Y khoa, y dược - The muscular system: Part B

10 The Muscular System: Part BMuscles of the ThoraxMuscles of respirationExternal intercostals—more superficial muscles that elevate ribs for inspirationInternal intercostals—deeper muscles that aid forced expirationDiaphragmPartition between thoracic and abdominal cavitiesMost important muscle in inspirationInnervated by phrenic nervesFigure 10.10aExternalintercostal(a)InternalintercostalMuscles of the ThoraxPLAYA&P Flix™: Internal intercostalsPLAYA&P Flix™: External intercostalsFigure 10.10bForamen foresophagusCostal cartilageLumbarvertebraXiphoid process of sternumDiaphragmQuadratuslumborum Psoas majorForamen for inferiorvena cavaCentraltendon ofdiaphragmForamenfor aorta12th rib(b)Muscles of the Abdominal WallFour paired muscles; their fasciae and aponeuroses form the lateral and anterior abdominal wallInternal obliquesExternal obliquesTransversus abdominisRectus abdominis Figure 10.11aTransversus abdominisInternal obliqueExternal obliqueAponeurosis of theexternal oblique (a)Pectoralis majorLinea albaTendinousintersectionRectusabdominis Inguinal ligament(formed by free inferior border of the external oblique aponeurosis)Serratus anteriorMuscles of the Abdominal WallFascicles of these muscles run at angles to one another, providing added strengthAll are innervated by intercostal nervesActions of these musclesLateral flexion and rotation of the trunkHelp promote urination, defecation, childbirth, vomiting, coughing, and screamingFigure 10.11bTransversusabdominisInguinalligamentLumbarfasciaLumbarfasciaInternalobliquePubictubercleRectusabdominisExternaloblique(b)IIiac crestMuscles of the Abdominal WallPLAYA&P Flix™: Internal obliquesPLAYA&P Flix™: External obliquesPLAYA&P Flix™: Rectus abdominisPLAYA&P Flix™: Transversus abdominisMuscles of the Pelvic Floor Pelvic floor (pelvic diaphragm) is composed of two paired musclesLevator aniCoccygeusBoth are innervated by sacral nervesMuscles of the Pelvic Floor Functions of the pelvic diaphragmSeals the inferior outlet of the pelvisSupports pelvic organsLifts pelvic floor to help release feces Resists increased intra-abdominal pressure Muscles of the PerineumUrogenital diaphragmAnterior half of perineum, inferior to pelvic floorDeep transverse perineal muscleExternal urethral sphincter (voluntary control of urination)Figure 10.12aPelvicdiaphragmSymphysis pubis(a)Levator aniPiriformisPosteriorAnteriorCoccyxCoccygeusObturatorinternusIIiococcygeusLevatorani PubococcygeusUrogenital diaphragmUrethraVaginaAnal canalFigure 10.12bInferior pubic ramusExternal urethralsphincterUrethralopening Vaginalopening Deeptransverseperineal muscleCentral tendonAnusExternal analsphincterMale(b)FemaleMuscles of the PerineumMuscles of superficial perineal spaceIschiocavernosusBulbospongiosusSuperficial transverse perineal musclesExternal anal sphincter (in posterior half of perineum)Figure 10.12cMaleFemalePenisMidline rapheIschiocavernosusClitorisUrethralopeningAnusVaginalopeningBulbospongiosusSuperficialtransverseperineal muscleLevator ani(c)Gluteus maximusPLAYA&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b)PLAYA&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (a)Superficial Muscles of the ThoraxMost are extrinsic shoulder musclesAct in combination to fix the shoulder girdle (mostly the scapula) and move it to increase range of arm movementsActions include elevation, depression, rotation, lateral and medial movements, protraction, and retraction Two groups of muscles: anterior and posteriorSuperficial Muscles of the ThoraxAnterior extrinsic shoulder musclesPectoralis minorSerratus anteriorSubclavius(Pectoralis major considered later with muscles that act on the humerus)PLAYA&P Flix™: Muscles of the pectoral girdle (b)PLAYA&P Flix™: Muscles of the pectoral girdle (a)PLAYA&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b)Figure 10.13aSubclaviusClavicleSubscapularisPectoralis minorCoracobrachialisSerratus anteriorHumerusSternocleido-mastoidDeltoidPectoralismajor SternumBiceps brachii(a)Superficial Muscles of the ThoraxPLAYA&P Flix™: Serratus anteriorPLAYA&P Flix™: Pectoralis minorSuperficial Muscles of the Posterior ThoraxPosterior extrinsic shoulder musclesTrapeziusLevator scpulaeRhomboids (major and minor)(Latissimus dorsi considered later with muscles that act on the humerus)PLAYA&P Flix™: Movement of the pectoral girdlePLAYA&P Flix™: Muscles of the pectoral girdle (c)Figure 10.13cTrapezius(c)LevatorscapulaeSupraspinatusClavicleSpine ofscapula InfraspinatusTeres minorHumerusDeltoidTeres majorLatissimusdorsiRhomboidminorRhomboidmajorSuperficial Muscles of the Posterior ThoraxPLAYA&P Flix™: Levator scapulaPLAYA&P Flix™: TrapeziusPLAYA&P Flix™: Rhomboid majorPLAYA&P Flix™: Rhomboid minor