An Introduction to the Muscular System The Muscular System Consists only of skeletal muscles Muscle Organization and Function Muscle organization

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

1. Parallel

2. Convergent

3. Pennate

4. Circular


Parallel Muscles

Fibers parallel to the long axis of muscle, e.g., ___________________

1 in.2 (6.45 cm2) of cross section develops 50 lb (23 kg) of tension


Convergent Muscles

A broad area converges on attachment site (tendon, aponeurosis, or raphe)

Muscle fibers pull in different directions, depending on stimulation, e.g.,

_______________________


Pennate Muscles

Form an angle with the tendon

Do not move as far as parallel muscles

Contain more myofibrils than parallel muscles

Develop more tenson than parallel muscles

Unipennate

Fibers on one side of tendon, e.g., ________________

Bipennate

Fibers on both sides of tendon, e.g., _________________

Multipennate

Tendon branches within muscle, e.g., __________________


Circular Muscles

Also called sphincters

Open and close to guard entrances of the body, e.g., _________muscle

of the mouth

Muscle Attachments to Other Tissues

Origins and Insertions

Muscles have one fixed point of attachment

(______) and one moving point of attachment

(______________)

Most muscles originate or insert on the

skeleton

_________ is usually __________ 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 Opposition

Agonists and antagonists work in pairs:

When one contracts, the other stretches

Such as flexors–extensors, abductors–adductors,

etc.

Naming Skeletal Muscles

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

Shape

Trapezius, deltoid, rhomboid

Size

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings


Figure 11–3a An Overview of the Major Skeletal Muscles.



Figure 11–3a An Overview of the Major Skeletal Muscles.



Figure 11–3b An Overview of the Major Skeletal Muscles.



Figure 11–3b 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

Muscles of the pharynx: Begin swallowing process

Anterior muscles of the neck:

Control position of larynx

Depress the mandible

Support tongue and pharynx

Axial Musculature

Muscles of Facial Expression

Orbicularis oris: constricts the mouth opening

________________: moves food around the cheeks

Muscles of the epicranium (scalp)

Temporoparietalis – Tenses the scalp

Occipitofrontalis – Raises eyebrows, wrinkles forehead

Platysma (Covers anterior surface of neck) – Tenses skin of

neck, depresses mandible


Axial Musculature

Figure 11–4a Muscles of Facial Expression.


Axial Musculature

Figure 11–4b Muscles of Facial Expression.

Axial Musculature

Six Extrinsic Eye Muscles (Extra ocular): Action

Inferior rectus: Eye looks down

Medial rectus: Eye looks medially

Superior rectus: Eye looks up

Lateral rectus: Eye looks laterally

______________: Eye rolls, looks up and laterally

Superior oblique: Eye rolls, looks down and laterally


Axial Musculature

Figure 11–5a,b Extrinsic Eye Muscles.


Axial Musculature

Figure 11–5c, d Extrinsic Eye Muscles.


Axial Musculature

Figure 11–6a Muscles of Mastication.


Axial Musculature

Figure 11–9a Muscles of the Anterior Neck.


Axial Musculature

[INSERT FIG. 11.10a]

Figure 11–10a Muscles of the Vertebral Column.


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

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 11–13a An Overview of the Appendicular Muscles of the Trunk.



[INSERT FIG. 11.13b]

Figure 11–13b An Overview of the Appendicular Muscles of the Trunk.


Muscles of the Shoulders and Upper

Limbs

Position the pectoral girdle

Move the arm

Move the forearm and hand

Move the hand and fingers


Muscles That Position the Pectoral Girdle

__________________

Superficial

Covers back and neck to base of skull

Inserts on clavicles and scapular spines

Actions: (1) elavate, retract, depress, or rotate

scapula upward; (2) elevate clavicle; (3) extend

neck


Muscles That Position the Pectoral Girdle

_________________ and levator scapulae

Deep to trapezius

Attach to cervical and thoracic vertebrae

Insert on scapular border

Action of the Rhomboid: Adducts scapula and performs

____________________ motion

Action of the ____________ scapulae: ___________

scapula




Figure 11–14a Muscles That Position the Pectoral Girdle.


Other Muscles That Position the Pectoral Girdle

Serratus anterior: Protracts shoulder, rotates scapula

On the chest

Originates along ribs

Inserts on anterior scapular margin

Subclavius: Depresses and protracts shoulder

Originates on ribs

Inserts on clavicle

Pectoralis minor: Depresses and protracts shoulder,

rotates scapula, elevates ribs

Attaches to scapula




Figure 11–14b Muscles That Position the Pectoral Girdle.


Muscles That Move the Arm

Deltoid

The major abductor (also flexion and extension)

Supraspinatus

Assists deltoid

Subscapularis and Teres major

Produce medial rotation at shoulder

Infraspinatus and Teres minor

Produce lateral rotation at shoulder



Figure 11–15a Muscles That Move the Arm.



Figure 11–15b(Part 1 of 2) Muscles That Move the Arm.


Muscles That Move the Arm

Pectoralis major

Between anterior chest and greater tubercle of humerus

Originates from the sternum and ventral portoins of the ribs

Produces ________ at shoulder joint, adduction, and medial

rotation at the shoulder

Latissimus dorsi

Between thoracic vertebrae and humerus

Originates from the vertebral column and dorsal ribs

Produces ______________ at shoulder joint, adduction, and

medial rotation at the shoulder



Figure 11–15 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)



Figure 11–16b Muscles That Move the Forearm and Hand.

Flexors of the Elbow

Biceps brachii

_____________ elbow

Stabilizes shoulder joint

Originates on scapula

Inserts on _____________



Figure 11–16a Muscles That Move the Forearm and Hand.

Extensors of the Elbow

Triceps brachii

____________ elbow

Originates on scapula

Inserts on _________


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



Figure 11–16a Muscles That Move the Forearm and Hand.





Muscles That Move the Forearm and Hand

Pronation and supination

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 Fingers

Also called extrinsic muscles of the hand

Lie entirely within forearm

Only ____________ 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 11–18b Intrinsic Muscles of the Hand.



Figure 11–18a Intrinsic Muscles of the Hand.






Muscles of the Lower Limbs

36 muscles move the bones of the lower

extremities:

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


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 11–19a Muscles That Move the Thigh.


Muscles That Move the Thigh: Lateral rotators

Group of six muscles, including:

– Piriformis

» Also hip abduction

– Obturator (externus and internus)

– Gemilli (superior and inferior)

– Quadratus femoris


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


Muscles That Move the Thigh: Iliopsoas

Two hip flexors insert on the same tendon

Psoas major

Iliacus


Muscles That Move the Leg

__________________ of the knee

Originate on the ______________________

__________________ of the knee

Originate on the _________________ surface

Insert on the patella



Flexors of the Knee

________________________

Biceps femoris

Semimembranosus

Semitendinosus

Sartorius

Originates superior to the acetabulum

Popliteus

Rotates the tibia to unlock the knee



Figure 11–20a Muscles That Move the Leg.


Muscles That Move the Leg

Extensors of the knee

Four muscles of the _______________________

– Three vastus muscles

» Extension at the knee

– Rectus femoris muscle

» Extension at the knee

» Flexion at the hip




Figure 11–20b 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 - also inversion of the foot, flexion at knee

Soleus

Fibularis (group)

Tibialis posterior



Figure 11–21a 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 (extensor)

Except both are involved with inversion of the foot


Muscles That Produce Extension at the

Toes

Extensor digitorum longus

Extension at joint of toes 2-5

Extensor hallucis longus

Extension of joints at great toe

Extensor retinacula: fibrous sheaths hold tendons

of toes as they cross the ankle




Figure 11–21b Extrinsic Muscles That Move the Foot and Toes.



[INSERT FIG. 11.22d]

Figure 11–21d Extrinsic Muscles That Move the Foot and Toes.


Muscles That Produce Flexion at the Toes

Flexor digitorum longum

Flexion at joint of toes 2-5

Flexor hallucis longus

Flexion at joints of great toe

Oppose the extensors



Figure 11–21c 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 11–22a Intrinsic Muscles of the Foot.




Figure 11–22b Intrinsic Muscles of the Foot.



[INSERT FIG. 11.23c]

Figure 11–22c Intrinsic Muscles of the Foot.

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 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


Integration with Other Systems

Figure 11–24 Functional Relationships Between the Muscular System and Other Systems.

Documents

An Introduction to the Muscular System The Muscular System Consists only of skeletal muscles Muscle Organization and Function Muscle organization