This document provides an overview of the muscular system chapter in a textbook. It discusses the organization of muscles in the body, their functions, and connective tissues. It also describes specific muscle groups like the muscles of the head and neck, trunk, shoulder, and hip and lower limb. Diagrams show the muscles and their attachments, shapes, actions, and innervation. The summary focuses on key muscle groups like the muscles of mastication, swallowing, respiration, and the shoulder.

1. 10-1
Chapter
10
Muscular
System

2. 10-2
The Muscular System
• Structural and
functional
organization of
muscles
• Muscles of the
head and neck
• Muscles of the
trunk
• Muscles acting
on the
shoulder and
upper limb
• Muscles acting
on the hip
and lower limb

3. 10-3
Organization of Muscles
• 600 Human skeletal muscles
• General structural and functional
topics
– muscle shape and function
– connective tissues of muscle
– coordinated actions of muscle groups
– intrinsic and extrinsic muscles
– muscle innervation
• Regional descriptions

4. 10-4
The Functions of Muscles
• Movement of body parts and organ
contents
• Maintain posture and prevent
movement
• Communication - speech, expression
and writing
• Control of openings and passageways
• Heat production

5. 10-5
Connective Tissues of a Muscle
Perimysium
Epimysium
Endomysium
Tendon
Deep fascia

6. 10-6
Connective Tissues of a Muscle
• Epimysium
– covers whole muscle belly
– blends into CT between muscles
• Perimysium
– slightly thicker layer of connective tissue
– surrounds bundle of cells called a fascicle
• Endomysium
– thin areolar tissue around each cell
– allows room for capillaries and nerve
fibers

7. 10-7
Location of Fascia
Superficial Fascia
Deep Fascia
• Deep fascia
– found between adjacent muscles
• Superficial fascia (hypodermis)
– adipose between skin and muscles

8. 10-8
Muscle Attachments
• Direct (fleshy) attachment to bone
– epimysium is continuous with periosteum
– intercostal muscles
• Indirect attachment to bone
– epimysium continues as tendon or aponeurosis that
merges into periosteum as perforating fibers
– biceps brachii or abdominal muscle
• Attachment to dermis
• Stress will tear the tendon before pulling the
tendon loose from either muscle or bone

9. 10-9
Parts of a Skeletal Muscle
• Origin
– attachment to
stationary end of
muscle
• Belly
– thicker, middle region
of muscle
• Insertion
– attachment to mobile
end of muscle

10. 10-10
Skeletal Muscle Shapes

11. 10-11
Skeletal Muscle Shapes 2
• Fusiform muscles
– thick in middle and tapered at ends
– biceps brachii m.
• Parallel muscles have parallel fascicles
– rectus abdominis m.
• Convergent muscle
– broad at origin and tapering to a narrower insertion
• Pennate muscles
– fascicles insert obliquely on a tendon
– unipennate, bipennate or multipennate
– palmar interosseus, rectus femoris and deltoid
• Circular muscles
– ring around body opening
– orbicularis oculi

12. 10-12
Coordinated Muscle Actions
• Prime mover or agonist
– produces most of force
• Synergist aids the prime mover
– stabilizes the nearby joint
– modifies the direction of movement
• Antagonist
– opposes the prime mover
– preventing excessive movement and injury
• Fixator
– prevents movement of bone

13. 10-13
Muscle Actions during Elbow
Flexion
• Prime mover (agonist) =
brachialis
• Synergist = biceps brachii
• Antagonist = triceps brachii
• Fixator = muscle that holds
scapula firmly in
place
– rhomboideus m.

14. 10-14
Intrinsic and Extrinsic
Muscles
• Intrinsic muscles are
contained within a
region such as the
hand.
• Extrinsic muscles
move the fingers but
are found outside the
region.

15. 10-15
How Muscles are Named
• Nomina Anatomica
– system of Latin names developed in 1895
– updated since then
• English names for muscles are slight
modifications of the Latin names.
• Figure 10.5 = terms used to name
muscles
– levator = elevates a body part
– profundus = deepest
– quadriceps = having 4 heads

16. 10-16
Learning Strategy
• Explore the location, origin, and
insertion of 160 skeletal muscles
– use tabular information in this chapter.
• Increase your retention
– examining models and atlases
– palpating yourself
– observe an articulated skeleton
– say the names aloud and check your
pronunciation

17. 10-17
The Muscular System

18. 10-18
Muscles of Facial Expression
• Small muscles that insert into the
dermis
• Innervated by facial nerve (CN VII)
• Paralysis causes face to sag
• Found in scalp, forehead, around the
eyes, nose and mouth, and in the
neck

19. 10-19
Muscles in Facial Expression

20. 10-20
Muscles in Facial Expression

21. 10-21

22. 10-22

23. 10-23
Musculature of the Tongue
• Intrinsic muscles = vertical, transverse and
longitudinal fascicles
• Extrinsic muscles connect tongue to hyoid, styloid
process, palate and inside of chin
• Tongue shifts food onto teeth and pushes it into
pharynx
Intrinsic tongue muscles
Extrinsic tongue muscles

24. 10-24

25. 10-25
Muscles of Mastication
• 4 Major muscles
• Arise from skull and
insert on mandible
• Temporalis and
Masseter elevate the
mandible
• Medial and Lateral
Pterygoids help
elevate, but produce
lateral swinging of jaw
Temporalis
Masseter
Lateral pterygoid
Medial pterygoid

26. 10-26
Suprahyoid Muscles and Swallowing
• Digastric and Mylohyoid = open mouth
• Geniohyoid = widens pharynx during
swallowing
• Stylohyoid = elevates hyoid
• Thyrohyoid = elevates larynx, closing glottis
Digastric Mylohyoid
Thyrohyoid

27. 10-27

28. 10-28
Muscles involved in Swallowing
• Pharyngeal constrictors push food down throat
• Infrahyoid muscles pulls larynx downward
• Intrinsic laryngeal muscles control speech
Pharyngeal constrictors

29. 10-29
Muscles of Respiration
• Breathing requires the use of muscles
– Diaphragm and external intercostal muscles
– internal intercostal muscles
• Contraction of first 2 produces inspiration
• Contraction of last produces forced
expiration
• Normal expiration requires little muscular
activity
– elastic recoil and gravity collapses the chest
– inspiratory muscles active in braking action,
so exhalation is smooth

30. 10-30
Muscles of Respiration -- Diaphragm
• Muscular dome between
thoracic and abdominal
cavities
• Muscle fascicles extend to
a fibrous central tendon
• Contraction flattens it
– increases the vertical dimension of the thorax
drawing air into the lungs
– raises the abdominal pressure to help expel urine,
feces and facilitating childbirth
Central tendon

31. 10-31
Muscles of Respiration - Intercostals
• External intercostals
– extend downward and
anteriorly from rib to rib
– pull ribcage up and outward
during inspiration
• Internal intercostals
– extend upward and anteriorly
from rib to rib
– pull ribcage downward
during forced expiration

32. 10-32
Muscles of Shoulder
• Trapezius
• Rhomboid Major
• Rhomboid Minor
• Levator Scapula
• Latissimus Dorsi
• Triangle of Auscultation
• Serratus Anterior
• Winged Scapula
• Deltoid
• Crutch Paralysis
Supraspinatus
Rotator Cuff
Tears
Infraspinatus
Subscapularis
Teres Minor
Teres Major
Pectoral Muscles
Pectoralis Major
Pectoralis Minor
Subsclavius

33. 10-33
• Shoulder Muscles
• The shoulder muscles cover the
upper part of the anterior thorax and
spread posterior to cover the
posterior thoracic region.
• We divide the muscles into
three distinct groups:
1. those that connect the upper limb to
the vertebral column
2. those that connect the upper limb to
the thoracic wall
3. the scapular muscles, those that
connect the scapula to the humerus.
Muscles of the Shoulder

34. 10-34
Muscles connecting upper limb to
vertebral column
Muscles in this group:
1. Trapezius 4. Levator Scapula
2. Rhomboid Major 5. Latissimus Dorsi
3. Rhomboid Minor

35. 10-35
Trapezius
Trapezius
A flat muscle which extends over the
back of the neck and upper thoracic
area. The left and right muscles form
an irregular four sided figure, a
trapezoid.
Origin: Superior Nuchal Line
of the occiput
External Occipital Protuberance
Ligmentum Nuchae
Spine of Thoracic Vertebrae
Insertion: Clavicle
Acromion Process/scapula
Action:
1. Stabilize the scapula
(anatomical position)
2. Upper portion:elevates
scapula
3. Middle and lower
portions:adduct the scapula

36. 10-36
Trapezius
Its fibers form three portions:
1. Superior: fibers pass
downward and lateral
2. Middle: fibers pass
transversely
3. Inferior: fibers pass upward
and lateral
This muscle is easily palpated
on the back of the neck
and upper posterior
thorax.

37. 10-37
Rhomboid Major & Minor
• Rhomboid Major
A thin, flat muscle
which is rhomboid in
shape and lies deep
to the trapezius.
Origin: Spines of the
upper thoracic
vertebrae
Insertion: Vertebral
Border of the scapula
•Rhomboid Minor
This muscle lies
superior and parallel to the
rhomboid major with which
it is sometimes fused.
Origin: Spines of
lower cervical and T1
Insertion: Vertebral
border of scapula

38. 10-38
Rhomboid Major & Minor
The action of both muscles include:
1. Elevate and adduct the scapula
2. Stabilize the scapula

39. 10-39
Levator Scapula
A muscle found on the side of
the neck, deep to the
superior portion of the
trapezius.
Origin: Transverse Process of
upper cervical vertebrae
Insertion: Superior Angle of
the scapula
The muscle is involved with
the following actions:
1. Elevate, adduct scapula
2. Stabilize scapula

40. 10-40
Latissimus Dorsi
A large flat muscle which
extends over the lower
posterior thoracic region and
the lumbar region. The
muscle is superficial.
Origin: Spines of lower thoracic
vertebrae
Thoraco-dorsal fascia
Crest of the ilium
Lower ribs
Insertion: Intertubercle goove
(crest of lesser tubercle) of
humerus
The actions of this muscle
include:
1. Extends, adducts, medially
rotates arm
2. Takes part in forced
expiration

41. 10-41
Clinical Notes:
Triangle of Auscultation: is found at the superior portion of
the latissimus dorsi and bounded by the:
Latissimus dorsi
Trapezius
Vertebral border of the scapula
Clincal significance of the triangle: if the scapula is abducted by
folding the arms across the chest, and flexing the trunk, the
triangle enlarges and respiratory sounds may be heard with a
stethoscope in this triangle.

42. 10-42
Muscle connecting thoracic
wall to upper extremity
Serratus Anterior (serrate=tooth)
Known as the Fencer’s muscle. It is a broad muscular sheet which
passed posterior around the thoracic cage from an extensive costal
attachment to a more limited attachment on the scapula. Its anterior
portion lies immediately beneth the skin just below the axilla and it can
plainly be seen in well developed individuals when arm is raised against
resistance.
Origin: Upper ribs
Insertion: Vertebral border of the scapula
Its actions are as follows:
1. Abducts/protracts the scapula
2. Stabilizes the scapula
3. Involved in force inspiration ONLY when humerus abducted

43. 10-43
Clinical Notes:
Winged Scapula:
When the serratus anterior is weaked or paralyzed by damage to the
long thoracic nerve, the patient experiences difficulty:
• abducting the scapula and thus problem raising the arm above the
head
• in keeping the vertebral border and inferior angle of the scapula
closely applied to the posterior thoracic cage.
Thus the vertebral border protrudes from the chest wall, a condition
called “winged scapula”.

44. 10-44
Scapular Muscles
These muscles which originate on the scapula
and insert on the humerus.
The muscle group include:
1. Deltoid 4. Subscapularis
2. Supraspinatus 5. Teres Major
3. Infraspinatus 6. Teres Minor
The supraspinatus, infraspinatus,
subscapularis, and teres minor for the
ROTATOR CUFF Muscles.

45. 10-45
DeltoidA large muscle which is named because it’s
resemblance to the Greek letter delta. The
muscle forms the roundness of the shoulder.
1. Anterior/Clavicular portion
Origin: Clavicle
2. Middle/Acromial Portion
Origin: Acromion Process of scapula
3. Posterior Spinous Portion
Origin: Spine of the scapula
Insertion: deltoid tuberosity of the humerus
The muscle is involved with the following actions:
Anterior portion- Flex, medially rotates humerus
Middle portion- abducts the humerus
Posterior Portion-extends, laterally rotates
humerus

46. 10-46
Crutch Paralysis-
Damage to the axillary nerve causes a
weakness and eventually paralysis of the
deltoid muscle. The deltoid is the most
frequently paralyzed muscle of the upper
extremity.
1. Fracture of surgical neck of humerus
2. Dislocation of shoulder
3. Pressure from crutch in the axilla.
Clinical Note

47. 10-47
Supraspinatus
Supraspinatus
The muscle accupies the
supraspinous fossa of the
scapula and is deep to the
trapezius. The most commonly
injured muscle of the rotator cuff.
Origin: Supraspinous fossa of
scapula
Insertion: Greater tuberosity of
the humerus
The action of this muscle is:
1. initiates abduction of arn
2. lateral rotation of arm
3.stabilize the shoulder joint

48. 10-48
Subacromial Bursitis-
the subacromial bursa separates the tendon of the
supraspinatus from the acromion process and deltoid. An
individual with a weak or inflamed tendon of the
supraspinatus muscle is particularly susceptible to this
condition. The inflammation of the bursa makes abduction
of the humerus extremely painful to carry out. This type of
bursitis is commonly seen in swimmers, tennis player and
gymnasts.
Clincal Notes

49. 10-49

50. 10-50
Infraspinatus
A muscle that occupies the
infraspinous fossa of the
scapula and is deep to the skin.
It is often fused to the teres
minor muscle.
Origin: Infraspinous fossa of
scapula
Insertion: Greater Tuberosity of
humerus
The muscle is involved with the
following actions:
1. lateral rotation of humerus
2. helps stabilize shoulder joint

51. 10-51
Subscapularis
The muscle that occupies
the ventral surface of the
scapula.
Origin: subscapular fossa
of scapula
Insertion: lesser tuberosity
of the humerus
The has the following
actions:
1. Medial rotate humerus
2. Helps stabilize shoulder
joint
Subscapularis

52. 10-52
Teres Minor
A narrow muscle which is
found parallel to the lateral
border of the scapula
between the infraspinatus
and the teres major muscle.
Origin: axillary border of the
scapula
Insertion: Greater Tuberosity
of the humerus
The muscle is involved with the
following actions:
1. lateral rotates humerus
2. stabilizes shoulder joint

53. 10-53
Teres Major
A well developed muscle
which helps form the
posterior wall of the axilla.
Origin: Inferior angle of the
scapula
Insertion: Lesser tuberosity
of humerus
The muscle is involved with:
1. Adducts the humerus
2. Stabilizes shoulder joint

54. 10-54
Pectoralis Major
Origin: Clavicule (Clavicular portion)
Sternum and upper ribs
(sterno-costal portion)
Tendon of the external oblique
muscle (abdominal p)
Insertion: Greater tubercle of humerus
The portions of the muscle are capable
of acting in combination or
independently of each other and
its actions include:
Entire Muscle: adduction, medial
rotation of humerus, forced
inspiration by elevating the rib cage
Clavicular Portion: Flexion of humerus
Sternocostal Portion: extension of
humerus

55. 10-55
Pectoralis Minor
A flat, thin muscle which lies
deep to the Pec. Mjr.
Origin: Upper ribs (5th-7th)
Insertion: Coracoid process
of scapula
The muscle acts in the
following ways:
1. protracts/abducts scapula
2. elevates rib cage, forced
inspiration

56. 10-56
Subclavius
As the name implies, this
muscle is found below
the clavicle in the space
between the first rib and
clavicle.
Origin: First rib
Insertion: Subclavian groove
of clavicle
The muscle is involved
with the following
actions:
1. pulls clavicle medially
2. protective cushion between
clavicle and blood vessels

57. 10-57
Muscles on Pectoral Girdle
• Originate on axial skeleton and insert
onto
clavicle or scapula
• Anterior muscle group = 2 muscles
• Posterior muscle group = 4 muscles
• Scapular movements produced include
– medial and lateral rotation of the scapula
– elevation and depression of the scapula
– protraction and retraction of the scapula
• Clavicle braces the shoulder and limits
movement

58. 10-58
Muscles of Anterior Forearm
• Flex/extend wrist and fingers, adduct/abduct wrist
• Digitorum = inserts into fingers
• Carpi = inserts onto carpal bones
• Pollicis = inserts into thumb

59. 10-59
Muscles of Posterior Forearm
• Extension of wrist and fingers, Adduct/abduct wrist
• Extension and abduction of thumb (pollicis)
• Brevis = short, Ulnaris = on ulna side of forearm
Extensors

60. 10-60
• Thenar group = fleshy base of thumb muscles
• Hypothenar group = base of little finger muscles
• Midpalmar group = Interosseus mm. and Lumbrical
mm.
Intrinsic Hand Muscles

61. 10-61
Carpal Tunnel Syndrome
Repetitive motions cause
inflammation and
pressure on median nerve

62. 10-62
Anterior Muscles Acting on the Hip
• Iliopsoas muscle
– crosses anterior
surface of hip joint
and inserts on femur
– iliacus portion
arises from iliac
fossa
– psoas portion arises
from lumbar
vertebrae
– major hip flexor
Iliopsoas

63. 10-63
Posterior Muscles Acting on Hip
• Gluteus maximus
– forms mass of the
buttock
– prime hip extensor
– provides most of
lift when you climb
stairs
• Iliotibial band
– band of fascia lata
attached to the
tibia
Gluteus maximus
Gluteus medius
Iliotibial
band

64. 10-64
Deep Gluteal
Muscles
• Most laterally rotate femur
• Except: Gluteus minimus medially
rotates femur
• Shifts body weight when foot is lifted
• Quadratus femoris is adductor of hip
• Piriformis and Gluteus minimus = hip
abductors
Quadratus
femoris
Piriformis
Gluteus minimus

65. 10-65
Adductors of the Hip Joint
• 5 muscles act as
adductors
• Adductor magnus
is hip joint
extensor
• Gracilis is flexor of
knee
• Pectineus,
Adductor brevis
and Adductor
longus adduct
femur
Adductor
longus
Adductor
brevis
Pectineus
Adductor magnus

66. 10-66
Muscles Acting on the Knee
• 4 headed muscle
attaches to tibial
tuberosity
– extends knee joint
• rectus femoris
arises from ilium so
flexes hip joint
• quadriceps femoris
tendon attaches to
patella
• patellar ligament
attaches to tibia

67. 10-67
Anterior Thigh Cadaver Muscles

68. 10-68
Muscles of the Leg
• Crural muscles are separated into 3
compartments.
– anterior compartment (green)
– fibular (lateral) compartment (blue)
– posterior (superficial = brown) (deep = purple)

69. 10-69
Anterior Compartment of Leg
• Extensor digitorum longus = extension of toes and ankle
• Extensor hallucis longus = extension of big toe and ankle
• Fibularis tertius = dorsiflexes and everts foot
• Tibialis anterior = dorsiflexes and inverts foot

70. 10-70
Posterior Compartment of Leg
Superficial Group of Plantar Flexors
• Gastrocnemius = flexes knee and plantar flexes ankle
• Soleus = plantar flexes ankle
Gastrocnemius
Soleus
Plantaris

71. 10-71
Posterior Compartment of Leg
Deep Group of Plantar Flexors
• Tibialis posterior, Flexor digitorum longus, and Flexor
hallucis longus and are plantar flexors.
• Popliteus unlocks the knee joint for knee flexion.

72. 10-72
Lateral Compartment of the Leg
• 2 muscles in this
compartment
• Both plantar flex
and evert the foot
• Provides lift and
forward thrust
Fibularis brevis
Fibularis longus

73. 10-73
Intrinsic Muscles of Sole
• Four muscle
layers
• Support for
arches
– abduct and
adduct the
toes
– flex the toes
• One dorsal
muscle
– extensor
digitorum
brevis
extends toes
Dorsal
view

74. 10-74
Athletic Injuries
• Vulnerable to sudden and intense stress
• Proper conditioning and warm-up needed
• Common injuries
– shinsplints
– pulled hamstrings
– tennis elbow
• Treat with rest, ice, compression and elevation
• “No pain, no gain” is a dangerous
misconception