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Muscular system

Open Posted By: highheaven1 Date: 11/01/2021 High School Rewriting & Paraphrasing

 

Essay about the Muscular system.  

Introduction, description, and conclusion.

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Category: Accounting & Finance Subjects: Behavioral Finance Deadline: 12 Hours Budget: $150 - $300 Pages: 3-6 Pages (Medium Assignment)

Attachment 1

Fundamentals of Anatomy & Physiology

Eleventh Edition

Chapter 11

The Muscular System

Lecture Presentation by

Deborah A. Hutchinson

Seattle University

© 2018 Pearson Education, Inc.

© 2018 Pearson Education, Inc.

1

Learning Outcomes

11-1 Describe the arrangement of fascicles in the various types of muscles, and explain the resulting functional differences.

11-2 Describe the classes of levers, and explain how they make muscles more efficient.

11-3 Predict the actions of a muscle on the basis of its origin and insertion, and explain how muscles interact to produce or oppose movements.

11-4 Explain how the name of a muscle can help identify its location, appearance, or function.

2

© 2018 Pearson Education, Inc.

Learning Outcomes

11-5 Compare and contrast the axial and appendicular muscles.

11-6 Identify the principal axial muscles of the body, plus their origins, insertions, actions, and innervation.

11-7 Identify the principal appendicular muscles of the body, plus their origins, insertions, actions, and innervation, and compare the major functional differences between the upper and lower limbs.

11-8 Explain the functional relationship between the muscular system and other body systems, and explain the role of exercise in producing various responses in other body systems.

3

© 2018 Pearson Education, Inc.

An Introduction to the Muscular System

The muscular system

Consists only of skeletal muscles

Muscle organization dramatically affects power, range, and speed of movement

4

© 2018 Pearson Education, Inc.

11-1 Fascicle Arrangement

Skeletal muscle fibers form bundles called fascicles

Muscles are classified based on patterns of fascicle arrangement

Parallel muscles

Convergent muscles

Pennate muscles

Circular muscles

5

© 2018 Pearson Education, Inc.

11-1 Fascicle Arrangement

Parallel muscles

Fascicles are parallel to long axis of muscle

Some are flat

Cylindrical muscles have a central body (belly)

Example: biceps brachii

Tension developed during a contraction depends on total number of myofibrils

6

© 2018 Pearson Education, Inc.

Figure 11–1a Muscle Types Based on Pattern of Fascicle Arrangement.

Parallel Muscles

Parallel muscle

(Biceps brachii)

(a)

Fascicle

Body

(belly)

Cross section

a

7

Figure 11–1b Muscle Types Based on Pattern of Fascicle Arrangement.

Parallel Muscles

Parallel muscle

with tendinous

bands

(Rectus abdominis)

(b)

b

8

Figure 11–1c Muscle Types Based on Pattern of Fascicle Arrangement.

Parallel Muscles

Wrapping

muscle

(Supinator)

(c)

c

9

11-1 Fascicle Arrangement

Convergent muscles

Muscle fibers spread out like a fan and converge on an attachment site

Example: pectoralis muscles

Muscle may pull on

Tendon

Aponeurosis

Raphe (slender band of collagen fibers)

Fibers pull in different directions, depending on activity

10

© 2018 Pearson Education, Inc.

Figure 11–1d Muscle Types Based on Pattern of Fascicle Arrangement.

Convergent Muscles

(d)

Convergent muscle

(Pectoralis)

Tendon

Base of

muscle

Cross

section

d

11

11-1 Fascicle Arrangement

Pennate muscles

Muscle fibers pull at an angle relative to tendon

Compared to parallel muscles, pennate muscles

Do not move their tendons as far

Contain more myofibrils

Develop more tension

12

© 2018 Pearson Education, Inc.

11-1 Fascicle Arrangement

Pennate muscles

Unipennate

All fascicles on same side of tendon

Example: extensor digitorum

Bipennate

Fascicles on both sides of a central tendon

Example: rectus femoris

Multipennate

Tendon branches within muscle

Example: deltoid

13

© 2018 Pearson Education, Inc.

Figure 11–1e Muscle Types Based on Pattern of Fascicle Arrangement.

Pennate Muscles

Unipennate

muscle

(Extensor digitorum)

(e)

Extended

tendon

e

14

Figure 11–1f Muscle Types Based on Pattern of Fascicle Arrangement.

Pennate Muscles

Bipennate

muscle

(Rectus femoris)

(f)

f

15

Figure 11–1g Muscle Types Based on Pattern of Fascicle Arrangement.

Pennate Muscles

Multipennate muscle

(Deltoid)

(g)

Tendons

Cross section

g

16

11-1 Fascicle Arrangement

Circular muscles (sphincters)

Act as valves in digestive and urinary tracts

Surround body openings and hollow organs

Contraction makes diameter of opening smaller

Example: orbicularis oris of the mouth

17

© 2018 Pearson Education, Inc.

Figure 11–1h Muscle Types Based on Pattern of Fascicle Arrangement.

(h)

Circular Muscles

Circular muscle

(Orbicularis oris)

Contracted

Relaxed

h

18

11-2 Levers

Almost all skeletal muscles attach to bones

Site of connection to a bone affects force, speed, and range of movement

Each bone acts as a lever (a rigid, moving structure)

Moves on a fixed point (fulcrum) when muscles provide applied force to overcome the load

Each joint is a fulcrum

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© 2018 Pearson Education, Inc.

11-2 Levers

Levers can change

Direction of applied force (AF)

Distance and speed produced by AF

Effective strength of AF

Three classes of levers

Based on relative positions of applied force, fulcrum, and load

First-class lever

Second-class lever

Third-class lever

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© 2018 Pearson Education, Inc.

11-2 Levers

First-class lever

Fulcrum lies between applied force and load

Like a pry bar or crowbar

Example: extension of the neck and lifting the head

21

© 2018 Pearson Education, Inc.

Figure 11–2a The Three Classes of Levers.

First-class lever

The fulcrum (F) lies between the

applied force (AF) and the load (L).

Splenius capitis and

semispinalis capitis

Example: Pry bar

L

AF

L

Load

L

F

AF

Fulcrum

F

AF

Applied

force

F

a

22

11-2 Levers

Second-class lever

Load lies between applied force and fulcrum

Like a wheelbarrow

Small force moves a large weight

Example: ankle extension (plantar flexion) by calf muscles

23

© 2018 Pearson Education, Inc.

Figure 11–2b The Three Classes of Levers.

Second-class lever

The load (L) lies between the applied force

(AF) and the fulcrum (F).

AF

AF

L

Gastrocnemius

Example: Wheelbarrow

Load

AF

Fulcrum

F

L

L

Applied

force

F

F

b

24

11-2 Levers

Third-class lever

Applied force is between load and fulcrum

Like a pair of tongs

Most common lever in the body

Maximizes speed and distance traveled at expense of effective force

25

© 2018 Pearson Education, Inc.

Figure 11–2c The Three Classes of Levers.

Third-class lever

The force (F) is applied between

the load (L) and the fulcrum (F).

Applied

force

AF

AF

F

AF

Load

L

L

Biceps brachii

L

Fulcrum

F

Example: Tongs

F

c

26

11-3 Origins and Insertions

Origins and insertions

Fixed point of attachment of a muscle to bone is the origin

Movable point of attachment is the insertion

Origin is usually proximal to insertion

27

© 2018 Pearson Education, Inc.

11-3 Origins and Insertions

Actions

Movements produced by muscle contraction

Example: adduction, elevation, pronation, etc.

Described in terms of effect on bone or joint

Example: flexion of the forearm, or flexion at the elbow

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© 2018 Pearson Education, Inc.

11-3 Origins and Insertions

Muscle interactions

Muscles work in groups to maximize efficiency

Smaller muscles reach maximum tension first, followed by larger, primary muscles

Four terms refer to how muscles work together

Agonist

Antagonist

Synergist

Fixator

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© 2018 Pearson Education, Inc.

11-3 Origins and Insertions

Agonist (prime mover)

Mostly responsible for producing a particular movement

Antagonist

Opposes movement of a particular agonist

Synergist

A smaller muscle that assists a larger agonist

Fixator

A synergist that assists an agonist by preventing movement at another joint

30

© 2018 Pearson Education, Inc.

11-3 Origins and Insertions

Muscle opposition

Agonists and antagonists work in pairs

When one contracts, the other stretches

Such as flexors–extensors and abductors–adductors

31

© 2018 Pearson Education, Inc.

Figure 11–3 Muscle Action (Part 1 of 3).

Flexion and Extension

At joints that permit flexion and extension, muscles whose

lines of action cross the anterior side of a joint are flexors

of that joint, and muscles whose lines of action cross the

posterior side of a joint are

extensors of that joint.

ANTERIOR

Flexor

The biceps brachii

crosses on the

anterior side of the

elbow joint. So it is

a flexor of the

elbow joint.

FLEXION

Elbow joint

POSTERIOR

Extensor

The triceps brachii

crosses on the

posterior side of

the elbow joint. So

it is an extensor of

the elbow joint.

EXTENSION

32

Figure 11–3 Muscle Action (Part 2 of 3).

Abduction and Adduction

At joints that permit adduction and abduction, muscles whose

lines of action cross the medial side of a joint are adductors

of that joint, and muscles whose lines of action cross the lateral

side of a joint are abductors

of that joint.

LATERAL

Abductor

The gluteus medius

and minimus cross

the lateral side of

the hip joint. So

they are abductors

of the hip joint.

Hip joint

MEDIAL

Adductor

The adductor

magnus crosses

on the medial

side of the hip

joint. So it is an

adductor of the

hip joint.

ABDUCTION

ADDUCTION

33

Figure 11–3 Muscle Action (Part 3 of 3).

Medial and Lateral Rotation

Shoulder joint

POSTERIOR

Lateral rotator

The teres minor

crosses the posterior

side of the shoulder

joint. When it

contracts, it rotates

the shoulder laterally.

ANTERIOR

Medial rotator

The subscapularis

crosses on the

anterior side of the

shoulder joint. When it

contracts, it rotates

the shoulder medially.

Scapula

Humerus

At joints that permit rotation,

movement or turning of the body

part occurs around its axis. The

shoulder joint is a

ball-and-socket joint that

permits rotation. The

subscapularis has lines of action

that cross the anterior aspect of

the shoulder joint. When the subscapularis contracts it produces medial rotation at the joint. The teres minor has lines of action that cross the posterior aspect of the shoulder joint. When the teres minor contracts, it produces lateral rotation at the shoulder.

34

11-4 Naming Skeletal Muscles

The body has approximately 700 skeletal muscles

Names of muscles include descriptive information about

Region of the body (e.g., temporalis)

Position, direction, or fascicle arrangement

Structural characteristics

Action

35

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating specific regions of the body

Abdominal (abdomen)

Ancon (elbow)

Auricular (ear)

Brachial (arm)

Capitis (head)

Carpi (wrist)

Cervicis (neck)

36

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating specific regions of the body

Coccygeal (coccyx)

Costal (rib)

Cutaneous (skin)

Femoris (thigh)

Glossal (tongue)

Hallux (great toe)

Ilium (groin)

Inguinal (groin)

37

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating specific regions of the body

Lumbar (lumbar region)

Nasalis (nose)

Nuchal (back of neck)

Ocular (eye)

Oris (mouth)

Palpebra (eyelid)

Pollex (thumb)

Popliteal (posterior to knee)

Psoas (loin)

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© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating specific regions of the body

Radial (forearm)

Scapular (scapula)

Temporal (temple)

Thoracic (thorax)

Tibial (tibia; shin)

Ulnar (ulna)

39

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Position, direction, or fascicle arrangement

Externus (superficialis)

Muscles visible at body surface

Internus (profundus)

Deeper muscles

Extrinsic muscles

Position or stabilize an organ

Intrinsic muscles

Located entirely within an organ

40

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Position, direction, or fascicle arrangement

Transversus muscles

Run across the long axis of the body

Oblique muscles

Run at a slant to long axis

Rectus (straight) muscles

Run along the long axis

Example: rectus abdominis

41

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating position, direction, or fascicle arrangement

Anterior (front)

External (on the outside)

Extrinsic (outside the structure)

Inferior (below)

Internal (away from the surface)

Intrinsic (within the structure)

Lateral (on the side)

Medial (middle)

42

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating position, direction, or fascicle arrangement

Oblique (slanting)

Posterior (back)

Profundus (deep)

Rectus (straight)

Superficial (toward the surface)

Superior (toward the head)

Transverse (crosswise)

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© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Structural characteristics

Origin and insertion

First part of name indicates origin

Second part indicates insertion

Example: genioglossus

Number of tendons

Example: biceps brachii

Shape and size

Example: trapezius, deltoid, rhomboid

Many terms refer to muscle size

44

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating structural characteristics

Nature of origin

Biceps (two heads)

Triceps (three heads)

Quadriceps (four heads)

45

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating structural characteristics

Shape

Deltoid (triangle)

Orbicularis (circle)

Pectinate (comblike)

Piriformis (pear shaped)

Platysma (flat plate)

Pyramidal (pyramid)

46

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11-4 Naming Skeletal Muscles

Terms indicating structural characteristics

Shape

Rhomboid (parallelogram)

Serratus (serrated)

Splenius (bandage)

Teres (round and long)

Trapezius (trapezoid)

47

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11-4 Naming Skeletal Muscles

Terms indicating structural characteristics

Other striking features

Alba (white)

Brevis (short)

Gracilis (slender)

Latae (wide)

Latissimus (widest)

Longissimus (longest)

Longus (long)

48

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating structural characteristics

Other striking features

Magnus (large)

Major (larger)

Maximus (largest)

Minimus (smallest)

Minor (smaller)

Vastus (great)

49

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Action

Movements

Example: flexor, extensor, pronator, etc.

Occupations or habits

Example: buccinator means “trumpeter”

50

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating general actions

Abductor (movement away)

Adductor (movement toward)

Depressor (lowering movement)

Extensor (straightening movement)

Flexor (bending movement)

Levator (raising movement)

Pronator (turning into prone position)

Supinator (turning into supine position)

Tensor (tensing movement)

51

© 2018 Pearson Education, Inc.

11-4 Naming Skeletal Muscles

Terms indicating specific actions

Buccinator (trumpeter)

Risorius (laugher)

Sartorius (like a tailor)

52

© 2018 Pearson Education, Inc.

11-5 Axial and Appendicular Muscles

Divisions of the muscular system

Axial muscles

60 percent of skeletal muscles

Position head and vertebral column

Move rib cage

Form pelvic floor

Appendicular muscles

Move and support pectoral and pelvic girdles and limbs

53

© 2018 Pearson Education, Inc.

Figure 11–4a An Overview of the Major Skeletal Muscles (Part 1 of 6).

Axial Muscles

Frontal belly of occipitofrontalis

Temporoparietalis (reflected)

Temporalis

Sternocleidomastoid

Rectus abdominis

External oblique

Clavicle

Sternum

Appendicular Muscles

Trapezius

Deltoid

Pectoralis major

Latissimus dorsi

Serratus anterior

Biceps brachii

Triceps brachii

Brachialis

Pronator teres

Brachioradialis

Extensor carpi radialis longus

Extensor carpi radialis brevis

Palmaris longus

Flexor carpi radialis

Flexor digitorum superficialis

Flexor carpi ulnaris

Linea alba

Anterior view

ATLAS: Plates 1a; 39a–d

a

54

Figure 11–4a An Overview of the Major Skeletal Muscles (Part 2 of 6).

Appendicular Muscles

Gluteus medius

Tensor fasciae latae

Pectineus

Adductor longus

Gracilis

Sartorius

Rectus femoris

Vastus lateralis

Vastus medialis

Gastrocnemius

Fibularis longus

Tibialis anterior

Soleus

Extensor digitorum longus

Medial malleolus of tibia

Lateral malleolus of fibula

Iliopsoas

Iliotibial tract

Patella

Tibia

Superior extensor retinaculum

Inferior extensor retinaculum

Anterior view

ATLAS: Plates 1a; 39a–d

a

55

Figure 11–4b An Overview of the Major Skeletal Muscles (Part 1 of 6).

Axial Muscles

Occipital belly of

occipitofrontalis

Sternocleidomastoid

Appendicular Muscles

Trapezius

Deltoid

Infraspinatus

Teres minor

Teres major

External oblique

Triceps brachii (long head)

Latissimus dorsi

Brachioradialis

Anconeus

Rhomboid major

Triceps brachii (lateral head)

Extensor carpi radialis longus

Flexor carpi ulnaris

Extensor digitorum

Extensor carpi ulnaris

Posterior view

ATLAS: Plates 1b; 40a,b

b

56

Figure 11–4b An Overview of the Major Skeletal Muscles (Part 2 of 6).

Appendicular Muscles

Gluteus medius

Tensor fasciae latae

Gluteus maximus

Adductor magnus

Semitendinosus

Iliotibial tract

Semimembranosus

Gracilis

Biceps femoris

Sartorius

Plantaris

Gastrocnemius

Soleus

Calcaneal tendon

Calcaneus

Posterior view

ATLAS: Plates 1b; 40a,b

b

57

11-6 Axial Muscles

Axial muscles

Grouped based on location and function

Muscles of the head and neck

Muscles of the vertebral column

Oblique and rectus muscles

Muscles of the pelvic floor

58

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11-6 Axial Muscles

Muscles of the head and neck

Muscles of facial expression

Originate on skull

Muscles of mastication

Move the mandible

Muscles of the tongue

Names end in glossus

Muscles of the pharynx

Begin swallowing process

59

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11-6 Axial Muscles

Muscles of the head and neck

Extrinsic eye muscles

Originate on surface of orbit

Control position of eyes

Muscles of the anterior neck

Control position of larynx

Depress the mandible and tense floor of mouth

Support muscles of tongue and pharynx

60

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11-6 Axial Muscles

Muscles of facial expression

Orbicularis oris

Constricts the mouth opening

Buccinator

Moves food across the teeth

In infants, provides suction for nursing

61

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11-6 Axial Muscles

Muscles of facial expression

Muscles of the epicranium (scalp)

Temporoparietalis

Occipitofrontalis

Frontal belly and occipital belly are separated by epicranial aponeurosis

Platysma

Covers anterior surface of neck

62

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Figure 11–5a Muscles of Facial Expression.

Epicranial aponeurosis

Frontal belly of occipitofrontalis

Procerus

Orbicularis oculi

Nasalis

Levator labii superioris

Zygomaticus minor

Levator anguli oris

Zygomaticus major

Mentalis (cut)

Orbicularis oris

Depressor labii inferioris

Depressor anguli oris

Omohyoid

Temporoparietalis

(cut and reflected)

Temporalis

Occipital belly of

occipitofrontalis

Masseter

Buccinator

Sternocleidomastoid

Trapezius

Platysma (cut and reflected)

Lateral view

a

63

Figure 11–5b Muscles of Facial Expression.

Frontal belly of

occipitofrontalis

Corrugator supercilii

Temporalis

(temporoparietalis removed)

Orbicularis oculi

Nasalis

Zygomaticus minor

Zygomaticus major

Orbicularis oris

Risorius

Platysma

Mentalis (cut)

Thyroid cartilage of the larynx

Epicranial aponeurosis

Temporoparietalis

(cut and reflected)

Temporalis

Procerus

Levator labii superioris

Levator anguli oris

Masseter

Buccinator

Depressor anguli oris

Depressor labii inferioris

Sternal head of

sternocleidomastoid

Clavicular head of

sternocleidomastoid

Trapezius

Clavicle

Platysmae (cut and

reflected)

Anterior view

b

64

11-6 Axial Muscles

Extrinsic eye muscles (oculomotor muscles)

Inferior rectus

Medial rectus

Superior rectus

Lateral rectus

Inferior oblique

Superior oblique

65

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Figure 11–6a Extrinsic Eye Muscles.

Optic

nerve

Frontal

bone

Levator

palpebrae

superioris

Trochlea

(ligamentous sling)

Extrinsic Eye

Muscles

Superior oblique

Superior rectus

Lateral rectus

Inferior oblique

Inferior rectus

Maxilla

Lateral surface, right eye

a

66

Figure 11–6b Extrinsic Eye Muscles.

Trochlea

Extrinsic Eye

Muscles

Superior oblique

Superior rectus

Levator

palpebrae

superioris

Optic

nerve

Medial rectus

Inferior rectus

Medial surface, right eye

b

67

Figure 11–6c Extrinsic Eye Muscles.

Superior

rectus

Trochlea

Superior

oblique

Lateral

rectus

Inferior

oblique

Medial

rectus

Inferior

rectus

Anterior view, right eye

c

68

Figure 11–6d Extrinsic Eye Muscles.

Trochlear

nerve (IV)

Levator palpebrae

superioris

Superior rectus

Oculomotor

nerve (III)

Trochlea

Superior

oblique

Medial rectus

Optic nerve (II)

Inferior rectus

Lateral rectus

Abducens

nerve (VI)

Inferior oblique

Anterior view, right orbit

d

69

11-6 Axial Muscles

Muscles of mastication

Masseter

Strongest jaw muscle

Temporalis

Helps elevate the mandible

Pterygoid muscles

Elevate, depress, and protract mandible

Slide mandible from side to side (lateral excursion)

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Figure 11–7a Muscles of Mastication.

Superior temporal line

Muscles of

Mastication

Temporalis

Masseter

Capsule of

temporomandibular joint

Lateral view. The temporalis passes medial to the zygomatic

arch to insert on the coronoid process of the mandible. The

masseter inserts on the angle and lateral surface of the mandible.

a

71

Figure 11–7b Muscles of Mastication.

Muscles of

Mastication

Lateral pterygoid

Medial pterygoid

Cut edge of mandible

Lateral view, pterygoid muscles exposed. The location

and orientation of the pterygoid muscles are seen after the

overlying muscles and a portion of the mandible are removed.

b

72

11-6 Axial Muscles

Muscles of the tongue

All named for origin and insertion

Palatoglossus

Styloglossus

Genioglossus

Hyoglossus

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Figure 11–8 Muscles of the Tongue.

Muscles of the

Tongue

Palatoglossus (cut)

Styloglossus

Hyoglossus

Mandible

(cut)

Genioglossus

Hyoid bone

Styloid

process

74

11-6 Axial Muscles

Muscles of the pharynx

Pharyngeal constrictor muscles

Move food into esophagus

Palatal muscles

Elevate the soft palate and adjacent portions

Pull open entrance to auditory tube

Laryngeal elevators

Raise the larynx

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Figure 11–9 Muscles of the Pharynx.

Palatal Muscles

Tensor veli

palatini

Levator veli

palatini

Laryngeal elevators

Pharyngeal

Constrictors

Superior

Middle

Inferior

Esophagus

76

11-6 Axial Muscles

Muscles of the anterior neck

Digastric

Controls position of larynx

Extends from chin to hyoid bone

And from hyoid to mastoid portion of temporal bone

Mylohyoid

Elevates floor of the mouth

Depresses jaw

Geniohyoid

Extends between hyoid bone and chin

77

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11-6 Axial Muscles

Muscles of the anterior neck

Stylohyoid

Between hyoid bone and styloid process of skull

Sternocleidomastoid

Extends from clavicle and sternum to mastoid

Turns head obliquely to opposite side

Omohyoid

Attaches scapula, clavicle, first rib, and hyoid

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Figure 11–10a Muscles of the Anterior Neck.

Mylohyoid

(cut and

reflected)

Mandible

Mylohyoid

Digastric

Anterior belly

Posterior belly

Sternocleidomastoid

(cut)

Omohyoid

Superior belly

Inferior belly

Clavicle

Sternocleidomastoid

(cut heads)

Geniohyoid

Stylohyoid

Hyoid bone

Thyrohyoid

Thyroid cartilage

of larynx

Sternothyroid

Sternohyoid

Sternocleidomastoid

Clavicular head

Sternal head

Sternum

Anterior view

a

79

Figure 11–10b Muscles of the Anterior Neck.

Genioglossus

(cut)

Mylohyoid

Geniohyoid

Mandible

Hyoid bone

Superior view

b

80

11-6 Axial Muscles

Muscles of the vertebral column

Erector spinae muscles

Superficial and deep layers

Spinal flexors

81

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11-6 Axial Muscles

Muscles of the vertebral column

Erector spinae, superficial layer

Spinalis group

Longissimus group

Iliocostalis group

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11-6 Axial Muscles

Muscles of the vertebral column

Erector spinae, deep layer

Semispinalis group

Multifidus

Interspinales

Intertransversarii

Rotatores

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Figure 11–11 Muscles of the Vertebral Column (Part 1 of 2).

Erector Spinae, Deep Layer

Semispinalis Group

Semispinalis capitis

Semispinalis cervicis

Semispinalis thoracis

Erector Spinae, Superficial Layer

Splenius capitis

Spinalis, Longissimus, and

Iliocostalis Groups

Longissimus capitis

Spinalis cervicis

Longissimus cervicis

Iliocostalis cervicis

Multifidus

Iliocostalis thoracis

Longissimus thoracis

Spinalis thoracis

Iliocostalis lumborum

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11-6 Axial Muscles

Muscles of the vertebral column

Spinal flexors

Neck

Longus capitis and longus colli

Rotate and flex the neck

Lumbar region

Quadratus lumborum

Flexes vertebral column and depresses ribs

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Figure 11–11 Muscles of the Vertebral Column (Part 2 of 2).

Intervertebral Muscles,

Posterior View

Rotatores

Quadratus lumborum

Flexors of the Anterior

Cervical and Thoracic Spine

Spinal Flexors

Spinous

process

of

vertebra

Interspinales

Transverse

process of

vertebra

Longus

capitis

Thoracodorsal

fascia

Posterior view

Longus

colli

Intertransversarii

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11-6 Axial Muscles

Oblique and rectus muscles

Lie within body wall

Oblique muscles

Compress underlying structures

Rotate vertebral column

Rectus muscles

Flex vertebral column

Oppose erector spinae

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11-6 Axial Muscles

Oblique muscles

Cervical region

Scalene muscles

Flex the neck and elevate ribs

Thoracic region

External and internal intercostal muscles

Aid in breathing movements of ribs

Transversus thoracis

Crosses posterior surface of sternum

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11-6 Axial Muscles

Oblique muscles

Abdominopelvic region (same pattern as thoracic)

External oblique

Internal oblique

Transversus abdominis

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11-6 Axial Muscles

Rectus muscles

Rectus abdominis

Between xiphoid process and pubic symphysis

Divided longitudinally by linea alba

Divided transversely by tendinous inscriptions

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11-6 Axial Muscles

The diaphragm

Divides thoracic and abdominopelvic cavities

Major muscle used in breathing

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Figure 11–12a Oblique and Rectus Muscles and the Diaphragm.

Scalenes

Anterior

Middle

Posterior

Anterior view,

cervical region

a

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Figure 11–12b Oblique and Rectus Muscles and the Diaphragm.

Serratus

anterior

External

oblique

Tendinous

inscription

Internal intercostal

External intercostal

External oblique (cut)

Internal oblique

Cut edge of

rectus sheath

Rectus abdominis

Anterior view

Linea alba

b

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Figure 11–12c Oblique and Rectus Muscles and the Diaphragm.

Transversus

thoracis

Xiphoid

process

Costal

cartilages

External

oblique

Inferior

vena cava

T10

External

intercostal

Internal

intercostal

Esophagus

Serratus

anterior

Diaphragm

Thoracic aorta

Spinal cord

Central tendon

of diaphragm

Erector spinae group

Superior view of the diaphragm

Rectus

abdominis

c

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Figure 11–12d Oblique and Rectus Muscles and the Diaphragm.

Rectus abdominis

Linea alba

External

oblique

Transversus

abdominis

Internal

oblique

L3

Quadratus

lumborum

Thoracolumbar

fascia

Transverse section through

the abdominal cavity

Rectus sheath

d

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11-6 Axial Muscles

Muscles of the pelvic floor

Function to

Support organs of pelvic cavity

Flex sacrum and coccyx

Control movement of materials through urethra and anus

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11-6 Axial Muscles

Muscles of the pelvic floor

Perineum

Region bounded by inferior margins of pelvis

Divided by ischial tuberosities into

Anterior urogenital triangle

Posterior anal triangle

Pelvic diaphragm

Forms muscular foundation of anal triangle

Extends to pubic symphysis

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11-6 Axial Muscles

Perineum

Urogenital and pelvic diaphragms

Do not completely close pelvic outlet

Urethra, anus, vagina (in females), muscles, nerves, and blood vessels pass through

Sphincters permit voluntary control of urination and defecation

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Figure 11–13a Muscles of the Pelvic Floor (Part 1 of 2).

Superficial Dissections

Vagina

Urogenital Triangle

Ischiocavernosus

Bulbospongiosus

Superficial

transverse perineal

muscle

Anus

Gluteus maximus

Female

a

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Figure 11–13a Muscles of the Pelvic Floor (Part 2 of 2).

Deep Dissections

UROGENITAL TRIANGLE

OF PERINEUM

Urethra

External urethral sphincter

Deep transverse perineal

muscle

Central tendon of perineum

Pelvic Diaphragm

Pubococcygeus

Iliococcygeus

Coccygeus

Sacrotuberous ligament

Levator

ani

External anal sphincter

Female

ANAL TRIANGLE

a

100

Figure 11–13b Muscles of the Pelvic Floor (Part 1 of 2).

Superficial Dissections

Testis

Urethra (connecting

segment removed)

Urogenital Triangle

Bulbospongiosus

Ischiocavernosus

Superficial

transverse perineal

muscle

Anus

Gluteus maximus

Male

b

101

Figure 11–13b Muscles of the Pelvic Floor (Part 2 of 2).

Deep Dissections

UROGENITAL TRIANGLE

OF PERINEUM

External urethral sphincter

Deep transverse perineal

muscle

Pelvic Diaphragm

Pubococcygeus

Central tendon of perineum

Levator

ani

Iliococcygeus

External anal sphincter

Coccygeus

Sacrotuberous ligament

Male

ANAL TRIANGLE

b