The muscular system
The muscular system is also called the active musculoskeletal system. Because muscle cells can contract, they can move the skeletal bones, allowing us to perform actively controlled movements. The muscles provide heat for our body through movement.
Skeletal muscles are the muscles that are attached to our skeleton. They ensure that the body can assume certain postures, that we can grasp things, they can initiate a movement, complete a movement and inhibit a movement.
A skeletal muscle consists of two parts
- The muscle belly
- The tendon
The muscle belly
The muscle belly is the part of the skeletal muscle that is made of muscle tissue. It has muscle tissues that are grouped in the muscle. The number of muscle fibers in a bundle determines how accurately we can regulate the force. The more fibers, the coarser the movement. So for fine movements, fewer fibers are needed in a bundle.
The muscle tissue mainly contains proteins that make up the muscle fibers. The muscle fibers contract, initiating a movement.
Connective tissue surrounds the muscle belly. We call this the muscle sheath or the fascia. The muscle sheath ensures that the muscle can shift somewhat during the movement and for dimensional stability when the muscle is relaxed.
A skeletal muscle always has two attachments on two different pieces of bone by means of tendons
The muscle tendon runs from the muscle belly to the bone. The length of the tendon can be different. For example, the tendons in the fingers are quite long. In some animal species, the Achilles tendon can even be several feet long.
Tendons have little blood flow, so that healing of a damaged tendon takes place slowly.
A tendon is surrounded by a tendon sheath that gives the tendon the necessary room to move. The tendon sheath is a double-walled tube filled with synovia, a type of lubricant.
Bursa protect against bone damage. They are bags filled with a lubricant that we call synovia. You can find a bursa in the elbow, for example. If the bursa gets irritated it swells. The swelling is caused by extra synovia being created. The swelling can be seen on the outside of the joint as a kind of bump. It often occurs in farm animals because they bump themselves quite regularly. In horses, the humps have been given special names. For example, a bursa bump on the horse’s wrist has a front knee bump. A bump on the horse’s elbow is called a legger.
Each joint has at least two muscles. This is because muscles can only shorten, so to make a joint move in two directions, the joint needs two muscles. At the elbow we are talking about the biceps and the triceps. We call antogonists two muscles on a joint that make the bone move in opposite directions.
Although it does not seem so, muscles at rest still have a certain muscle tone. We call this the so-called rest tension or tone. The strength of the tone determines the position of the joint at rest. You can see this clearly when relaxing the fingers. The fingers are somewhat curved in a relaxed position.
Our body contains many muscles. There are some interesting ones, such as the large pectoral muscle. This is also called the pectoralis muscle and runs from the sternum to the humerus. There are also muscles between the ribs, which we call the interrib muscles. They help enlarge the chest when inhaled.
Everyone knows the abs, of course (and especially the terrible abs exercises associated with them). Man has straight abs and oblique abs. Abdominal muscles help protect the organs behind them and are needed to flex the spine.
A very separate muscle is also called the diaphragm. This is a domed muscle tendon plate. When contracting it enlarges the chest cavity, we can see this in abdominal breathing.