THE MUSCULAR SYSTEM (ANATOMY)

Copyright © 2010 Pearson Education, Inc.

THE MUSCULAR SYSTEM(ANATOMY)

CHAPTER # 10(b)


Muscles of the Thorax

• Muscles of respiration

• External intercostals—more superficial muscles that elevate ribs for inspiration

• Internal intercostals—deeper muscles that aid forced expiration

• Diaphragm

• Partition between thoracic and abdominal cavities

• Most important muscle in inspiration

• Innervated by phrenic nerves

Copyright © 2010 Pearson Education, Inc. Figure 10.10a

Externalintercostal

(a) Internalintercostal


Muscles of the Thorax

PLAYPLAY A&P Flix™: Internal intercostals

PLAYPLAY A&P Flix™: External intercostals

Copyright © 2010 Pearson Education, Inc. Figure 10.10b

Foramen foresophagusCostal cartilage

Lumbarvertebra

Xiphoid process of sternum

Diaphragm

Quadratuslumborum Psoas major

Foramen for inferiorvena cava

Centraltendon ofdiaphragm

Foramenfor aorta

12th rib

(b)


Muscles of the Abdominal Wall

• Four paired muscles; their fasciae and aponeuroses form the lateral and anterior abdominal wall

• Internal obliques

• External obliques

• Transversus abdominis

• Rectus abdominis


Transversus abdominis

Internal oblique

External oblique

Aponeurosis of theexternal oblique

(a)

Pectoralis major

Linea alba

Tendinousintersection

Rectusabdominis

Inguinal ligament(formed by free inferior border of the external oblique aponeurosis)

Serratus anterior



• Fascicles of these muscles run at angles to one another, providing added strength

• All are innervated by intercostal nerves

• Actions of these muscles

• Lateral flexion and rotation of the trunk

• Help promote urination, defecation, childbirth, vomiting, coughing, and screaming


Transversusabdominis

Inguinalligament

Lumbarfascia

Lumbarfascia

Internaloblique

Pubictubercle

Rectusabdominis

Externaloblique

(b)

IIiac crest



PLAYPLAY A&P Flix™: Internal obliques

PLAYPLAY A&P Flix™: External obliques

PLAYPLAY A&P Flix™: Rectus abdominis

PLAYPLAY A&P Flix™: Transversus abdominis


Muscles of the Pelvic Floor

• Pelvic floor (pelvic diaphragm) is composed of two paired muscles

• Levator ani

• Coccygeus

• Both are innervated by sacral nerves


Muscles of the Pelvic Floor

• Functions of the pelvic diaphragm

• Seals the inferior outlet of the pelvis

• Supports pelvic organs

• Lifts pelvic floor to help release feces

• Resists increased intra-abdominal pressure


Muscles of the Perineum

• Urogenital diaphragm

• Anterior half of perineum, inferior to pelvic floor

• Deep transverse perineal muscle

• External urethral sphincter (voluntary control of urination)


Pelvicdiaphragm

Symphysis pubis

(a)

Levator aniPiriformis

Posterior

Anterior

Coccyx

Coccygeus

Obturatorinternus

IIiococcygeusLevatorani

PubococcygeusUrogenital diaphragm

UrethraVaginaAnal canal


Inferior pubic ramus

External urethralsphincter

Urethralopening

Vaginalopening

Deeptransverseperineal muscleCentral tendon

Anus

External analsphincter

Male(b) Female


Muscles of the Perineum

• Muscles of superficial perineal space

• Ischiocavernosus

• Bulbospongiosus

• Superficial transverse perineal muscles

• External anal sphincter (in posterior half of perineum)

Copyright © 2010 Pearson Education, Inc. Figure 10.12c

Male Female

PenisMidline rapheIschiocavernosus

ClitorisUrethralopening

Anus Vaginalopening

BulbospongiosusSuperficialtransverseperineal muscle

Levator ani

(c)

Gluteus maximus


PLAYPLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b)

PLAYPLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (a)

Superficial Muscles of the Thorax

• Most are extrinsic shoulder muscles

• Act in combination to fix the shoulder girdle (mostly the scapula) and move it to increase range of arm movements

• Actions include elevation, depression, rotation, lateral and medial movements, protraction, and retraction

• Two groups of muscles: anterior and posterior



• Anterior extrinsic shoulder muscles

• Pectoralis minor

• Serratus anterior

• Subclavius

• (Pectoralis major considered later with muscles that act on the humerus)

PLAYPLAY A&P Flix™: Muscles of the pectoral girdle (b)

PLAYPLAY A&P Flix™: Muscles of the pectoral girdle (a)


PLAYPLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b)

Figure 10.13a

Subclavius

Clavicle

SubscapularisPectoralis minor

Coracobrachialis

Serratus anterior

Humerus

Sternocleido-mastoid

DeltoidPectoralismajor Sternum

Biceps brachii

(a)



PLAYPLAY A&P Flix™: Serratus anterior

PLAYPLAY A&P Flix™: Pectoralis minor


Superficial Muscles of the Posterior Thorax

• Posterior extrinsic shoulder muscles

• Trapezius

• Levator scpulae

• Rhomboids (major and minor)

• (Latissimus dorsi considered later with muscles that act on the humerus)

PLAYPLAY A&P Flix™: Movement of the pectoral girdle

PLAYPLAY A&P Flix™: Muscles of the pectoral girdle (c)

Copyright © 2010 Pearson Education, Inc. Figure 10.13c

Trapezius

(c)

Levatorscapulae

Supraspinatus

Clavicle

Spine ofscapula

InfraspinatusTeres minor

Humerus

Deltoid

Teres major

Latissimusdorsi

RhomboidminorRhomboidmajor


Superficial Muscles of the Posterior Thorax

PLAYPLAY A&P Flix™: Levator scapula

PLAYPLAY A&P Flix™: Trapezius

PLAYPLAY A&P Flix™: Rhomboid major

PLAYPLAY A&P Flix™: Rhomboid minor

THE MUSCULAR SYSTEM (ANATOMY)

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