Chapter 10—The Muscular
System
10-1
Ch. 10 Muscular system-Study Guide
1. Critically read Chapter 10 pp. 320-327. Also
read Tables 10.4 and 10.5 (pp. 339-343)
2. Comprehend Terminology (those in bold in
the textbook) within the reading scope above
3. Study-- Figure questions, Think About It
questions, and Before You Go On (sectionending) questions (within the reading scope
above) . Before You Go On Questions 1-6 (on
p. 325) and Questions 11-12 (on p. 349).
4. Do end-of-chapter questions—
–
–
Testing Your Recall— 2, 11-13, 17-20
True or False– 1
10-26-2
I. Introduction &
connective tissues of a
muscle
10-3
§ Introduction of Muscles
• 600 Human skeletal muscles
• The study of muscles–
M___________
10-4
§ The Functions of Muscles
1. Movement of body parts and body
contents– Examples
2. Maintain posture and prevent unwanted
movement— resist the gravity etc.
3. Communication –
4. Control of openings and passageways–
Examples-- eyelids, __________________
5. Heat production– 85% of our body heat is
from skeletal muscle contraction
10-5
§ Connective Tissues of a Muscle
5. Tendon
4. Deep fascia
3. Epimysium
2. Perimysium
Muscle fascicle
1. Endomysium
Muscle fiber
10-6
Connective Tissues of a Muscle
1. Endomysium
– thin areolar tissue around each muscle fiber
– allows room for ____________________
2. Perimysium
– slightly thicker layer of connective tissue
– surrounds bundle of cells called a fascicle
3. Epimysium
– covers whole muscle belly
– blends into CT sheets called fascia (next
slide)
10-7
Location of Fascia
• Deep fascia
– found between
adjacent
muscles; no fat
• Superficial fascia
(adipose tissue;
hypodermis)
– between skin and
muscles
Superficial Fascia
Deep Fascia
Femur
Skin
10-8
§ Ways of Muscle Attachments
1. To bone directly-– epimysium is continuous with periosteum of a bone
– Ex.– intercostal muscles
2. To bone indirectly--
– epimysium continues as tendon that merges into
periosteum
– Ex.-- many including biceps brachii to scapula
3. To fascia or tendon of another muscle-4. To collagen fibers (dermis)-– Ex.--muscles for facial expression
5. To a broad sheetlike tendon, aponeurosis-– Ex.--certain abdominal muscles (Fig. 10.15)
10-9
10-10
II. General anatomy of
skeletal muscles and
classification of muscles
10-11
§ Anatomy of Skeletal Muscles
• Origin—
– stationary end of a
muscle when
contracts
Biceps
brachii
• Belly-– thicker, middle
region of muscle
• Insertion—
– mobile end of muscle
– Detail fig. next slide
10-12
10-13
§ Muscle types based on fascicle direction-1
10-14
Skeletal Muscle types —based on
fascicle direction-2
1. Fusiform muscles
– Features:
– biceps brachii m., gastrocnemius of the calf
2. Parallel muscles; long, uniform width, having
parallel fascicles
– rectus abdominis m., sartorius of the thigh,
zygomaticus major
3. Convergent muscle; fan-shaped, broad at
origin and tapering to a narrower insertion
– pectoralis major of the chest
Fig. 10.15
10-15
10-16
Skeletal Muscle type—based on
fascicle direction-3
4. Pennate muscles (feather-shaped)
– fascicles insert obliquely on a tendon, like the shaft
of the feather
– Unipennate—fascicles approach the tendon from
one side; palmar interosseus (hand) (Fig.)
– Bipennate—fascicles approach the tendon from
both sides; rectus femoris (thigh) (Fig.)
– Multipennate--like feathers with their quills on a
single point; deltoid (shoulder) (Fig.)
5. Circular muscles (sphincters)
– Features:
– orbicularis oculi (eyelids), orbicularis oris, urethral
and anal sphincters
10-17
Figure
10.29c
10-18
Fig.
10.35a
10-19
Fig. 10.22a
10-20
III. Action of muscle groups
and muscle innervation
10-21
§ 4 categories of muscles based
on actions
• Action— movement produced by a muscle
1. Prime mover or agonist
–
–
produces . . .
Example: in flexing the elbow, the prime mover
is the brachialis
2. Synergist aids the prime mover
–
–
–
May stabilize the nearby joint
Or modify the direction of movement
Example: works with brachialis, biceps brachii
as a synergist to flex the elbow
* In some textbooks 1 and 2 are opposite.
10-22
§ 4 categories of muscles
based on actions
3. Antagonist is a muscle that . . .
– opposes the _____________
– Moderates the speed or range of the
agonist; preventing excessive movement
and injury
– Example: Triceps brachii
4. Fixator is a muscle that . . .
– prevents _______________
– Elbow flexion– the rhomboids holds the
scapula in place (Fig. 10.17)
10-23
10-24
In-class activity
Question--Muscle Actions during
Elbow Flexion • ID which specific muscle
of the upper arm is
responsible for the above
action. (based on the text)
• Prime mover (agonist) = ?
• Synergist = ?
• Antagonist = ?
• Fixator = ?
10-25
§ Skeletal Muscle Innervation
• Cranial nerves arising from the brain
– exit the skull through foramina
– numbered I to XII (Fig. 14.27)
– Innervate muscles of the ______________
• Spinal nerves arising from the spinal
cord
– Muscles elsewhere are supplied by these
nerves
– From spinal cord and exit the vertebral
column through intervertebral foramina (Fig.
13.1, 8.23b)
10-26
10-27
Oh
Once
One
Takes
The
Anatomy
Final
Very
Good
Vacations
Are
Heavenly
Olfactory (I)
Optic (II)
Oculomotor (III)
Trochlear (IV)
Trigeminal (V)
Abducens (VI)
Facial (VII)
Vestibulocochlear (VIII)
Glossopharyngeal (IX)
Vagus (X)
Accessory (XI)
Hypoglossal (XII)
14-28
Figure
13.1b;
posterior
view
10-29
Figure
8.23b
10-30
§ How Muscles are Named
• Terminologia Anatomica
– system of Latin names developed in 1895
– updated since then
• English names for muscles are slight
modifications of the Latin names.
• Table 10.1 = terms used to name muscles;
Examples:
– Major = large (Criteria: ____); pectoralis major
– Deltoid = triangular (Criteria: _____); Deltoid
– Quadriceps = having 4 heads; quadriceps
femoris etc.
10-31
§ Learning Strategy (start with
Fig. 10.4a and b)
• Explore the location, origin, insertion
and innervation of 160 skeletal
muscles
– use tabular information in this chapter.
• Increase your retention
– examining models and atlases
– palpating yourself (atlas B)
– observe an articulated skeleton
– say the names aloud and check your
pronunciation
10-32
Quadriceps
femoris
10-33
10-34
IV. Muscles involved in
respiration
10-35
§ Muscles of Respiration
• Breathing requires the use of muscles
– Diaphragm (prime mover of inspiration)
– external intercostal muscles
– internal intercostal muscles
• Contraction of first 2 produces inspiration
• Expiration-- ??
• Contraction of last produces-- forced
expiration
• Normal expiration requires little muscular
activity
10-36
1. Muscles of Respiration- Diaphragm
• Muscular dome between
thoracic and abdominal
cavities
• Muscle fascicles converge
from the margins (Origin)
toward a fibrous central
tendon (Insertion)
• Contraction flattens it
Central tendon
– Increases/decreases the
vertical dimension of the
thorax
10-37
2. External/internal Intercostals
• External intercostals
– O- inferior margin of rib above; Isuperior border of next lower rib
– extend downward and
anteriorly from rib to rib
– pull ribcage up/down (when
contract)
• Internal intercostals
– O- and I- opposite of that in
external intercostals
– extend upward and anteriorly
from rib to rib
– pull ribcage downward/upward
(during forced expiration)
10-38
3. Breathing-a mechanical step
 Mechanism of normal quiet inspiration
(expiration are opposite)—
•
•
•
•
•
•
Diaphragm contracts and move downward
External intercostals muscles contract
 the ribs elevated
 Chest volume:
 intra-alveolar pressure:
 Air flows inward; why?
Deeper inspiration, 2 neck muscles are
involved
10-39
Contraction
of external
intercostal
muscles
External
intercostal
muscles
(relaxed)
Elevated
rib cage
Elevation of ribs
& sternum
Increase side-toside and front-toback
dimensions of
thoracic cavity (X
& Y axes)
Sternum
Contraction
of diaphragm
Diaphragm
(relaxed)
Before inspiration
Contractions of external intercostal
muscles causes elevation of ribs,
which increases side-to-side
dimension of thoracic cavity
Inspiration
vertical (Z axis)
dimension increases in
thoracic cavity
10-40
760
Size of thorax  on
contraction of
inspiratory muscles
759 mm Hg
During inspiration
Size of lungs  as
they
are stretched to fill
the expanded thorax
10-41
4. Muscles in breathing
Accessory
muscles of
inspiration
Internal
intercostal
muscles
1. Sternocleidomastoid
2. Scalenus
Muscles
of active
expiration
1. External
intercostal
muscles
2. Diaphragm
Major
muscles of
inspiration
Abdominal
muscles
10-42
Relaxation
of external
intercostal
muscles
Contraction
of internal
intercostal
muscles
Contraction of internal intercostal
muscles flattens ribs and
sternum, further reducing
side-to-side and front-to-back
dimensions of thoracic cavity
Contraction
of abdominal
muscles
Position of relaxed
abdominal muscles
Relaxation of
diaphragm
Passive expiration
Return of diaphragm, ribs, and sternum
to resting position on relaxation of
inspiratory muscles restores thoracic
cavity to preinspiratory size
Contractions of abdominal
muscles cause diaphragm to
be pushed upward, further
reducing vertical dimension
of thoracic cavity
Active expiration
10-43
§ Muscles of the Abdomen
• 4 Pairs of sheetlike muscles
– external oblique (most superficial)
– internal oblique
– transverse abdominal
(the first three: from superficial to deep)
– rectus abdominal
• Functions
– support the viscera
– stabilize the vertebral column
– help in respiration, urination, defecation and
childbirth
10-44
Aponeuroses (broad
fibrous sheet-like
tendons)– tendons of
the oblique and
transverse muscles
Rectus abdominis-wrapped by rectus
sheath
Linea alba (“white
line”)– at the median
line where
aponeuroses meet
10-45
External Oblique & Rectus Abdominal
• External abdoominal oblique
– Superficial (O-Ribs 5-12; to
I-pelvis and linea alba)
– Fibers downward and
anteriorly
– The aponeurosis of
external oblique forms
inguinal ligament
• Rectus abdominal
– vertical, straplike from
pubis (O) to xiphoid
process (I)
– 3 tendinous intersections
– rectus sheath encloses
rectus abdominal
– They meet at the median
line called linea alba
External oblique
Rectus abdominis
10-46
Internal oblique & transverse abdominis
• Internal oblique
– Fibers pass upward
and anteriorly
– Perpendicular to
those of external
oblique
Internal oblique
• Transverse abdominal
– Horizontal fiber
orientation
– Deepest layer
Transverse
abdominis
10-47