Thoracic vertebra: features of the anatomical structure

Vertebral structure

Regardless of which department they belong to, all vertebrae have a more massive part, located anteriorly and taking on the main load. It is called the vertebral body. In addition to it, there is an arch that closes the ring where the spinal cord is located. Vertebral processes extend from them. The vertebrae are connected to each other by intervertebral discs, which ensure mobility of the spine, as well as ligaments and muscles. In an adult, intervertebral discs can make up up to twenty-five percent of the length of the spinal column.

In those areas where its mobility is higher, that is, in the cervical and lumbar, the height of the discs is greater, and in less mobile areas - the thoracic and sacral - less. However, the thickness of the intervertebral discs is not a constant value. Under the influence of loads, their height can decrease, and after stopping or reducing the load, they can increase. As a rule, the length of a healthy human spine can fluctuate up to two centimeters per day due to compression of the intervertebral discs. In cases where they lose their elasticity, many serious diseases develop.

Posture concept

Posture is the position of the torso and head when standing, sitting and walking. It is determined by the physiological curves of the spine, the position of the head relative to the body, the position of the pelvis, the length of the lower limbs and the position of the feet.

Normal posture

The physiological curves of the spine form as the child grows and acquire a normal shape by the age of 7

With a normal type of posture, there are moderately pronounced physiological curves of the spine in the sagittal plane (lordosis - in the cervical region, kyphosis - in the thoracic region, lordosis - in the lumbar region), while the vertical axis of the body runs along a line from the middle of the parietal region of the head behind the line connecting both angles of the lower jaw, through a line connecting both hip joints. A normal type of posture counteracts the occurrence of pathological curvatures of the spine

Postural disorders

The increased elasticity of the intervertebral discs and ligaments causes increased mobility of the child's spine. At the same time, the weak stabilizing function of the intervertebral discs, combined with increased extensibility of the ligamentous apparatus, creates the preconditions for the occurrence of instability of the SMS and, as a result, poor posture.

Poor posture in itself is not a disease. However, the position of the spine in this case can lead to a number of serious diseases of the spine and spinal cord roots, because in this case vicious conditioned reflex connections are formed that reinforce the incorrect position of the body. Nervous regulation is disrupted, which leads to disorders of the internal organs: cardiovascular system, respiratory system, metabolism, digestion. The excursion of the chest and diaphragm, vital capacity of the lungs and fluctuations in intrathoracic pressure decrease, which leads to a decrease in physiological reserves and disruption of the body's adaptive capabilities. Weakness of the abdominal muscles and a bent body position cause disturbances in intestinal motility and bile outflow. In patients with a flat back, a decrease in the spring function of the spine contributes to constant microtrauma to the brain during movement: walking, running, jumping, etc. This leads to rapid fatigue and frequent headaches. With poor posture, the muscles are usually weakened, and their physical performance is reduced. In general, posture depends on many reasons. It is connected, firstly, with the state of the muscular system, that is, with the degree of development of the muscles of the neck, back, chest, abdomen and lower extremities, as well as with the functional capabilities of the muscles, its ability to long-term static tension. Secondly, posture is influenced by the elastic properties of the intervertebral discs, cartilaginous and connective tissue formations of the joints of the spine (this, in turn, is associated with the mobility of the spine), as well as the pelvis and lower extremities.

Deviations from normal posture are called disorders, or postural defects :

• stoop —increased thoracic kyphosis and decreased lumbar lordosis;
• round back (total, or continuous, kyphosis) - an increase in thoracic kyphosis in the complete absence of lumbar lordosis (to compensate for the deviation of the center of gravity from the midline, a person with such posture usually stands with his legs slightly bent at the knees).
• With a stooped and round back, the chest sinks, the shoulders, neck and head are tilted forward, the stomach is protruded, the buttocks are flattened, the shoulder blades are protruded wing-shaped;
• round-concave back - an increase in all the curves of the spine, as well as the angle of the pelvis. With a round-concave back, the head, neck, and shoulders are tilted forward, the stomach protrudes, the knees are extended as much as possible, the muscles of the back of the thighs, attached to the ischial tuberosity, are stretched and thinned compared to the muscles of the front of the thighs.
• flat back - flattening of the lumbar lordosis, in which the pelvic tilt is reduced, thoracic kyphosis is poorly expressed, the chest is shifted forward, the lower abdomen is protruded, the shoulder blades are wing-shaped - the corners and their inner edges lag behind the back; a flat back is the weakest type of posture, and there is a significant predisposition to the development of scoliosis;
• flat-concave back - a decrease in thoracic kyphosis with normal or slightly increased lumbar lordosis (the chest is narrow, the abdominal muscles are weakened).
• scoliotic or asymmetrical posture (a typical violation of posture in the frontal plane, that is, a violation of symmetry between the right and left halves of the body). In this case, the spine is an arc with its apex facing to the right or left, and the triangles of the waist (the space located between the elbow joint of the hanging arm and the waist) become different due to the fact that one shoulder and shoulder blade are lowered.

Anatomy of the thoracic vertebra

The thoracic vertebrae (vertebrae thoracicae) have certain differences in their anatomy compared to the vertebrae of other parts of the spine. One of them is more massive vertebral bodies. This is due to the increased load that the thoracic vertebrae experience. On both sides, the thoracic vertebra is connected to the ribs, which is what significantly influenced its anatomy.

The thoracic vertebra includes the following sections:

• superior and inferior vertebral notches;
• superior and inferior articular processes;
• transverse process; upper and lower costal fossa;
• vertebral body;
• costal fossa of the transverse process;
• spinous process;
• vertebral arch;
• vertebral foramen.

On the body of the thoracic vertebra there are costal fossae (foveae costdles), which are designed to connect to the ribs. They are located not far from the arc. Due to the fact that the ribs, as a rule, connect to the vertebrae located next to each other, two pairs of incomplete (half) costal fossae can be found on their body - on the upper (fovea costalis superior) and lower (fovea costalis inferior) . An exception is vertebra I, which has one full fossa at the top of the body for attaching the corresponding rib, and a half fossa for II at the bottom. In addition to them, the X, XI and XII vertebrae have differences in the anatomical structure. X has only one half-hole, intended for the X edge. It is located above, and on the XI and XII vertebrae there is a complete fossa for attaching the corresponding pairs of ribs.

The thoracic vertebrae have articular processes located frontally in the spine, and the transverse ones are retracted to the sides and posteriorly. On the anterior surfaces of ten thoracic vertebrae there are articular surfaces (fovea costalis processus transversus), which serve to connect with the tubercle of the rib, but the XI and XII vertebrae do not have them. Another distinctive feature that distinguishes the thoracic vertebrae from their counterparts in other sections is the structure of the spinous processes. They are quite long and strongly inclined downwards so that, when connected, they form a kind of tile. This is most pronounced in the middle part, at the level of the IV - X vertebrae.

Anatomical and functional features of the thoracic spine

1. 
   The height of the intervertebral discs is small and amounts to 1/5 of the height of the corresponding vertebra.

2. The intervertebral foramina in this region are narrower than in the cervical region.
3. The joint spaces of the intervertebral joints are almost vertical in the frontal plane.
4. The spinal canal is narrower than in the lumbar region.
5. The relatively massive spinous processes, thickened at the ends, are sharply inclined downward (imbricated).
6. There are additional joints: costovertebral.

Pathology of the thoracic spine can be divided into congenital and acquired. Regardless of the cause, the pathogenesis of these processes has a number of common features. It is also based on the redistribution of loads in support complexes.

Statistics on medical examination of children in Russia showed that poor posture is one of the most common changes in the musculoskeletal system.

Thoracic kyphosis

During development, the human spine acquires physiological curves. In the absence of pathologies, normally the cervical and lumbar sections bend forward (cervical and lumbar lordosis), and the thoracic and sacral sections bend backward, forming kyphosis. The anatomy of the human skeleton, using this feature, allows optimal use of the shock-absorbing abilities of the spinal column.

Often, under the influence of injuries, weakened muscles and ligaments, or prolonged incorrect static body position, pathological posture develops. This, a very common phenomenon in our time, is the cause of many diseases. For example, often pain in the chest area can be associated with a change in the biomechanics of the body that occurs against the background of a flat back - a fairly common type of pathological posture.

Human anatomy, using the physiological characteristics of the skeleton, contributes to the fact that the thoracic vertebrae, connecting and forming thoracic kyphosis, take on a certain load and absorb it. At the same time, it is unevenly distributed on the anterior and posterior parts of the body. When the conditions of such a load change and the impact shifts in one direction or another, various deformations of the shape of the vertebral body occur, which, in turn, becomes a decisive factor in the development of degenerative changes, leading to many diseases.

Methods to combat postural disorders

Correcting postural disorders will be effective only with a complex effect on the body, including a thoughtful and comprehensive system of measures:

• use of posture correctors;
• correct and precise correction of shoes, firstly, eliminating the functional shortening of the limb that has arisen due to postural disorders in the pelvic area, and leveling the level of the iliac bones and, secondly, compensating for foot defects - flat feet, valgus or varus position;
• organization and strict adherence to the correct daily routine (sleep, wakefulness, nutrition, etc.);
• sleep on a hard bed, lying on your stomach or back, use an orthopedic pillow while sleeping;
• giving up such bad habits as standing on one leg, incorrect body position while sitting (at a desk and desk, at home and in the library);
• control over the correct, uniform load on the spine when wearing backpacks, bags, briefcases and other luggage;
• constant physical activity, including walks, sports, tourism, recommended individually for each (coordinated with a physical education specialist). Currently, it is believed that strict restrictive tactics should be followed only in relation to those sports that are associated either with constant vertical loads on the spine (cycling and equestrian sports, weightlifting), or with the possibility of direct injury (contact wrestling, boxing, apparatus gymnastics), or with asymmetric muscle tension (tennis, fencing). On the contrary, playing team sports and dancing promote harmonious muscle development and, within reasonable limits, should be recommended for patients with spinal deformities.

According to many experts, the use of posture correctors is basic in the overall range of measures taken.