Muscle movement

 Muscle movement

Muscle function in pairs to produce movements.

When first muscle contracts, second muscle relaxes to allow movement.

When second muscle contracts, first muscle relaxes to allow movement in opposite direction.

Flexion and extension, abduction and adduction, rotation to left and to the right.

Supination and pronation are opposite movement that are controlled by muscle pairs.

How skeletal muscle produce Movement

1. Origin and insertion

2. Lever systems and leverage

3. Effect of fascicle arrangement

4. Coordination with muscle group

1. Origin and insertion

Contractions of skeletal muscle produce movement by exerting a pulling force on tendons, which in turn pull on bone.

When muscle contract, one bone remain stationary while other movable bone is pulled towards it.

During muscle contraction insertion is pulled toward the origin resulting in observed movement.

2. Lever system and leverage

Joints and muscles in the human body function as levers.

To produce body movement, bones act as lever and joint function as fulcrums.

Based on arrangement of joint and muscle levers are classified into three types;

1. First class lever fulcrum in the middle. (See-saw).

For example, joints between skull and atlas vertebrae of spine.

2. Second class lever have load in the middle.

Example; heel joint

3. Third class lever have effort in middle.

Exame; elbow joint

3. Effect of fascicle arrangement

Skeletal muscle, fibre are arranged within muscle in bundle called fascicles.

Pattern of fascicles effects muscle strength and range of motion.

Different types of fascicle arrangement

1. Parallel 

2. Circular

3. Convergent/triangular

4. Pinnate

1. Parallel 

In this arrangement, fascicles run parallel to the along axis of muscle.

For example; fusiform muscle stylohyoid muscle of neck ; example, Digastric muscle

2. Circular 

Fascicles are arranged in circular pattern and enterclose orifice. 

For example; Orbicularis oculi muscle

3. Convergent/ Triangular

Fascicles have broad origin and converge to narrow insertion.

For example; Pectoralis major

4. Pinnate

Fascicles are short in relation to the entire length of muscle.

Pinnate;

1. Unipennate

Fascicles insert into one side of tendon.

2. Bipennate

Fascicles insert into tendon from both side. For example; Rectus femoris muscle

3. Multipennate

Fascicles insert into one large tendon from all sides. For example; Deltoid muscle

4. Coordination within muscle groups