Chapter 2- Musculoskeletal System PART 2

The muscles that can be seen from the anterior view are at the front of the body.

Have a look at the image to find some of the major muscles at the front of the body.

NOTE: Some muscles span around both the front and back of the body.

The muscles that can be seen from the posterior are at the back of the body.

NOTE: Just like the anterior view, there are some muscles that span around the body and can be seen from the front also.

There are three types of muscles in your body:

Skeletal- attached to bones and responsible for voluntary movement.

Smooth- involuntary muscles found in blood vessels and walls of the intestines.

Cardiac- involuntary muscles that make up the walls of the heart.

* Muscles are attached to bone by tendons.

* The main body of the muscle is called the muscle belly.

* The points of attachment are called the:

- Origin- attachment of the muscle to a stable bone, which the muscle can pull against

- Insertion- attachment of the muscle to a bone that is moved by the action of the muscle.

Reciprocal inhibition is a term used to explain the relaxation of one muscle to allow for the contraction of an opposing muscle to allow movement.

Agonists are the muscles primarily responsible for movement.

Antagonists are the muscles opposite to the agonist which relax during contraction to allow movement.

Stabilisers are also involved in contractions by holding or stabilising a body part, making it immobile with another part is moving.

Example: quadriceps may stabilise the knee in an extended position to permit plantar flexion of the ankle when pushing off the ground during the running action.

1. Circular- fibres arranged in rings.

2. Convergent- broad origin converging to single tendon insertion.

3. Parallel- fascicles run parallel to the long axis of the muscle

4. Pennate- fibres are short & attach obliquely to a central tendon

5. Fusiform- muscle belly is wider that insertion and origin.

Pennate muscles come in three forms:

1. Unipennate- Fascicles insert into only one side of the tendon.

2. Bipennate- fascicles insert into opposite into tendon from opposite sides (feather)

3. Multipennate- Looks like many feathers side by side inserted into one large tendon.