chapter 10—the muscular system 10-1. 6-2 ch. 10 muscular system-- study guide 1.critically read...
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Chapter 10—The Muscular System
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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 (section-ending) 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
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I. Introduction & connective tissues of a muscle
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§ Introduction of Muscles
• 600 Human skeletal muscles
• The study of muscles– M___________
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§ 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
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§ Connective Tissues of a Muscle
2. Perimysium
3. Epimysium
1. Endomysium
5. Tendon
4. Deep fascia
Muscle fascicle
Muscle fiber
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Connective Tissues of a Muscle1. 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)
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Location of FasciaSuperficial Fascia
Deep Fascia
• Deep fascia– found between
adjacent muscles; no fat
• Superficial fascia (adipose tissue; hypodermis)– between skin and
muscles
Skin
Femur
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§ Ways of Muscle Attachments1. 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)
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II. General anatomy of skeletal muscles and classification of muscles
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§ Anatomy of Skeletal Muscles
• Origin—– stationary end of a
muscle when contracts
• Belly--– thicker, middle
region of muscle
• Insertion—– mobile end of muscle– Detail fig. next slide
Biceps brachii
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§ Muscle types based on fascicle direction-1
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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
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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
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Figure 10.29c
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Fig. 10.35a
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Fig. 10.22a
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III. Action of muscle groups and muscle innervation
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§ 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.
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§ 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)
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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 = ?
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§ 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)
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Oh Olfactory (I)Once Optic (II)One Oculomotor (III)Takes Trochlear (IV)The Trigeminal (V)Anatomy Abducens (VI)Final Facial (VII)Very Vestibulocochlear (VIII)Good Glossopharyngeal (IX)Vacations Vagus (X)Are Accessory (XI)Heavenly Hypoglossal (XII) 14-28
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Figure 13.1b;
posterior view
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Figure 8.23b
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§ 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.
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§ 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
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Quadriceps femoris 10-33
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IV. Muscles involved in respiration
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§ 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
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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– Increases/decreases the
vertical dimension of the thorax
Central tendon
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2. External/internal Intercostals• External intercostals
– O- inferior margin of rib above; I-
superior 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)
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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
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Externalintercostalmuscles(relaxed)
Contractions of external intercostalmuscles causes elevation of ribs,which increases side-to-sidedimension of thoracic cavity
vertical (Z axis)dimension increases in thoracic cavity
Elevation of ribs & sternumIncrease side-to-side and front-to-back dimensions of thoracic cavity (X & Y axes)
Before inspiration Inspiration
Elevated
rib cage
Contractionof externalintercostalmuscles
Sternum
Diaphragm(relaxed)
Contractionof diaphragm
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759 mm Hg
Size of thorax oncontraction ofinspiratory muscles
Size of lungs as theyare stretched to fillthe expanded thorax
During inspiration
760
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Accessorymuscles ofinspiration
Musclesof activeexpiration
Majormuscles ofinspiration
1. Sternocleidomastoid
2. Scalenus
1. Externalintercostalmuscles
2. Diaphragm
Internalintercostalmuscles
Abdominalmuscles
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4. Muscles in breathing
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Relaxationof externalintercostalmuscles
Return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size
Contractions of abdominalmuscles cause diaphragm tobe pushed upward, furtherreducing vertical dimension of thoracic cavity
Contraction of internal intercostal muscles flattens ribs and sternum, further reducingside-to-side and front-to-back dimensions of thoracic cavity
Passive expiration
Active expiration
Contractionof internalintercostalmuscles
Relaxation ofdiaphragm
Contractionof abdominal muscles
Position of relaxedabdominal muscles
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• 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
§ Muscles of the Abdomen
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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
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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
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Internal oblique & transverse abdominis
• Internal oblique– Fibers pass upward
and anteriorly– Perpendicular to
those of external oblique
• Transverse abdominal– Horizontal fiber
orientation– Deepest layer
Transverse abdominisInternal oblique