chapter 11 the muscular system biol 141 a p l.
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Chapter 11: The Muscular System Biol 141 A&P. The Muscular System. Consists only of skeletal muscles How are fascicles arranged in the various types of muscles, and what are the resulting functional differences?. Muscle Organization and Function.

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the muscular system
The Muscular System
  • Consists only of skeletal muscles
  • How are fascicles arranged in the various types of muscles, and what are the resulting functional differences?
muscle organization and function
Muscle Organization and Function
  • Muscle organization affects power, range, and speed of muscle movement

Fascicles

  • Muscle cells (fibers) are organized in bundles (fascicles)

Classification of Skeletal Muscles

  • By the way fascicles are organized
  • By relationships of fascicles to tendons
organization of skeletal muscle fibers
Organization of Skeletal Muscle Fibers
  • 4 patterns of fascicle organization:
  • 1) Parallel-
    • Fibers parallel to the long axis of muscle

- e.g., biceps brachii

  • 2) Convergent-
  • 3) Pennate-
  • 4) Circular-
parallel muscles
Parallel Muscles

Figure 11–1a

parallel muscle body
Parallel Muscle Body
  • The center or body of the muscle thickens when parallel muscle contracts
  • Parallel muscles contract about 30%

Parallel Muscle Tension

  • Depends on total number of myofibrils
  • Directly relates to cross section of muscle
  • 1 in.2 (6.45 cm2) of cross section develops 50 lb (23 kg) of tension
convergent muscles
Convergent Muscles

Figure 11–1b

convergent muscles8
Convergent Muscles
  • A broad area converges on attachment site (tendon, aponeurosis, or raphe)
  • Muscle fibers pull in different directions, depending on stimulation
  • e.g., pectoralis muscles
pennate muscles
Pennate Muscles

Figure 11–1c, d, e

pennate muscles10
Pennate Muscles
  • Unipennate:
    • fibers on 1 side of tendon
    • e.g., extensor digitorum
  • Bipennate:
    • fibers on both sides of tendon
    • e.g., rectus femoris
  • Multipennate:
    • tendon branches within muscle
    • e.g., deltoid
pennate muscles11
Pennate Muscles
  • Form an angle with the tendon
  • Do not move as far as parallel muscles
  • Contain more myofibrils than parallel muscles
  • Develop more tension than parallel muscles
circular muscles
Circular Muscles

Figure 11–1f

circular muscles13
Circular Muscles
  • Also called sphincters
  • Open and close to guard entrances of body
  • e.g., obicularis oris
skeletal motion
Skeletal Motion
  • Skeletal muscles attach to skeleton, produce motion
  • Type of muscle attachment affects power, range, and speed of muscle movement
what are the classes of levers and how do they make muscles more efficient
What are the classes of levers, and how do they make muscles more efficient?

Levers

  • Mechanically, each bone is a lever (a rigid, moving structure):
    • and each joint a fulcrum (a fixed point)
  • Muscles provide applied force (AF):
    • required to overcome resistance (R)
functions of a lever
Functions of a Lever
  • To change:
    • direction of an AF
    • distance and speed of movement produced by an AF
    • effective strength of an AF
3 classes of levers
3 Classes of Levers
  • Depend on the relationship between applied force, fulcrum, and resistance:
    • first class
    • second class
    • third class

PLAY

First, Second, and Third-Class Levers

first class levers
First-Class Levers

Figure 11–2a

first class levers19
First-Class Levers
  • Seesaw is an example
  • Center fulcrum between applied force and resistance
  • Force and resistance are balanced
second class levers
Second–Class Levers

Figure 11–2b

second class levers21
Second-Class Levers
  • Wheelbarrow is an example
  • Center resistance between applied force and fulcrum
  • A small force moves a large weight
third class levers
Third-Class Levers

Figure 11–2c

third class levers23
Third-Class Levers
  • Most common levers in the body
  • Center applied force between resistance and fulcrum
  • Greater force moves smaller resistance
  • Maximizes speed and distance traveled
key concept
KEY CONCEPT
  • Skeletal muscles can shorten to 70% of resting length
  • Power, speed, and range of movement
  • Depend on positions of muscle attachment
  • Relative to joints
origins and insertions
Origins and Insertions
  • Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)
  • Most muscles originate or insert on the skeleton
  • Origin is usually proximal to insertion
actions
Actions
  • Movements produced by muscle contraction
  • Body movements
    • e.g., flexion, extension, adduction, etc.
  • Described in terms of bone, joint, or region
how do muscles interact to produce or oppose movements muscle interactions
How do muscles interact to produce or oppose movements?Muscle Interactions
  • Muscles work in groups to maximize efficiency
  • Smaller muscles reach maximum tension first, followed by larger, primary muscles
muscle terminology based on function
Muscle Terminology Based on Function
  • Agonist (prime mover):
    • produces a particular movement
  • Antagonist:
    • opposes movement of a particular agonist
  • Synergist:
    • a smaller muscle that assists a larger agonist
    • helps start motion or stabilize origin of agonist (fixator)
muscle opposition
Muscle Opposition
  • Agonists and antagonists work in pairs:
    • when 1 contracts, the other stretches
    • i.e., flexors–extensors, abductors–adductors, etc.
names of skeletal muscles
Names of Skeletal Muscles
  • Correct names of muscles include the term muscle
  • Exceptions:
    • platysma
    • diaphragm
naming skeletal muscles
Naming Skeletal Muscles

Table 11–1 (1 of 2)

naming skeletal muscles34
Naming Skeletal Muscles

Table 11–1 (2 of 2)

descriptive names for skeletal muscles
Descriptive Names for Skeletal Muscles
  • Location in the body-Identifies body regions: e.g.- temporalis muscle
  • Origin and insertion- First part of name indicates origin, Second part of name indicates insertion: e.g. genioglossus muscle
  • Fascicle organization-Describes fascicle orientation within muscle:
    • i.e.,rectus (straight), transversus, oblique
descriptive names for skeletal muscles36
Descriptive Names for Skeletal Muscles

4. Relative position- Externus(superficialis):

    • visible at body surface
  • Internus(profundus):deep muscles
  • Extrinsic:muscles outside an organ
  • Intrinsic:muscles inside an organ

5. Structural characteristics- Number of tendons:

    • bi = 2, tri = 3
  • Shape: trapezius, deltoid, rhomboid
  • Size-

6. Action- Movements: e.g., flexor, extensor, retractor

  • Occupations or habits: e.g., risor = laughter
names for muscle size 1 of 2
Names for Muscle Size (1 of 2)
  • Longus = long
  • Longissimus = longest
  • Teres = long and round
  • Brevis = short
  • Magnus = large
  • Major = larger
  • Maximus = largest
  • Minor = small
  • Minimus = smallest
divisions of the muscular system
Divisions of the Muscular System
  • Axial muscles:
    • position head and spinal column
    • move rib cage
    • 60% of skeletal muscles
  • Appendicular muscles:
    • support pectoral and pelvic girdles
    • support limbs
    • 40% of skeletal muscles
slide41
What are the principle axial muscles of the body, their origins, insertions, actions, and innervation?The Axial Muscles
  • Divisions based on location and function:
    • muscles of head and neck
    • muscles of vertebral column
    • oblique and rectus muscles
    • muscles of pelvic floor
6 muscle groups of the head and neck
6 Muscle Groups of the Head and Neck
  • Muscles of facial expression:
    • originate on skull
  • Extrinsic eye muscles:
    • originate on surface of orbit
    • control position of eye

3D Peel-Away of Muscles of the Head and Neck

PLAY

6 muscle groups of the head and neck43
6 Muscle Groups of the Head and Neck
  • Muscles of mastication:
    • move the mandible
  • Muscles of the tongue:
    • names end in glossus
  • Muscles of the pharynx:
    • begin swallowing process
6 muscle groups of the head and neck44
6 Muscle Groups of the Head and Neck
  • Anterior muscles of the neck:
    • control position of larynx
    • depress the mandible
    • support tongue and pharynx
muscles of facial expression47
Muscles of Facial Expression
  • Orbicularis oris:
    • constricts the mouth opening
  • Buccinator:
    • moves food around the cheeks
  • Muscles of the epicranium (scalp)
muscles of the epicranium scalp
Muscles of the Epicranium (Scalp)
  • Temporoparietalis
  • Occipitofrontalis:
    • frontal and occipital bellies
    • separated by epicranial aponeurosis
  • Platysma:
    • covers anterior surface of neck
extrinsic eye muscles
Extrinsic Eye Muscles
  • Also called extra-ocular muscles

Figure 11–5a, b

extrinsic eye muscles52
Extrinsic Eye Muscles

Inferior rectus

Medial rectus

Superior rectus

Lateral rectus

Inferior oblique

Superior oblique

Figure 11–5c

3 muscles of mastication
3 Muscles of Mastication
  • Masseter:
    • the strongest jaw muscle
  • Temporalis:
    • helps lift the mandible
  • Pterygoid muscles:
    • position mandible for chewing
4 muscles of the tongue
4 Muscles of the Tongue
  • Palatoglossus:
    • originates at palate
  • Styloglossus:
    • originates at styloid process
  • Genioglossus:
    • originates at chin
  • Hypoglossus:
    • originates at hyoid bone
3 muscles of the pharynx
3 Muscles of the Pharynx
  • Pharyngeal constrictor muscles:
    • move food into esophagus
  • Laryngeal elevator muscles:
    • elevate the larynx
  • Palatal muscles:
    • lift the soft palate
6 anterior muscles of the neck
6 Anterior Muscles of the Neck
  • Digastric:
    • from chin to hyoid
    • and hyoid to mastoid
  • Mylohyoid:
    • floor of the mouth
  • Geniohyoid:
    • between hyoid and chin
  • Stylohyoid:
    • between hyloid and styloid
  • Sternocleidomastoid:
    • from clavicle and sternum to mastoid
  • Omohyoid:
    • attaches scapula, clavicle, first rib, and hyoid
muscles of the vertebral column67
Muscles of the Vertebral Column
  • Spinal extensors or erector spinae muscles (superficial and deep)
  • Spinal flexors (transversospinalis)
superficial spinal extensors
Superficial Spinal Extensors
  • Spinalis group
  • Longissimus group
  • Iliocostalis group

Deep Spinal Extensors

  • Semispinalis group
  • Multifidus muscle
  • Interspinalis muscles
  • Intertransversarii muscles
  • Rotatores muscles
spinal flexors
Spinal Flexors
  • Neck:
    • longus capitis and longus colli
    • rotate and flex the neck
  • Lumbar:
    • quadratus lumborum muscles
    • flex spine and depress ribs
oblique and rectus muscles
Oblique and Rectus Muscles
  • Lie within the body wall

Figure 11–11a, b

oblique and rectus muscles73
Oblique and Rectus Muscles

Figure 11–11a, c

oblique and rectus muscles74
Oblique and Rectus Muscles
  • Oblique muscles:
    • compress underlying structures
    • rotate vertebral column
  • Rectus muscles:
    • flex vertebral column
    • oppose erector spinae
oblique muscles
Oblique Muscles

Cervical region:

  • scalene muscles
  • flex the neck

Thoracic region:

  • intercostal muscles (external and internal intercostals):
    • respiratory movements of ribs
  • transversus thoracis:
    • cross inner surface of ribs
oblique muscles76
Oblique Muscles
  • Abdominopelvic region (same pattern as thoracic):
    • external oblique muscles
    • internal oblique muscles
  • Transversus abdominis
rectus group
Rectus Group
  • Rectus abdominis:
    • between xiphoid process and pubic symphysis
    • divided longitudinally by linea alba
    • divided transversely by tendinous inscriptions
  • Diaphragmatic muscle or diaphragm:
    • divides thoracic and abdominal cavities
    • performs respiration
functions of pelvic floor muscles
Functions of Pelvic Floor Muscles
  • Support organs of pelvic cavity
  • Flex sacrum and coccyx
  • Control movement of materials through urethra and anus
perineum
Perineum
  • Muscular sheet forming the pelvic floor, divided into:
    • anterior urogenital triangle
    • posterior anal triangle

Pelvic Diaphragm

    • Deep muscular layer extending to pubis:
    • supports anal triangle
urogenital diaphragm
Urogenital Diaphragm
  • Deep muscular layer between pubic bones:
    • supports the pelvic floor
    • and muscles of the urethra
  • Superficial muscles of the urogenital triangle:
    • support external genitalia
slide87
What are the principal appendicular muscles of the body and their origins, insertions, actions, and innervations?
the appendicular muscles90
The Appendicular Muscles
  • Position and stabilize pectoral and pelvic girdles
  • Move upper and lower limbs
divisions of appendicular muscles
Divisions of Appendicular Muscles

1) Muscles of the shoulders and upper limbs:

  • Position the pectoral girdle
  • Move the arm
  • Move the forearm and hand
  • Move the hand and fingers

2) Muscles of the pelvis and lower limbs

muscles that position the pectoral girdle
Muscles that Position the Pectoral Girdle

3D Peel-Away of Muscles of the Pectoral Girdle

PLAY

Figure 11–14a

6 muscles that position the pectoral girdle
6 Muscles that Position the Pectoral Girdle
  • Trapezius:
    • superficial
    • covers back and neck to base of skull
    • inserts on clavicles and scapular spines
  • Rhomboid and levator scapulae:
    • deep to trapezius
    • attach to cervical and thoracic vertebrae
    • insert on scapular border
6 muscles that position the pectoral girdle95
6 Muscles that Position the Pectoral Girdle
  • Serratus anterior:
    • on the chest
    • originates along ribs
    • inserts on anterior scapular margin
  • Subclavius:
    • originates on ribs
    • inserts on clavicle
  • Pectoralis minor:
    • attaches to scapula
9 muscles that move the arm 1 of 3
9 Muscles that Move the Arm (1 of 3)
  • Deltoid:
    • the major abductor
  • Supraspinatus:
    • assists deltoid
  • Subscapularis and teres major:
    • produce medial rotation at shoulder

PLAY

3D Rotation: Muscles of the Arm

9 muscles that move the arm 2 of 3
9 Muscles that Move the Arm (2 of 3)
  • Infraspinatus and teres minor:
    • produce lateral rotation at shoulder
  • Coracobrachialis:
    • attaches to scapula
    • produces flexion and adduction at shoulder
9 muscles that move the arm 3 of 3
9 Muscles that Move the Arm (3 of 3)
  • Pectoralis major:
    • between anterior chest and greater tubercle of humerus
    • produces flexion at shoulder joint
  • Latissimus dorsi:
    • between thoracic vertebrae and humerus
    • produces extension at shoulder joint
the rotator cuff
The Rotator Cuff
  • Muscles involved in shoulder rotation
    • supraspinatus, subscapularis, infraspinatus, teres minor,and their tendons
muscles that move the forearm and hand106
Muscles that Move the Forearm and Hand
  • Originate on humerus and insert on forearm
  • Exceptions:
    • the major flexor (biceps brachii)
    • the major extensor (triceps brachii)

3D Rotation: Muscles of the

Forearm and Hand

PLAY

extensors and flexors
Extensors and Flexors
  • Extensors:
    • mainly on posterior and lateral surfaces of arm
  • Flexors:
    • mainly on anterior and medial surfaces
13 muscles that move the forearm and hand
13 Muscles that Move the Forearm and Hand
  • Biceps brachii:
    • flexes elbow
    • stabilizes shoulder joint
  • Triceps brachii:
    • extends elbow
    • originates on scapula
    • inserts on olecranon
  • Brachialis and brachioradialis:
    • flex elbow
    • originates on scapula
    • inserts on radial tuberosity
13 muscles that move the forearm and hand109
13 Muscles that Move the Forearm and Hand
  • Anconeus:
    • opposes brachialis
  • Palmaris longus:
    • superficial
    • flexes wrist
  • Flexor carpi ulnaris:
    • superficial
    • flexes wrist
    • adducts wrist
13 muscles that move the forearm and hand110
13 Muscles that Move the Forearm and Hand
  • Flexor carpi radialis:
    • superficial
    • flexes wrist
    • abducts wrist
  • Extensor carpi radialis:
    • superficial
    • extends wrist
    • abducts wrist
  • Extensor carpi ulnaris:
    • superficial
    • extends wrist
    • adducts wrist
13 muscles that move the forearm and hand 8 of 8
13 Muscles that Move the Forearm and Hand (8 of 8)
  • Pronator teres and supinator:
    • originate on humerus and ulna
    • rotate radius
  • Pronator quadratus:
    • originates on ulna
    • assists pronator teres
muscles that move the hand and fingers116
Muscles that Move the Hand and Fingers
  • Also called extrinsic muscles of the hand
  • Lie entirely within forearm
  • Only tendons cross wrist (in synovial tendon sheaths)
tendon sheaths
Tendon Sheaths
  • Extensor retinaculum:
    • wide band of connective tissue
    • posterior surface of wrist
    • stabilizes tendons of extensor muscles
  • Flexor retinaculum:
    • anterior surface of wrist
    • stabilizes tendons of flexor muscles
muscles of the pelvis and lower limbs
Muscles of the Pelvis and Lower Limbs
  • Pelvic girdle is tightly bound to axial skeleton:
    • permits little movement
    • has few muscles

Muscles that Position the Lower Limbs

  • Muscles that move the thigh
  • Muscles that move the leg
  • Muscles that move the foot and toes
muscles that move the thigh
Muscles that Move the Thigh

Figure 11–19a, b

muscles that move the thigh125
Muscles that Move the Thigh

Figure 11–19c, d

muscles that move the thigh126
Muscles that Move the Thigh
  • Gluteal muscles
  • Lateral rotators
  • Adductors
  • Iliopsoas

PLAY

3D Peel-Away of Muscles of the Thigh

PLAY

3D Peel-Away of Rectus Muscle

gluteal muscles 1 of 2
Gluteal Muscles (1 of 2)
  • Cover lateral surfaces of ilia
  • Gluteus maximus:
    • largest, most posterior gluteal muscle
    • produces extension and lateral rotation at hip
gluteal muscles 2 of 2
Gluteal Muscles (2 of 2)
  • Tensor fasciae latae:
    • works with gluteus maximus
    • stabilizes iliotibial tract
  • Gluteus medius and gluteus minimus:
    • originate anterior to gluteus maximus
    • insert on trochanter
lateral rotators
Lateral Rotators
  • Group of 6 muscles, including:
    • piriformis
    • obturator
adductors
Adductors
  • Adductor magnus:
    • produces adduction, extension, and flexion
  • Adductor brevis:
    • hip flexion and adduction
  • Adductor longus:
    • hip flexion and adduction
  • Pectineus:
    • hip flexion and adduction
  • Gracilis:
    • hip flexion and adduction
iliopsoas
Iliopsoas
  • 2 hip flexors insert on the same tendon:
  • psoas major
  • iliacus
muscles that move the leg135
Muscles that Move the Leg

Figure 11–20b, c

muscles that move the leg136
Muscles that Move the Leg
  • Flexors of the knee:
    • originate on the pelvic girdle
  • Extensors of the knee:
    • originate on the femoral surface
    • insert on the patella
flexors of the knee
Flexors of the Knee
  • Biceps femoris- Hamstrings
  • Semimembranosus- “
  • Semitendinosus- “
  • Sartorius:
    • originates superior to the acetabulum
  • Popliteus:
    • rotates the tibia to unlock the knee
extensors of the knee
Extensors of the Knee
  • 4 muscles of the quadriceps femoris:
    • 3 vastus muscles
    • rectus femoris muscle
muscles that move the foot and toes143
Muscles that Move the Foot and Toes
  • Extrinsic muscles that move the foot and toes include:
    • muscles that produce extension at the ankle
    • muscles that produce flexion at the ankle
    • muscles that produce extension at the toes
    • muscles that produce flexion at the toes
4 muscles that produce extension at the ankle
4 Muscles that Produce Extension at the Ankle
  • Gastrocnemius
  • Soleus
  • Fibularis
  • Tibialis posterior

+ The Achilles Tendon-

The calcaneal tendon (Achilles tendon):

    • shared by the gastrocnemius and soleus
muscles that produce flexion at the ankle
Muscles that Produce Flexion at the Ankle
  • Tibialis anterior:
    • opposes the gastrocnemius

Muscles that Produce Flexion at theToes

  • Flexor digitorum longum
  • Flexor hallucis longus:
    • oppose the extensors
muscles that produce extension at the toes
Muscles that Produce Extension at the Toes
  • Extensor digitorum longum
  • Extensor hallucis longus
  • Extensor retinacula:
    • fibrous sheaths hold tendons of toes as they cross the ankle
effects of aging on the muscular system
Effects of Aging on the Muscular System
  • Skeletal muscle fibers become smaller in diameter
  • Skeletal muscles become less elastic:
    • develop increasing amounts of fibrous tissue (fibrosis)
  • Decreased tolerance for exercise
  • Decreased ability to recover from muscular injuries
integration with other systems153
Integration with Other Systems
  • Cardiovascular system:
    • delivers oxygen and fuel
    • removes carbon dioxide and wastes
  • Respiratory system:
    • responds to oxygen demand of muscles
  • Integumentary system:
    • disperses heat from muscle activity
  • Nervous and endocrine systems:
    • direct responses of all systems
summary
SUMMARY
  • Effects of muscle structure on function
  • Organization of skeletal muscle fibers:
    • parallel, convergent, pennate, circular
  • Relationships between levers and movement
  • Actions of first, second, and third class levers
  • Origins and insertions of skeletal muscles
  • Actions of skeletal muscles:
    • agonist, antagonist, synergist
  • How skeletal muscles are named
summary155
SUMMARY
  • Structures and functions of axial muscles:
    • muscles of head and neck
    • muscle of vertebral column
    • oblique and rectus muscles
    • muscles of pelvic floor
  • Structures and functions of the appendicular muscles:
    • muscles of shoulders and upper limbs
    • muscles of pelvis and lower limbs
  • Effects of aging on the muscular system