Muscles and bones

Muscles and bones

Together, our musculature and skeletal system form a functional unit. The muscles, tendons, ligaments and fascia (connective tissue membrane) connected to the bone structures (spinal column, pelvis, skull, etc.) must together all be in balance in terms of tensile strength and load-bearing capacity.

The term 'tensegrity' (actually comes from architecture and is an amalgamation of tension and structural integrity ) refers to

this functional unit. It refers to tensile strength and load-bearing capacity. In construction, tensile forces  are absorbed in flexible steel cables, similar to muscles, ligaments and fascia. Whereas pressure forces are absorbed in steel or wooden bars, similar to our skeleton. Even though our skeletons are unstable, we are still able to stand upright.

The musculature, muscles and bones

The muscles have several tasks, namely:

• Generating movement.
• Maintaining a certain posture through muscle tension
• Protecting soft tissues/organs (e.g. the abdominal cavity).
• Producing heat. Muscles are the most important producers of heat, for example, during strenuous activity.

 

Types of muscles

The total amount of muscle in our body is quite substantial. We have approx. 650 (656) muscles, about 3 muscles per bone. Muscle tissue makes up about 60% of the body.

We differentiate between three types of muscle tissue:

• Striated muscle tissue:

Striated or random muscle tissue appears to have transverse stripes under the microscope. These muscles react according to our will (as in randomly). They work fast and tire quickly. The strength depends on the function.

2. Smooth muscle tissue:

Smooth muscle tissue or involuntary muscle tissue does not have these transverse stripes and therefore looks smooth under a microscope. Smooth muscle tissue is autonomous, i.e.: works independently of our will (as in involuntarily). It is present in our organs (stomach, intestines, lungs, bladder) and in the skin. In contrast to striaded muscle tissue, smooth muscle tissue is much less prone to fatigue. Sometimes it's affected by hormones.

3. Heart muscle tissue

The heart muscle is a special muscle because, although it has transverse stripes, it has the characteristics of a smooth muscle. It is fast, rhythmic and involuntary (autonomous). It produces and conducts impulses.

We are also familiar with other classifications of muscles: By function:

Tonic muscles: "posture muscles" (endurance) Phasic muscles: "movement muscles" (speed, strength)

By function:

• Agonists: these muscles cause movements through their own activation
• Antagonists: muscles that oppose the agonist in their function.
• Synergists: These muscles work in synergy with the agonists or antagonists.

On joints:

• Monoarticular muscles: these muscles extend across 1 joint.
• Biarticular muscles: these muscles extend over 2 joints (or sometimes several joints (in the hands/feet).

On form: see skeletal muscle structure.

When muscles are warm they use the oxygen more efficiently. When it comes to muscle function, ¼ is converted into action and ¾ is lost as heat.

Structure skeletal muscle

Skeletal muscle has a place where it originates from: the origin (origo) This is the place on a muscle where the muscle originates from and which does not move when the muscle is tensed (located on the immobile part of the bone). And skeletal muscles have an attachment point: the insertion. This is the attachment area for the muscle that does move when the muscle is tensed (located on the immobile part of the leg).

Often lying on the origin is a muscle head, which turns into a muscle belly and ends as a tendon. Tendons are made up tough connective tissue and are incapable of contraction. Some muscles have only short tendons, while others have long tendons, which usually run through a membrane layer, the tendon sheath, allowing them to slide back and forth without losing their place.

The position of the muscle belly depends on the space that is available on that location. A long tendon can be an advantage if there is a lack of space in the organ itself. The best examples of this are the long finger muscles with the muscle belly in the forearms and the long tendons towards the hand and the fingers. Depending on the position of the muscle fibres in relation to the tendon, various muscle types can be distinguished:

 

• Fusiform (spindle-shaped) muscle: long fibres, facilitates a great deal of movement, but not very powerful. Relatively short tendon.
• Unipennate muscle
• Bipennate muscle
• Two- or multi-headed muscle (e.g. biceps, triceps)
• Two- or multi-bellied muscle (abdominal muscles)
• Flat muscles (e.g. trapezius)

Muscles and bones : Each muscle is made up of a number of muscle bundles surrounded by a tough layer of connective tissue. The muscle itself is also surrounded by this kind of connective tissue layer. This layer is also known as fascia.

 

Each muscle bundle is made up of a number of muscle fibres. A muscle fibre is an elongated, multicellular cell, which has a transverse striped appearance under the microscope. The combined muscle fibres can contract, causing them to become shorter and denser. Although the force that each muscle fibre can exert on its own is very limited, together the muscle fibres can exert a great deal of force.

Contraction of the muscle fibres is caused by impulses that travel from the central nervous system to the muscle fibres.

Aside from that, as mentioned above, there are also agonists and antagonists, the opposing muscles, such as biceps and triceps. One tenses up while the other relaxes. In order to ensure that the muscles do not constantly work against each other, the antagonist slackens when the agonist in turn tenses up. This is called reciprocal inhibition.

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