MUSCLE TISSUE

A few short facts:•Movement of the body is important

for survival.

•There are more than 600 muscles in the human body

•40% - 50% of body weight

•Muscles pulling on bones is responsible for movement

•The way muscle is grouped and their relationship to joints determines the

type of movement they create

• Endomysium – around muscle cells

or fibers• Perimysium - hold

groups of muscle fibers together

•Epimysium – covers the entire muscle

group

All these layers attach the muscle to

the bone so the muscle pulls as one

unit

Connective tissue surrounding muscles tissue

Broad flat sheet of connective tissue

that covers muscle groups called

aponeurosis usually merges with fibrous

wrappings of another muscle

You will see that clearly on the cat

Structure of skeletal muscle

Size, shape and fiber arrangement

The movement and strength of a muscle is

determined by its overall shape and type of

attachment

Parallel

•Vary in length but are strap-

like•Fibers are

running parallel to each other

Convergent

Wide point of attachment to a small point of attachment

Pennate

Feather-like

Fusiform

Close to parallel in the middle or belly of muscle but converge to tendon at both

ends

Spiral

Fibers that twistBetween their

points of attachments

Circular

Called sphincters

Circle around a body tube or

opening

Most muscles span at least

one joint, some span two joints

Names for the attachments of muscles

OriginThe point of attachment that does

not move when the muscle contracts

InsertionThe point of attachment that

moves when the muscle contracts

•Skeletal Muscles act in groups•Some contract

while others relax

Prime mover•Agonist

•The muscle or group of muscles that directly performs a specific movement

Antagonists•Muscles that directly oppose the prime

mover•The antagonists is relaxed when the

prime mover is contracting•Provides precision and control during

the contraction of the prime mover the name antagonists is misleading

Synergists•Muscles that contract at the same time as

the prime mover• Complement the prime mover actions to

make a more effective movement

Fixator• Joint stabilizers

•Maintain posture or balance• Example would be the muscles in the front

and back of the thigh stabilizing the leg when standing

Most movements are very complex

Most muscles function as

prime mover, antagonists

synergists or fixators at some time depending

on the movement

A prime mover in flexing arm at the elbow is…….

The Antagonist is…….

Is it different when the

arm is above the

head?

Do you remember levers, which one is which?

Figure 10-4C. Lever classes. A, Class I: fulcrum (F) between the load (L) and force or pull (P); B, Class II: load (L) between the fulcrum (F) and force or pull (P); C, Class III: force or pull (P) between the fulcrum (F) and the load (L). The lever rod is yellow in each.

In the body: face is the load, the c2 vertebrae is the fulcrum, the muscles of the neck and upper back is the pull

In the body: some anatomists do not agree. Some say raising up on one’s toes is a 2nd class lever. Fulcrum is the toes point of contact with the ground, load is the ankle, pull is the gastrocnemius muscle in the lower legOpening mouth against resistance

In the body: all movement is made by 3rd class levers. The muscle insertion is very close to the joint being moved.

The movement is strong but it is also fast

So……

When a body part is moved the muscle moving that part usually does not lie over the part being

moved.The muscle doing the moving is usually

proximal to the part

being m0ved

Muscle doing the

moving

Body part being

moved

Before we go to the lab to look at the cats we

need to understand how muscles are named.

If we understand how they are named the language

isn’t as foreign as it appears at first glance

Locationbrachialis - arm, upper arm

gluteus - buttock

Functionadductor – moving the leg toward the

midline of the bodyabductor – moving the part away from

the midline of the body

Shapedeltoid – triangular

Direction of Fibersrectus – meaning straight

Number of Heads or Divisions

“cep” - means head triceps, quadriceps

biceps bracahii

Point of Attachmentorigin and/or insertion points

Sternocleidomastoid

Size of MuscleSize compared to size of nearby

musclesgluteus maximus, gluteus medius,

gluteus minimus

When you and your lab partner start looking at the cat keep

these things in mind

•Use the larger muscles as a guide•Try to figure out to which bones the

two ends attach•Determine what is being moved

when the muscle shortens – what is being moved, what is staying

stationaryinsertion and origin

•Deltoid•Pectoralis

major•Latissimus

dorsi•Serratus anterior

•Linea alba•Rectus

abdominis•External

oblique•Transverse abdominis

•Internal oblique