Ch 10 Lecture Outline

C h a p t e r

The Muscular System

PowerPoint® Lecture Slides prepared by Jason LaPres

Lone Star College - North Harris

An Introduction to the Muscular System

The Muscular System

Consists only of skeletal muscles

Muscle Organization and Function

Muscle organization affects power, range, and speed

of muscle movement

Fascicles

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

Fascicle Arrangement

Classification of Skeletal Muscles

By the way fascicles are organized

By relationships of fascicles to tendons

Organization of Skeletal Muscle Fibers

Four patterns of fascicle organization

Parallel

Convergent

Pennate

Circular

Parallel Muscles

Fibers parallel to the long axis of muscle

For example, biceps brachii

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

[INSERT FIG. 11.1a]

Figure 10–1a Muscle Types Based on Pattern of Fascicle Organization.

Convergent Muscles

A broad area converges on attachment site (tendon,

aponeurosis, or raphe)

Muscle fibers pull in different directions, depending on

stimulation

For example, pectoralis muscles

[INSERT FIG. 11.1b]

Figure 10–1b Muscle Types Based on Pattern of Fascicle Organization.

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

Pennate Muscles Unipennate

Fibers on one side of tendon For example, extensor digitorum

Bipennate Fibers on both sides of tendon For example, rectus femoris

Multipennate Tendon branches within muscle For example, deltoid

[INSERT FIG. 11.1c, d, e]

Figure 10–1c, d, e Muscle Types Based on Pattern of Fascicle Organization.

Circular Muscles

Also called sphincters

Open and close to guard entrances of body

For example, orbicularis oris muscle of the mouth

Figure 10–1f Muscle Types Based on Pattern of Fascicle Organization.

Levers

Skeletal Motion

Skeletal muscles attach to skeleton, produce

motion

Type of muscle attachment affects power,

range, and speed of muscle movement

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)

Levers

Function of a lever is to change

Direction of an AF

Distance and speed of movement produced by an AF

Effective strength of an AF

The Three Classes of Levers

Depend on the relationship between applied force,

fulcrum, and resistance

First class, second class, and third class

Levers

First-Class Lever

Seesaw or teeter-totter is an example

Center fulcrum between applied force and

resistance

Force and resistance are balanced

Levers

[INSERT FIG. 11.2a]

Figure 10–2a The Three Classes of Levers.

Levers

Second-Class Levers

Wheelbarrow is an example

Center resistance between applied force and

fulcrum

A small force moves a large weight

Levers

[INSERT FIG. 11.2b]

Figure 10–2b The Three Classes of Levers.

Levers

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

First, Second, and Third-Class Levers

Levers

[INSERT FIG. 11.2c]

Figure 10–2c The Three Classes of Levers.

Muscle Attachments to Other Tissues

Origins and Insertions

Muscles have one fixed point of attachment (origin)

and one moving point of attachment (insertion)

Most muscles originate or insert on the skeleton

Origin is usually proximal to insertion

Actions

Movements produced by muscle contraction

Body movements

For example, flexion, extension, adduction, etc.

Described in terms of bone, joint, or region

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

Agonist (or 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

Agonists and antagonists work in pairs:

When one contracts, the other stretches

Such as flexors–extensors, abductors–adductors,

Naming Skeletal Muscles

Names of Skeletal Muscles

Correct names of muscles include the term

muscle

Exceptions

Platysma

Diaphragm

Descriptive Names for Skeletal Muscles

Location in the body

Origin and insertion

Fascicle organization

Relative position

Structural characteristics

Action

Location in the Body

Identifies body regions

For example, temporalis muscle

Origin and Insertion

First part of name indicates origin

Second part of name indicates insertion

For example, genioglossus muscle

Fascicle Organization

Describes fascicle orientation within muscle

i.e., rectus (straight), transversus, oblique

Relative Position Externus (superficialis)

Visible at body surface

Internus (profundus) Deep muscles

Extrinsic Muscles outside an organ

Intrinsic Muscles inside an organ

Structural Characteristics

Number of tendons

bi = 2, tri = 3

Trapezius, deltoid, rhomboid

Many terms refer to muscle size

Descriptive Terms for Muscle Size Longus = long Longissimus = longest Teres = long and round Brevis = short Magnus = large Major = larger Maximus = largest Minor = small Minimus = smallest

Action

Movements

For example, flexor, extensor, retractor

Occupations or habits

For example, risor = laughter

[INSERT Table. 11.1-please use 2 slides if necessary]

Muscular System Overview

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

Figure 10–3a (Part 1 of 2) An Overview of the Major Skeletal Muscles.

Figure 10–3a (Part 2 of 2) An Overview of the Major Skeletal Muscles.

Figure 10–3b (Part 1 of 2) An Overview of the Major Skeletal Muscles.

Figure 10–3b (Part 2 of 2) An Overview of the Major Skeletal Muscles.

Axial Musculature

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

Axial Musculature

Six 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

Muscles of mastication Move the mandible

Muscles of the tongue Names end in glossus

Axial Musculature

Six Muscle Groups of the Head and Neck

Muscles of the pharynx

Begin swallowing process

Anterior muscles of the neck

Control position of larynx

Depress the mandible

Support tongue and pharynx

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

Axial Musculature

Muscles of Facial Expression

Orbicularis oris: constricts the mouth opening

Buccinator: moves food around the cheeks

Muscles of the epicranium (scalp)

Buccinator

Axial Musculature

Muscles of Facial Expression

Muscles of the epicranium (scalp)

Temporoparietalis

Occipitofrontalis

– Frontal and occipital bellies

– Separated by epicranial aponeurosis

Platysma

– Covers anterior surface of neck

Axial Musculature

Figure 10–4a Muscles of Facial Expression.

Axial Musculature

Figure 10–4b Muscles of Facial Expression.

Axial Musculature

[INSERT Table. 11.2- please split onto 2 slides if necessary]

Axial Musculature

Six Extrinsic Eye Muscles (Extra ocular)

Inferior rectus

Medial rectus

Superior rectus

Lateral rectus

Inferior oblique

Superior oblique

Axial Musculature

Figure 10–5a,b Extrinsic Eye Muscles.

Axial Musculature

Figure 10–5c, d Extrinsic Eye Muscles.

Axial Musculature

Muscles of Mastication

Masseter

The strongest jaw muscle

Temporalis

Helps lift the mandible

Pterygoid muscles

Positions mandible for chewing

Masseter Temporalis

Axial Musculature

Figure 10–6a Muscles of Mastication.

Axial Musculature

[INSERT FIG. 11.6b]

Figure 10–6b Muscles of Mastication.

Axial Musculature

[INSERT Table. 11.4]

Axial Musculature

Muscles of the Tongue

Palatoglossus

Originates at palate

Styloglossus

Originates at styloid process

Genioglossus

Originates at chin

Hypoglossus

Originates at hyoid bone

Axial Musculature

Figure 10–7 Muscles of the Tongue.

Axial Musculature

Muscles of the Pharynx

Pharyngeal constrictor muscles

Move food into esophagus

Laryngeal elevator muscles

Elevate the larynx

Palatal muscles

Lift the soft palate

Axial Musculature

Figure 10–8 Muscles of the Pharynx.

Axial Musculature

Anterior Muscles of the Neck

Digastric

From chin to hyoid

And hyoid to mastoid

Mylohyoid

Floor of the mouth

Geniohyoid

Between hyoid and chin

Axial Musculature

Anterior Muscles of the Neck

Stylohyoid

Between hyloid and styloid

Sternocleidomastoid

From clavicle and sternum to mastoid

Omohyoid

Attaches scapula, clavicle, first rib, and hyoid

Axial Musculature

Figure 10–9a Muscles of the Anterior Neck.

Axial Musculature

Figure 10–9b Muscles of the Anterior Neck.

Axial Musculature

Muscles of the Vertebral Column

Spinal extensors or erector spinae muscles

(superficial and deep)

Spinal flexors (transversospinalis)

Axial Musculature

Superficial Spinal Extensors

Spinalis group

Longissimus group

Iliocostalis group

Iliocostalis

Longissimus

Spinalis

Axial Musculature

Deep Spinal Extensors

Semispinalis group

Multifidus muscle

Interspinalis muscles

Intertransversarii muscles

Rotatores muscles

SemispinalisCapitus

Axial Musculature

[INSERT FIG. 11.10a]

Figure 10–10a Muscles of the Vertebral Column.

Axial Musculature

[INSERT FIG. 11.10c]

Figure 10–10c Muscles of the Vertebral Column.

Axial Musculature

[INSERT Table. 11.8 (top portion)]

Axial Musculature

[INSERT Table. 11.8 (middle portion)]

Axial Musculature

Spinal flexors

– Longus capitis and longus colli

– Rotate and flex the neck

Lumbar

– Quadratus lumborum muscles

– Flex spine and depress ribs

Axial Musculature

[INSERT FIG. 11.10b]

Figure 10–10b Muscles of the Vertebral Column.

Axial Musculature

Figure 10–10a Muscles of the Vertebral Column.

Axial Musculature

[INSERT Table. 11.8 (bottom portion)]

Axial Musculature

Oblique and Rectus Muscles

Lie within the body wall

Oblique muscles

Compress underlying structures

Rotate vertebral column

Rectus muscles

Flex vertebral column

Oppose erector spinae

Axial Musculature

Oblique Muscles Cervical region

Scalene muscles Flex the neck

Thoracic region Intercostal muscles (external and internal)

– Respiratory movements of ribs

Transversus thoracis– Cross inner surface of ribs

Internal Intercostals External Intercostals

Axial Musculature

Oblique Muscles

Abdominopelvic region (same pattern as

thoracic) External oblique muscles

Internal oblique muscles

Transversus abdominis

Transversus Abdominis Internal Obliques

External Obliques

Axial Musculature

Rectus Muscles

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

Rectus Abdominis

Axial Musculature

Figure 10–11a Oblique and Rectus Muscles and the Diaphragm.

Axial Musculature

Figure 10–11b Oblique and Rectus Muscles and the Diaphragm.

Axial Musculature

Figure 10–11c Oblique and Rectus Muscles and the Diaphragm.

Axial Musculature

[INSERT Table. 11.9-please split onto 2 slides if necessary]

Axial Musculature

Muscles of the Pelvic Floor

Functions of pelvic floor muscles

Support organs of pelvic cavity

Flex sacrum and coccyx

Control movement of materials through urethra and anus

Axial Musculature

Perineum

Muscular sheet forming the pelvic floor, divided

– Anterior urogenital triangle

– Posterior anal triangle

Axial Musculature

Perineum

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

Axial Musculature

Perineum

Pelvic diaphragm

– Deep muscular layer extending to pubis

» Supports anal triangle

Axial Musculature

Figure 10–12a Muscles of the Pelvic Floor.

Axial Musculature

Figure 10–12b Muscles of the Pelvic Floor.

Axial Musculature

Appendicular Musculature

Position and stabilize pectoral and pelvic

girdles

Move upper and lower limbs

Divisions of Appendicular Muscles

Muscles of the shoulders and upper limbs

Muscles of the pelvis and lower limbs

Figure 10–13a An Overview of the Appendicular Muscles of the Trunk.

Figure 10–13b An Overview of the Appendicular Muscles of the Trunk.

Muscles of the Shoulders and Upper

Position the pectoral girdle

Move the arm

Move the forearm and hand

Move the hand and fingers

Muscles That Position the Pectoral Girdle

Trapezius

Superficial

Covers back and neck to base of skull

Inserts on clavicles and scapular spines

Trapezius

Rhomboid and levator scapulae

Deep to trapezius

Attach to cervical and thoracic vertebrae

Insert on scapular border

Rhomboid Minor

Rhomboid Major

Levator Scapulae

Figure 10–14a Muscles That Position the Pectoral Girdle.

Serratus anterior

On the chest

Originates along ribs

Inserts on anterior scapular margin

Serratus Anterior

Subclavius

Originates on ribs

Inserts on clavicle

Pectoralis minor

Attaches to scapula

Pectoralis Minor

Figure 10–14b Muscles That Position the Pectoral Girdle.

Muscles That Move the Arm

Deltoid

The major abductor

Supraspinatus

Assists deltoid

Supraspinatus

Subscapularis and Teres major

Produce medial rotation at shoulder

Teres Major

Subscapularis

Figure 10–15a Muscles That Move the Arm.

Infraspinatus and teres minor

Produce lateral rotation at shoulder

Coracobrachialis

Attaches to scapula

Produces flexion and adduction at shoulder

Infraspinatus

Figure 10–15b(Part 1 of 2) Muscles That Move the Arm.

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

Pectoralis Major Latissimus Dorsi

The Rotator Cuff

Muscles involved in shoulder rotation

Supraspinatus, subscapularis, infraspinatus, teres

minor, and their tendons

Teres Minor

Figure 10–15a (Part 1 of 2) Muscles That Move the Arm.

Figure 10–15b Muscles That Move the Arm.

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)

Extensors

Mainly on posterior and lateral surfaces of arm

Flexors

Mainly on anterior and medial surfaces

Flexors of the Elbow

Biceps brachii

Flexes elbow

Stabilizes shoulder joint

Originates on scapula

Inserts on radial tuberosity

Brachialis and brachioradialis

Flex elbow

Biceps Brachii

Figure 10–16a Muscles That Move the Forearm and Hand.

Extensors of the Elbow

Triceps brachii

Extends elbow

Originates on scapula

Inserts on olecranon

Anconeus

Opposes brachialis

Triceps Brachii

Figure 10–16b Muscles That Move the Forearm and Hand.

[INSERT Table. 11.13 top portion]

Flexors of the Wrist Palmaris longus

Superficial

Flexes wrist

Flexor carpi ulnaris Superficial

Flexes wrist

Adducts wrist

Flexor carpi radialis Superficial

Flexes wrist

Abducts wrist

Extensors of the Wrist

Extensor carpi radialis

Superficial

Extends wrist

Abducts wrist

Extensor carpi ulnaris

Superficial

Extends wrist

Adducts wrist

[INSERT Table. 11.13 bottom portion]

Pronation and supination

Pronator teres and supinator

– Originate on humerus and ulna

– Rotate radius

Pronator quadratus

– Originates on ulna

– Assists pronator teres

[INSERT Table. 11.13 middle portion]

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)

Muscles that Move the Hand and Fingers

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

Figure 10–17a Muscles That Move the Hand and Fingers.

Figure 10–17b Muscles That Move the Hand and Fingers.

Figure 10–17c Muscles That Move the Hand and Fingers.

[INSERT FIG. 11.18d]

Figure 10–17d Muscles That Move the Hand and Fingers.

The Intrinsic Muscles of the Hand

Muscles that move the metacarpals and

phalanges and originate and insert only on

those bones

Figure 10–18a Intrinsic Muscles of the Hand.

Figure 10–18b Intrinsic Muscles of the Hand.

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 Gluteal muscles

Lateral rotators

Adductors

Iliopsoas

3D Peel-Away of Muscles of the Thigh

Figure 10–19a Muscles That Move the Thigh.

Muscles That Move the Thigh: Gluteal Muscles Cover lateral surfaces of ilia

Gluteus maximus Largest, most posterior gluteal muscle

Produces extension and lateral rotation at hip

Tensor fasciae latae Works with gluteus maximus

Stabilizes iliotibial tract

Gluteus medius and gluteus minimus Originate anterior to gluteus maximus

Insert on trochanter

Figure 10–19b Muscles That Move the Thigh.

Muscles That Move the Thigh

Lateral rotators

Group of six muscles, including

– Piriformis

– Obturator

Figure 10–19c Muscles That Move the Thigh.

[INSERT Table. 11.16 2nd section]

Muscles That Move the Thigh: 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

Figure 10–20b Muscles That Move the Leg.

Figure 10–19d Muscles That Move the Thigh.

[INSERT Table. 11.16 3rd section]

Muscles That Move the Thigh: Iliopsoas

Two hip flexors insert on the same tendon

Psoas major

Iliacus

Iliopsoas

Figure 10–19d Muscles That Move the Thigh.

[INSERT Table. 11.16 bottom]

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

Hamstrings

Biceps femoris

Semimembranosus

Semitendinosus

Sartorius

Originates superior to the acetabulum

Popliteus

Rotates the tibia to unlock the knee

Figure 10–20a Muscles That Move the Leg.

Muscles That Move the Leg

Extensors of the knee

Four muscles of the quadriceps femoris

– Three vastus muscles

– Rectus femoris muscle

Figure 10–20b Muscles That Move the Leg.

[INSERT Table. 11.17 bottom]

Figure 10–20c Muscles That Move the Leg.

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

Four Muscles That Produce Extension (plantar

flexion) at the Ankle Gastrocnemius

Soleus

Fibularis (group)

Tibialis posterior

3D Peel-Away of Muscles of the Leg and Foot

Figure 10–21a Extrinsic Muscles That Move the Foot and Toes.

Figure 10–21b Extrinsic Muscles That Move the Foot and Toes.

Muscles That Move the Foot and Toes

The Achilles Tendon

The calcaneal tendon (Achilles tendon)

– Shared by the gastrocnemius and soleus

Muscles That Produce Flexion

(Dorsiflexsion) at the Ankle

Tibialis anterior

Opposes the gastrocnemius

Muscles That Produce Extension at the

Extensor digitorum longum

Extensor hallucis longus

Extensor retinacula: fibrous sheaths hold tendons

of toes as they cross the ankle

Figure 10–21b Extrinsic Muscles That Move the Foot and Toes.

Figure 10–21d Extrinsic Muscles That Move the Foot and Toes.

Muscles That Produce Flexion at the Toes

Flexor digitorum longum

Flexor hallucis longus

Oppose the extensors

Figure 10–21c Extrinsic Muscles That Move the Foot and Toes.

The Intrinsic Muscles of the Foot

Muscles that move the tarsals, metatarsals,

and phalanges and originate and insert only

on those bones

Figure 10–22a Intrinsic Muscles of the Foot.

Figure 10–22b Intrinsic Muscles of the Foot.

Figure 10–22c Intrinsic Muscles of the Foot.

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