) is the scientific study of the structure, function, and diseases of skeletal, car- diac, and smooth muscular tissues. Although the three types of muscular tissue share some properties, they differ from one another in their microscopic anatomy, location, and how they are controlled by the nervous and endocrine systems. Skeletal Muscle tissue is so named because the function of most Skeletal Muscles is to move the bones of the skeleton. (There are a few that attach to structures other than bone, such as the skin or even other Skeletal Muscles.) Skeletal Muscle tis- sue is referred to as striated because alternating light and dark protein bands (striations) are visible when the tissue is exam- ined under a microscope (see Table 3.9). Skeletal Muscle tis- sue works primarily in a voluntary manner; its activity can be consciously (voluntarily) controlled. Cardiac muscle tissue is found only in the heart, where it forms most of the heart wall. Like Skeletal Muscle, cardiac mus- cle is striated, but its action is involuntary—its alternating con- traction and relaxation cannot be consciously controlled. The heart beats because it has a natural pacemaker that initiates each contraction; this built-in (intrinsic) rhythm is called auto- rhythmicity. Several hormones and neurotransmitters adjust heart rate by speeding up or slowing down the pacemaker. Smooth muscle tissue is located in the walls of hollow internal structures, such as blood vessels, airways, and most organs in the abdominopelvic cavity.
eBook - PDF- Craig Freudenrich, Gerard J. Tortora(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
Smooth muscle b. Skeletal Muscle c. Cardiac muscle Skeletal Muscle Tissue Is Attached to the Bones There are about 700 Skeletal Muscles in your body. Skeletal Muscles produce body movements, stabilize the skeleton, and produce much of the heat that helps main- tain body temperature. Movements of Skeletal Muscle can be voluntary—you can knowingly contract and relax them—or involuntary. Skeletal Muscle tissue is banded, or striated; the striations can be seen only under a mi- croscope. The ability of Skeletal Muscle to regenerate is somewhat limited and involves satellite cells, a type of stem cell that becomes activated to form new Skeletal Muscle cells. The Body Contains Three Types of Muscular Tissues 155 Cardiac Muscle Tissue Is Found Only in the Heart Cardiac muscle tissue makes up the walls of the heart and generates the force necessary to pump your blood. Cardiac muscle contractions are involuntary: You don’t think about contracting and relaxing this muscle. Unlike most other muscle tissue, cardiac muscle tissue has the ability to contract without the assistance of the nervous system. Like Skeletal Muscle, cardiac muscle is striated. The regeneration ability of cardiac muscle is minimal. Smooth Muscle Tissue Is Found in Most Body Organs Smooth muscle tissue forms the walls of hollow organs such as blood vessels, airways, the stomach, the intestines, and the uterus. The smooth muscle of these organs helps to store and move substances within the body and regu- lates organ volume. Smooth muscle cells are considerably smaller than other muscle cells and are not striated. Like cardiac muscle, the contraction and relaxation of smooth muscle is involuntary. Of the three types of musclar tissue, smooth muscle tissue regenerates most easily, most likely because this type of muscle has a less complex structure than that of the striated cardiac or Skeletal Muscle tissues. 1. Which type of muscular tissue is striated and voluntary? 2.
eBook - PDF- Jennifer Ellie(Author)
- 2011(Publication Date)
- Wiley(Publisher)
13-2 Skeletal Muscle ORGANIZATION The Skeletal Muscles in your body are considered organs, since they are constructed out of many different tissue types. Within each Skeletal Muscle, blood vessels supply muscle fibers (muscle cells) with the oxygen and nutrients required for contraction. Motor neurons Inhalation Exhalation Diaphragm: (b) Changes in size of thoracic cavity during inhalation and exhalation Inhalation Exhalation Sternum: MUSCLES OF INHALATION Diaphragm External intercostals Internal intercostals MUSCLES OF EXHALATION (a) Muscles of inhalation and their actions Vein Distal valve closed Contracted Skeletal Muscle Proximal valve open FIGURE 13.1 Muscles of Respiration FIGURE 13.2 The Skeletal Muscle Pump In addition to generating heat, certain muscles actually push blood through veins as they contract. This phenomenon is illustrated in Figure 13.2. When a person stands still for a long period of time, blood pools within the legs and cause a drop in blood pres- sure. If the brain receives inadequate blood flow due to hypotension (low blood pressure), then this person may start to feel dizzy and eventually wind up fainting. 13-3 LAB 13: The Muscular System stimulate muscle contraction when they are prompted to do so by the central nervous system. Sheaths of connective tissue also encapsulate individual muscle fibers, clusters of muscle fibers, and the Skeletal Muscle as a whole. Figure 13.3 shows the levels of organiza- tion found within a Skeletal Muscle. A tendon is a resilient rope of dense connective tissue that anchors a Skeletal Muscle to another structure in the body. Typically, tendons anchor Skeletal Muscles to bony projections. Another sheet of connective tissue called the epimy- sium covers the entire surface (epi-) of the muscle (my- or myo-). The Skeletal Muscle itself consists of long, cylindrical structures called fascicles. A fascicle is a group of muscle fibers surrounded (peri-) by a sheet of connective tissue called the perimysium.
eBook - PDF- Daniel J. Schneck(Author)
- 1991(Publication Date)
- NYU Press(Publisher)
Forces interna l t o th e organis m ar e derive d fro m a specia l mech -anism whic h is designed t o transfor m chemica l fre e (o r bond ) energ y int o INTRODUCTION 3 mechanical work . Thi s mechanis m is the striate d skeleta l muscle , and th e work don e is , or th e force s develope d ar e transmitte d t o a typ e o f engi -neering structur e designe d t o conver t muscula r effor t int o th e mainte -nance o f postural balanc e o r the locomotio n o f parts o r al l of the anima l body. Th e latte r is , of course , th e skeleta l syste m an d it s associate d ar -ticulations (joints) . The stud y o f muscle is calle d Myology, agai n afte r th e Greek , mys , meaning muscle . Ther e ar e thre e type s o f muscle: 1) Cardiac Muscle , whic h ha s the anatomi c an d physiologi c charac -teristics o f striate d skeleta l muscle , bu t whic h show s electrica l stimulation an d excitation-contractio n behavio r mor e typica l o f smooth muscl e tissue ; 2) Vascula r an d Viscera l Smoot h Muscle , which , togethe r wit h Cardiac Muscle , maintai n th e internal environmen t (tone an d dynamics) o f the human body ; and , 3) Striate d Skeleta l (voluntary ) muscles , attache d t o bone s b y tendons, an d acting : a) T o maintai n postura l balanc e b y servin g (togethe r wit h liga -ments) as tensil e load-bearin g member s -i n equilibriu m wit h bones actin g a s rigi d compressiv e member s -o f th e physiologic system ; and , b) T o caus e locomotio n o f part s o r al l o f th e anima l bod y b y pulling o n th e bone s t o whic h the y ar e attached , thereb y cre -ating a lever-typ e actio n aroun d joint s servin g as pivot points . Skeletal muscl e is the singl e largest tissu e in the body, accounting fo r up t o 40-43 % o f tota l bod y weight i n me n an d 23-25 % i n women .
- Gerard J. Tortora, Bryan H. Derrickson, Brendan Burkett, Gregory Peoples, Danielle Dye, Julie Cooke, Tara Diversi, Mark McKean, Simon Summers, Flavia Di Pietro, Alex Engel, Michael Macartney, Hayley Green(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
CHAPTER 10 Muscular tissue 391 TABLE 10.3 Levels of organisation within a Skeletal Muscle Level Description Skeletal Muscle Bone (covered by periosteum) Tendon Skeletal Muscle Epimysium Fascicle Organ made up of fascicles that contain muscle fibres (cells), blood vessels, and nerves; wrapped in epimysium. Fascicle Fascicle Muscle fibre Perimysium Bundle of muscle fibres wrapped in perimysium. Muscle fibre (cell) Sarcolemma Sarcoplasm Sarcoplasmic reticulum Myofibril Muscle fibre Nucleus Mitochondrion Terminal cisterns Transverse tubule Long cylindrical cell covered by endomysium and sarcolemma; contains sarcoplasm, myofibrils, many peripherally located nuclei, mitochondria, transverse tubules, sarcoplasmic reticulum, and terminal cisterns. The fibre has a striated appearance. Myofibril Z disc Thin filament Thick filament Sarcomere Threadlike contractile elements within sarcoplasm of muscle fibre that extend entire length of fibre; composed of filaments. Filaments (myofilaments) Thin filament Thick filament Z disc Z disc Sarcomere Contractile proteins within myofibrils that are of two types: thick filaments composed of myosin and thin filaments composed of actin, tropomyosin, and troponin; sliding of thin filaments past thick filaments produces muscle shortening. ....................................................................................................................................................................................... CHECKPOINT 4. What types of fascia cover Skeletal Muscles? 5. Why is a rich blood supply important for muscle contraction? 6. How are the structures of thin and thick filaments different? 392 Principles of anatomy and physiology 10.3 Contraction and relaxation of Skeletal Muscle fibres LEARNING OBJECTIVE 10.3 Investigate the origination of muscle action potentials at the neuromuscular junction and the steps involved in the sliding filament mechanism of muscle contraction.
eBook - PDF- Gerard J. Tortora, Mark Nielsen(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
Volkmann contracture (FO ¯ LK-man kon-TRAK-chur; contra-= against) Permanent shortening (contracture) of a muscle due to replacement of destroyed muscle fibers by fibrous connective tissue, which lacks extensibility. Typically occurs in forearm flexor muscles. Destruction of muscle fibers may occur from interference with circulation caused by a tight bandage, a piece of elastic, or a cast. Fasciculation (fa-sik-u ¯-LA ˉ -shun) An involuntary, brief twitch of an en- tire motor unit that is visible under the skin; it occurs irregularly and is not associated with movement of the affected muscle. Fascicula- tions may be seen in multiple sclerosis or in amyotrophic lateral scle- rosis (Lou Gehrig’s disease). Fibrillation (fi-bri-LA ˉ -shun) A spontaneous contraction of a single mus- cle fiber that is not visible under the skin but can be recorded by electro- myography. Fibrillations may signal destruction of motor neurons. Myalgia (mı ¯-AL-je ˉ-a; -algia=painful condition) Pain in or associated with muscles. Myoma (mı ¯-O ¯ -ma; -oma=tumor) A tumor consisting of muscular tissue. Myomalacia (mı ¯-O ¯ -ma-LA ˉ -she ˉ-a; -malacia=soft) Pathological soften- ing of muscular tissue. KEY MEDICAL TERMS ASSOCIATED WITH MUSCULAR TISSUE CHAPTER REVIEW AND RESOURCE SUMMARY Review Resource Introduction 1. Muscles constitute 40–50 percent of total body weight. 2. The prime function of muscle is changing chemical energy into mechanical energy to perform work. 10.1 Overview of Muscular Tissue 1. The three types of muscular tissue are skeletal, cardiac, and smooth. Skeletal Muscle tissue is primarily attached to bones; it is striated and under voluntary control. Cardiac muscle tissue forms the wall of the heart; it is striated and involuntary. Smooth muscle tissue is located primarily in internal organs; it is nonstriated (smooth) and involuntary. Anatomy Overview - Muscular Tissue pair of somites appears on day 20 of embryonic development.
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