PowerPoint® Lecture Slidesprepared byBarbara Heard,Atlantic Cape Community College

C H A P T E R

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10

The Muscular System: Part B

The Muscular System: Part B

© 2013 Pearson Education, Inc.

Deep Muscles of the Thorax: Breathing

• Muscles of respiration• External intercostals—more superficial

muscles; elevate ribs for inspiration• Internal intercostals—deeper muscles;

aid forced expiration• Diaphragm

– Partition between thoracic and abdominal cavities

– Most important muscle in inspiration– Innervated by phrenic nerves

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Figure 10.11a Muscles of respiration.

Externalintercostal

Internalintercostal

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PLAYPLAY A&P Flix™: Internal intercostals

PLAYPLAY A&P Flix™: External intercostals

Muscles of the Thorax

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Figure 10.11b Muscles of respiration.

Xiphoid process of sternum

Foramen foresophagus

Costal cartilage

Diaphragm

Lumbarvertebra

Quadratus lumborum

Psoas major

Foramen for inferiorvena cava

Centraltendon ofdiaphragmForamenfor aorta

12th rib

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Figure 10.11c Muscles of respiration.

Body of thoracic vertebra

Aorta

Diaphragm (muscular part)

Inferior vena cava

Esophagus

Pericardial sac

Central tendon of diaphragm

Pericardium (cut)

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Muscles of the Abdominal Wall

• Four paired muscles, their fasciae and aponeuroses form lateral and anterior abdominal wall– Rectus abdominis – External obliques– Internal obliques– Transversus abdominis

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Figure 10.12a Muscles of the abdominal wall.

Linea alba

Pectoralis major

Tendinous intersection

Rectus abdominis

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

Aponeurosis of the external oblique

Transversus abdominis

Internal oblique

External oblique

Serratus anterior

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Muscles of the Abdominal Wall

• Fascicles run at angles to one another, provide added strength

• All innervated by intercostal nerves

• Actions of these muscles– Lateral flexion and rotation of trunk– Help promote urination, defecation, childbirth,

vomiting, coughing, and screaming

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Figure 10.12b Muscles of the abdominal wall.

External oblique

Iliac crest

Rectus abdominis

Internal oblique

Pubic tubercle

Lumbar fascia

Transversusabdominis

Inguinal ligament

Lumbar fascia

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Figure 10.12c Muscles of the abdominal wall.

Linea alba

Peritoneum

Skin

Rectus abdominisInternal oblique

Transversus abdominis

External obliqueAponeuroses

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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 Abdominal Wall

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Muscles of the Pelvic Floor

• Pelvic floor (pelvic diaphragm) composed of two paired muscles– Levator ani– Coccygeus

• Both innervated by sacral nerves

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Muscles of the Pelvic Floor

• Functions of pelvic diaphragm– Seals inferior outlet of pelvis– Supports pelvic organs– Lifts pelvic floor to help release feces – Resists increased intra-abdominal pressure

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Muscles of the Perineum

• Urogenital diaphragm– Anterior half of perineum, inferior to pelvic

floor– Deep transverse perineal muscle– Contains external urethral sphincter

(voluntary control of urination)

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Figure 10.13a Muscles of the pelvic floor and perineum.

Posterior

Coccyx

Obturatorinternus

Anterior

Levator aniPubococcygeusIliococcygeus

Symphysis pubis

Urogenital diaphragmUrethraVaginaAnalcanal

Pelvicdiaphragm

Levator aniCoccygeus

Piriformis

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Figure 10.13b Muscles of the pelvic floor and perineum.

Male Female

UrethralopeningVaginalopening

Inferior pubic ramusExternalUrethralsphincterDeeptransverseperineal muscle

Central tendon

Anus

Externalanal sphincter

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Muscles of the Pelvic Floor and Perineum

• Muscles of superficial perineal space– Ischiocavernosus– Bulbospongiosus– Superficial transverse perineal muscles

• External anal sphincter in posterior half of perineum

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Figure 10.13c Muscles of the pelvic floor and perineum.

AnusGluteus maximus

Male Female

Clitoris

Urethralopening

Midline raphe

Ischiocavernosus

Bulbospongiosus

Penis

Levator ani

Superficialtransverse perineal muscle

Vaginalopening

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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 - extrinsic shoulder muscles– Act in combination to fix shoulder girdle (mostly

scapula); move it to increase range of arm movements

– Actions - elevation, depression, rotation, lateral and medial movements, protraction, and retraction

• Two groups of muscles: anterior and posterior

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

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

Superficial Muscles of the Thorax

• Muscles of anterior thorax– Pectoralis minor– Serratus anterior– Subclavius

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

Figure 10.14a Superficial muscles of the thorax and shoulder acting on the scapula and arm.

Subclavius

Clavicle

Subscapularis

Pectoralis minor

Coracobrachialis

Serratus anterior

Humerus

Sternocleidomastoid

Deltoid

Pectoralis major

Sternum

Biceps brachii

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PLAYPLAY A&P Flix™: Serratus anterior

PLAYPLAY A&P Flix™: Pectoralis minor

Superficial Muscles of the Thorax

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

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

Superficial Muscles of the Posterior Thorax

• Posterior extrinsic shoulder muscles– Trapezius– Levator scapulae– Rhomboids (major and minor)

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Figure 10.14c Superficial muscles of the thorax and shoulder acting on the scapula and arm.

Levatorscapulae

Supraspinatus

Clavicle

Spine ofscapulaInfraspinatus

Teres minor

Teresmajor

Humerus

Trapezius

Deltoid

Rhomboidminor

Rhomboidmajor

Latissimusdorsi

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PLAYPLAY A&P Flix™: Levator scapula

PLAYPLAY A&P Flix™: Trapezius

PLAYPLAY A&P Flix™: Rhomboid major

PLAYPLAY A&P Flix™: Rhomboid minor

Superficial Muscles of the Posterior Thorax