Diagnostics of vertebroneurological syndromes, manual and reflex therapy techniques require knowledge of the structural and functional features of the spinal column and adjacent tissues. The spine has at least four functions: support, protection, shock absorption and motor. It is a flexible rod – support for the head, shoulder girdle and arms, organs of the chest and abdominal cavities, the mass of which is transferred to the pelvic girdle and legs. In connection with the supporting function, the vertebrae have a different structure, with an increase in the size of the vertebral bodies from the cervical to the sacral region. The effect of gravity in the process of phylogenesis leads to the fact that the sacral vertebrae are fused together in the form of a massive bone. The protective function of the spinal column is to protect the spinal cord from mechanical damage. To this it must be added that the flexibility of the spine is also important for the shock absorption and shock absorption, protecting the basal regions and the entire brain from trauma to the bone structure of the skull. Muscles, intervertebral discs, joint spaces and articular surfaces of the vertebrae are involved in the amortization function. The presence of physiological curvature (cervical and lumbar lordosis) also plays a significant role in this. The motor function is carried out in the intervertebral joints around three axes: frontal, sagittal and vertical. At the same time, a distinction is made between the passive part (vertebrae, joints, ligaments, discs) and the active part – the muscular apparatus. To understand the basic functions of the spine in health and disease, the idea of the spinal motion segment is important.
The vertebral-motor segment (VMS) is formed by two adjacent “hemivertebrae”, an intervertebral disc, intervertebral joints, intervertebral ligaments and muscle formations. The normal function of the PDS is possible due to the dynamic equilibrium of these structures.
The intervertebral discs, being in close anatomical and functional connection with all structures of the spine, largely ensure the mobility of the spine, its elasticity and resilience, withstanding significant loads.
The disc consists of:
1) two hyaline plates tightly adjacent to the end plates of the adjacent vertebral bodies;
2) nucleus pulposus;
3) annulus fibrosus.
The pulpous nucleus is an avascular formation, elastic consistency, consists of individual cartilage and connective tissue cells, collagen fibers. The composition of the intercellular substance includes proteins, mucopolysaccharides, including hyaluronic acid. The high ability to bind water is explained by the presence of OH-groups of polysaccharides. The gelatinous nucleus in the elderly contains up to 70% water. In the center of the nucleus, there is a normal cavity with a volume of 1.0-1.5 cm3. Thanks to the turgor, the pressure of the disc is transmitted to the fibrous ring and adjacent hyaline plates, providing shock absorption and elastic mobility of the spine.
Anulus fibrosus – consists of cross-cutting collagen fibers, which are soldered with their ends into the margins of the vertebral bodies. Unlike the avascular nucleus, the fibrous nucleus is abundantly supplied with blood. The posterior semicircle of the ring is weaker than the anterior one, especially in the cervical and lumbar spine. The lateral and anterior sections of the intervertebral disc protrude slightly beyond the limits of the bone tissue, since the disc is somewhat wider than the bodies of the adjacent vertebrae.
The innervation of the outer parts of the annulus fibrosus, the posterior longitudinal ligament, the periosteum, the capsule of the joints, the vessels and the membranes of the spinal cord is carried out by the synuvertebral nerve (Lyushka’s nerve), consisting of sympathetic and somatic fibers. In an adult, disc nutrition occurs by diffusion through the hyaline plates.
The capsules of the intervertebral joints are very elastic. Their inner layer forms flat folds that deeply penetrate the joint space – the articular mniscoids, which contain cartilage cells. The intervertebral joints perform the following functions:
Static – participation in maintaining the position of individual vertebrae and the spine as a whole;
Dynamic – participation in the movement of adjacent vertebrae relative to each other, and at a higher level – participation in changing the configuration of the spine as a separate organ, its position relative to other parts of the body;
Adaptive – participation in myostatic change reactions;
Respiratory – the vertebral-costal joints and the articulation of the tubercle of the rib with the transverse process indirectly take part in the act of breathing;
Supporting, especially pronounced in the PDS, devoid of an intervertebral disc: Os-C1 and C1-C2.
The articular cavities are closed by the articular surfaces and the capsule, inside there is synovial fluid, which performs a spring (buffer) function.
The intervertebral foramen are paired formations. The upper and lower borders are formed by incisions on the roots of the arches (the upper one is large), the inner one is formed by the lateral edges of the bodies and the intervertebral disc, the outer one is formed by two articular processes (especially the upper one), the
inner part of the articular capsule and the yellow ligament. In the cervical vertebrae of the middle and lower levels, the inner wall is the Lyushka joints, in the intervertebral foramen of the thoracic region (up to T9-T10), the anterolateral borders are the capsules of the costal-vertebral joints with heads of II – X ribs.
In the intervertebral foramen there are extradural segments (anterior and ganglioradical of the posterior) of the roots, from which the cable carriages are formed. From the inside to the periosteum of the intervertebral foramen, the dura mater is fixed, which covers each Nagotte radicular nerve with a cuff.
The bony walls of the intervertebral foramen lengthen as the root of the arches in the vertebrae thickens – from 4 mm in the cervical to 10 mm in the fifth lumbar. The presacral foramen often exceeds 15 mm in length and turns into a canal due to the massive arch at the sacrum and the peculiar location of the articular processes.
Ligamentous apparatus. The anterior longitudinal ligament runs along the entire anterior surface of the vertebral bodies. It is well defined in the lumbar region and poorly in the cervical region. The ligament prevents overextension of the spine. It is tightly welded to the vertebral bodies and loosely to the intervertebral disc. The posterior longitudinal ligament runs along the posterior surface of the vertebral bodies, preventing the bending of the spine. It is closely connected with the discs and loosely with the bodies of the vertebrae; well expressed in the cervical spine and almost not expressed in the lower lumbar, where it creates a paramedian direction to the hernial protrusion of the nucleus pulposus.
The supraspinous ligament is stretched between the tops of the spinous processes; well expressed in the cervical region, passes into the nuchal; missing between L5-S1.
The interspinous ligament is stretched between the spinous processes of the adjacent vertebrae. The yellow ligament connects the arches of the adjacent vertebrae, participates in the formation of capsules of the intervertebral joints; consists entirely of elastic fibers. These ligaments are very thick at the lumbosacral level, reaching from 2 to 7 mm; bringing together the vertebrae, preventing their kyphosis.
The intertransverse ligament connects the transverse processes of adjacent vertebrae, prevents their movement in the frontal plane.
The transverse spinous ligament connects the transverse and spinous processes of the adjacent vertebrae, restricting their rotational movements.
The transverse muscles consist of 2 independent bundles: medial-dorsal and lateral-ventral. They are like shrouds holding the mast in an upright position
and run upward and inward. A neurovascular bundle passes between the two muscle bundles. The interspinous muscles are paired and they run from bottom to top, ventrally and downward. Isolated movements of an individual PDS are carried out by the short muscles of the spine, partly by rotators that spread over the vertebra and individual parts of the long paravertebral muscles (in the front – the iliopsoas, in the back – multipart). Tilt to the side, within one PDS, is carried out by interpolar muscles, backward – interspinous, forward – by turning off the corresponding interspinous active contraction of the iliopsoas, anterior cervical; rotation – due to the rotator cuff muscles. Long muscles are also involved in fixing such segment bends. The interaction of these muscles occurs reflexively according to the type of synergy of all muscles of the PDS and the entire spine. This provides the main local myofixation.
All reflex forms of regulation of the musculoskeletal function of the spine and the entire kinematic chain “spine-limbs”, as well as voluntary motor functions of this system, determine its strength, the state of the dynamic muscle corset.
One of the characteristic features of the spinal column is the presence of 4 physiological curvatures located in the sagittal plane:
1) cervical lordosis, formed by all cervical and upper thoracic vertebrae. The maximum convexity occurs at the C5 and C6 levels;
2) thoracic kyphosis. The maximum of the bulge is at levels T6-T7;
3) lumbar lordosis, formed by the last thoracic and all lumbar vertebrae. Maximum bulge at L4;
4) sacrococcygeal kyphosis. Normally, the sacrum is at an angle of 30 ° in relation to the frontal axis of the body.
The curvature of the spine is a consequence of a specific feature of a person and is due to the vertical position of the body. The curves of the spine are held by the active strength of the muscles, ligaments and the shape of the vertebrae themselves. The S-shaped profile of the spine is the result of the orthostatic position of the person. The double curvature gives the structure more strength than a single curvature. The S-shape cushions shocks and impacts during movement.
In most people, the line of gravity runs in front of the spine, which is maintained in a straight position by reflex contraction of the back muscles, so the line of gravity does not increase all the curves of the spine, but rather straightens the lumbar lordosis. When standing, tension of the muscular ligamentous apparatus occurs, exerting a certain pressure on the vertebral bodies.
To ensure reliable support of the spine, there should be no great mobility between its individual segments.
This is dangerous for the spinal cord. At the same time, the movements of many segments, when added together, provide significant mobility of the spine as a whole. The degree of mobility in each segment is directly proportional to the square of the disc height and inversely proportional to the square of its cross section.
The lowest height is at the uppermost cervical and upper chest discs. Discs below this level increase in height, reaching a maximum at the L5-S1 level. Therefore, the greatest range of motion is in the lumbosacral and lower cervical regions. The least mobility in the thoracic spine also depends on the inhibitory effects of the ribs connecting the thorax into a rigid cylinder, as well as on the adhesion of the spinous processes connected to each other by a powerful ligamentous apparatus.
In adults, the total height of the intervertebral discs is 25% of the length of the spine.
The spine moves along three axes:
1) flexion and extension along the transverse axis;
2) lateral tilts (lateroflexia) around the sagittal axis;
3) rotation (rotocio) – around the longitudinal axis.
Rotation predominates in the cervical and upper thoracic regions. Flexion and extension are greatest in the lumbar and cervical regions, lateroflexia – in the lower thoracic spine.
During flexion, the following changes occur:
stretching of the posterior longitudinal ligament and the fibers of the posterior part of the disc ring;
posterior displacement of the disc nucleus; the tension of the posterior half-ring increases;
stretching of the yellow and interspinous ligaments;
expansion of the intervertebral foramen and tension of the capsule of the intervertebral joints;
tension of the abdominal muscles and relaxation of the extensors of the back;
tension of the dura mater and roots.
When unbending occurs:
stretching of the anterior half-ring of the disc;
the relative displacement of the disc core inward;
reduction of yellow and relaxation of the interspinous ligaments;
narrowing of the intervertebral foramen;
stretching of the abdominal muscles and tension of the long muscles of the back;
relaxation of the dura mater of the roots.
Thus, any form of work of the PDS and the spine as a whole, its strength is determined by the state of the nervous system, including its higher sections, which are responsible for forecasting and coordination as a whole.
