A normally functioning spine is a natural kinematic chain consisting of separate links – vertebrae, articulating with each other using intervertebral discs, paired true joints and ligaments.
The cervical spine consists of seven cervical vertebrae, of which the two upper ones are significantly different from the rest. The first two cervical vertebrae provide rotation of the head (the so-called rotational vertebrae), the rest – bending (flexion vertebrae). The muscular apparatus of the neck also plays a huge role in ensuring the motor function of the cervical spine.
The bodies of the cervical vertebrae in an adult form a support for the head, and due to the saddle shape of their upper and lower surfaces, head movements in the frontal and sagittal planes are carried out. The saddle-like concavity of the upper surface of the cervical vertebrae is due to the fact that its lateral edges are raised due to the presence of two protrusions located almost vertically, called hook-shaped or lunate processes. The inner lunar surface of these processes, in contact with the intervertebral disc, is often damaged in osteochondrosis of the cervical spine.
Adult macerated V cervical vertebra
a – top view; b – front view, c – side view, d – deformation of the vertebra CVI with osteochondrosis of the adjacent discs (deviation of the lunate processes to the sides): 1 – the body of the vertebra; 2 – arc; 3 – vertebral foramen; 4 – the root of the arc; 5 – upper vertebral notch; 6 – lower vertebral notch; 7 – spinous process with a bifurcated apex; 8 – transverse process; 8a – costal process with an opening of the transverse process (shaded); 9 and 10, respectively, the upper and lower articular processes; 10a – the posterior surface of the lower articular process; 11 – limbus; 12 – locking plate; 13 – lunate processes
The articular processes of the cervical vertebrae are located on the sides of the vertebral foramen, which in this part of the spine have a triangular shape. A characteristic feature of all cervical vertebrae is the presence in their transverse processes of holes through which (except the opening of the VII cervical vertebra) pass the vertebral arteries and the accompanying veins. In the pathogenesis of vertebrogenic disorders, these holes play a significant role.
The cervical spine, the most mobile spine, normally describes a regular arch with a bulge forward (lordosis). The presence of lordosis is due to the shape of the intervertebral discs (in the ventral region • they are slightly higher than in the dorsal region). In the biomechanics of the spine, the main role is played by the intervertebral disk, which provides amortization during axial loads on the spine and mobility in it. Normally, the intervertebral disc consists of two plates of hyaline cartilage that are tightly adjacent to the closure plates of the bodies of adjacent vertebrae, the pulpous nucleus and the fibrous ring.
The figure shows that the pulpous nucleus, in the center of which there is a cavity up to 1.5 cm3 (containing synovial fluid), is surrounded by a fibrous ring along the lateral surface, consisting of dense connective tissue bundles that provide strength and elasticity of the intervertebral disc. Any pressure on the core evenly spreads in all directions, which softens tremors and tremors. The counteraction of these two forces lies at the basis of degenerative processes of the spine (N. S. Kosinskaya). With pathological changes in these departments, an additional load falls on the muscular apparatus, which atrophies with prolonged stress.
Osteochondrosis usually begins with degeneration of the pulpous nucleus. Moreover, if the turgor of the nucleus is at least slightly preserved, then the weakened fibrous ring cannot counteract the expansion of the nucleus. This leads to pathological mobility of adjacent vertebral bodies.