HAN 200 CHAPTER 11

Muscle tissue

all contractile tissues

- Skeletal, cardiac, smooth muscle

Focus on skeletal muscle

- How muscles interact to increase movement

- Criteria for naming muscles

- Principles of leverage

Muscles can only pull never push

True

Agonist

primary mover

Antagonist

opposes or reverses particular movement

Synergist helps prime movers

- Adds extra force to same movement

- Reduces undesirable or unnecessary movement

Fixator

- Synergist that immobilizes bone or muscle's origin (rotator cuff and G-H joint)

- Gives prime mover stable base on which to act (ex scap and G-H joint)

Muscle location

bone or body region with which muscle associated

Muscle shape

e.g., deltoid muscle (deltoid = triangle)

Muscle size

e.g., maximus (largest), minimus (smallest), longus (long

Direction of muscle fibers or fascicles

e.g., rectus (fibers run straight), transversus (fibers run at right angles), and oblique (fibers run at angles to imaginary defined axis)

Number of origins

e.g., biceps (2 origins) and triceps (3 origins)

Location of attachments

named according to point of origin and insertion (origin named first)

- sternocleidomastoid

Muscle action

named for action they produce, e.g., flexor or extensor

T tubules are an extension of the _________.

- sarcomere

- sarcoplasmic reticulum

- sarcolemma

- endomysium

sarcolemma

The force exerted by a contracting muscle is _______.

- muscle summation

- muscle twitch

- muscle tension

- muscle load

Muscle tension

Additional factors contributing to muscle force and speed

- Fascicle arrangement

- Lever systems

5 patterns of fascicle arrangement

parallel, fusiform, circular, triangular, pennate

Circular

Fascicles arranged in concentric rings (e.g., orbicularis oris, orbicularis oculi)

Convergent

Broad origin; fascicles converge toward single tendon insertion (e.g., pectoralis major)

Parallel fascicles

Fascicles parallel to long axis of straplike muscle (e.g., sartorius)

Fusiform fasicles

Spindle-shaped muscles with parallel fibers (e.g., biceps brachii)

Pennate

Short fascicles attach obliquely to central tendon running length of muscle (e.g., rectus femoris)

Unipennate

fascicles attach only to one side of tendon

(e.g., extensor digitorum longus)

Bipennate

fascicles insert from opposite sides of tendon (e.g., rectus femoris)

Multipennate

appears as feathers inserting into one tendon (e.g., deltoid)

Lever systems

Levers allow given effort to move heavier load; move load farther or faster

What are the components of a lever system?

- Lever—rigid bar (bone) that moves on a fixed point called

fulcrum (joint)

- Effort—force (supplied by muscle contraction) applied to lever to move resistance (load)

- Load—resistance (bone + tissues + any added weight) moved

by the effort

Mechanical advantage (power lever)

load close to fulcrum; effort far from fulcrum

- Small effort can move large load

Mechanical disadvantage (speed lever)

load far from fulcrum; effort close to fulcrum

- Load moved rapidly over large distance; wide range of motion

First-class levers

fulcrum is between the effort and the load

- example: seesaws

Second-class lever

the load is between the fulcrum and the effort

- example: wheelbarrow

Third-class lever

The effort is between the fulcrum and the load

- example: pair of forceps

Zygomaticus

Smile muscle

Risorius

grin

Orbicular Oculi

closes eyelids

Orbicularis Oris

puckers lips

Platysma

Pulls corners of mouth down

Three muscles anchor and move tongue

- Genioglossus

- Hyoglossus

- Styloglossus

Sternocleidomastoid

major head flexor and rotator

Sternocleidomastoid and scalenes

lateral head movements

Splenius capitis and cervicis portions

head extension, rotation, and lateral bending

Semispinalis capitis

synergist with sternocleidomastoid

Erector spinae (sacrospinalis) group

prime movers of back extension and lateral bending

• Iliocostalis (most lateral)

• Longissimus

• Spinalis (most medial)

Semispinalis and quadratus lumborum

synergists in extension and rotation

External intercostals

more superficial muscles; elevate ribs for inspiration

Internal intercostals

deeper muscles; aid forced expiration

Diaphragm

- Partition between thoracic and abdominal cavities

- Most important muscle in inspiration

Four paired muscles

- Rectus abdominis

- External obliques

• Most superficial

- Internal obliques

- Transversus abdominis

• deepest

Valsalva maneuver

increased intra abdominal pressure used during coughing, vomiting, sneezing, defecation and childbirth

The coracobrachialis muscle has its origin and insertion on what two bones? (use the name to guide you!)

• vertebral column and clavicle

• femur and tibia

• scapula and humerus

• trapezium and radius

Scapula and humerus

When you bite down on an ice cube, this muscle strongly contracts.

• Lateral pterygoid

• Buccinator

• Hyoglossus

• Masseter

Masseter

Pelvic floor (pelvic diaphragm)

composed of two paired muscles

- Levator ani

- Coccygeus

Urogenital diaphragm

Contains external urethral sphincter (voluntary control of urination)

Pectoralis minor

protraction & downward rotation of scapula

Serratus anterior (saw tooth)

protraction

Subclavius

stabilizes pectoral girdle

Posterior extrinsic shoulder muscles

trapezius, levator scapulae, rhomboids

Upper trapezius

elevation of scapula (shrug)

Middle trapezius

retraction of scapula

Lower trapezius

depression of scapula

Rhomboids (major and minor)

retraction and downward rotation of scapula

Pectoralis major

adduction & flexion

Latissimus dorsi

adduction & extension

Deltoid

• anterior fibers - flexion

• middle fibers - abduction

• Posterior fibers - extension

Supraspinatus

assists deltoid in abducting arm

Infraspinatus

shoulder external rotation

Teres minor

Shoulder external rotation

Subscapularis

Shoulder internal rotation

Brachialis and biceps brachii (2 heads)

chief forearm flexors

Brachioradialis

synergist and stabilizer

Triceps brachii

(3 heads) prime mover of elbow extension

Anconeus

weak synergist

The ______ muscles are antagonistic to each other when moving the scapula

forward and backward (protraction and retraction).

• pectoralis major and subclavius

• latissimus dorsi and rhomboid

• pectoralis minor and serratus anterior

• serratus anterior and rhomboids

serratus anterior and rhomboids

The prime mover in abduction of the arm is the ______.

- triceps brachii

- deltoid

- biceps brachii

- supraspinatus

deltoid

This muscle flexes the elbow and inserts on the ulnar

• Biceps brachi

• Brachialis

• Brachioradialis

• Coracobrachialis

Brachialis

Pronator teres and pronator quadratus...

pronate forearm

Supinator

synergist with biceps brachii in forearm supination

- Flexor carpi radialis

- Palmaris longus

- Flexor carpi ulnaris

flexes wrist

Flexor digitorum superficialis and flexor digitorum profundus

flexes finger

Flexor pollicis longus

flexes thumb

The ______ is (are) the most important muscle(s) for inspiratory breathing.

• internal intercostals

• diaphragm

• scalenes

• rectus abdominis

Diaphragm

What arm muscle is prime mover for this activity?

• biceps brachii

• latissimus dorsi

• triceps brachii

• flexor carpi radialis longus

triceps brachii

The rotator cuff muscles include the supraspinatus, infraspinatus, teres minor,

and _________.

• Subscapularis

• Pectoralis major

• Teres major

• Deltoid

Subscapularis

- Extensor carpi radialis longus and brevis

- Extensor carpi ulnaris

wrist extensions

Extensor digitorum

finger extension

Extensor pollicis brevis and longus

thumb extension

Extensor indicis

index finger

Abductor pollicis longus

thumb abduction

Thenar eminence (ball of thumb)

Produce opposition—move thumb toward little finger

Hypothenar eminence (ball of the little finger)

Each of above groups has flexor, abductor, and opponens muscle

Midpalmar muscles

lumbricals and interossei

• abduct and adduct fingers

Do medial muscles all adduct or abduct thigh?

adduct thigh

Do lateral muscles adduct or abduct thigh?

abduct thigh

Iliopsoas

prime mover of flexion

Rectus femoris (hip flexion)

This muscle is the only quadricep muscle that acts on the hip

Hamstring muscles

prime movers of extension

Biceps femoris

lateral hamstring

- Semitendinosus

- Semimembranosus

medial hamstring

Gluteus maximus

assists hamstrings in forceful thigh extension