Muscle Fibre arrangments

Question 1

Skeletal muscle def

Answer 1

A skeletal muscle is a type of muscle that is attached to bones and helps with movement.

Question 2

How are skeletal muscle fibres organised

Answer 2

organised in different ways according to the shape and function of the muscle.

Fusiform (type of Parallel muscle)
Pennate
Radiate

Question 3

1. Fusiform muscles

Answer 3

A type of parallel/strap muscle.

Characteristics (C): Run the length of the muscle belly.

Functions (F): Designed for mobility, produce contractions over a large range and produce low force.

uniform muscles are better for sustained, controlled movements

Eg. Biceps

Question 3

2. Pennate muscles

Answer 3

C → Run at angles to the tendons.
C → greater numbers of muscle fibres are packed into the muscle.
C → low lengths of fibres in comparison to the overall muscle length.

F: Designed for strength and force, tire easily and quickly.

Three categories of pennate muscles:
unipennate muscles
bipennate muscles
multipennate muscles

Question 3

• Unipennate:

Answer 3

Fibres on one side of a central tendon
Examples: the tibialis anterior (shin).

Question 4

• Bipennate muscles

Answer 4

fibres run off either side of a central tendon
Example: the rectus femoris (quadriceps)

Question 5

• Multipennate muscles

Answer 5

fibres branch out from several tendons.
F: Enables the greatest force.
Examples: the deltoid (shoulder).

Question 6

3. Radiate muscles (also known as convergent)

Answer 6

Has a broad origin at one end and the fascicles converge into a small insertion at the other end.

F: Produces a lot of force.

Eg- pectoralis major (chest)

Question 7

Radiate Muscle

Answer 7

The muscle fibres radiate or
spread from one main tendon.

They are a compromise between
fusiform & pennate muscles,
capable of producing power whilst
maintaining mobility.

Example: Pectoralis Major