A&P 101
ANATOMY OF THE MUSCULAR SYSTEM – PART 1
CH 10 (Thibodeau)
I. INTRODUCTION TO THE MUSCULAR SYSTEM
A. STRUCTURE – MUSCLES
*Note: Skeletal Muscles are the Primary Focus in Ch 10 (Most Common and Numerous Muscles)
1. SKELETAL
- Attached to Bones
- Striated, Voluntary
2. SMOOTH
- Located in the Viscera
- Nonstriated, Visceral, Involuntary
3. CARDIAC
- Located in the Wall of the Heart
- Striated, Involuntary
B. PRIMARY FUNCTION – MOVEMENT
II.
SKELETAL MUSCLE STRUCTURE
A. TISSUES THAT COMPOSE SKELETAL MUSCLES
1. SKELETAL MUSCLE TISSUE
- Composed of Skeletal Muscle Fibers, Arranged in Fascicles
2. CONNECTIVE TISSUE
*Note: a,b,c Are Continous With One Another , Arise From Deep Fascia, and Provide Protection
a. ENDOMYSIUM - Connective Tissue That Wraps Around Each Individual SMF
b. PERIMYSIUM - Connective Tissue That Wraps Around Each Fascicle
c. EPIMYSIUM - Connective Tissue That Wraps Around the Entire Skeletal Muscle
d. TENDON
- Fibrous Cords That Connect Muscle to Bone
- Example: Achilles Tendon
- On Muscle End ; An Extension of Endo, Epi, and Perimysium
- On Bone End; An Extension Of Periosteum
e. APONEUROSIS
- Broad Flat Sheet of Connective Tissue That Connects Muscle to Muscle
- Example: Linea Alba
- An Extension of Endo,Epi, Perimysium of Both Muscles
f. TENDON SHEATH
- Connective Tissue Envelop That Encloses Tendons Where Much Movement is Required
(Wrist, Ankle)
- Sheath is Lined With Synovial Membrane, Secretes Synovial Fluid
- Provides Lubrication for Friction Free Movement of Tendon(s)
3. NERVOUS TISSUE
- Neurons Attach to SMF’s
- Required for Normal Function of Skeletal Muscles (Stimulation Before Contractio)
B. SIZE, SHAPE, FIBER ARRANGEMENT
1. SIZE: Varies From Large to Small
2. SHAPE: Varies
- Broad (L. dorsi) / Narrow (Sartorius)
- Flat (L. dorsi) / Bulky (Gastrocnemius)
- Long (Sartorius) / Short (S. anterior)
- Circular (O. oris)
- Triangular (Deltoid)
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3. FIBER ARRANGEMENT
- Arrangement of SMF’s Within the Muscle, Varies
a. PARALLEL
- Fibers Extend Lengthwise and Are Parallel to One Another
- Horizontal: T. abdominus
- Vertical: R. abdominus
b. CONVERGENT
- Fibers Merge to a Narrow Attachment
- P. major
c. OBLIQUE
- Fibers Are Slanted
- E. oblique
d. PENNATE - “Feathered”, Fibers Resemble the Feathers in an Old Fashioned Pen
- Vastus Group
e. BIPENNATE
- “Two-Feathered”
- R. femoris
f. CURVED
- Fibers Are Circular
- O. oris
*Note: Size, Shape, Fiber Arrangement Relates to Function (Structure Complements Function)
C. ATTACHMENT OF MUSCLES
- Skeletal Muscles Attached to Bones (Tendons)
- Points of Attachment: Origin, Insert
1. ORIGIN
- Point of Attachment (Muscle to Bone) That Does Not Move When the Muscle Contracts
2. INSERTION
- Point of Attachment (Muscle to Bone) That Does Move When the Muscle Contracts
- Example: B. brachii
- Generalization: When a Muscle Contracts, It Moves Its Insertion End Toward Its Origin End
D. MUSCLE ACTIONS
- Generalization: Muscles Usually Work in Groups Rather Than Alone
- Typically, There Are 4 Types of Muscles in a Muscle Group
1. PRIME MOVER
- Muscle(s) Whose Contraction Primarily Produces a Given Movement
- Example: Flexion of Forearm - B. brachii = Prime Mover
2. ANTAGONISTS
- Muscle(s) That Relaxes When the Prime Mover is Contracting
(Allows Prime Mover to Contract to the Fullest Extent Possible)
- Example: Flexion of Forearm - T.brachii = Antagonist
- Antagonists Have an Opposite Location and an Opposite Action From the Prime Mover
3. SYNERGISTS
- Muscle(s) That Assist the Prime Mover
(Contract at the Same Time as Prime Mover, Makes Contraction More Efficient)
- Example: Flexion of Forearm - Brachialis = Synergist
4. FIXATOR MUSCLES
- Muscles That Function as Joint Stabilizers
*Note: The Specific Movement Determines Each Muscle Type in the Group
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E.
III.
ROLE OF MUSCLES, BONES, AND JOINTS IN MOVEMENT
1. MECHANISM
- Skeletal Muscle Attached to Bones (by Tendons) With Joint in Between POA’s
- Skeletal Muscle Stimulated by Nerve Impulse
- Skeletal Muscle Contracts, Pulls on Bone(s), Produces Movement at a Joint
2. COMPARISON TO LEVER
a. RIGID BAR (BONE)
b. FULCRUM (JOINT)
c. PULL (MUSCLE CONTRACTION)
- Components of a Lever: Rigid Bar, Fulcrum, Pull
- Mechanism: Pull Applied to Rigid Bar, Rigid Bar Turns at Fulcrum
- Comparison to Muscles, Bones, Joints
HOW MUSCLES ARE NAMED
- A Muscle’s Name May Describe One or More of the Following Features About the Muscle
A. LOCATION
Muscle’s Name May Indicate Its Location
Examples: Gluteus, Femoris, Tibialis, Abdominus
B. FUNCTION
Muscle’s Name May Indicate Its Function
Example: Adductor Group
C. SHAPE
Muscle’s Name May Indicate Its Shape
Examples: Deltoid, Latissimus, Serratus
D. DIRECTION OF FIBERS
Muscle’s Name May Indicate the Direction of Its Muscle Fibers (i.e., Fiber Arrangement)
Examples: Oblique, Rectus, Transversus
E. NUMBER OF HEADS OR DIVISIONS
Muscle’s Name May Indicate Its Number of Heads (Origins) or Divisions
Examples: Biceps, Triceps
F. POINTS OF ATTACHMENT
Muscle’s Name May Indicate Its Points of Attachment (Origin/Insertion)
Example: Sternocleidomastoid
G. RELATIVE SIZE
Muscle’s Name May Indicate Its Relative Size (Size in Relation to Others in the Group)
Example: G. maximus, G. medius, G. minimus
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A&P 101
ANATOMY OF THE MUSCULAR SYSTEM – PART 2
CH 10 (Thibodeau)
IV. IMPORTANT SKELETAL MUSCLES
A. MUSCLES OF FACIAL EXPRESSION
1. ORBICULARIS OCULI: Closes Eyes (Blinking)
2. ZYGOMATICUS MAJOR: Pulls Corners of Mouth Upward (Laughing)
3. ORBICULARIS ORIS: Puckers Mouth (Kissing)
4. BUCCINATOR: Presses Lips and Cheeks Against Teeth (Blowing, Whistling)
B. MUSCLES OF MASTICATION
1. MASSETER
‑ Elevates Mandible (Closes Mouth)
2. TEMPORALIS: Same as Masseter
C. MUSCLES THAT MOVE THE HEAD: STERNOCLEIDOMASTOID
‑ Flexes Head ("Prayer Muscle") (When Both Contract)
‑ Turns Head to Side (When Each Contracts Alone)
D. TRUNK MUSCLES
*NOTE: All of These Muscles Play an Important Role in Respiration.
1. MUSCLES OF THE THORAX
a. EXTERNAL INTERCOSTALS
‑ Elevates Ribs
b. INTERNAL INTERCOSTALS
‑ Depresses Ribs
c. DIAPHRAGM
‑ Enlarges Thorax (Causes Inspiration)
2. MUSCLES OF THE ABDOMINAL WALL
a. EXTERNAL OBLIQUE
b. INTERNAL OBLIQUE
c. TRANSVERSUS ABDOMINUS
d. RECTUS ABDOMINUS
‑ All Four of These Muscles Have the Following
Functions
1) Compress (Tighten) Abdomen
2) Rotate Trunk Laterally
3) Pull Front of Pelvis Up (Flattens Lumbar Curve of Spine)
‑ Also, Rectus Abdominus Flexes Trunk
E. UPPER LIMB MUSCLES
1. MUSCLES ACTING ON THE SHOULDER GIRDLE
a. TRAPEZIUS
‑ Raises and Lowers Shoulders (Shrugs Shoulders)
b. SERRATUS ANTERIOR
‑ Pulls Shoulder Forward and Upward (Punching Movements)
2. MUSCLES THAT MOVE THE UPPER ARM
a. PECTORALIS MAJOR
‑ Flexes Upper Arm
‑ Adducts Upper Arm Anteriorly (Draws It Across Chest)
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b. LATISSIMUS DORSI
‑ Extends Upper Arm
‑ Adducts Upper Arm Posteriorly (Draws It Across Back)
c. DELTOID
‑ Assists with Flexion and Extension of Upper Arm
‑ Abducts Upper Arm
3. MUSCLES THAT MOVE THE FOREARM
a. BICEPS BRACHII
‑ Supinates Forearm and Hand
‑ Flexes Supinated Forearm
b.
BRACHIALIS
‑ Flexes Pronated Forearm
c.
BRACHIORADIALIS
‑ Supinates Forearm and Hand
‑ Flexes Forearm (Semipronated or Semisupinated)
d. TRICEPS BRACHII
‑ Extends Forearm
4. MUSCLES THAT MOVE THE WRIST, HAND, AND FINGERS
a. FLEXOR CARPI RADIALIS
‑ Flexes Hand
b. PALMARIS LONGUS
‑ Flexes Hand
c. FLEXOR CARPI ULNARIS
‑ Flexes Hand
d. FLEXOR DIGITORUM (SUPERFICIALIS)
‑ Flexes Fingers
e. EXTENSOR CARPI RADIALIS
‑ Extends Hand
‑ Abducts Hand (Moves Toward Thumb Side When Hand Supinated)
f. EXTENSOR CARPI ULNARIS
‑ Extends Hand
‑ Adducts Hand (Moves Toward Little Finger Side When Hand Supinated)
g. EXTENSOR DIGITORUM
‑ Extends Fingers
h. OPPONENS POLLICIS
‑ Opposes Thumb to Fingers
F. LOWER LIMB MUSCLES
1. MUSCLES THAT MOVE THE THIGH
a. ILIOPSOAS
‑ Flexes Thigh
‑ Flexes Trunk
b. RECTUS FEMORIS
‑ Flexes Thigh
‑ Extends Lower Leg
c. GLUTEAL GROUP
1. MAXIMUS
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‑ Extends Thigh
2. MEDIUS
‑ Abducts Thigh
3. MINIMUS
‑ Abducts Thigh
d. TENSOR FASCIAE LATAE
‑ Abducts Thigh
e. PECTINEUS
‑ Adducts Thigh
‑ Flexes Thigh
f. ADDUCTOR GROUP
1. BREVIS
2. LONGUS
3. MAGNUS
‑ ALL of These Muscles Adduct the Thigh.
g. GRACILIS
‑ Adducts Thigh
‑ Flexes Lower leg
2. MUSCLES THAT MOVE THE LOWER LEG
a. QUADRICEPS FEMORIS GROUP
1. RECTUS FEMORIS
‑ Extends Lower leg
‑ Flexes Thigh
2. VASTUS LATERALIS
3. VASTUS MEDIALIS
4. VASTUS INTERMEDIUS
(ALL Muscles in the Vastus Group Extend Lower Leg)
b. SARTORIUS
‑ Flexes Lower Leg
‑ Permits Sitting in Tailor Fashion
c. HAMSTRING GROUP
1. BICEPS FEMORIS
‑ Flexes Lower Leg
‑ Extends Thigh
2. SEMITENDINOSUS
‑ Extends Thigh
3. SEMIMEMBRANOSUS
‑ Extends Thigh
3. MUSCLES THAT MOVE THE FOOT
a. TIBIALIS ANTERIOR
‑ Flexes Foot (Dorsiflexion)
‑ Inverts Foot (Inversion)
b. GASTROCNEMIUS
‑ Extends Foot (Plantar Flexion)
‑ Flexes Lower Leg
c. SOLEUS
‑ Extends Foot
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