Intraossal Lesions of the Cranial Bones
Because the bones grow from the ossification points out into the periphery, compression of the sutures is the most likely cause of intraossal lesions in the cranial bones. Tensions in the cranial membranes can also be a cause.
Intrauterine and perinatal factors are mainly responsible for a compression of the sutures. It is obvious that these lesions, as we view them from the osteopathic perspective, only arise during the developing years.
Note: To ensure functionality, the balancing organs (comparable to a spirit level) and eyes have to be horizontal. The eyes, moreover, have to be in the same frontal plane to avoid excessive strain on the eye muscles. The ideal adjustment zone for this purpose is in the OAA joints.
As with the bones in the extremities, trauma, compression, or persistent tension in the growth sutures can also lead to deformation in the cranial bones. This is particularly dramatic when the sphenoidal, temporal, occipital, or sacral bones are affected.
All of these bones consist at birth of several parts that are only fused together completely by the age of 8-12 years. Deformation in these bones can result in malposition of the SBS and the craniocervical junction, thereby affecting the locomotor system.
Intraossal lesions in these bones can cause specific damage in certain areas of the body:
• Lesions between the presphenoid and postsphenoid affect the facial skull (especially the eyes).
• Lesions in the temporal bone can negatively affect hearing, the organs of equilibrium, and the temporomandibular joint.
• Intraossal lesions in the sacrum can have a negative impact on the postural and motion functions of the spinal column and lower extremities.
• The most far-reaching effect, not only on posture, is most likely caused by lesions in the occipitoatlantal region.
• According to Sutherland, deformations in the area of the basilar part and condylar part are responsible for a number of complaints101'102:
— Disorders in the cranial nerves VI-XII due to compression around the foramina or tension of the membranes. We must not forget that the dura mater accompanies the cranial nerves up to the foramina and is anchored securely there.
— Impaired circulation: 95% of the venous blood leaves the head via the jugular foramina. Shifts in the condylar or basilar parts can change these openings. On the other hand, malpositions of the cranial basis can cause SBS lesions that lead to tension in the membranes. As a result, the venous sinuses are affected, which can in turn influence circulation in the brain. We must not forget that the dura mater accompanies the cranial nerves up to the foramina and is anchored securely there.
— A change in the lumina of the foramen magnum can exert pressure on the brain stem and thereby cause a number of effects. The medulla and pons lie on top of the basilar part of the occiput and the SBS. Damage to the pyramidal tracts is a common cause of spastic states in cerebral palsy. Malpositions in the region of the basilar part can be involved in this.
Note: For nerve function to be disturbed, the nerve mass must not necessarily be compromised. Disturbed vascular supply is enough. Pressure or membranous tensions are able to irritate the vessels that supply the nerves.
As we mentioned earlier, tensions in one part of the cerebral membranes are transferred to the entire dural system. Because the dura mater is anchored solidly to the foramen magnum and S2, deformations in these areas have consequences for the entire postural system. For this reason, we are going to take a closer look at intraossal lesions in the occiput.
We need to point out once more that cranial base originates from cartilage, while the arch is made from membranes. The roof is therefore more adaptable than the base.
During birth and in early childhood, the membranes are more resistant than the bones. The membranes hold together the bones that consist of several parts. Perinatal trauma or tension, as well as accidents in infancy, can therefore affect the growth sutures of the bones and immediately or later manifest during growth spurts (scoliosis, kypholordosis, cross-bite, and so on).
At birth, the occiput consists of four parts (Fig. 4.11a) that are held together by the dura mater and the pericranium:
1. Squamous part of the occipital bone
2. and 3. The two lateral masses or condylar parts 4. Basilar part
These four parts form the frame of the foramen magnum.
The two occipital condyles are not yet fully developed at birth and consist of two-thirds of the condylar part and one-third of the basilar part. The atlas also consists of several parts (Fig 4.11b).
In contrast to the occiput, the facets are formed earlier. In addition, the atlas arches are stabilized by the strong transverse ligament of the atlas. As a result, the occiput condyles and the foramen magnum are more likely to suffer from deformations than the atlas. It is also significant that the occiput condyles and atlas facets are oriented medially forward.
The longitudinal axes of both joints converge in the front in a point below the SBS. They form an angle of ± 30° with each other. Forced flexion and extension movements can result in compression of the growth sutures because the condyles "threaten to derail." Most common is the deformation of the cranial base during the birth process.
During a normal natural birth, the head of the newborn is compromised during the passage through the birth canal according to a certain pattern. In addition, a rotation and flexion-extension movement occurs in the cervical spinal column. If for any reason the birth canal is too narrow for the child's head, the mother's contractions can exert such pressure on the cervico-occipital junction that the weakest structures give in. Depending on the condition of the head at the time, the forces focus on a certain point, which causes a characteristic lesion there.
Compression in the sagittal plane (symmetrical pressure on the supraocciput) can press the condyles forward too strongly. This can change the position of the condylar parts.
The lumen of the foramen magnum, as well as that of the jugular foramina, may become reduced. This can result in compression of the sutures between the occiput and the temporal bone. The pressure can also shift the basilar part. As a result, vertical strains (a caudal shift of the basilar part) can arise.
The therapist can palpate this position from the shape of the supraocciput and the position of the in-ion, among other things. Under diagonal pressure on the occiput, when the baby's head is in a rotated position above the atlas, it can happen that a condyle is pushed forward. This condyle is then shifted forward medially and the condyle on the other side is shifted laterally. As a result, we may see torsions, sidebending rotation, or lateral strains (a shift of the basilar part to lateral) in the SBS.
The foramen magnum and jugular foramina can change. The sutures between the occiput and the temporal bone can become compromised. The therapist can recognize this malposition from the relation between the occiput and the lateral mass of the atlas, as well as by comparing the nuchal (or supraoccipital) line on the left and right side. In both cases, the posture of the spinal column and the muscle tone are affected:
• The position of the condyles influences the tension of the dural tube up to the sacrum as well as forward up to the crista galli.
• Symmetrical malpositions are felt as an increased flexed or extended posture.
• Asymmetrical positions of the occiput condyles lead to twisting of the dural tube, with a resulting pelvic twist.
Fig. 4.11a, b a Occipital bone, b atlas and axis in a newborn.
• The suboccipital muscles are particularly important for muscle tone.
• The great sensitivity of the muscle spindles as well as the extremely rich supply of the short neck muscles with muscle spindles in the suboccipital area are responsible for the fact that this area is so significant for regulating muscle tension in general and posture in particular.
• Posturologists were able to demonstrate with experiments, in which the distribution of weight to both feet was measured, that a manipulation of C2, the relaxation of the falx, and the treatment of the temporomandibular joint results in obvious improvement in the distribution of weight.153,154 All osteopaths should be familiar with the connection between these three structures and the short neck muscles.
• In microscopic examinations of the short neck muscles, it was proven that they contain ± 6 times as many muscle spindles as the gluteal musculature (per cm3 of muscle mass).
• Viola Frymann was able to show with a substantial collection of skulls that deformations of the skull basis are common and that malpositions and malformations of the condyles and changes in the foramen magnum, jugular foramina, and hypoglossal canal commonly occur together.57 In most cases, these are accompanied by asymmetries in the cranial vault. When cranial scoliosis is visible, parietal scoliosis is also present. How pronounced it is depends on the adaptive capabilities of the organism.
• The research results of I. Korr and M. Patterson strongly suggest that longer-lasting myofascial tensions and imbalances cause structural changes.79,112
• It is also an interesting fact that the clivus and the SBS plane have the same vertical inclination as the longitudinal axis and the promontorium of the sacrum.
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