SPINE The spine and its most frequent diseases in childhood

2. SPINE The spine and its most frequent diseases in childhood In childhood, the spinal diseases are the most frequent problems in the locomotors system.

3. The typical structural characteristic of the human body is the two-sided proportionality i.e. the bilateral symmetry. It means that the sagittal plane positioned at the middle of body — the median sagittal plane — divides the body into two equal part forming reflected images of each other.

5. The spine is in the intersection line of the frontal and the medial sagittal plane. Normally the spine is straight in the frontal plane. In the sagittal plane, however, curves of variable direction appear on the standing spine: the cervical lordosis, the dorsal kyphosis and the lumbar lordosis. These curves are physiological, the appearance of them are necessary, and within specific extent, normal.

7. The physiological curves are developing gradually from the infancy up to the full extent in the period after the puberty. In older age, the curves usually increased due to the dehydration of the vertebral discs that fill ¼ part of the length of the spine.

8. The importance of physiologic curves • In mechanical respect: larger load bearing capacity • In respect of statics: to ensure the equilibrium

9. The spine is not a single block. The vertebral column containing the vertebral bodies, joints and vertebral discs is a functional unit, called as - a kinetic chain.

11. From C3 to L4, the elementary structural design of the spine- can be modeled by means of three pillars where the first pillar is the vertebral body and the other two ones are the joint surfaces. i.e. the processusarticulares.

12. The pillars of the elementary structures placed on the top of each other form vertical columns, and - at the same time – comparing to each other they are mobile segments having three joint surfaces.

14. Compression forces and shearing forces act on the spine as a whole. The compression force is held primarily by the trabecular structure of the vertebral body.

15. The intervertebral disc consists of three parts as follows: • anulusfibrosus, - is built up from collagen fibers of type different in childhood from those in adult age, • nucleus pulposus • cartilaginous plate.

17. The anulusfibrosusconsists of concentric ring shaped plates of the horizontal plane. Their fibers are look like the layers of onion. A nucleus pulposus is a very hydrophilic loose fibrillar structure with 85% water content, consisting of mucopolysaccharids and collagen fibers that occupies the central part of anulusfibrosus. The cartilaginous plate ensures the origin of the fibers of the anulusfibrosus and the diffusion of liquid from the blood circulation for filling up the nucleus pulposus.

19. The discus bears the axial compression acting on it through the osmotic pressure of the well- hydrated nucleus. In case of increase in load, the nucleus loses water until a new equilibrium is established.

20. In case of cyclic repetition of the compression forces the water loss continues at a highly increased rate. Examinations show that the high loss of nucleus during standing of one and a half an hour can be normalized in lying position within 15 minutes.

21. As the spine consists of 3 vertical columns, all the three joint surfaces in each mobile segment – the discus and the two rear joints- bear the forces in common. In standing position, the resultant of the gravitation force acting in front of the spine as well as the muscle force balancing it behind the spine exerts compression force on the discus and the vertebral body and shearing force on the rear joints.

23. As the load acting on the spine is increased towards caudal, accordingly, the whole joint surface is also increased towards caudal in each mobile segment.

25. The intervertebral discs are also the largest ones in the lumbar region; their height lies between 10 and 15 mm and their surface is 50 x 30 mm in case of adults.

26. The motions of the spinal column depend on the structure of its joints. Each mobile segment includes three joints according to the three pillars.

27. The discus in itself could be function as a ball joint, with optional number of motional axis, howeverThe mechanism of two joints formed by the same bone in part shall be common, that is, the axle of motion shall meet the geometric conditions of both joints. This is the common axle of temporary arrangement. / Szentágothai/ Thus, the motions are always determined by the common axis of temporary arrangement, or more than this, —as the structure of the discs is the same in each segment — depending of the planes of the processusarticulares.

28. The rear small joints (zygoapophysealis articulation): according to their mechanisms, they are trochoids, or pivotal joints. The planes of rear joints are different in the various sections of the spine: they are located - in the cervical spine in the horizontal plane, - in the dorsal section in the frontal plane, - in the lumbar section in the sagittal plane.

29. Accordingly, the motions of the spine – flexion-extension, rotation as well as the inclination – are occur in different manner and to different extent in the various sections of the spine.

30. The flexion – extension that takes place in the sagittal plane is a circular motion around a transversal axle. On the lumbar spine, this motion is of the largest range

32. The rotation • in the cervical spine follows an elliptical segment, • in the thoracic spine the joint surfaces are rotated along an arc. In the thoracic section, this form of motion is the freest one; the others are restricted due to the connection of ribs. • in the lumbar region the rotation is significantly restricted due to the sagittal position of rear joints.

33. A lateral-inclination is connected with simultaneous rotation. This, and any other forms of motion are the freest ones in the cervical spine.

35. Each mobile segment composed of two neighboring vertebra is able to do motions of small amplitude. Adding up of these motions results in the considerable mobility of the spine functioning as a kinetic chain.

36. The static function of the spine is to ensure the equilibrium of the head and the trunk by means of the physiologic curves established in the sagittal plane .

37. Stand The position standing on two legs is a human-specific posture.

38. The gravitation force, that can be considered parallel distributed set of forces, acts on each element of the body. The center of parallel gravitational forces — the center of gravity —lies in the median sagittal plane; therefore, it also corresponds to the center line of gravity Under normal conditions, the center line of gravity passes through the center of the supporting surface delimited by the soles.

40. From the lateral view, the center line passes from the base of the cranium and crosses each load bearing joints of the body. The parts in front of and behind the center line are of equal mass that helps to keep the position of equilibrium.

42. In standing position the stability structurally • Determined by the • physiological curvatures of the spine, • inclination angle of the pelvis (sacrum) and the sacroiliacal ligaments.

44. The spine rests on the pelvis through the sacrum. The pelvis transfers the weight of the trunk in the hip joints through the femoral head/neck to the lower extremities.

45. In order to ensure the equilibrium, the supporting point of the spine on the sacrum and the hip joints shall lie on a single vertical line in the frontal plane. To ensure this, the pelvic has to tilt forwards resulting in the lordosis of the lumbar spine. Under normal condition the tilt of the pelvis - the aperture pelvis superior - forms an angle of 60 – 65 degrees with the horizontal plane.

47. The pelvis is a ring/shaped structure of double vault in the frontal plane. It has to ensure the distribution of single-point loading onto double-point support. The sacrum is the headstone of this vault.

49. The sacrum is a special headstone, because it`s wedge-shape facing upward. In spite of it does not "break" in the pelvis as the spine loads the sacrum not in the axle of the sacroiliac joint, but in front of and above it.