PowerPoint® Lecture Slides

prepared by

Karen Dunbar Kareiva

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Chapter 10 Part B

The Muscular

System

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Table 10.5: Deep Muscles of the Thorax:

Breathing

• Two phases of breathing: inspiration (inhaling) and

expiration (exhaling)

• Inspiratory muscles include diaphragm and external

intercostals

– Contraction of these muscles enlarges rib cage

– Diaphragm divides thoracic and abdominal cavities

• Expiration brought on by relaxation of inspiratory

muscles, as well as contraction of internal

intercostals

– Relaxation of muscles decreases size of rib cage

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Table 10.5 Deep Muscles of the Thorax: Breathing

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Figure 10.11a Muscles of respiration.

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Internalintercostal

Externalintercostal

Table 10.5 Deep Muscles of the Thorax: Breathing

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Figure 10.11b Muscles of respiration.

12th rib

Foramenfor aorta

Centraltendon ofdiaphragm

Foramen for inferiorvena cava

Lumbarvertebra

Quadratuslumborum

Lumbarvertebra

Diaphragm

Costal cartilage

Foramen foresophagus

Xiphoid process of sternum

Psoas major

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Figure 10.11c Muscles of respiration.

Pericardium (cut)

Inferior vena cava

Esophagus

Diaphragm (muscular part)

Pericardial sac

Aorta

Body of thoracic vertebra

Central tendon of diaphragm

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A&P Flix™: External intercostals

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A&P Flix™: Internal intercostals

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Table 10.6: Muscles of the Abdominal Wall:

Trunk Movements and Compression of

Abdominal Viscera

• 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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Table 10.6: Muscles of the Abdominal Wall:

Trunk Movements and Compression of

Abdominal Viscera (cont.)

• 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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Table 10.6 Muscles of the Abdominal Wall: Trunk Movements and Compression of Abdominal Viscera

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Figure 10.12a Muscles of the abdominal wall.

Serratus anterior

Transversus abdominis

Internal oblique

External oblique

Aponeurosisof the externaloblique

Inguinal ligament(formed by free inferiorborder of the externaloblique aponeurosis)

Pectoralis major

Linea alba

Tendinous intersection

Rectus abdominis

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Figure 10.12b Muscles of the abdominal wall.

IIiac crest

Externaloblique

Rectusabdominis

Internaloblique

Pubictubercle

Lumbarfascia

Transversusabdominis

Inguinalligament

Lumbarfascia

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Figure 10.12c Muscles of the abdominal wall.

Rectus abdominis

Internal oblique

PeritoneumTransversus abdominis

External obliqueAponeuroses

Lineaalba

Skin

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A&P Flix™: Rectus abdominis

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A&P Flix™: External obliques

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A&P Flix™: Internal obliques

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A&P Flix™: Transversus abdominis

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Table 10.7: Muscles of the Pelvic Floor and

Perineum: Support of Abdominopelvic

Organs

• Muscles of the pelvic diaphragm

– Composed of two paired muscles

• Levator ani

• Coccygeus

– Both are innervated by sacral nerves

– 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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Table 10.7 Muscles of the Pelvic Floor and Perineum: Support of Abdominopelvic Organs

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Figure 10.13a Muscles of the pelvic floor and perineum.

Levator ani

Posterior

Anterior

Coccygeus

Levator ani

CoccygeusPelvicdiaphragm

Symphysis pubis

Piriformis

Coccyx

PubococcygeusUrogenital diaphragm

Urethra

Vagina

IIiococcygeus

AnalcanalObturator

internus

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Table 10.7: Muscles of the Pelvic Floor and

Perineum: Support of Abdominopelvic

Organs (cont.)

• Muscles of the 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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Table 10.7 Muscles of the Pelvic Floor and Perineum: Support of Abdominopelvic Organs

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Figure 10.13b Muscles of the pelvic floor and perineum.

Inferior pubic ramus

Central tendon

Anus

Male Female

External analsphincter

Deep transverseperineal muscle

External urethralsphincter

Vaginalopening

Urethralopening

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Table 10.7: Muscles of the Pelvic Floor and

Perineum: Support of Abdominopelvic

Organs (cont.)

• Muscles of superficial perineal space

– Ischiocavernosus and bulbospongiosus help

maintain erection of penis and clitoris

– Superficial transverse perineal muscles

• External anal sphincter is located in posterior

half of perineum

– Allows voluntary control of defecation

• Central tendon of perineum

– Strong tendon that many perineal muscles insert

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Table 10.7 Muscles of the Pelvic Floor and Perineum: Support of Abdominopelvic Organs

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Figure 10.13c Muscles of the pelvic floor and perineum.

Penis

Male Female

Midline raphe

Ischiocavernosus

Anus

Levator ani

Gluteus maximus

Clitoris

Bulbospongiosus

Superficialtransverseperineal muscle

Urethralopening

Vaginalopening

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Table 10.8: Superficial Muscles of the

Anterior and Posterior Thorax: Movements of

the Scapula and Arm

• Most are 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

– Muscles of the anterior thorax

– Muscles of the posterior thorax

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Table 10.8-1 Superficial Muscles of the Anterior and Posterior Thorax: Movements of the Scapula and Arm

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

Sternocleidomastoid

Deltoid

Pectoralis major

Sternum

Biceps brachii

Subclavius

Subscapularis

Pectoralis minor

Coracobrachialis

Serratus anterior

Humerus

Clavicle

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

Deltoid

Sternocleidomastoid

Subclavius

Serratus anterior

Coracobrachialis

Rectus abdominis

Pectoralis minor

Biceps brachii

Internal intercostals(seen through externalintercostal membranes)

Cephalicvein

Pectoralismajor

Externaloblique

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A&P Flix™: Muscles of Pectoral Girdle (a)

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A&P Flix™: Muscles of Pectoral Girdle (b)

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A&P Flix™: Pectoralis minor

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A&P Flix™: Serratus anterior

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Table 10.8-2 Superficial Muscles of the Anterior and Posterior Thorax: Movements of the Scapula and Arm (continued)

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

Trapezius

Deltoid

Supraspinatus

Clavicle

Spine of scapula

Infraspinatus

Teres minor

Humerus

Teres major

Rhomboid

minor

Rhomboid

major

Latissimus

dorsi

Levator

scapulae

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

Trapezius

Deltoid

Teres major

Triceps brachii

Latissimus

dorsi

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

Deltoid

Infraspinatus

Teres major

Teres minor

Latissimus dorsi

Rhomboid

major

Rhomboid

minor

Levator scapulae

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A&P Flix™: Trapezius

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A&P Flix™: Levator scapulae

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A&P Flix™: Rhomboid major

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A&P Flix™: Rhomboid minor

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A&P Flix™: Muscles of Pectoral Girdle

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A&P Flix™: Movement of Pectoral Girdle

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