Lecture Human anatomy and physiology - Chapter 10: The muscular system (part b)

PowerPoint® Lecture Slides
prepared by
Janice Meeking,
Mount Royal College

CHAPTER

10

The Muscular
System:
Part B
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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
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External
intercostal

(a)
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Internal
intercostal
Figure 10.10a


Muscles of the Thorax

PLAY

A&P Flix™: External intercostals

PLAY

A&P Flix™: Internal intercostals

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Foramen for inferior
vena cava
Central
tendon of
diaphragm
Foramen
for aorta
12th rib
(b)

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Xiphoid process of sternum
Foramen for
esophagus
Costal cartilage
Diaphragm
Lumbar
vertebra
Quadratus
lumborum
Psoas major

Figure 10.10b


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

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Pectoralis major

Serratus anterior
Linea alba
Transversus abdominis
Internal oblique
External oblique
Aponeurosis of the
external oblique
(a)

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Tendinous
intersection
Rectus
abdominis

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

Figure 10.11a


Muscles of the Abdominal Wall
• 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

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Rectus
abdominis
Internal
oblique
Pubic
tubercle

External
oblique
IIiac crest

Transversus
abdominis
Inguinal
ligament

Lumbar
fascia

Lumbar
fascia

(b)

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Figure 10.11b


Muscles of the Abdominal Wall

PLAY

A&P Flix™: External obliques

PLAY

A&P Flix™: Internal obliques

PLAY

A&P Flix™: Rectus abdominis

PLAY

A&P Flix™: Transversus abdominis

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Muscles of the Pelvic Floor
• Pelvic floor (pelvic diaphragm) is composed of
two paired muscles
• Levator ani

• Coccygeus

• Both are innervated by sacral nerves

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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

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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)

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Levator
ani

Pubococcygeus
IIiococcygeus

Anterior

Obturator
internus
Coccyx

Levator ani
Coccygeus

Piriformis

(a)

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Symphysis pubis
Urogenital diaphragm
Urethra
Vagina
Anal canal

Posterior

Pelvic
diaphragm

Figure 10.12a


Urethral
opening

External urethral
sphincter
Inferior pubic ramus
Deep
transverse
perineal
muscle
Central tendon

Vaginal
opening

Anus
External anal
sphincter
(b)

Male

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Female

Figure 10.12b

Muscles of the Perineum
• Muscles of superficial perineal space
• Ischiocavernosus
• Bulbospongiosus
• Superficial transverse perineal muscles

• External anal sphincter (in posterior half of
perineum)

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Urethral
opening
Vaginal
opening

Clitoris
Anus
Penis
Midline raphe
Ischiocavernosus
Bulbospongiosus
Superficial
transverse
perineal muscle
Levator ani
Gluteus maximus

(c)

Male

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Female

Figure 10.12c


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
PLAY
PLAY

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

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Superficial Muscles of the Thorax
• Anterior extrinsic shoulder muscles
• Pectoralis minor
• Serratus anterior
• Subclavius

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

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

PLAY

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

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Sternocleidomastoid

Subclavius
Clavicle
Subscapularis
Pectoralis minor

Deltoid
Pectoralis

major
Sternum

Coracobrachialis
Serratus anterior

Biceps brachii

Humerus

(a)
PLAY

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

Copyright © 2010 Pearson Education, Inc.

Figure 10.13a


Superficial Muscles of the Thorax

PLAY

A&P Flix™: Pectoralis minor

PLAY

A&P Flix™: Serratus anterior

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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)
PLAY

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

PLAY

A&P Flix™: Movement of the pectoral girdle

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Levator
scapulae
Trapezius

Supraspinatus
Clavicle

Deltoid
Rhomboid
minor
Rhomboid
major

Spine of
scapula
Infraspinatus
Teres minor
Teres major
Humerus

Latissimus
dorsi

(c)
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Figure 10.13c


Superficial Muscles of the Posterior Thorax

PLAY

A&P Flix™: Trapezius

PLAY

A&P Flix™: Levator scapula

PLAY

A&P Flix™: Rhomboid major

PLAY

A&P Flix™: Rhomboid minor

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