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内容提示: 280 PA RT T WO Support and MovementTABLE 11.5 Muscles of Respiration (continued)Name Action Skeletal Attachments InnervationDiaphragm 38 (DY-ah-fram)Prime mover of inspiration (responsible for about two-thirds of air intake); contracts in preparation for sneezing, coughing, crying, laughing, and weight lifting; contraction compresses abdominal viscera and aids in childbirth and expulsion of urine and feces.• Xiphoid process of sternum; ribs and costal cartilages 7–12; lumbar vertebrae• Central tendo...

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280 PA RT T WO Support and MovementTABLE 11.5 Muscles of Respiration (continued)Name Action Skeletal Attachments InnervationDiaphragm 38 (DY-ah-fram)Prime mover of inspiration (responsible for about two-thirds of air intake); contracts in preparation for sneezing, coughing, crying, laughing, and weight lifting; contraction compresses abdominal viscera and aids in childbirth and expulsion of urine and feces.• Xiphoid process of sternum; ribs and costal cartilages 7–12; lumbar vertebrae• Central tendon of diaphragmPhrenic nervesExternal Intercostals 39 (IN-tur-COSS-tul)When scalenes fix rib 1, external intercostals elevate and protract ribs 2–12; this expands the thoracic cavity and creates a partial vacuum, causing inflow of air. Exercise a braking action during expiration so that expiration is not overly abrupt.• Inferior margins of ribs 1–11• Superior margin of next lower ribIntercostal nervesInternal Intercostals In inspiration, the intercartilaginous part aids in elevating the ribs and expanding the thoracic cavity. In expiration, the interosseous part depresses and retracts the ribs, compressing the thoracic cavity and expelling air. The latter occurs only in forceful expiration, not in relaxed breathing.• Superior margins and costal cartilages of ribs 2–12; margin of sternum• Inferior margin of next higher ribIntercostal nervesInnermost Intercostals Presumed to have the same action as the internal intercostals.• Superomedial surface of ribs 2–12; may be absent from upper ribs• Medial edge of costal groove of next higher ribIntercostal nervesMany other muscles of the chest and abdomen contribute significantly to breathing (see Deeper Insight 11.1): the sternocleidomastoid and scalenes of the neck; pectoralis major and serratus anterior of the chest; serratus posterior superior and serratus posterior inferior of the back; latissimus dorsi of the lower back; internal and external abdominal obliques and transverse abdominal muscle; and even some of the anal muscles. The respiratory actions of all these muscles are described in chapter 23.38 dia = across; phragm = partition39 inter = between; costa = ribApply What You KnowWhat muscles are eaten as “spare ribs”? What is the tough fibrous membrane between the meat and the bone?D E E P E R I N S I G H T 11.1Difficulty BreathingAsthma, emphysema, heart failure, and other conditions can cause dyspnea, difficulty catching one’s breath. People with dyspnea make increased use of accessory muscles to aid the diaphragm and intercostals in breathing, and often lean on a table or chair back to breathe more deeply. This action fixes the clavicles and scapulae so that accessory muscles such as the pectoralis major and serratus anterior (see chapter 12) move the ribs instead of the bones of the pectoral girdle. CH A P T E R E L E V E N The Muscular System II: Axial Musculature 28140 rectus = straightTABLE 11.6 Muscles of the Anterior Abdominal WallUnlike the thoracic cavity, the abdominal cavity has little skeletal support. It is enclosed, however, in layers of broad flat muscles whose fibers run in different directions, strengthening the abdominal wall on the same principle as the alternating layers of plywood. Three layers of muscle enclose the lumbar region and extend about halfway across the anterior abdomen (fig. 11.10). The most superficial layer is the external abdominal oblique. Its fibers pass downward and anteriorly. The next deeper layer is the internal abdominal oblique, whose fibers pass upward and anteriorly, roughly perpendicular to those of the external oblique. The deepest layer is the transverse abdominal (transversus abdominis), with horizontal fibers. Anteriorly, a pair of vertical rectus abdominis muscles extend from sternum to pubis. These are divided into segments by three transverse tendinous intersections, giving them an appearance that bodybuilders nickname the “six pack.”The tendons of the oblique and transverse muscles are aponeuroses—broad fibrous sheets that continue medially and inferiorly (figs. 11.11 and 11.12). At the rectus abdominis, they diverge and pass around its anterior and posterior sides, enclosing the muscle in a vertical sleeve called the rectus sheath. They meet again at a median line called the linea alba between the rectus muscles. Another line, the linea semilunaris, marks the lateral boundary where the rectus sheath meets the aponeurosis. The aponeurosis of the external oblique also forms a cordlike inguinal ligament at its inferior margin. This extends obliquely from the anterior superior spine of the ilium to the pubis. The linea alba, linea semilunaris, and inguinal ligament are externally visible on a person with good muscle definition (see fig. A.8, p. 338).Name Action Skeletal Attachments InnervationExternal Abdominal ObliqueSupports abdominal viscera against pull of gravity; stabilizes vertebral column during heavy lifting; maintains posture; compresses abdominal organs, thus aiding in forceful expiration and loud vocalization as in singing and public speaking; aids in childbirth, urination, defecation, and vomiting. Unilateral contraction causes contralateral rotation of waist.• Ribs 5–12• Anterior half of iliac crest, pubic symphysis, and superior margin of pubisAnterior rami of spinal nerves T7–T12Internal Abdominal ObliqueSame as external oblique except that unilateral contraction causes ipsilateral rotation of waist• Inguinal ligament, iliac crest, and thoracolumbar fascia• Ribs 10–12, costal cartilages 7–10, pubisAnterior rami of spinal nerves T7–L1Transverse Abdominal Compresses abdominal contents, with same effects as external oblique, but does not contribute to movements of vertebral column• Inguinal ligament, iliac crest, thoracolumbar fascia, costal cartilages 7–12• Linea alba, pubis, aponeurosis of internal obliqueAnterior rami of spinal nerves T7–L1Rectus 40 Abdominis (REC-tus ab-DOM-ih-nis)Flexes lumbar region of vertebral column; flexes waist as in bending forward or doing sit-ups; stabilizes pelvic region during walking; compresses abdominal viscera• Pubic symphysis and superior margin of pubis• Xiphoid process, costal cartilages 5–7Anterior rami of spinal nerves T6–T12Figure 11.10 Cross Section of the Anterior Abdominal Wall.Skin Linea albaPeritoneumRectus sheathSubcutaneous fatMuscles: External abdominal oblique Internal abdominal oblique Transverse abdominal Rectus abdominisAponeurosis of Transverse abdominal Internal abdominal oblique External abdominal obliqueAnteriorPosteriorsal03709_ch11_263-292.indd 281 06/11/15 10:28 AM 282 PA RT T WO Support and MovementTABLE 11.6 Muscles of the Anterior Abdominal Wall (continued)Linea albaTendinous intersectionsUmbilicusSuperficial inguinal ringSpermatic cordAponeurosis ofexternal obliqueInguinal ligamentTransversus abdominisExternal obliqueInternal obliqueRectus abdominisFigure 11.11 Thoracic and Abdominal Muscles of the Cadaver. The rectus sheath is removed on the anatomical left to expose the left rectus abdominis muscle. Inset shows area of dissection.© McGraw-Hill Education/Photo and Dissection by Christine Eckel TABLE 11.6 Muscles of the Anterior Abdominal Wall (continued)Pectoralis majorTendinousintersectionsLinea albaLatissimus dorsiRectus abdominisInguinal ligamentRectus sheath (cut edges)Serratus anteriorAponeurosis ofexternal abdominal obliqueUmbilicusLinea semilunarisTransverse abdominalInternal abdominaloblique (cut)External abdominaloblique (cut)Rectus sheath(a) SuperficialSubclaviusPectoralis minor (cut)Internal intercostalsExternal intercostalsRectus abdominis (cut)External abdominaloblique (cut)Internal abdominaloblique (cut)Transverse abdominal (cut)Posterior wall of rectus sheath(rectus abdominis removed)Internal abdominalobliqueInguinal ligamentRectus sheathSerratus anteriorPectoralis minor(b) DeepFigure 11.12 Thoracic and Abdominal Muscles. (a) Superficial muscles. The left rectus sheath is cut away to expose the rectus abdominis muscle. (b) Deep muscles. On the anatomical right, the external abdominal oblique has been removed to expose the internal abdominal oblique, and the pectoralis major has been removed to expose the pectoralis minor. On the anatomical left, the internal abdominal oblique has been cut to expose the transverse abdominal, and the middle of the rectus abdominis has been cut out to expose the posterior rectus sheath.• Name at least three muscles that lie deep to the pectoralis major. to expose the transverse abdominal, and the middle of the rectus abdominis has been cut out to expose the posterior rectus sheasal03709_ch11_263-292.indd 283 06/11/15 10:28 AM 284 PA RT T WO Support and Movement41 ilio = ilium of the hip bone; costalis = pertaining to the ribs 42 longissimus = longestTABLE 11.7 Muscles of the BackMuscles of the back primarily extend, rotate, and laterally flex the vertebral column. The most prominent superficial back muscles are the latissimus dorsi and trapezius (fig. 11.13), but they are concerned with upper limb movements and covered in chapter 12. Deep to these are the serratus posterior superior and inferior (fig. 11.14). They extend from the vertebrae to the ribs. They aid in deep breathing and are discussed in chapter 23.Deep to these is a prominent muscle, the erector spinae, which runs vertically for the entire length of the back from the cranium to the sacrum. It is a thick muscle, easily palpated on each side of the vertebral column in the lumbar region. (Pork chops and T-bone steaks are erector spinae muscles.) As it ascends, it divides in the upper lumbar region into three parallel columns (figs. 11.14 and 11.15). The most lateral of these is the iliocostalis, 41 which is divided from inferior to superior into the iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis (lumbar, thoracic, and cervical regions). The next medial column is the longissimus, 42 divided from inferior to superior into the longissimus thoracis, longissimus cervicis, and longissimus capitis (thoracic, cervical, and cephalic regions). The most medial column is the spinalis, divided into spinalis thoracis, spinalis cervicis, and spinalis capitis. The functions of all three columns are sufficiently similar that we will treat them collectively as the erector spinae.The major deep muscles are the semispinalis thoracis in the thoracic region and quadratus lumborum in the lumbar region. The erector spinae and quadratus lumborum are enclosed in a fibrous sheath called the thoracolumbar fascia, an attachment for some of the abdominal and lumbar muscles. The multifidus is a collective name for a series of tiny muscles that connect adjacent vertebrae to each other from the cervical to lumbar region.Semispinalis capitisSternocleidomastoidDeltoidLatissimusdorsiThoracolumbarfasciaExternal abdominalobliqueLevator scapulaeRhomboid minorRhomboid majorInfraspinatusTeres minorInternal abdominalobliqueGluteus maximusGluteus mediusGluteus minimusLateral rotatorsSerratus posteriorinferiorSerratus anteriorSupraspinatusErector spinaeSplenius capitisTeres majorExternal abdominalobliqueTrapeziusSuperficial DeepFigure 11.13 Neck, Back, and Gluteal Muscles. The most superficial muscles are shown on the left and the next deeper layer on the right. shown on the left and the next deeper layer sal03709_ch11_263-292.indd 284 06/11/15 10:28 AM CH A P T E R E L E V E N The Muscular System II: Axial Musculature 28543 erector = that which straightens; spinae = of the spineTABLE 11.7 Muscles of the Back (continued)Name Action Skeletal Attachments InnervationErector Spinae 43 (eh-REC-tur SPY-nee)Maintains posture; straightens spine after one bends at the waist; arches back; laterally flexes vertebral column; longissimus capitis also produces ipsilateral rotation of the head• Nuchal ligament, ribs 3–12, thoracic and lumbar vertebrae, median and lateral sacral crests, thoracolumbar fascia• Mastoid process, cervical and thoracic vertebrae, and all ribsPosterior rami of cervical to lumbar spinal nervesSemispinalis Thoracis (SEM-ee-spy-NAY-liss tho-RA-sis)Extension and contralateral rotation of vertebral column• Vertebrae T6–T10• Vertebrae C6–T4Posterior rami of cervical and thoracic spinal nervesLongissimus capitisSemispinalis capitisInternal abdominal obliqueErector spinae:SemispinalisthoracisMultifidusQuadratus lumborumSuperior nuchal lineSplenius capitisSerratus posteriorsuperiorSplenius cervicisExternal abdominaloblique (cut)Semispinalis cervicisSerratus posterior inferiorIliocostalisLongissimusSpinalisFigure 11.14 Muscles Acting on the Vertebral Column. Those on the right are deeper than those on the left. Those on the right are deeper than those sal03709_ch11_263-292.indd 285 06/11/15 10:28 AM 44 quadrat = four-sided; lumborum = of the lumbar region 45 multi = many; fid = branched, sectionedWhen a skeletal muscle is excessively stretched, its sarcomeres are so stretched that its thick and thin myofilaments have little or no overlap. When such a muscle is stimulated to contract, few of the myosin heads are able to attach to the actin filaments (see chapter 10), the contraction is very weak, and the muscle and connective tissues are subject to injury.When you are fully bent over forward, as in touching your toes, the erector spinae is extremely stretched. Standing up from such a position is therefore initiated by the hamstring muscles on the back D E E P E R I N S I G H T 11.2of the thigh and the gluteus maximus of the buttocks. The erector spinae joins in the action when it is partially contracted. Stand-ing too suddenly or improperly lifting a heavy weight, however, can strain the erector spinae, cause painful muscle spasms, tear tendons and ligaments of the lower back, and rupture interver-tebral discs. The lumbar muscles are adapted for maintaining posture, not for lifting. This is why it is important, in heavy lifting, to bend at the knees and use the powerful extensor muscles of the thighs and buttocks to lift the load. Heavy Lifting and Back InjuriesTABLE 11.7 Muscles of the Back (continued)Name Action Skeletal Attachments InnervationQuadratus Lumborum 44 (quad-RAY-tus lum-BORE-um)Aids respiration by fixing rib 12 and stabilizing inferior attachments of diaphragm. Unilateral contraction causes ipsilateral flexion of lumbar vertebral column; bilateral contraction extends lumbar vertebral column.• Iliac crest, iliolumbar ligament• Rib 12 and vertebrae L1–L4Anterior rami of spinal nerves T12–L4Multifidus 45 (mul-TIFF-ih-dus)Stabilization of adjacent vertebrae, maintenance of posture, control of vertebral movement when erector spinae acts on vertebral column• Vertebrae C4–L5, posterior superior iliac spine, sacrum, aponeurosis of erector spinae• Laminae and spinous processes of vertebraePosterior rami of cervical to lumbar spinal nervesFigure 11.15 Deep Back Muscles of the Cadaver.TrapeziusErector spinae: Spinalis thoracis Iliocostalis thoracis Longissimus thoracisRibsExternal intercostalsIliocostalis lumborumLatissimus dorsiThoracolumbar fascia© McGraw-Hill Education/Rebecca Gray, photographer/Don Kincaid, dissections CH A P T E R E L E V E N The Muscular System II: Axial Musculature 28746 ischio = ischium of the hip bone; cavernosus = corpus cavernosum of the penis or clitoris47 bulbo = bulb of the penis; spongiosus = corpus spongiosum of the penis48 levat = to elevate; ani = of the anusTABLE 11.8 Muscles of the Pelvic FloorThe floor of the pelvic cavity is formed mainly by an extensive muscle called the levator ani. Inferior to this is the perineum (PERR-ih-NEE-um), a diamond-shaped area between the thighs bordered by four bony landmarks: the pubic symphysis anteriorly, the coccyx posteriorly, and the ischial tuberosities laterally. The pelvic floor and perineum are penetrated by the anal canal, urethra, and vagina. The anterior half of the perineum is the urogenital triangle and the posterior half is the anal triangle (fig. 11.16b). These are especially important landmarks in obstetrics. The urogenital triangle is divided into two muscle compartments separated by a strong fibrous perineal membrane. The muscle compartment between this membrane and the skin is called superficial perineal space, and the compartment between the perineal membrane and levator ani is the deep perineal space. We will examine these structures beginning inferiorly, just beneath the skin, and progressing superiorly to the pelvic floor.Superficial Perineal Space. The superficial perineal space (fig. 11.16a) contains three pairs of muscles: the ischiocavernosus, bulbospongiosus, and superficial transverse perineal. In females, this space also contains the clitoris; various glands and erectile tissues of the genitalia (see fig. 26.20, p. 725); and adipose tissue, which extends into and fattens the mons pubis and labia majora. In males, it contains the root of the penis. The ischiocavernosus muscles converge like a V from the ischial tuberosities toward the penis or clitoris. In males, the bulbospongiosus (bulbocavernosus) muscles form a sheath around the root of the penis, and in females they enclose the vagina like a pair of parentheses. Cavernosus in these names refers to the spongy, cavernous structure of tissues in the penis and clitoris. The superficial transverse perineal muscles extend from the ischial tuberosities to a strong median fibromuscular anchorage, the perineal body, and a median seam called the perineal raphe (RAY-fee) that extends anteriorly from the perineal body. The muscles may help to anchor the perineal body, but they are weakly developed and not always present, therefore not tabulated below. The other two muscle pairs of this layer serve primarily sexual functions.Name Action Skeletal Attachments InnervationIschiocavernosus 46 (ISS-kee-oh-CAV-er-NO-sus)Maintains erection of penis or clitoris by compressing deep structures of the organ and forcing blood forward into its body• Ramus and tuberosity of ischium• Ensheaths internal structures of penis or clitorisPudendal nerveBulbospongiosus 47 (BUL-bo-SPUN-jee-OH-sus)Expels residual urine from urethra after bladder has emptied. Aids in erection of penis or clitoris. In males, spasmodic contractions expel semen during ejaculation. In females, contractions constrict vaginal orifice and expel secretions of greater vestibular glands.• Perineal body and median raphe• Male: Ensheaths root of penis Female: Pubic symphysisPudendal nerveDeep Perineal Space. The deep perineal space (fig. 11.16b) contains a pair of deep transverse perineal muscles and, in females only, the compressor urethrae muscles. The deep transverse perineal muscles anchor the perineal body on the median plane; the perineal body, in turn, anchors other pelvic muscles. The female external urethral sphincter, long thought to be part of the deep perineal space, is now regarded as part of the urethra itself and not part of the pelvic floor musculature.Deep Transverse Perineal Anchors perineal body, which supports other pelvic muscles; supports vaginal and urethral canals• Ischiopubic rami• Perineal bodyPudendal nerveCompressor Urethrae Aids in urine retention; found in female only • Ischiopubic rami• Right and left compressor urethrae meet each other inferior to external urethral sphincterPudendal nerve; spinal nerves S2–S4; pelvic splanchnic nerveAnal Triangle. The anal triangle contains the external anal sphincter and anococcygeal ligament (fig. 11.16b). The external anal sphincter is a tubular muscle surrounding the lower anal canal. The anococcygeal ligament is the median attachment of the levator ani muscles, and the ligament, in turn, leads to the coccyx. It is therefore a major anchorage for the structures that compose the pelvic floor.External Anal Sphincter Retains feces in rectum until voluntarily voided • Coccyx, perineal body• Encircles anal canal and orificePudendal nerve; spinal nerves S2–S4; pelvic splanchnic nervePelvic Diaphragm. The pelvic diaphragm (fig. 11.16c) is deep to the foregoing structures and is composed mainly of the right and left levator ani muscles. (The piriformis, also illustrated, is primarily a lower limb muscle.) The levator ani spans most of the pelvic outlet and forms the floor of the lesser (true) pelvis. It is divided into three portions that are sometimes regarded as separate muscles—the ischiococcygeus (or coccygeus), iliococcygeus, and pubococcygeus. The left and right levator ani muscles converge on the anococcygeal ligament, through which they are indirectly anchored to the coccyx.Levator Ani 48 (leh-VAY-tur AY-nye)Compresses anal canal and reinforces external anal and urethral sphincters; supports uterus and other pelvic viscera; aids in the falling away of the feces; vertical movements affect pressure differences between abdominal and thoracic cavities and thus aid in deep breathing.• Inner surface of lesser pelvis from pubis through margin of obturator internus to spine of ischium• Coccyx via anococcygeal body; walls of urethra, vagina, and anal canalPudendal nerve; spinal nerves S2–S3sal03709_ch11_263-292.indd 287 06/11/15 10:28 AM 288 PA RT T WO Support and MovementTABLE 11.8 Muscles of the Pelvic Floor (continued)Perineal bodyIschiocavernosusBulbospongiosusUrogenital triangle ClitorisVaginaPerineal bodyDeep transverseperinealExternal analsphincterPubic symphysisPiriformisNerve rootsLevator ani:PubococcygeusIliococcygeusIschiococcygeusUrethraUrethraVaginaRectumFascia ofobturator internusAnococcygeal bodySacrumCompressor urethraeAnusAnal triangleSuperficial transverse perinealLevator aniGluteus maximusCoccyx(a) Superf icial per ineal space, inferior vie w, male(b) Deep perineal space, inferior view, female(c) Pelvic diaphragm, superior view, femaleFigure 11.16 Muscles of the Pelvic Floor. (a) The superficial perineal space, male, viewed from below (the inferior aspect). (b) The deep perineal space, female, viewed from the same perspective. Other than the vaginal canal, the sexes are nearly identical at this level, including the urogenital and anal triangles. The root of the penis does not extend to this level. (c) The pelvic diaphragm, female, viewed from above (from within the pelvic cavity). CH A P T E R E L E V E N The Muscular System II: Axial Musculature 289A hernia is any condition in which the viscera protrude through a weak point in the muscular wall of the abdominopelvic cavity. The most common type to require treatment is an inguinal hernia (fig. 11.17). In the male fetus, each testis descends from the pelvic cavity into the scrotum by way of a passage called the inguinal canal through the muscles of the groin. This canal remains a weak point in the pelvic floor, especially in infants and children. When pressure rises in the abdominal cavity, it can force part of the intestine or bladder into this canal or even into the scrotum. This also sometimes occurs in men who hold their breath while lifting heavy weights. When the diaphragm and abdominal muscles contract, pressure in the abdominal cavity can soar to 1,500 pounds per square inch—more than 100 times the normal pressure and quite sufficient to produce an inguinal hernia, or “rupture.” Inguinal hernias rarely occur in women.Two other sites of hernia are the diaphragm and navel. A hiatal hernia is a condition in which part of the stomach protrudes through the diaphragm into the thoracic cavity. This is most com-mon in overweight people over age 40. It may cause heartburn due to the regurgitation of stomach acid into the esophagus, but most cases go undetected. In an umbilical hernia, abdominal viscera protrude through the navel.D E E P E R I N S I G H T 11.3HerniasFigure 11.17 Inguinal Hernia. A loop of small intestine has protruded through the inguinal canal into a space beneath the skin. Herniated loop ofsmall intestineExternal inguinal ringInguinal canalUpper scrotumAponeurosis of externalabdominal oblique muscleBefore You Go OnAnswer the following questions to test your understanding of the preceding section:7. Which muscles are used more often, the external intercostals or internal intercostals? Explain.8. Explain how pulmonary ventilation affects abdominal pres-sure, and vice versa.9. Name a major superficial muscle and two major deep muscles of the back.10. Define perineum, urogenital triangle, and anal triangle.11. Name one muscle in the superficial perineal space, one in the urogenital diaphragm, and one in the pelvic diaphragm. State the function of each. 290 PA RT T WO Support and MovementS T U D Y G U I D EAssess Your Learning OutcomesTo test your knowledge, discuss the following topics with a study partner or in writing, ideally from memory.General1. For all muscles named in this study guide, and to the extent specified by your course or instructor, an ability to locate the mus-cle on a model, photograph, diagram, or dissection; to palpate the muscle or its ten-dons on the living body; and to identify its attachments, innervation, and actions11.1 Learning Approaches (p. 264)1. Ability to translate words commonly used in the naming of muscles and denoting such characteristics as muscle size, shape, location, number of heads, orientation, and action (table 11.1)2. The meaning of muscle innervation; the relationship of cranial and spinal nerves to the muscles; and the common symbols for these nerves11.2 Muscles of the Head and Neck (p. 268)1. Two scalp muscles—the frontalis and occipitalis—and their relationship to the galea aponeurotica (table 11.2)2. Three muscles of the ocular region—the orbicularis oculi, levator palpebrae superi­oris, and corrugator supercilii (table 11.2)3. The nasalis muscle of the nasal region (table 11.2)4. The location of the modiolus and how it is related to muscles of the oral and buccal regions5. Nine muscles of the oral region—the orbicularis oris, levator labii superioris, levator anguli oris, zygomaticus major and minor, risorius, depressor anguli oris, and depressor labii inferioris (table 11.2)6. Three muscles of the cheek, chin, and ante-rior neck—the mentalis, buccinator, and platysma (table 11.2)7. The difference between the intrinsic and extrinsic muscles of the tongue8. Four extrinsic tongue muscles—the genio­glossus, hyoglossus, styloglossus, and pal­atoglossus (table 11.3)9. Four muscles of chewing—the temporalis, masseter, medial pterygoid, and lateral pterygoid (table 11.3)10. The difference between the suprahyoid and infrahyoid muscle groups11. Four muscles in the suprahyoid group—the digastric, geniohyoid, mylohyoid, and stylohyoid (table 11.3)12. Four muscles of the infrahyoid group—the omohyoid, sternohyoid, thyrohyoid, and sternothyroid (table 11.3)13. The three pharyngeal constrictors and their role in swallowing (table 11.3)14. Four flexor muscles of the neck—the ster­nocleidomastoid and three scalene muscles15. Locations of the anterior and posterior triangles of the neck in relation to the sternocleidomastoid16. Five major extensors of the neck—the tra­pezius, splenius capitis, splenius cervicis, semispinalis capitis, and semispinalis cer­vicis (table 11.4)11.3 Muscles of the Trunk (p. 279)1. The diaphragm and the three layers of intercostal muscles—external, internal, and innermost intercostals (table 11.5)2. The contributions of other thoracic and abdominopelvic muscles to breathing3. The four principal muscles that form the abdominal wall—the external abdomi­nal oblique, internal abdominal oblique, transverse abdominal, and rectus abdomi­nis (table 11.6)4. The relationship of the abdominal muscles to the rectus sheath, inguinal ligament, linea alba, and linea semilunaris5. The erector spinae and its three columns—the iliocostalis, longissimus, and thora­cis—and the regional subdivisions of each column (lumbar, thoracic, cervical, and cephalic, with variations from one column to another) (table 11.7)6. The semispinalis thoracis, quadratus lum­borum, and multifidus (table 11.7)7. The thoracolumbar fascia and its relation-ship to the erector spinae and quadratus lumborum8. The boundaries of the perineum; its two triangles; and its two muscle compartments9. The two main muscles of the superficial perineal space—the ischiocavernosus and bulbospongiosus (table 11.8)10. The deep perineal space and its princi-pal muscle, the deep transverse perineal muscle (table 11.8); how the sexes differ in anatomy of the deep perineal space11. The one muscle of the anal triangle—the external anal sphincter—and significance of the anococcygeal ligament12. The pelvic diaphragm and its levator ani musclesTesting Your Recall1. Which of the following muscles is the prime mover in spitting out a mouthful of liquid?a. platysmab. buccinatorc. risoriusd. massetere. palatoglossus2. The word _____ in a muscle name indi-cates a function related to the head.a. cervicisb. carpic. capitisd. hallucise. teres3. Which of these is not a suprahyoid muscle?a. genioglossusb. geniohyoidc. stylohyoidd. mylohyoide. digastric CH A P T E R E L E V E N The Muscular System II: Axial Musculature 2914. Which of these muscles is an extensor of the neck?a. external obliqueb. sternocleidomastoidc. splenius capitisd. iliocostalise. latissimus dorsi5. Which of these muscles of the pelvic floor is the deepest?a. superficial transverse perinealb. bulbospongiosusc. ischiocavernosusd. deep transverse perineale. levator ani6. The facial nerve supplies all of the follow-ing muscles excepta. the frontalis.b. the orbicularis oculi.c. the orbicularis oris.d. the depressor labii inferioris.e. the mylohyoid.7. The _____ produce(s) lateral grinding movements of the jaw.a. pterygoidsb. temporalisc. hyoglossusd. zygomaticus major and minore. risorius8. All of the following muscles act on the vertebral column excepta. the serratus posterior superior.b. the iliocostalis thoracis.c. the longissimus thoracis.d. the spinalis thoracis.e. the multifidus.9. A muscle that aids in chewing without moving the mandible isa. the temporalis.b. the mentalis.c. the buccinator.d. the levator anguli oris.e. the splenius cervicis.10. Which of the following muscles raises the upper lip?a. levator palpebrae superiorisb. orbicularis orisc. masseterd. zygomaticus minore. mentalis11. The prime mover of spinal extension is the _____.12. Ejaculation results from contraction of the _____ muscle.13. The muscle that opens your eyes is the _____.14. As its name implies, the _____ nerve con-trols several muscles of the tongue.15. The _____ muscle, named for its two bel-lies, opens the mouth.16. The anterior half of the perineum is a region called the _____.17. The abdominal aponeuroses converge on a median fibrous band on the abdomen called the _____. 18. The thyrohyoid muscle attaches to the thy-roid cartilage of the _____.19. The _____ muscles diverge like a V from the middle of the upper thorax to attach-ments behind the ears.20. The largest muscle of the upper back is the _____.Answers in appendix ABuilding Your Medical VocabularyState a medical meaning of each of the following word elements, and give a term in which it is used.1. delt-2. levat-3. oculo-4. apo-5. oris6. digito-7. labio-8. ipsi-9. glosso-10. di-Answers in appendix ATrue or FalseDetermine which five of the following statements are false, and briefly explain why.1. The sternocleidomastoid muscle acts mainly as a fixator of the sternum.2. The largest deep muscle of the lower back is the quadratus lumborum.3. The muscle used to stick out your tongue is the genioglossus.4. The abdominal oblique muscles rotate the vertebral column.5. Exhaling requires contraction of the inter-nal intercostal muscles.6. The digastric muscles form the floor of the mouth.7. The scalenes are superficial to the trapezius.8. Cutting the phrenic nerves would paralyze the prime mover of respiration.9. The orbicularis oculi and orbicularis oris are sphincters.10. All of the cranial nerves innervate muscles of the head and neck.Answers in appendix A 292 PA RT T WO Support and MovementTesting Your Comprehension1. Name one antagonist of each of the fol-lowing muscles: (a) orbicularis oculi, (b) genioglossus, (c) masseter, (d) sterno-cleidomastoid, (e) rectus abdominis.2. Name one synergist of each of the follow-ing muscles: (a) temporalis, (b) diaphragm, (c) platysma, (d) semi spinalis capitis, (e) bulbospongiosus.3. Dental procedures, vaccination, HIV infec-tion, and some other infections occasion-ally injure branches of the facial nerve and weaken or paralyze the affected muscles. Predict the problems that a person would have if the orbicularis oris and buccinator muscles were paralyzed by such a nerve lesion.4. Remova...

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