Human body is a balanced system. Its activity is subject to well-coordinated work of all systems:
- Central Nervous System consists of brain and spinal cords, through the nerve roots it manages and controls all processes in a body.
- Endocrine System carries out the control function, but, unlike the Central Nervous System, the control is performed not by transmitting of signals to the nerves. But through the action of hormones (glands produce chemicals), which are transported through the blood to the organs of influence.
- Cardiovascular System provides exchange of nutrients between tissues, transports the toxic products to organs (kidneys, skin and lungs), that lead out these substances.
- Digestive System absorbs nutrients from food.
- Urinary System removes from the blood toxic substances and provides reproduction.
- Musculoskeletal System.
The largest system of the body is Musculoskeletal. It creates the shape of our body and defines the external manifestations of life, such as work, entertainment, gestures, etc.
Movement is the basis of our life. It is realized through coordinated work of muscle, contractions of which are transmitted to the bones, where joints are located.
Unlike other mammals, the human body has a unique structure, which determines its function: bipedalism (when we move in space, relying on two legs, holding the body in a vertical position and have two upper limbs for everyday tasks and balancing while our walk). Structures of the locomotor apparatus in such position bear loads because of gravity force. These loads increase for several times while carrying cargo.
The vertical position of the body likens man to a spring, which is ready to be leveled and convert the potential energy of motion into kinetic energy.
Vertebral Column – is the base of our body and axis, that allocates the load from head to the pelvis and transmits it to the lower limbs. It performs following functions: supporting, protective (protects spinal cord) and motor.
Vertebral Column consists of separate parts that perform individual functions:
1. Cervical region– mobile region, which consists of seven vertebrae, supports the head, turns it to the source of anything or allows us to see something.
2. Thoracic rigion – sedentary region, consists of twelve vertebrae, fixed with ribs, which participates in the creation of the chest cavity.
3. Lumbar rigion– very moviable, built of massive 4-5 vertebrae, that bear the main load, keeping body weight.
4. Lumbosacral region – fixed formed vertebrae, which anatomically in the development of the human body fused into a single bone. Form joints and bones of the pelvis, involved in the redistribution of body weight on lower limbs.
5. Coccygeal region or tailbone – the final region of the spinal column, which is also formed from fused vertebrae. The tailbone is one of the supportive points while sitting and fixing point for pelvic floor muscles.
So spine consists of vertebrae, united in a complex system – intervertebral motor segment(movable connection located along two vertebrae).
What is the structure and function of the intervertebral motor segment?
Each vertebra can be roughly divided into anterior and posterior sections. Anterior -vertebral body, posterior – the bow of spinous, transverse and articular processes. These sections are allocated, even in a structure of the intervertebral motor segment.
Anterior section is formed by articular disc with surrounding parts of the vertebral bodies, front and rear longitudinal ligaments that limit mobility at anterior and rear.
Articular disc has a special structure. It consists of two parts:
- central – Nucleus Pulposus (Gelatin-like substance that for 88% consists of water and the rest of it are proteins);
- peripheral – the fibrous ring (connective formation, which is closed in a circle around the nucleus pulposus and limits its displacement to the sides).
Posterior section is strengthed by yellow sacrospinale and illiolumbar ligaments. Movement is provided by zygapophysial (facet) joints.Based on the functions of Nucleus Pulposus, it should be seen as a ball between two planes. It is called articulated joint, it moves in varies dimensions. While loading of Nucleus Pulposus, it expands to sideways and amortizes (reduces) the load on Vertebral Column in general.
How does the Vertebral Column functions in general?
Movements in the intervertebral segment are possible in many dimensions, but their amplitude is very small because they are limited with ligaments and facet joints in the posterior section of the spine. Only through the complex of movements, many spinal motor segments ensure a greater range of spine motion. It is characterized by three degrees of motion: flexion-extension, bending from side to side, rotation around the central axis.