Nail courses – Muscular system
The muscular system is an active organ that allows movement. Almost half of the body’s weight (45%) is made up of muscle tissue. Their main motion is contraction. The parts of the muscle are the muscle belly (contractile portion of the middle part) and the tendon-like sections on both ends (stem on one end (fixing: head of the muscle), the point of cohesion on the other end where the motion occurs). (So tendons are parts of muscles, but ligaments are parts of joints. Consequently, tendon ligament as such does not exist).
Based on their histological structure there are three groups of muscles:
1. Smooth muscle
- functions involuntarily,
- can be found e.g. in the walls of intestines, nerves,
- it is capable of slow but steady contraction.
2. Skeletal striated muscle
- constitutes the skeletal muscle,
- it contracts fast and gets tired quickly,
- the muscular strength can be improved with exercises, its fatigue will be diminished (training),
- its overexertion causes pain (stiffness),
- it is under the control of the somatic nervous system
- only if at least one joint is found between the stem and point of cohesion will motion be caused by muscle contraction in the skeleton,
- in most cases it is fixed on the bone, on its cohesion point, through the tendon that is made up of dense fibrous connective tissues.
3. Heart muscle
- has the same qualities as those of the two above-mentioned,
- the muscle is separated into two distinct parts,
– the middle part that is capable of contraction and relaxation,
– the tendon-like part on both ends.